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  • 1
    Electronic Resource
    Electronic Resource
    BEM/FVM conjugate heat transfer analysis of a three-dimensional film cooled turbine blade (2003)
    Bradford : Emerald
    International journal of numerical methods for heat & fluid flow 13 (2003), S. 581-610 
    Details
    ISSN: 0961-5539
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We report on the progress in the development and application of a coupled boundary element/finite volume method temperature-forward/flux-back algorithm developed to solve conjugate heat transfer arising in 3D film-cooled turbine blades. We adopt a loosely coupled strategy where each set of field equations is solved to provide boundary conditions for the other. Iteration is carried out until interfacial continuity of temperature and heat flux is enforced. The NASA-Glenn explicit finite volume Navier-Stokes code Glenn-HT is coupled to a 3D BEM steady-state heat conduction solver. Results from a CHT simulation of a 3D film-cooled blade section are compared with those obtained from the standard two temperature model, revealing that a significant difference in the level and distribution of metal temperatures is found between the two. Finally, current developments of an iterative strategy accommodating large numbers of unknowns by a domain decomposition approach is presented. An iterative scheme is developed along with a physically-based initial guess and a coarse grid solution to provide a good starting point for the iteration. Results from a 3D simulation show the process that converges efficiently and offers substantial computational and storage savings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/09615530310482463
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Enhancing control of grid distribution in algebraic grid generation (1992)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 15 (1992), S. 297-311 
    Details
    ISSN: 0271-2091
    Keywords: Grid generation ; Transfinite interpolation ; Stretching functions ; Blending functions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Three techniques are presented to enhance the control of grid-point distribution for a class of algebraic grid generation methods known as the two-, four- and six-boundary methods. First, multidimensional stretching functions are presented, and a technique is devised to construct them based on the desired distribution of grid points along certain boundaries. Second, a normalization procedure is proposed which allows more effective control over orthogonality of grid lines at boundaries and curvature of grid lines near boundaries. And third, interpolating functions based on tension splines are introduced to control curvature of grid lines in the interior of the spatial domain. In addition to these three techniques, consistency conditions are derived which must be satisfied by all user-specified data employed in the grid generation process to control grid-point distribution. The usefulness of the techniques developed in this study was demonstrated by using them in conjunction with the two- and four-boundary methods to generate several grid systems, including a three-dimensional grid system in the coolant passage of a radial turbine blade with serpentine channels and pin fins.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650150304
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    Paper (German National Licenses)
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  • 3
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    An autopsy study of latent prostatic cancer (1953)
    Wiley
    Details
    Publication Date: 1953-05-01
    Print ISSN: 0008-543X
    Electronic ISSN: 1097-0142
    Topics: Biology , Medicine
    Published by Wiley on behalf of American Cancer Society.
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    PAPER CURRENT
  • 4
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    Implicit treatment of diffusion terms in lower-upper algorithms (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A method is presented which allows diffusion terms to be treated implicitly in the lower-upper (LU) algorithm (which is a commonly used method for solving 'compressible' Euler and Navier-Stokes equations) so that the algorithm's good stability properties will not be impaired. The new method generalizes the concept of LU factorization from that associated with the sign of eigenvalues to that associated with backward- and forward-difference operators without regard to eigenvalues. The method is verified in a turbulent boundary layer study.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 31; 4; p. 788-791.
    Format: text
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  • 5
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    Algebraic grid generation for coolant passages of turbine blades with serpentine channels and pin fins (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: In order to study numerically details of the flow and heat transfer within coolant passages of turbine blades, a method must first be developed to generate grid systems within the very complicated geometries involved. In this study, a grid generation package was developed that is capable of generating the required grid systems. The package developed is based on an algebraic grid generation technique that permits the user considerable control over how grid points are to be distributed in a very explicit way. These controls include orthogonality of grid lines next to boundary surfaces and ability to cluster about arbitrary points, lines, and surfaces. This paper describes that grid generation package and shows how it can be used to generate grid systems within complicated-shaped coolant passages via an example.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 91-2366
    Format: text
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  • 6
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    GRID3D-v2: An updated version of the GRID2D/3D computer program for generating grid systems in complex-shaped three-dimensional spatial domains (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In order to generate good quality systems for complicated three-dimensional spatial domains, the grid-generation method used must be able to exert rather precise controls over grid-point distributions. Several techniques are presented that enhance control of grid-point distribution for a class of algebraic grid-generation methods known as the two-, four-, and six-boundary methods. These techniques include variable stretching functions from bilinear interpolation, interpolating functions based on tension splines, and normalized K-factors. The techniques developed in this study were incorporated into a new version of GRID3D called GRID3D-v2. The usefulness of GRID3D-v2 was demonstrated by using it to generate a three-dimensional grid system in the coolent passage of a radial turbine blade with serpentine channels and pin fins.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TM-103766 , E-6028 , NAS 1.15:103766
    Format: application/pdf
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  • 7
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    Computations of the three-dimensional flow and heat transfer within a coolant passage of a radial turbine blade (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A numerical code is developed for computing three-dimensional, turbulent, compressible flow within coolant passages of turbine blades. The code is based on a formulation of the compressible Navier-Stokes equations in a rotating frame of reference in which the velocity dependent variable is specified with respect to the rotating frame instead of the inertial frame. The algorithm employed to obtain solutions to the governing equation is a finite-volume LU algorithm that allows convection, source, as well as diffusion terms to be treated implicitly. In this study, all convection terms are upwind differenced by using flux-vector splitting, and all diffusion terms are centrally differenced. This paper describes the formulation and algorithm employed in the code. Some computed solutions for the flow within a coolant passage of a radial turbine are also presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 91-2238
    Format: text
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  • 8
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    Development of an explicit multiblock/multigrid flow solver for viscous flows in complex geometries (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A new computer program is being developed for doing accurate simulations of compressible viscous flows in complex geometries. The code employs the full compressible Navier-Stokes equations. The eddy viscosity model of Baldwin and Lomax is used to model the effects of turbulence on the flow. A cell centered finite volume discretization is used for all terms in the governing equations. The Advection Upwind Splitting Method (AUSM) is used to compute the inviscid fluxes, while central differencing is used for the diffusive fluxes. A four-stage Runge-Kutta time integration scheme is used to march solutions to steady state, while convergence is enhanced by a multigrid scheme, local time-stepping, and implicit residual smoothing. To enable simulations of flows in complex geometries, the code uses composite structured grid systems where all grid lines are continuous at block boundaries (multiblock grids). Example results shown are a flow in a linear cascade, a flow around a circular pin extending between the main walls in a high aspect-ratio channel, and a flow of air in a radial turbine coolant passage.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-106356 , E-8140 , ICOMP-93-34 , NAS 1.15:106356 , AIAA PAPER 93-2380 , Joint Propulsion Conference and Exhibit; Jun 28, 1993 - Jun 30, 1993; Monterey, CA; United States
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  • 9
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    Computation of Turbulent Heat Transfer on the Walls of a 180 Degree Turn Channel With a Low Reynolds Number Reynolds Stress Model (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Low Reynolds number version of the Stress-omega model and the two equation k-omega model of Wilcox were used for the calculation of turbulent heat transfer in a 180 degree turn simulating an internal coolant passage. The Stress-omega model was chosen for its robustness. The turbulent thermal fluxes were calculated by modifying and using the Generalized Gradient Diffusion Hypothesis. The results showed that using this Reynolds Stress model allowed better prediction of heat transfer compared to the k-omega two equation model. This improvement however required a finer grid and commensurately more CPU time.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/CR-2002-211515 , E-13308 , NAS 1.26:211515 , GT-2002-30211 , Turbo Expo 2002; Jun 03, 2002 - Jun 06, 2002; Amsterdam; Netherlands
    Format: application/pdf
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  • 10
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    Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in Axial Turbines (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Calculations were performed to assess the effect of the tip leakage flow on the rate of heat transfer to blade, blade tip and casing. The effect on exit angle and efficiency was also examined. Passage geometries with and without casing recess were considered. The geometry and the flow conditions of the GE-E 3 first stage turbine, which represents a modem gas turbine blade were used for the analysis. Clearance heights of 0%, 1%, 1.5% and 3% of the passage height were considered. For the two largest clearance heights considered, different recess depths were studied. There was an increase in the thermal load on all the heat transfer surfaces considered due to enlargement of the clearance gap. Introduction of recessed casing resulted in a drop in the rate of heat transfer on the pressure side but the picture on the suction side was found to be more complex for the smaller tip clearance height considered. For the larger tip clearance height the effect of casing recess was an orderly reduction in the suction side heat transfer as the casing recess height was increased. There was a marked reduction of heat load and peak values on the blade tip upon introduction of casing recess, however only a small reduction was observed on the casing itself. It was reconfirmed that there is a linear relationship between the efficiency and the tip gap height. It was also observed that the recess casing has a small effect on the efficiency but can have a moderating effect on the flow underturning at smaller tip clearances.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-1998-208514 , E-11287 , NAS 1.26:208514 , ICOMP-98-04 , Turbo; Jun 02, 1998 - Jun 05, 1998; Stockholm; Sweden
    Format: application/pdf
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