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  • 1
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    Prediction of incidence and surface roughness effects on turbine performance (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The results of a Navier-Stokes analysis for predicting the change in turbine efficiency due to a change in either incidence or surface roughness is discussed. It was experimentally determined by Boynton, Tabibzadeh, and Hudson that polishing the SSME high pressure fuel turbine blades improved turbine efficiency by about 2 points over a wide range of operating conditions. These conditions encompassed the range of incidence seen by the turbine blading during flight. It is also necessary to be able to predict turbine performance at various operating points for future rocket turbopump applications. The code RVCQ3D, developed by Rod Chima, was used to determine the effects of changes in incidence angle on turbine blade row efficiency. The midspan Navier-Stokes results were used in conjunction with an inviscid flow analysis code to predict the efficiency of the two stage SSME over a wide range of operating conditions for smooth and rough turbine blades. The use of the Navier-Stokes analysis to predict changes in turbine efficiency due to variation in incidence angles was found to be superior to other incidence loss correlations available in the literature. The sensitivity of the Navier-Stokes results to grid parameters is discussed. The effects of the surface roughness were accounted for using the Cebeci-Chang rough wall turbulence model. This model was implemented in the code RVCQ3D. The implementation of this model for predicting the change in efficiency is also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center, Eleventh Workshop for Computational Fluid Dynamic Applications in Rocket Propulsion; p 1259-1285
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  • 2
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    Two-dimensional Navier-Stokes heat transfer analysis for rough turbine blades (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A quasi-three-dimensional thin-layer Navier-Stokes analysis was used to predict heat transfer to rough surfaces. Comparisons are made between predicted and experimental heat transfer for turbine blades and flat plates of known roughness. The effect of surface roughness on heat transfer was modeled using a mixing length approach. The effect of near-wall grid spacing and convergence criteria on the accuracy of the heat transfer predictions are examined. An eddy viscosity mixing length model having an inner and outer layer was used. A discussion of the appropriate model for the crossover between the inner and outer layers is included. The analytic results are compared with experimental data for both flat plates and turbine blade geometries. Comparisons between predicted and experimental heat transfer showed that a modeling roughness effects using a modified mixing length approach results in good predictions of the trends in heat transfer due to roughness.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 91-2129
    Format: text
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  • 3
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    Navier-Stokes analysis of turbine blade heat transfer (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Comparisons with experimental heat transfer and surface pressures were made for seven turbine vane and blade geometries using a quasi-three-dimensional thin-layer Navier-Stokes analysis. Comparisons are made for cases with both separated and unseparated flow over a range of Reynolds numbers and freestream turbulence intensities. The analysis used a modified Baldwin-Lomax turbulent eddy viscosity mode. Modifications were made to account for the effects of: (1) freestream turbulence on both transition and leading edge heat transfer; (2) strong favorable pressure gradients on relaminarization; and (3) variable turbulent Prandtl number heat transfer. In addition, the effect of heat transfer on the near wall model of Deissler is compared with the Van Driest model.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 90-GT-42
    Format: text
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  • 4
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    Impact of ETO propellants on the aerothermodynamic analyses of propulsion components (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The operating conditions and the propellant transport properties used in Earth-to-Orbit (ETO) applications affect the aerothermodynamic design of ETO turbomachinery in a number of ways. Some aerodynamic and heat transfer implications of the low molecular weight fluids and high Reynolds number operating conditions on future ETO turbomachinery are discussed. Using the current SSME high pressure fuel turbine as a baseline, the aerothermodynamic comparisons are made for two alternate fuel turbine geometries. The first is a revised first stage rotor blade designed to reduce peak heat transfer. This alternate design resulted in a 23 percent reduction in peak heat transfer. The second design concept was a single stage rotor to yield the same power output as the baseline two stage rotor. Since the rotor tip speed was held constant, the turbine work factor doubled. In this alternate design, the peak heat transfer remained the same as the baseline. While the efficiency of the single stage design was 3.1 points less than the baseline two stage turbine, the design was aerothermodynamically feasible, and may be structurally desirable.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-101303 , E-4262 , NAS 1.15:101303 , AVSCOM-TP-88-C-001 , AIAA PAPER 88-3091
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  • 5
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    Grid orthogonality effects on predicted turbine midspan heat transfer and performance (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effect of five different C type grid geometries on the predicted heat transfer and aerodynamic performance of a turbine stator is examined. Predictions were obtained using two flow analysis codes. One was a finite difference analysis, and the other was a finite volume analysis. Differences among the grids in terms of heat transfer and overall performance were small. The most significant difference among the five grids occurred in the prediction of pitchwise variation in total pressure. There was consistency between results obtained with each of the flow analysis codes when the same grid was used. A grid generating procedure in which the viscous grid is embedded within an inviscid type grid resulted in the best overall performance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-106931 , E-9652 , NAS 1.15:106931 , International Gas Turbine and Aeroengine Congress and Exposition; Jun 13, 1994 - Jun 16, 1994; The Hague; Netherlands
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  • 6
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    Two-dimensional Navier-Stokes heat transfer analysis for rough turbine blades (1991)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A quasi-three-dimensional thin-layer Navier-Stokes analysis was used to predict heat transfer to rough surfaces. Comparisons are made between predicted and experimental heat transfer for turbine blades and flat plates of known roughness. The effect of surface roughness on heat transfer was modeled using a mixing length approach. The effect of near-wall grid spacing and convergence criteria on the accuracy of the heat transfer predictions are examined. An eddy viscosity mixing length model having an inner and outer layer was used. A discussion of the appropriate model for the crossover between the inner and outer layers is included. The analytic results are compared with experimental data for both flat plates and turbine blade geometries. Comparisons between predicted and experimental heat transfer showed that a modeling roughness effects using a modified mixing length approach results in good predictions of the trends in heat transfer due to roughness.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-106008 , E-7755 , NAS 1.15:106008 , ARL-MR-14 , AIAA PAPER 91-2129 , AD-A269299 , Joint Propulsion Conference and Exhibit; Jun 24, 1991 - Jun 27, 1991; Sacramento, CA; United States
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  • 7
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    Heat transfer predictions for two turbine nozzle geometries at high Reynolds and Mach numbers (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Predictions of turbine vane and endwall heat transfer and pressure distributions are compared with experimental measurements for two vane geometries. The differences in geometries were due to differences in the hub profile, and both geometries were derived from the design of a high rim speed turbine (HRST). The experiments were conducted in the Isentropic Light Piston Facility (ILPF) at Pyestock at a Reynolds number of 5.3 x 10(exp 6), a Mach number of 1.2, and a wall-to-gas temperature ratio of 0.66. Predictions are given for two different steady-state three-dimensional Navier-Stokes computational analyses. C-type meshes were used, and algebraic models were employed to calculate the turbulent eddy viscosity. The effects of different turbulence modeling assumptions on the predicted results are examined. Comparisons are also given between predicted and measured total pressure distributions behind the vane. The combination of realistic engine geometries and flow conditions proved to be quite demanding in terms of the convergence of the CFD solutions. An appropriate method of grid generation, which resulted in consistently converged CFD solutions, was identified.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: E-9706 , Gas Turbine and Aeroengine Congress and Exposition; Jun 05, 1995 - Jun 08, 1995; Houston, TX; United States
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  • 8
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    Elusive Ethylene Detected in Saturns Northern Storm Region (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The massive eruption at 40 deg. N (planetographic latitude) on Saturn in 2010 December has produced significant and lasting effects in the northern hemisphere on temperature and species abundances. The northern storm region was observed on many occasions in 2011 by Cassini's Composite Infrared Spectrometer (CIRS). In 2011 May, temperatures in the stratosphere greater than 200 K were derived from CIRS spectra in the regions referred to as "beacons" (warm regions in the stratosphere). Ethylene has been detected in the beacon region in Saturn's northern storm region using CIRS. Ground-based observations using the high-resolution spectrometer Celeste on the McMath-Pierce Telescope on 2011 May 15 were used to confirm the detection and improve the altitude resolution in the retrieved profile. The derived ethylene profile from the CIRS data gives a C2H4 mole fraction of 5.9 +/- 4.5 x 10(exp -7) at 0.5 mbar, and from Celeste data it gives 2.7 +/- 0.45 x 10(exp -6) at 0.1 mbar. This is two orders of magnitude higher than the amount measured in the ultraviolet at other latitudes prior to the storm. It is also much higher than predicted by photochemical models, indicating that perhaps another production mechanism is required or a loss mechanism is being inhibited.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN6335
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  • 9
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    Navier-Stokes analysis of turbine blade heat transfer (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Comparisons with experimental heat transfer and surface pressures were made for seven turbine vane and blade geometries using a quasi-three-dimensional thin-layer Navier-Stokes analysis. Comparisons are made for cases with both separated and unseparated flow over a range of Reynolds numbers and freestream turbulence intensities. The analysis used a modified Baldwin-Lomax turbulent eddy viscosity mode. Modifications were made to account for the effects of: (1) freestream turbulence on both transition and leading edge heat transfer; (2) strong favorable pressure gradients on relaminarization; and (3) variable turbulent Prandtl number heat transfer. In addition, the effect of heat transfer on the near wall model of Deissler is compared with the Van Driest model.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-102496 , E-5219 , NAS 1.15:102496 , International Gas Turbine and Aeroengine Congress and Exposition; Jun 11, 1990 - Jun 14, 1990; Brussels; Belgium
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  • 10
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    Time-averaged heat transfer and pressure measurements and comparison with prediction for a two-stage turbine (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Time-averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row and the first-stage blade row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. These measurements were made at 10 percent, 50 percent, and 90 percent span on both the pressure and suction surfaces of the component. Stanton-number distributions are also reported for the second-stage vane at 50 percent span. A shock tube is used as a short-duration source of heated and pressurized air to which the turbine is subjected. Platinum thin-film gages are used to obtain the heat-flux measurements and miniature silicone-diaphragm pressure transducers are used to obtain the surface pressure measurements. The first-stage vane Stanton number distributions are compared with predictions obtained using a quasi-3D Navier-Stokes solution and a version of STAN5. This same N-S technique was also used to obtain predictions for the first blade and the second vane.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 92-GT-194 , ASME, International Gas Turbine and Aeroengine Congress and Exposition; Jun 01, 1992 - Jun 04, 1992; Cologne; Germany|; 13 p.
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