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  • FLUID MECHANICS AND HEAT TRANSFER  (583)
  • 1985-1989  (580)
  • 1975-1979
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  • 1965-1969
  • 1950-1954  (3)
  • 1987  (580)
  • 1951  (3)
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  • 1985-1989  (580)
  • 1975-1979
  • 1970-1974
  • 1965-1969
  • 1950-1954  (3)
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  • 101
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    Shear-layer structures in near-wall turbulence (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The structure of internal shear layer observed in the near-wall region of turbulent flows is investigated by analyzing flow fields obtained from numerical simulations of channel and boundary-layer flows. It is found that the shear layer is an important contributor to the turbulence production. The conditionally averaged production at the center of the structure was almost twice as large as the long-time mean value. The shear-layer structure is also found to retain its coherence over streamwise distances on the order of a thousand viscous length units, and propagates with a constant velocity of about 10.6 u sub rho throughout the near wall region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 237-251
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  • 102
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    The simulation of coherent structures in a laminar boundary layer (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Coherent structures in turbulent shear flows were studied extensively by several techniques, including the VITA technique which selects rapidly accelerating or decelerating regions in the flow. The evolution of a localized disturbance in a laminar boundary layer shows strong similarity to the evolution of coherent structures in a turbulent-wall bounded flow. Starting from a liftup-sweep motion, a strong shear layer develops which shares many of the features seen in conditionally-sampled turbulent velocity fields. The structure of the shear layer, Reynolds stress distribution, and wall pressure footprint are qualitatively the same, indicating that the dynamics responsible for the structure's evolution are simple mechanisms dependent only on the presence of a high mean shear and a wall and independent of the effects of local random fluctuations and outer flow effects. As the disturbance progressed, the development of streak-like-high- and low-speed regions associated with the three-dimensionality.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 253-261
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  • 103
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    Relations between two-point correlations and pressure strain terms (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The structure of the two-point spatial correlations (velocity-velocity, velocity-scalar, and scalar-scalar) were studied with a view to improve turbulence closure models. The linear model for the two-point correlations proposed by Naot provides a method of including the information about the turbulence structure in the turbulence models. The assumptions and adequacy of this model were tested against the homogeneous shear flow simulation data base. The model performs poorly in some details and it is suggested how it may be improved. The models were also tested for rapid pressure-strain terms in a variety of flows including axisymmetric expansion and contraction flows, homogeneous shear flow, channel flow, and boundary layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 221-230
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  • 104
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    Evaluation of a theory for pressure-strain rate (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A theoretical expression for the slow part (the nonlinear fluctuation part) of the pressure-strain rate is compared with simulations of anisotropic homogeneous flows. The objective is to determine the quantitative accuracy of the theory and to test its prediction that the generalized Rotta coefficient, a non-dimensionalized ratio of slow term to the Reynolds stress anisotropy, varies with direction and can be negative. Comparisons are made between theoretical and simulation values of the slow term itself and of the generalized Rotta coefficients. The implications of the comparison for two-point closure theories and for Reynolds stress modeling are pointed out.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 213-220
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  • 105
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    Reynolds stress models of homogeneous turbulence (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Existing and new models for the rapid and the return terms in the Reynolds stress equations were tested in two ways. One, by direct comparison of the model with simulation data. The other, by simulating the flows using the models and comparing the predicted Reynolds stresses with the data. It was found that existing linear models can be improved and that nonlinear models are in better agreement with the simulation data for a wide variety of flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 191-204
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  • 106
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    The decay of isotropic turbulence in a rapidly rotating frame (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A direct numerical simulation of the decay of initially isotropic turbulence in a rapidly rotating frame was conducted. This 128 x 128 x 128 simulation was completed for a Reynolds number Re sub lambda = 15.3 and a Rossby number Ro sub lambda = 0.07 based on the initial turbulent kinetic energy and Taylor microscale. The numerical results indicate that the turbulence remains essentially isotropic during the major part of the decay (i.e., beyond the point where the turbulent kinetic energy has decayed to less than 10 percent of its initial value). The rapid rotation has the primary effect of shutting off the energy transfer so that the turbulence dissipation (and hence the rate of decay of the turbulent kinetic energy) is substantially reduced. Consequently, the anisotropy tensor remains essentially unchanged while the energy spectrum undergoes a nearly linear viscous decay (the same results that are predicted by Rapid Distortion Theory which is only formally valid for much shorter elapsed times. Surprisingly, no Taylor-Proudman reorganization of the flow to a two-dimensional state is observed. The implications that these results have on turbulence modeling are discussed briefly along with prospective future research.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 205-211
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  • 107
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    Test code for the assessment and improvement of Reynolds stress models (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An existing two-dimensional, compressible flow, Navier-Stokes computer code, containing a full Reynolds stress turbulence model, was adapted for use as a test bed for assessing and improving turbulence models based on turbulence simulation experiments. To date, the results of using the code in comparison with simulated channel flow and over an oscillating flat plate have shown that the turbulence model used in the code needs improvement for these flows. It is also shown that direct simulation of turbulent flows over a range of Reynolds numbers are needed to guide subsequent improvement of turbulence models.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 185-190
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  • 108
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    A general form for the dissipation length scale in turbulent shear flows (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: It has been found that, for a wide range of turbulent wall-bounded shear flows with mean velocity profile U(y), the scale length L-epsilon determining the dissipation is approximately described in terms of distance from the wall (y), the mean shear (dU/dy), and the variance of the normal component of turbulence (bar u-squared), by the formula: L-epsilon to the -1 power is approximately equal to (A sub B / y) + A sub S (dU/dy / square root of bar u-squared) where L-epsilon = epsilon/(bar u-squared) to the 3/2 power. To match with shear-free boundary layers, A sub B is approximately 0.27, and to match with the log layer, A sub S is approximately 0.46. The shear flows tested here were: boundary layers over a flat plate, sink flow, oscillatory flow, and channel flow. The use of the square root of bar u-squared as a velocity scale minimizes the effects of Reynolds number. However, the formula fails within a distance of order L-epsilon for the regions where dU/dy = 0.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 179-184
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  • 109
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    Local structure of intercomponent energy transfer in homogeneous turbulent shear flow (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Intercomponent energy transfer by pressure-strain-rate was investigated for homogeneous turbulent shear flow. The rapid and slow parts of turbulent pressure (decomposed according to the influence of the mean deformation rate) are found to be uncorrelated; this finding provides strong justification for current modeling procedure in which the pressure-strain-rate term is split into the corresponding parts. Issues pertinent to scales involved in the intercomponent energy transfer are addressed in comparison with those for the Reynolds-stress and vorticity fields. A physical picture of the energy transfer process is described from a detailed study of instantaneous events of high transfer regions. It was found that the most significant intercomponent energy transfer events are highly localized in space and are imbedded within a region of concentrated vorticity.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 165-178
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  • 110
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    On local approximations of the pressure-strain term in turbulence models (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The results of numerical simulations of turbulent channel flows were used to examine the validity of the local approximation of the pressure-strain term in the Reynolds stress transport equation. Outside of the viscous sublayer the local approximation compares very well with the exact pressure strain. This agreement is due, at least in part, to the high correlation between the rapid pressure and its Laplacian, which suggests that only the near parts of the flow contribute to the rapid pressure at a point. In the viscous sublayer the distance over which the mean shear can be considered constant is comparable to the length scale in the normal direction of the correlations of velocity gradients, leading to failure of the local approximation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 159-164
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  • 111
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    A statistical investigation of the single-point pdf of velocity and vorticity based on direct numerical simulations (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Vorticity plays a fundamental role in turbulent flows. The dynamics of vorticity in turbulent flows and the effect on single-point closure models were investigated. The approach was to use direct numerical simulations of turbulent flows to investigate the pdf of velocity and vorticity. The preliminary study of homogeneous shear flow has shown that the expectation of the fluctuating pressure gradient, conditioned with a velocity component, is linear in the velocity component, and that the coefficient is independent of velocity and vorticity. In addition, the work shows that the expectation of the pressure gradient, conditioned with a vorticity component, is essentially zero.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 147-154
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  • 112
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    Analysis of non-premixed turbulent reacting flows (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Studies of chemical reactions occurring in turbulent flows are important in the understanding of combustion and other applications. Current numerical methods are limited in their applications due to the numerical resolution required to completely capture all length scales, but, despite the fact that realistic combustion cannot be solved completely, numerical simulations can be used to give insight into the interaction between the processes of turbulence and chemical reaction. The objective was to investigate the effects of turbulent motion on the effects of chemical reaction to gain some insight on the interaction of turbulence, molecular diffusion, and chemical reaction to support modeling efforts. A direct turbulence simulation spectral code was modified to include the effects of chemical reaction and applied to an initial value problem of chemical reaction between non-premixed species. The influence of hydrodynamics on the instantaneous structure of the reaction was investigated. The local scalar dissipation rates and the local reaction rates were examined to determine the influence of vorticity or rate of strain on the reaction and the structure of the scalar field.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 141-146
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  • 113
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    Modeling of turbulent transport as a volume process (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An alternative type of modeling was proposed for the turbulent transport terms in Reynolds-averaged equations. One particular implementation of the model was considered, based on the two-point velocity correlations. The model was found to reproduce the trends but not the magnitude of the nonisotropic behavior of the turbulent transport. Some interesting insights were developed concerning the shape of the contracted two-point correlation volume. This volume is strongly deformed by mean shear from the spherical shape found in unstrained flows. Of particular interest is the finding that the shape is sharply waisted, indicating preferential lines of communication, which should have a direct effect on turbulent transfer and on other processes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 133-140
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  • 114
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    Direct numerical simulation of buoyantly driven turbulence (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Numerical simulations of homogeneous turbulence subject to buoyant forcing were performed. The presence of a mean temperature gradient combined with a gravitational field results in a forcing term in the momentum equations. The development of the turbulence was studied and compared to the decay of similar fields in the absence of gravity. In the buoyantly driven field, the vorticity is preferentially aligned with the intermediate eigenvector of the strain-rate tensor and the local temperature gradient is more likely to be aligned with the most compressive eigenvector. These relationships are qualitatively similar to those observed in previous shear flow results studied by Ashurst (1987). A tensor diffusivity model for passive scalar transport developed from shear flow results in Rogers, Moin, and Reynolds (1986) also predicts this buoyant scalar transport, indicating that the relationship between the scalar flux and the Reynolds stress is similar in both flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 117-120
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  • 115
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    Modeling scalar flux and the energy and dissipation equations (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Closure models derived from the Two-Scale Direct-Interaction Approximation were compared with data from direct simulations of turbulence. Attention was restricted to anisotropic scalar diffusion models, models for the energy dissipation equation, and models for energy diffusion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 109-112
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  • 116
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    Big whorls carry little whorls (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The aim of the research was to explore the space-time structure of homogeneous turbulence by computing and then interpreting the two-point spectra and correlations of the velocity and pressure fields. Many of these statistics are of considerable practical importance. In particular, it is of interest to compare the different time and length integral scales and microscales for Eulerian and Lagrangian qualities, and to compare the space and time spectra.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 77-94
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  • 117
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    Study of one-dimensional spectral dynamic equations of the Reynolds stresses in homogeneous anisotropic turbulence: Application to split-spectrum modeling (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The CTR numerical data base generated by direct simulation of homogeneous anisotropic turbulence was used to calculate all of the terms in the spectral balance equations for the turbulent Reynolds stresses. The aim in not only to test the main closure assumptions used in the split-spectrum models, but also to try to devise improved hypotheses deduced from the statistical information. Numerical simulations of turbulent flows provide a large amount of data, a thought provoking wealth of information. The main advantage of this type of comparison is that a great variety of flows can be considered, and this is necessary to test closure hypotheses. Moreover various initial conditions can be introduced in the calculation, even if they are not experimentally feasible. All the terms in the spectral equations can be calculated. The limited Reynolds numbers of the simulations and the statistical noise caused by a small sample, particularly at the large scales, causes some difficulty in the interpretation of the results, but the method of approach proved to be a powerful tool for testing and improving spectral closures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 95-108
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  • 118
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    Angular distribution of turbulence in wave space (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An alternative to the one-point closure model for turbulence, the large eddy simulation (LES), together with its more exact relative, direct numerical simulation (DNS) are discussed. These methods are beginning to serve as partial substitutes for turbulence experiments. The eddy damped quasi-normal Markovian (EDQNM) theory is reviewed. Angular distribution of the converted data was examined in relationship to EDQNM.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 71-75
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  • 119
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    Validation of EDQNM for subgrid and supergrid models (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: From preliminary calculations it was concluded that the two-point Eddy Damping Quasi-Normal Markovian (EDQNM) closure accurately describes the behavior of second order moments. This closure can be applied as subgrid and supergrid models for Large Eddy Simulations at higher Reynolds numbers. In the case of homogeneous anisotropic turbulence, when the nonlinear terms are introduced the calculation becomes quite onerous but is still considerably less expensive than the calculation of a DS. The major merit of two-point closure models is that they can be easily applied to flows at Reynolds numbers that are unreachable by a DS. Work is in progress to derive expressions for the nonlinear terms that give good global conservation properties.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 63-69
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  • 120
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    EDQNM closure: A homogeneous simulation to support it. A quasi-homogeneous simulation to disprove it (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: It is known that two-point closures are useful tools for understanding and predicting turbulence. Among the various closures, the Eddy Damped Quasi-Normal Markovian (EDQNM) approach is one of the simplest and, at the same time, most useful. Direct numerical simulations (DNS) can provide information that can be used to test the validity of two-point theories. It is the purpose of the present work to use DNS to validate, or improve upon, EDQNM. A case was selected for which EDQNM is known to give satisfactory results: homogeneous isotropic turbulence. Quantities were then evaluated which may be used to test the assumptions of two-point closure approximations: spectral Lagrangian time scales. The goal was to make a careful and refined study to validate the EDQNM theory. A reference case was built for which EDQNM is likely to give poor results. An attempt to generate a quasi-homogeneous turbulent field containing organized structures, was built by artifically injecting them in the initial conditions. The results of direct simulations using such initial conditions are expected to provide a challenge for EDQNM since this kind of field is simple enough to allow comparisons with two-point theories, but at the same time contains coherent structures which cannot be expected to be accurately accounted for by closures based on expansions about Gaussianity.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 53-62
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  • 121
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    Ejection mechanisms in the sublayer of a turbulent channel (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A possible model for the inception of vorticity ejections in the viscous sublayer of a turbulent rectangular channel is presented. It was shown that this part of the flow is dominated by protruding strong shear layers of z-vorticity, and it was proposed as a mechanism for their maintenance and reproduction which is essentially equivalent to that responsible for the instability of 2-D Tollmien-Schlichting waves. The efforts to isolate computationally a single structure for its study have failed up to now, since it appears that single structures decay in the absence of external forcing, but a convenient computation model was identified in the form of a long and narrow periodic computational box containing at each moment only a few structures. Further work in the identification of better reduced systems is in progress.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 37-47
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  • 122
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    Self similarity of two point correlations in wall bounded turbulent flows (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The structure of turbulence at a height y from a wall is affected by the local mean shear at y, by the direct effect of the wall on the eddies, and by the action of other eddies close to or far from the wall. Some researchers believe that a single one of these mechanisms is dominant, while others believe that these effects have to be considered together. It is important to understand the relative importance of these effects in order to develop closure models, for example for the dissipation or for the Reynolds stress equation, and to understand the eddy structure of cross correlation functions and other measures. The specific objective was to examine the two point correlation, R sub vv, of the normal velocity component v near the wall in a turbulent channel flow and in a turbulent boundary layer. The preliminary results show that even in the inhomogeneous turbulent boundary layer, the two-point correlation function may have self similar forms. The results also show that the effects of shear and of blocking are equally important in the form of correlation functions for spacing normal to the wall. But for spanwise spacing, it was found that the eddy structure is quire different in these near flows. So any theory for turbulent structure must take both these effects into account.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 25-36
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  • 123
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    A low dimensional dynamical system for the wall layer (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Low dimensional dynamical systems which model a fully developed turbulent wall layer were derived.The model is based on the optimally fast convergent proper orthogonal decomposition, or Karhunen-Loeve expansion. This decomposition provides a set of eigenfunctions which are derived from the autocorrelation tensor at zero time lag. Via Galerkin projection, low dimensional sets of ordinary differential equations in time, for the coefficients of the expansion, were derived from the Navier-Stokes equations. The energy loss to the unresolved modes was modeled by an eddy viscosity representation, analogous to Heisenberg's spectral model. A set of eigenfunctions and eigenvalues were obtained from direct numerical simulation of a plane channel at a Reynolds number of 6600, based on the mean centerline velocity and the channel width flow and compared with previous work done by Herzog. Using the new eigenvalues and eigenfunctions, a new ten dimensional set of ordinary differential equations were derived using five non-zero cross-stream Fourier modes with a periodic length of 377 wall units. The dynamical system was integrated for a range of the eddy viscosity prameter alpha. This work is encouraging.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Stanford Univ., Studying Turbulence Using Numerical Simulation Databases. Proceedings of the 1987 Summer Program; p 21-23
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  • 124
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    Image processing system to analyze droplet distributions in sprays (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An image processing system was developed which automatically analyzes the size distributions in fuel spray video images. Images are generated by using pulsed laser light to freeze droplet motion in the spray sample volume under study. This coherent illumination source produces images which contain droplet diffraction patterns representing the droplets degree of focus. The analysis is performed by extracting feature data describing droplet diffraction patterns in the images. This allows the system to select droplets from image anomalies and measure only those droplets considered in focus. Unique features of the system are the totally automated analysis and droplet feature measurement from the grayscale image. The feature extraction and image restoration algorithms used in the system are described. Preliminary performance data is also given for two experiments. One experiment gives a comparison between a synthesized distribution measured manually and automatically. The second experiment compares a real spray distribution measured using current methods against the automatic system.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Automated Reduction of Data from Images and Holograms; p 607-640
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  • 125
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    Image analysis of particle field by means of computed tomography (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In order to visualize and investigate spray structures, computed tomography technique is applied to analyze droplet information. From the transmitted light intensity through the spray and/or the data of particle size distribution obtained from a Fraunhofer diffraction principle, the quantitative volume of spray droplet or local particle size was calculated and the reconstruction of spray structures was made. The background of computed tomography is described along with some experimental results of the structure of intermittent spray such as diesel spray.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Automated Reduction of Data from Images and Holograms; p 525-539
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  • 126
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    KC-135 aero-optical turbulent boundary layer/shear layer experiment revisited (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The aero-optical effects associated with propagating a laser beam through both an aircraft turbulent boundary layer and artificially generated shear layers are examined. The data present comparisons from observed optical performance with those inferred from aerodynamic measurements of unsteady density and correlation lengths within the same random flow fields. Using optical instrumentation with tens of microsecond temporal resolution through a finite aperture, optical performance degradation was determined and contrasted with the infinite aperture time averaged aerodynamic measurement. In addition, the optical data were artificially clipped to compare to theoretical scaling calculations. Optical instrumentation consisted of a custom Q switched Nd:Yag double pulsed laser, and a holographic camera which recorded the random flow field in a double pass, double pulse mode. Aerodynamic parameters were measured using hot film anemometer probes and a five hole pressure probe. Each technique is described with its associated theoretical basis for comparison. The effects of finite aperture and spatial and temporal frequencies of the random flow are considered.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Automated Reduction of Data from Images and Holograms; p 461-503
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    Computational fluid dynamics applications at McDonnel Douglas (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Representative examples are presented of applications and development of advanced Computational Fluid Dynamics (CFD) codes for aerodynamic design at the McDonnell Douglas Corporation (MDC). Transonic potential and Euler codes, interactively coupled with boundary layer computation, and solutions of slender-layer Navier-Stokes approximation are applied to aircraft wing/body calculations. An optimization procedure using evolution theory is described in the context of transonic wing design. Euler methods are presented for analysis of hypersonic configurations, and helicopter rotors in hover and forward flight. Several of these projects were accepted for access to the Numerical Aerodynamic Simulation (NAS) facility at the NASA-Ames Research Center.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Supercomputing in Aerospace; p 109-121
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    Internal computational fluid mechanics on supercomputers for aerospace propulsion systems (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The accurate calculation of three-dimensional internal flowfields for application towards aerospace propulsion systems requires computational resources available only on supercomputers. A survey is presented of three-dimensional calculations of hypersonic, transonic, and subsonic internal flowfields conducted at the Lewis Research Center. A steady state Parabolized Navier-Stokes (PNS) solution of flow in a Mach 5.0, mixed compression inlet, a Navier-Stokes solution of flow in the vicinity of a terminal shock, and a PNS solution of flow in a diffusing S-bend with vortex generators are presented and discussed. All of these calculations were performed on either the NAS Cray-2 or the Lewis Research Center Cray XMP.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Supercomputing in Aerospace; p 35-48
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    Geometric description and grid generation for space vehicles (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The understanding and analysis of three dimensional fluid behavior around reentry vehicles, like the Space Shuttle Orbiter, is of considerable importance for flight applications. Vehicle designers need pressure, heat transfer, and shear distributions to support design activities. Traditionally these have been obtained by experimental data. Significant reduction in design costs can be obtained if the calculated results based on finite difference procedures are used to verify and supplement experimental results. Computing the flow field over Space Shuttle Orbiter, which has complex cross sectional geometries is a major problem. A first step in this direction is development of body definition and grid generation procedure. In this project a digitized body definition and grid generation procedure, developed earlier at JSC, is modified and applied to the Shuttle Orbiter X24C-10D. Two dimensional grid and body definition for various sections of the space vehicle is obtained using the differential equation method. This study demonstrates that this geometry and grid generation procedure can be applied to other aerospace vehicles such as aerospaceplanes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lyndon B.; NASA. Lyndon B. John
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  • 130
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    Reynolds number effects on surface shear stress patterns around isolated hemispheres (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Obstacles projecting into the wind stream alter the shear stress on the surface around them, thus altering the erosion, transportation, and deposition of aeolian sediment. The effect of Reynolds number on the pattern of shear stress on the surface around an isolated hemisphere was investigated. An understanding of Reynolds number effects is necessary if wind tunnel results are to be scaled up to natural situations for meaningful applications. The experiment shows that the surface shear stress pattern is strongly affected by Reynolds number, at least within the range of Re used (1360 to 2977). This is presumably due to a decrease in flow around the sides of the hemisphere and an increase in flow over the object as the Reynolds number increases.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 282-284
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  • 131
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    Determination of surface shear stress with the naphthalene sublimation technique (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Aeolian entrainment and transport are functions of surface shear stress and particle characteristics. Measuring surface shear stress is difficult, however, where logarithmic wind profiles are not found, such as regions around large roughness elements. An outline of a method whereby shear stress can be mapped on the surface around an object is presented. The technique involves the sublimation of naphthalene (C10H8) which is a function of surface shear stress and surface temperature. This technique is based on the assumption that the transfer of momentum, heat and mass are analogous (Reynolds analogy). If the Reynolds analogy can be shown to be correct for a given situation, then knowledge of the diffusion of one property allows the determination of the others. The analytical framework and data acquisition for the method are described. The technique was tested in the Planetary Geology Wind Tunnel. Results show that the naphthalene sublimation technique is a reasonably accurate method for determining shear stress, particularly around objects where numerous point values are needed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 285-287
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  • 132
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    Development of wind tunnel techniques for the solution of problems in planetary Aeolian processes (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Kutzbach reports wind profiles over a series of roughness elements on a frozen lake and how the wind profile changed as the surface roughness was varied. The approach of the current study was to duplicate Kutzbach's roughness arrays in the wind tunnel at 1/20 and 1/40 scales, and to compare the wind profiles over these scale models to those derived by Kutzbach at full scale in the field. The effects of scale differences and data reduction techniques are discussed. Although the study suggests that wind tunnel scale models can predict parameters measured in the field, the development of more definitive guidelines requires a field experiment designed specifically for comparison with wind tunnel results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 276-278
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  • 133
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    Wind ripples in low density atmospheres (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The effect of varying fluid density (rho) on particle transport was examined by conducting tests at atmospheric pressures between 1 and 0.004 bar in the Martian Surface Wind Tunnel (MARSWIT). This study specifically concerns the effect of varying rho on the character of wind ripples, and elicits information concerning generalized ripple models as well as specific geological circumstances for ripple formation such as those prevailing on Mars. Tests were conducted primarily with 95 micron quartz sand, and for each atmospheric pressure chosen, tests were conducted at two freestream wind speeds: 1.1 U*(t) and 1.5 U*(t), where U*(t) is saltation threshold. Preliminary analysis of the data suggests: (1) ballistic ripple wavelength is not at variance with model predictions; (2) an atmospheric pressure of approximately 0.2 bar could represent a discontinuity in ripple behavior; and (4) ripple formation on Mars may not be readily predicted by extrapolation of terrestrial observations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 268-270
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  • 134
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    Peacekeeper tank slosh model (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Information on a tank slosh model for Peacekeeper missiles is given in viewgraph form. Allowable vehicle errors for nose cone ejection clearance, vehicle maneuver sloshing problems, slosh/moment prediction, slosh surface specification, code validation, experimental model-computational model comparison and the propellant storage assembly are covered.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 355-368
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  • 135
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    Low gravity liquid motions in spacecraft (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Low gravity liquid motions in a spacecraft are discussed in outline form and on viewgraphs. Free-surface sloshing, liquid draining, liquid reorientation, and sloshing in a bladdered tank are covered. Conclusions and recommendations are given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 345-354
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  • 136
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    Review of nucleation and incipient boiling under pool and forced convection conditions (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: An overview of liquid-vapor nucleation is given. The result of thermodynamic equilibrium across curved liquid-vapor interfaces is presented. The extension of this to include the interaction with idealizations of surface cavities is made to demonstrate how superheat requirements for nucleation will be affected by surface roughness, flow velocity and buoyancy. Experimental measurements of high liquid superheats and nucleation delay times are presented as examples of homogeneous nucleation. Examples of nucleation and boiling on smooth glass substrates and on metal surfaces with various surface roughnesses are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 269-299
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  • 137
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    Development of on-orbit fluid gaging techniques (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The objective was to measure liquid mass to plus or minus 1 percent in two-phase tanks in orbit. Viewgraphs present information on concept selection, program status and anticipated results. The program aims at test results showing 1 percent accuracy, the development of a breadboard test article usable in the lab or aboard a KC-135, and a concept that will permit flight article design to proceed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 241-251
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  • 138
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    Space environmental considerations for a long-term cryogenic storage vessel (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Information is given on the kind of protection that is needed against impact and perforation of a long-term cryogenic storage vessel in space by meteoroids and space debris. The long-term effects of the space environment on thermal control surfaces and coatings, and the question of whether the insulation and thermal control surfaces should be encased in a vacuum jacket shell are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 175-191
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  • 139
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    Cryogenic fluid management program flight concept definition (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The Lewis Research Center's cryogenic fluid management program flight concept definition is presented in viewgraph form. Diagrams are given of the cryogenic fluid management subpallet and its configuration with the Delta launch vehicle. Information is given in outline form on feasibility studies, requirements definition, and flight experiments design.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 99-115
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  • 140
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    LeRC cryogenic fluid management program overview (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An overview is given of the Lewis Research Center's cryogenic fluid management program in the form of viewgraphs. Objectives, approach, program elements, cost analysis, modeling, and flight experiment development are outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 83-97
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  • 141
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    Ames Research Center cryogenics program (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Viewgraphs describe the Ames Research Center's cryogenics program. Diagrams are given of a fluid management system, a centrifugal pump, a flow meter, a liquid helium test facility, an extra-vehicular activity coupler concept, a dewar support with passive orbital disconnect, a pulse tube refrigerator, a dilution refrigerator, and an adiabatic demagnetization cooler.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 59-82
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  • 142
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    Cryogenics program overview (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: An overview of the cryogenics program of the Goddard Space Flight Center is given in viewgraph form. Goddard's role and the flight programs requiring cryogenics are outlined. Diagrams are given of the Cosmic Background Explorer, the Broad Band X-Ray Telescope, the Hubble Space Telescope, an adiabatic demagnetization refrigerator, a liquid cryogenic cooler for the Shuttle Glow Experiment, a liquid helium dewar, and the X-ray spectrometer on the Advanced X-Ray Astrophysics Facility.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 21-58
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  • 143
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    AF cryogenic and fluid management spacecraft technology program (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Viewgraphs are given that outline the program objectives of long term cryogenic storage programs. Diagrams of the orbit transfer vehicle, thermal insulation blankets, cryogenic storage tanks, the advanced liquid feed experiment, and the acoustic measurement on satellite experiment are presented. The objectives, goals, and payoffs of the fluid management space experiment and the liquid droplet radiator are outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Cleveland, Ohio. Cryogenic Fluid Management Technology Workshop. Volume 1: Presentation Material and Discussion; p 7-20
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  • 144
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    Inlets, ducts and nozzles (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The internal fluid mechanics research program in inlets, ducts, and nozzles is described. The program consists of a balanced effort between the development of computational tools and the conduct of experimental research. The experiments are designed to better understand the fluid flow physics, to develop new or improved flow models, and to provide benchmark quality data sets for validation of the computational methods. The inlet, duct, and nozzle research program is described according to three major classifications of flow phenomena: highly three-dimensional flow fields; shock-boundary layer interactions; and shear layer control. Specific examples of current and future elements of the research program are described for each of these phenomena. In particular, the highly three-dimensional flow field phenomena is highlighted by describing the computational and experiemental research program in transition ducts having a round-to-rectangular area variation. In the case of shock-boundary layer interactions, the specific details of research for normal shock-boundary layer interactions are described. For shear layer control research in vortex generators and the use of aerodynamic excitation for enhancement of the jet mixing process are described. Future research in inlets, ducts, and nozzles will include more emphasis on three-dimensional full Navier-Stokes methods and corresponding experiments designed to concentrate on the appropriate three-dimensional fluid flow physics.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Aeropropulsion '87. Session 3: Internal Fluid Mechanics Research; 24 p
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  • 145
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    Automated reduction of instantaneous flow field images (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An automated data reduction system for the analysis of interference fringe patterns obtained using the particle image velocimetry technique is described. This system is based on digital image processing techniques that have provided the flexibility and speed needed to obtain more complete automation of the data reduction process. As approached here, this process includes scanning/searching for data on the photographic record, recognition of fringe patterns of sufficient quality, and, finally, analysis of these fringes to determine a local measure of the velocity magnitude and direction. The fringe analysis as well as the fringe image recognition are based on full frame autocorrelation techniques using parallel processing capabilities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Automated Reduction of Data from Images and Holograms; p 505-524
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  • 146
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    Numerical solution of the Navier-Stokes equations about three-dimensional configurations: A survey (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The numerical solution of the Navier-Stokes equations about three-dimensional configurations is reviewed. Formulational and computational requirements for the various Navier-Stokes approaches are examined for typical problems including the viscous flow field solution about a complete aerospace vehicle. Recent computed results, with experimental comparisons when available, are presented to highlight the presentation. The future of Navier-Stokes applications in three-dimensions is seen to be rapidly expanding across a broad front including internal and external flows, and flows across the entire speed regime from incompressible to hypersonic applications. Prospects for the future are described and recommendations for areas of concentrated research are indicated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Supercomputing in Aerospace; p 281-298
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  • 147
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    Computational fluid dynamics in a marine environment (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The introduction of the supercomputer and recent advances in both Reynolds averaged, and large eddy simulation fluid flow approximation techniques to the Navier-Stokes equations, have created a robust environment for the exploration of problems of interest to the Navy in general, and the Naval Underwater Systems Center in particular. The nature of problems that are of interest, and the type of resources needed for their solution are addressed. The goal is to achieve a good engineering solution to the fluid-structure interaction problem. It is appropriate to indicate that a paper by D. Champman played a major role in developing the interest in the approach discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Supercomputing in Aerospace; p 183-185
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  • 148
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    Computational fluid dynamics research at the United Technologies Research Center requiring supercomputers (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An overview of research activities at the United Technologies Research Center (UTRC) in the area of Computational Fluid Dynamics (CFD) is presented. The requirement and use of various levels of computers, including supercomputers, for the CFD activities is described. Examples of CFD directed toward applications to helicopters, turbomachinery, heat exchangers, and the National Aerospace Plane are included. Helicopter rotor codes for the prediction of rotor and fuselage flow fields and airloads were developed with emphasis on rotor wake modeling. Airflow and airload predictions and comparisons with experimental data are presented. Examples are presented of recent parabolized Navier-Stokes and full Navier-Stokes solutions for hypersonic shock-wave/boundary layer interaction, and hydrogen/air supersonic combustion. In addition, other examples of CFD efforts in turbomachinery Navier-Stokes methodology and separated flow modeling are presented. A brief discussion of the 3-tier scientific computing environment is also presented, in which the researcher has access to workstations, mid-size computers, and supercomputers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Research Center, Supercomputing in Aerospace; p 159-174
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  • 149
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    Simulation of multistage turbine flows (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A flow model has been developed for analyzing multistage turbomachinery flows. This model, referred to as the average passage flow model, describes the time-averaged flow field with a typical passage of a blade row embedded within a multistage configuration. Computer resource requirements, supporting empirical modeling, formulation code development, and multitasking and storage are discussed. Illustrations from simulations of the space shuttle main engine (SSME) fuel turbine performed to date are given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Structural Integrity and Durability of Reusable Space Propulsion Systems; p 13-20
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  • 150
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    Unsteady stator/rotor interaction (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The major thrust of the computational analysis of turbomachinery to date has been the steady-state solution of isolated blades using mass-averaged inlet and exit conditions. Unsteady flows differ from the steady solution due to interaction of pressure waves and wakes between blade rows. To predict the actual complex flow conditions one must look at the time accurate solution of the entire turbomachine. Three quasi-three-dimensional Euler and thin layer Navier-Stokes equations are solved for unsteady turbomachinery flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Structural Integrity and Durability of Reusable Space Propulsion Systems; p 5-11
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  • 151
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    Progress in the prediction of unsteady heat transfer on turbines blades (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Progress toward developing a general method for predicting unsteady heat transfer on turbine blades subject to blade-passing frequencies and Reynolds numbers relevant to the Space Shuttle Main Engine (SSME) is discussed. The method employs an invisid/viscous interactive procedure which has been tested extensively for steady subsonic and transonic external airfoil problems. One such example is shown. The agreement with experimental data and with Navier-Stokes calculations yields confidence in the method. The technique is extended to account for wake generated unsteadiness. The flow reversals around the stagnation point caused by the nonuniform onset velocity are accounted for by using the Characteristic Box scheme developed by Cebeci and Stewartson. The coupling between the inviscid and viscous methods is achieved by using a special procedure, which, with a novel inverse finite-difference boundary-layer method, allows the calculations to be performed for a wide range of flow conditions, including separation. Preliminary results are presented for the stagnation region of turbine blades for both laminar and turbulent flows. A laminar model problem corresponding to a flow on a circular cylinder which experiences the periodic passing of wakes from turbine blades is presented to demonstrate the ability of the method to calculate flow reversals around the stagnation region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Structural Integrity and Durability of Reusable Space Propulsion Systems; p 21-27
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  • 152
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    Dynamics of rotating and oscillating drops (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The dynamics of rotation and oscillation is investigated of a freely suspended liquid drop under the influence of surface tension and positioned inside an experimental apparatus by acoustic forces in the low acceleration environment of Spacelab 3. After a drop was observed to be spherical and stably located at the center of the chamber, it was set into rotation or oscillation by acoustic torque or modulated radiation pressure force.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacelab 3 Mission Science Review; p 27-30
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  • 153
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    G-300: The first French Getaway Special microgravity measurements of fluid thermal conductivity (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Thermal conductivity measurements on liquids are difficult to perform on Earth because of thermal motions due to convection. In microgravity, the convection due to buoyancy is evanescent, and a strong reduction of Rayleigh and Nusselt numbers can be expected. Three low viscosity liquids are selected to carry out the measurements; distilled water (standard) and two silicone oils. A modified hot plate method with a simplified guard ring is used; the reduction of convective motions permitted the use in the experimental cells of larger interplate distances and/or temperature differences than in Earth measurements, improving the accuracy. Comparisons between Earth and orbit results may help to understand the convection occurrence in the cells. Thermal, vibrational, and EMI tests have proved that the design satisfies the NASA requirements.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Goddard Space Flight Center The 1986 Get Away Special Experimenter's Symposium; p 199-206
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  • 154
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    USC/AIAA student get away special project liquid droplet collector experiment (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: This experimental payload was developed in order to observe, in a micro-gravity vacuum environment, the characteristics and stability of a thin fluid film flowing across a slightly curved surface. The test apparatus was designed based upon various ground-based thin film investigations, combined with the constraints imposed by the rigors of launch and the space environment. Testing of the fluid test article at atmospheric pressure and in vacuum verified the design provisions employed concerning ultra-low inlet pressure pump construction, as well as confirming expected pressure losses in the system. During the course of hardware development and construction modifications were required; however, the overall payload configuration remained largely unchanged. This will allow for modification and reflight of the apparatus based upon the findings of the initial flight. The specific applications of this experiment include Liquid Droplet Radiator development and various forms of material transport in vacuum.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: The 1986 Get Away Special Experimenter's Symposium; p 95-102
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    Experimental investigation of unsteady fan flow interaction with downstream struts (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 3; 157-163
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  • 156
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    Experimental investigation of a swirling, axisymmetric, turbulent boundary layer with pressure gradient (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 25; 521
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  • 157
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    Skin friction measurements following manipulation of a turbulent boundary layer (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results are presented from three experiments in which direct, local measurements of the skin friction reduction due to flat-plate turbulence manipulators for overall viscous drag reduction were obtained. The results suggest that only a very small overall net drag reduction will be possible for such devices at moderate momentum thickness-derived Reynolds number values, since maximum skin friction drag is neither large nor sustained.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 25; 498-500
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  • 158
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    Upwind relaxation algorithms for the Navier-Stokes equations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 25; 527-534
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  • 159
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    An implicit flux-split algorithm for the compressible Navier-Stokes equations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An implicit upwind scheme for the compressible Navier-Stokes equations is described and applied to the internal flow in a dual-throat nozzle. The method is second-order accurate spatially and naturally dissipative. A spatially-split approximate factorization method is used to obtain efficient steady-state solutions on the NASA Langley VPS-32 (CYBER 205) supercomputer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 160
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    Absolute instability of the Gaussian wake profile (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 30; 3383-338
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  • 161
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    Fuel thermal stability effects on spray characteristics (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The propensity of a heated hydrocarbon fuel toward solids deposition within a fuel injector is investigated experimentally. Fuel is arranged to flow through the injector at constant temperature, pressure, and flow rate and the pressure drop across the nozzle is monitored to provide an indication of the amount of deposition. After deposits have formed, the nozzle is removed from the test rig and its spray performance is compared with its performance before deposition. The spray characteristics measured include mean drop size, drop-size distribution, and radial and circumferential fuel distribution. It is found that small amounts of deposition can produce severe distortion of the fuel spray pattern. More extensive deposition restores spray uniformity, but the nozzle flow rate is seriously curtailed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 3; 502-507
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  • 162
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    Transient radiative cooling of a layer filled with solidifying drops (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An analysis is carried out for radiative cooling of a plane layer initially filled with liquid drops that solidify and then continue to cool by loss of sensible heat. This is in connection with a proposed lightweight radiator system for heat dissipation in space. Hot liquid drops would be ejected and then cooled by direct exposure in space; they would then pass into a collector for reuse. The cooling analysis contains three transient zones. In the first, the drops cool by losing latent heat until the outermost drops become solid. Then the cooling continues by loss of both latent and sensible heat. A similarity behavior is eventually achieved in which the transient emittance of the layer depends only on the optical thickness.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 109; 977-982
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  • 163
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    Thermal response of integral multicomponent composites to a high-energy aerothermodynamic heating environment with surface temperature to 1800 K (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Laminated composite insulations developed for potential use on advanced spacecraft operating between GEO and LEO were tested in an aerothermodynamic environment simulating an AOTV aerobraking maneuver (altitude 82.3 km and velocity = 9.0 km/s). Comparisons are discussed between these data and predictions of in-depth temperature response using dynamical thermal conductivity values to 2000 K.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 8; 613-625
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  • 164
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    Helicity fluctuations in incompressible turbulent flows (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results from direct numerical simulations of several homogeneous flows and fully developed turbulent channel flow indicate that the probability distribution function (pdf) of relative helicity density exhibits at most a 20 percent deviation from a flat distribution. Isotropic flows exhibit a slight helical nature but the presence of mean strain in homogeneous turbulence suppresses helical behavior. All the homogeneous turbulent flows studied show no correlation between relative helicity density and the dissipation of turbulent kinetic energy. The channel flow simulations indicate that, except for low-dissipation regions near the outer edge of the buffer layer, there is no tendency for the flow to be helical. The strong peaks in the relative helicity density pdf and the association of these peaks with regions of low dissipation found in previous simulations by Pelz et al.(1985) are not observed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 30; 2662-267
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  • 165
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    Dual Stokes cars measurements in supersonic combusting flow (1987)
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    Publication Date: 2011-08-19
    Description: Coherent antiStokes Raman spectroscopy (CARS) was used to make simultaneous measurements of temperature, nitrogen and oxygen density in a reacting supersonic flow. A supersonic burner (SSB) was designed to provide supersonic flow in which combustion can be studied in the laboratory. Measurements made with the CARS system will be used for validation of computational fluid dynamic (CFD) codes. Preliminary results of the CFD calculations are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Johns Hopkins Univ., The 24th JANNAF Combustion Meeting, Volume 2; p 171-178
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  • 166
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    Generation of Tollmien-Schlichting waves on interactive marginally separated flows (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper is concerned with the interaction of very-long-wavelength free-stream disturbances with the small but abrupt changes in the mean flow that occur near the minimum-skin-friction point in an interactive marginally separated boundary layer. The source frequency is chosen so that the eigensolutions with that frequency have an 'interactive' structure in the region of marginal separation. The eigensolution wavelength scale must then differ from the lengthscale of the marginal separation, and a composite expansion technique has to be used to obtain the solution. The initial instability wave amplitude turns out to be exponentially small, but eventually dominates the original disturbance owing to its exponential growth. It then begins to decay but ultimately turns into a standard spatially growing Tollmien-Schlichting wave much further downstream.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 181; 485-517
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  • 167
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    Numerical experiments on boundary-layer receptivity (1987)
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    Publication Date: 2011-08-19
    Description: The incompressible laminar flow over an infinitely thin flat plate is obtained using a Navier-Stokes code in vorticity-velocity variables. The flow at and near the leading edge of the plate is an integral part of the solution algorithm which requires no special treatment; thus allowing for the flow field in this region to be studied in detail. An incident plane sound wave is imposed in the free-stream flow and the receptivity of the boundary layer is studied with particular emphasis to the flow near and at the leading edge.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 168
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    Application of stability theory to laminar flow control - Progress and requirements (1987)
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    Publication Date: 2011-08-19
    Description: Paper briefly summarizes the current status of linear stability theory as applied to laminar flow control for aerodynamics. Results indicate that the conventional 'N factor' method of correlating stability theory and transition has a broad application range, including low- and high-speeds, two- and three-dimensional mean flow and TS, Gortler and crossflow disturbance modes. Linear theory is particularly applicable to the laminar flow control problem as, for system efficiency, control must be exercised and disturbances maintained in the linear regime. Current areas of concern for LFC, which require further stability theory research, include TS-crossflow interaction, combined disturbance fields (roughness, waviness, noise) and suction-induced disturbances. Some results on wave-interactions are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 169
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    Review of linear compressible stability theory (1987)
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    Publication Date: 2011-08-19
    Description: Aspects of the linear compressible stability theory are considered, with special attention given to the inviscid theory and the additional solutions that arise when there is a region of supersonic flow relative to the phase velocity. For the case of highly cooled flat-plate boundary layers at Mach number 5.8, the unstable region is found to include supersonic outgoing waves. A previously unknown neutral incoming wave has also been identified. An example of viscous multiple solutions is provided, and calculations of higher viscous discrete modes and the compressible counterpart of the Squire mode are presented. It is noted that compressible stability theory is missing a firm connection with boundary-layer transition.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 170
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    Interface stability in a slowly rotating low-gravity tank (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 24; 232-235
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  • 171
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    Numerical simulation of transient inviscid shock tube flows (1987)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 25; 245-251
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  • 172
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    Characteristics of a trailing flap flow with small separation (1987)
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    Publication Date: 2011-08-19
    Description: Detailed measurements of pressure and velocity characteristics are reported for the flow on and downstream of a trailing flap, whose 16 degree angle of incidence resulted in boundary layer separation, a small region of recirculating flow, and a curved downstream wake. Emphasis is placed on the region of recirculating flow and on the downstream wake. The characteristics were quantified by the use of pressure, hot-wire, and flying hot-wire probes. The flow characteristics are compared to those of a similar flow but with a larger region of recirculation reported by Thompson and Whitelaw (1985). The relative importance of the terms in the transport equations for mean momentum and turbulence energy are quantified and the implications of the results for viscous-inviscid interaction methods and turbulence modeling are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Experiments in Fluids (ISSN 0723-4864); 5; 2, 19; 114-128
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  • 173
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    Starvation effects on the hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion (1987)
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    Publication Date: 2011-08-19
    Description: The effect of inlet starvation on the hydrodynamic lubrication of lightly loaded rigid nonconformal contacts in combined rolling and normal motion is determined through a numerical solution of the Reynolds' equation for an isoviscous, incompressible lubricant. Starvation is effected by systematically reducing the fluid inlet level. The pressures are taken to be ambient at the inlet meniscus boundary and Reynolds' boundary condition is applied for film rupture in the exit region. Results are presented for the dynamic performance of the starved contacts in combined rolling and normal motion for both normal approach and separation. During normal approach the dynamic load ratio (i.e. ratio of dynamic to steady state load capacity) increases considerably with increase in the inlet starvation. The effect of starvation on the dynamic peak pressure ratio is relatively small. Further, it has been observed that with increasing starvation, film thickness effects become significant in the dynamic behavior of the nonconformal contacts. For significantly starved contacts the dynamic load ratio increases with increase in film thickness during normal approach and a similar reduction is observed during separation. A similar effect is noted for the dynamic peak pressure ratio.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASLE Transactions (ISSN 0569-8197); 30; 91-99
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  • 174
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    Vibrational and rotational analysis of the emission spectra of the arc jet flow (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Applying atomic and molecular physics to the analysis of the radiation emitted from the arc jet flow provides a means for determining the species and excitation temperature of the constituents of the flow. A rotational and vibrational analysis of the spectra obtained from the radiation emitted in the shock layer and in the free stream of the jet flow was performed, specifically, in the shock layer bands of the First Negative Group of ionized molecular nitrogen and in the free stream of the gamma-system of nitric oxide.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lyndon B.; NASA. Lyndon B. John
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  • 175
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    Implementation of the barotropic vorticity equation on the MPP (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: A finite difference version of the equations governing two-dimensional, non-divergent flow on a sphere is implemented and integrated on the Massively Parallel Processor (MPP). The MPP's performance is then compared with the Cyber's. The feasibility of using a massively parallel architecture to solve the hydrodynamic equations as they are used in numerical weather prediction (NWP) are described.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Frontiers of Massively Parallel Scientific Computation; p 161-164
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  • 176
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    Experimental and theoretical studies of time-averaged and time resolved rotor heat transfer (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Efforts in support of the Space Shuttle Main Engine (SSME) structural durability program have concentrated on obtaining detailed time-averaged and time-resolved (or phase-locked) measurements on a full-scale rotating turbine both with and without cold gas injection and on theoretical studies designed to improve the prediction capability for these turbine flows. The experimental efforts have concentrated on use of the Garrett TFE 731-2 hp turbine. However, it has been possible to apply the theoretical efforts to predicting heat-flux distributions obtained for two additional turbines - i.e., (1) the Garrett low aspect ratio turbine (LART) and (2) the Teledyne 702 turbine. The experimental technique is the short duration, shock-tunnel approach, in which fast-response, thin-film resistance thermometers are used to measure surface temperature histories at prescribed locations on the turbine component parts. Heat-flux values are then inferred from the temperature histories by using standard data reduction procedures. The turbine being used is the Garrett TFE 731-2 hp stage, and both the nozzle guide vanes and the rotor blades are heavily instrumented with thin-film heat-flux gauges. Depending on how the data from a particular heat-flux gauge are recorded, one can get either time-resolved (or phase-locked) or time-averaged results. Both types of data are illustrated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Structural Integrity and Durability of Reusable Space Propulsion Systems; p 29-32
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  • 177
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    Stability of time dependent and spatially varying flows; Proceedings of the Symposium, Hampton, VA, Aug. 19-23, 1985 (1987)
    In:  Other Sources
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    Publication Date: 2016-03-09
    Description: Papers are presented on the application of stability theory to laminar flow control, secondary instabilities in boundary layers, a Floquet analysis of secondary instability in shear flows, and the generation of Tollmien-Schlichting waves by long wavelength free stream disturbances. Also considered are numerical experiments on boundary-layer receptivity, short-scale inviscid instabilities in the flow past surface-mounted obstacles, wave phenomena in a high Reynolds number compressible boundary layer, and instability of time-periodic flows. Other topics include high frequency Rayleigh instability of Stokes layers, stability and resonance in grooved-channel flows, finite length Taylor Couette flow, and vortical structures in the breakdown stage of transition.
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  • 178
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    Studies of vortex dominated flows; Proceedings of the Symposium, Hampton, VA, July 9-11, 1985 (1987)
    In:  Other Sources
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    Publication Date: 2016-03-09
    Description: Papers are presented on waves and bifurcations in vortex filaments, a ring-vortex representation of an axisymmetric vortex sheet, and comparison of experiment with the dynamics of the von Karman vortex trail. Also considered are force-free and loss-free transitions between vortex flow states, a vortex breakdown simulation based on a nonlinear inviscid method, and the prediction of highly vortical flows using an Euler equation model. Other topics include the theory of high-Reynolds-number flow past a blunt body, progress on the calculation of large-scale separation at high Reynolds numbers, and viscous-inviscid interaction solvers and computation of highly separated flows. Papers are also presented on simulation studies of vortex dynamics of a leading edge vortex flap, methods for numerical simulation of leading edge vortex flow, and comparison of measured and computed pitot pressures in a leading edge vortex from a delta wing.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 179
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    An analysis of artificial viscosity effects on reacting flows using a spectral multi-domain technique (1987)
    In:  Other Sources
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    Publication Date: 2018-12-01
    Description: Analytical and experimental techniques for modeling the aerothermodynamics of hypersonic flight are assessed, together with the problems which will be encountered in developing reusable hypersonic vehicles. Emphasis is placed on a numerical coupling between a nonequilibrium chemistry model and hypersonic flow kinematics. Finite difference and finite element descriptions of flow fields in which molecules encounter a shock wave and undergo various motion (and thereby energy) transformations are discussed. The effects of artificial smearing of the shock wave are considered in terms of the resulting effects on the distribution of the energies and chemical composition of the transition region. Results are provided from schlieren photographs of shock-tube experiments, Navier-Stokes calculations of axisymmetric flow over a conical body, and calculations using a spectral multidomain approach for chemically reacting flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 180
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    Near-wall turbulence alteration through thin streamwise riblets (1987)
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    Publication Date: 2018-12-01
    Description: The possibility of improving the level of drag reduction associated with near-wall riblets is considered. The methodology involves the use of a hot-wire anemometer to study various surface geometries on small, easily constructed models. These models consist of small, adjacent rectangular channels on the wall aligned in the streamwise direction. The VITA technique is modified and applied to thin-element-array and smooth flat-plate data and the results are indicated schematically.
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  • 181
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    Direct drag and hot-wire measurements on thin-element riblet arrays (1987)
    In:  Other Sources
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    Publication Date: 2018-12-01
    Description: An experimental study of stream wise, near-wall, thin-element riblet arrays under a turbulent boundary layer has been conducted in low-speed air. Hot-wire data show that a single, isolated thin-element riblet causes formation of counter-rotating vortex-pairs with a spanwise wavelength of 130 viscous lengths. Abrupt shifts in turbulence intensity magnitude and peak location are observed for streamwise riblet arrays as spanwise riblet spacing is varied. Direct drag measurements show net drag reduction (up to 8.5 percent) over a wide range of riblet spacings along with behavior at discrete non-dimensional spacings indicative of vortex activity. Overall, the data suggest that more than one drag reduction mechanism may be involved.
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  • 182
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    CFD validation needs for advanced concepts at Northrop Corporation (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Information is given in viewgraph form on the Computational Fluid Dynamics (CFD) Workshop held July 14 - 16, 1987. Topics covered include the philosophy of CFD validation, current validation efforts, the wing-body-tail Euler code, F-20 Euler simulated oil flow, and Euler Navier-Stokes code validation for 2D and 3D nozzle afterbody applications.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NB-87-109 , NASA. Ames Research Center, NASA CFD Validation Workshop; p 578-592
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  • 183
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    Experimental Study of Shock Wave Interference Heating on a Cylindrical Leading Edge (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: An experimental study of shock wave interference heating on a cylindrical leading edge representative of the cowl of a rectangular hypersonic engine inlet at Mach numbers of 6.3, 6.5, and 8.0 is presented. Stream Reynolds numbers ranged from 0.5 x 106 to 4.9 x 106 per ft. and stream total temperature ranged from 2100 to 3400 R. The model consisted of a 3" dia. cylinder and a shock generation wedge articulated to angles of 10, 12.5, and 15 deg. A fundamental understanding was obtained of the fluid mechanics of shock wave interference induced flow impingement on a cylindrical leading edge and the attendant surface pressure and heat flux distributions. The first detailed heat transfer rate and pressure distributions for two dimensional shock wave interference on a cylinder was provided along with insight into the effects of specific heat variation with temperature on the phenomena. Results show that the flow around a body in hypersonic flow is altered significantly by the shock wave interference pattern that is created by an oblique shock wave from an external source intersecting the bow shock wave produced in front of the body.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-100484 , NAS 1.15:100484
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  • 184
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    Application of turbulence modeling to predict surface heat transfer in stagnation flow region of circular cylinder (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A theoretical analysis and numerical calculations for the turbulent flow field and for the effect of free-stream turbulence on the surface heat transfer rate of a stagnation flow are presented. The emphasis is on the modeling of turbulence and its augmentation of surface heat transfer rate. The flow field considered is the region near the forward stagnation point of a circular cylinder in a uniform turbulent mean flow. The free stream is steady and incompressible with a Reynolds number of the order of 10 to the 5th power and turbulence intensity of less than 5 percent. For this analysis, the flow field is divided into three regions: (1) a uniform free-stream region where the turbulence is homogeneous and isotropic; (2) an external viscid flow region where the turbulence is distorted by the variation of the mean flow velocity; and, (3) an anisotropic turbulent boundary layer region over the cylinder surface. The turbulence modeling techniques used are the kappa-epsilon two-equation model in the external flow region and the time-averaged turbulence transport equation in the boundary layer region. The turbulence double correlations, the mean velocity, and the mean temperature within the boundary layer are solved numerically from the transport equations. The surface heat transfer rate is calculated as functions of the free-stream turbulence longitudinal microlength scale, the turbulence intensity, and the Reynolds number.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-2758 , E-3418 , NAS 1.60:2758
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  • 185
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    A finite element computational method for high Reynolds number laminar flows (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A velocity-pressure integrated, mixed interpolation, Galerkin finite element method for the Navier-Stokes equations is presented. In the method, the velocity variables are interpolated using complete quadratic shape functions, and the pressure is interpolated using linear shape functions which are defined on a triangular element for the two-dimensional case and on a tetrahedral element for the three-dimensional case. The triangular element and the tetrahedral element are contained inside the complete bi- and tri-quadratic elements for velocity variables for two and three dimensional cases, respectively, so that the pressure is discontinuous across the element boundaries. Example problems considered include: a cavity flow of Reynolds numbers 400 through 10,000; a laminar backward facing step flow; and a laminar flow in a square duct of strong curvature. The computational results compared favorably with the finite difference computational results and/or experimental data available. It was found that the present method can capture the delicate pressure driven recirculation zones, that the method did not yield any spurious pressure modes, and that the method requires fewer grid points than the finite difference methods to obtain comparable computational results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-179135 , NAS 1.26:179135
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  • 186
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    Velocimetry with refractive index matching for complex flow configurations, phase 1 (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of obtaining detailed velocity field measurements in large Reynolds number flow of the Space Shuttle Main Engine (SSME) main injector bowl was demonstrated using laser velocimetry and the developed refractive-index-matching technique. An experimental system to provide appropriate flow rates and temperature control of refractive-index-matching fluid was designed and tested. Test results are presented to establish the feasibility of obtaining accurate velocity measurements that map the entire field including the flow through the LOX post bundles: sample mean velocity, turbulence intensity, and spectral results are presented. The results indicate that a suitable fluid and control system is feasible for the representation of complex rocket-engine configurations and that measurements of velocity characteristics can be obtained without the optical access restrictions normally associated with laser velocimetry. The refractive-index-matching technique considered needs to be further developed and extended to represent other rocket-engine flows where current methods either cannot measure with adequate accuracy or they fail.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-179160 , NAS 1.26:179160
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  • 187
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    Transport of passive scalars in a turbulent channel flow (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A direct numerical simulation of a turbulent channel flow with three passive scalars at different molecular Prandtl numbers is performed. Computed statistics including the turbulent Prandtl numbers are compared with existing experimental data. The computed fields are also examined to investigate the spatial structure of the scalar fields. The scalar fields are highly correlated with the streamwise velocity; the correlation coefficient between the temperature and the streamwise velocity is as high as 0.95 in the wall region. The joint probability distributions between the temperature and velocity fluctuations are also examined; they suggest that it might be possible to model the scalar fluxes in the wall region in a manner similar to the Reynolds stresses.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-89463 , A-87235 , NAS 1.15:89463
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  • 188
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    Wind tunnel requirements for computational fluid dynamics code verification (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The role of experiment in the development of Computational Fluid Dynamics (CFD) for aerodynamic flow field prediction is discussed. Requirements for code verification from two sources that pace the development of CFD are described for: (1) development of adequate flow modeling, and (2) establishment of confidence in the use of CFD to predict complex flows. The types of data needed and their accuracy differs in detail and scope and leads to definite wind tunnel requirements. Examples of testing to assess and develop turbulence models, and to verify code development, are used to establish future wind tunnel testing requirements. Versatility, appropriate scale and speed range, accessibility for nonintrusive instrumentation, computerized data systems, and dedicated use for verification were among the more important requirements identified.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-100001 , A-87261 , NAS 1.15:100001
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  • 189
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    An investigation of turbulence structure in a low-Reynolds-number incompressible turbulent boundary (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An existing high turbulence intensity level (5%) atmospheric boundary-layer wind tunnel has been successfully converted to a relatively low level turbulence (0.3%) wind tunnel through extensive modification, testing, and calibration. A splitter plate was designed, built, and installed into the wind-tunnel facility to create thick, mature, two-dimensional turbulent boundary layer flow at zero pressure gradient. Single and cross hot-wire measurements show turbulent boundary layer characteristics of good quality with unusually large physical size, i.e., viscous sublayer of the order of 1 mm high. These confirm the potential ability of the tunnel to be utilized for future high-quality near-wall turbulent boundary layer measurements. It compares very favorably with many low turbulence research tunnels.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-180332 , NAS 1.26:180332
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  • 190
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    Compressible Navier-Stokes equations: A study of leading edge effects (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A computational method is developed that allows numerical calculations of the time dependent compressible Navier-Stokes equations.The current results concern a study of flow past a semi-infinite flat plate.Flow develops from given inflow conditions upstream and passes over the flat plate to leave the computational domain without reflecting at the downstream boundary. Leading edge effects are included in this paper. In addition, specification of a heated region which gets convected with the flow is considered. The time history of this convection is obtained, and it exhibits a wave phenomena.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-178333 , ICASE-87-42 , NAS 1.26:178333
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  • 191
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    Spectral multigrid methods for the solution of homogeneous turbulence problems (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: New three-dimensional spectral multigrid algorithms are analyzed and implemented to solve the variable coefficient Helmholtz equation. Periodicity is assumed in all three directions which leads to a Fourier collocation representation. Convergence rates are theoretically predicted and confirmed through numerical tests. Residual averaging results in a spectral radius of 0.2 for the variable coefficient Poisson equation. In general, non-stationary Richardson must be used for the Helmholtz equation. The algorithms developed are applied to the large-eddy simulation of incompressible isotropic turbulence.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-178341 , ICASE-87-45 , NAS 1.26:178341 , AD-A189475
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  • 192
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    Turbulence modeling and surface heat transfer in a stagnation flow region (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Analysis for the turbulent flow field and the effect of freestream turbulence on the surface heat transfer rate of a stagnation flow is presented. The emphasis is on modeling and its augmentation of surface heat transfer rate. The flow field considered is the region near the forward stagnation point of a circular cylinder in a uniform turbulent mean flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-100132 , E-3682 , NAS 1.15:100132
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  • 193
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    Simplified curve fits for the thermodynamic properties of equilibrium air (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: New, improved curve fits for the thermodynamic properties of equilibrium air have been developed. The curve fits are for pressure, speed of sound, temperature, entropy, enthalpy, density, and internal energy. These curve fits can be readily incorporated into new or existing computational fluid dynamics codes if real gas effects are desired. The curve fits are constructed from Grabau-type transition functions to model the thermodynamic surfaces in a piecewise manner. The accuracies and continuity of these curve fits are substantially improved over those of previous curve fits. These improvements are due to the incorporation of a small number of additional terms in the approximating polynomials and careful choices of the transition functions. The ranges of validity of the new curve fits are temperatures up to 25 000 K and densities from 10 to the -7 to 10 to the 3d power amagats.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-RP-1181 , L-16276 , NAS 1.61:1181
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  • 194
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    Experimental study of two separating turbulent boundary layers (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A detailed study of two strong adverse pressure gradient flows, one with a free-stream velocity of 35 m/sec, at throat (producing a Re sub theta of 27000 at detachment) and another with free-stream velocity of 22 m/sec, at throat (producing a Re sub theta of 19000 at detachment) is presented. In these examples flows separate slowly and reattach very rapidly over a very short distance in a streamwise direction. In the backflow region, there appears to be a semi-logarithmically flat region in the streamwise fluctuating velocity component, u', which spreads over a definite range of y/delta. In power spectra, the flow variables phi sub upsilon upsilon (kappa sub 1 delta)/ -uv bar sub max vs. kappa sub 1 delta forms a unique set of scaling parameters for adverse pressure gradient flows. Experimental results show good agreement with previous studies.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-181011 , NAS 1.26:181011
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  • 195
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    Plume dispersion of the exhaust from a cryogenic wind tunnel (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An analytical model was developed to predict the behavior of the plume exhausting from the cryogenic National Transonic Facility. Temperature, visibility, oxygen concentration, and flow characteristics of the plume are calculated for distance downwind of the stack exhaust. Negative buoyancy of the cold plume is included in the analysis. Compared to photographic observations, the model predicts the centerline trajectory of the plume fairly accurately, but underpredicts the extent of fogging. The diffusion coefficient is revised to bring the model into better agreement with observations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-89148 , NAS 1.15:89148
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  • 196
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    Multiscale turbulence effects in supersonic jets exhausting into still air (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A modified version of the multiscale turbulence model of Hanjalic has been applied to the problem of supersonic jets exhausting into still air. In particular, the problem of shock-cell decay through turbulent interaction with the mixing layer has been studied for both mildly interacting and strongly resonant jet conditions. The modified Hanjalic model takes into account the nonequilibrium energy transfer between two different turbulent spectral scales. The turbulence model was incorporated into an existing shock-capturing, parabolized Navier-Stokes computational model in order to perform numerical experiments. The results show that the two-scale turbulence model provides significant improvement over one-scale models in the prediction of plume shock structure for underexpanded supersonic (Mach 2) and sonic (Mach 1) jets. For the supersonic jet, excellent agreement with experiment was obtained for the centerline shock-cell pressure decay up to 40 jet radii. For the sonic jet, the agreement with experiment was not so good, but the two-scale model still showed significant improvement over the one-scale model. It is shown that by relating some of the coefficients in the turbulent-transport equations to the relative time scale for transfer of energy between scales the two-scale model can provide predictions that bound the measured shock-cell decay rate for the sonic jet.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-2707 , L-16258 , NAS 1.60:2707
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  • 197
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    Space station experiment definition: Long-term cryogenic fluid storage (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The conceptual design of a space station Technology Development Mission (TDM) experiment to demonstrate and evaluate cryogenic fluid storage and transfer technologies is presented. The experiment will be deployed on the initial operational capability (IOC) space station for a four-year duration. It is modular in design, consisting of three phases to test the following technologies: passive thermal technologies (phase 1), fluid transfer (phase 2), and active refrigeration (phase 3). Use of existing hardware was a primary consideration throughout the design effort. A conceptual design of the experiment was completed, including configuration sketches, system schematics, equipment specifications, and space station resources and interface requirements. These requirements were entered into the NASA Space Station Mission Data Base. A program plan was developed defining a twelve-year development and flight plan. Program cost estimates are given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-4072 , E-3463 , NAS 1.26:4072 , BAC-ER-18056-8
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  • 198
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    Three-step cylindrical seal for high-performance turbomachines (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A three-step cylindrical seal configuration representing the seal for a high performance turbopump (e.g., the space shuttle main engine fuel pump) was tested under static (nonrotating) conditions. The test data included critical mass flux and pressure profiles over a wide range of inlet temperatures and pressures for fluid nitrogen and fluid hydrogen with the seal in concentric and fully eccentric positions. The critical mass flux (leakage rate) was 70% that of an equivalent straight cylindrical seal with a correspondingly higher pressure drop based on the same flow areas of 0.3569 sq cm but 85% that of the straight seal based on the third-step flow area of 0.3044 sq cm. The mass flow rates for the three step cylindrical seal in the fully eccentric and concentric positions were essentially the same, and the trends in flow coefficient followed those of a simple axisymmetric inlet configuration. However, for inlet stagnation temperatures less than the thermodynamic critical temperature the pressure profiles exhibited a flat region throughout the third step of the seal, with the pressure magnitude dependent on the inlet stagnation temperature. Such profiles represent an extreme positive direct stiffness. These conditions engendered a crossover in the pressure profile upstream of the postulated choke that resulted in a local negative stiffness. Flat and crossover profiles resulting from choking within the seal are practically unknown to the seal designer. However, they are of critical importance to turbomachine stability and must be integrated into any dynamic analysis of a seal of this configuration. In addition, choking is highly dependent on geometry, inlet-to-backpressure ratio, and inlet temperature and can occur within the seal even though the backpressure is above the critical pressure.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1849 , E-3185 , NAS 1.60:1849
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  • 199
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    Computation of full-coverage film-cooled airfoil temperatures by two methods and comparison with high heat flux data (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two methods were used to calculate the heat flux to full-coverage film cooled airfoils and, subsequently, the airfoil wall temperatures. The calculated wall temperatures were compared to measured temperatures obtained in the Hot Section Facility operating at real engine conditions. Gas temperatures and pressures up to 1900 K and 18 atm with a Reynolds number up to 1.9 million were investigated. Heat flux was calculated by the convective heat transfer coefficient adiabatic wall method and by the superposition method which incorporates the film injection effects in the heat transfer coefficient. The results of the comparison indicate the first method can predict the experimental data reasonably well. However, superposition overpredicted the heat flux to the airfoil without a significant modification of the turbulent Prandtl number. The results suggest that additional research is required to model the physics of full-coverage film cooling where there is significant temperature/density differences between the gas and the coolant.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-88931 , E-3372 , NAS 1.15:88931
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  • 200
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    Thermodynamic analysis and subscale modeling of space-based orbit transfer vehicle cryogenic propellant resupply (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The resupply of the cryogenic propellants is an enabling technology for spacebased orbit transfer vehicles. As part of the NASA Lewis ongoing efforts in microgravity fluid management, thermodynamic analysis and subscale modeling techniques were developed to support an on-orbit test bed for cryogenic fluid management technologies. Analytical results have shown that subscale experimental modeling of liquid resupply can be used to validate analytical models when the appropriate target temperature is selected to relate the model to its prototype system. Further analyses were used to develop a thermodynamic model of the tank chilldown process which is required prior to the no-vent fill operation. These efforts were incorporated into two FORTRAN programs which were used to present preliminary analyticl results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-89921 , E-3617 , NAS 1.15:89921 , AIAA PAPER 87-1764
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