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  • 1
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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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  • 2
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    Comparison of Predicted and Measured Turbine Vane Rough Surface Heat Transfer (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The proposed paper compares predicted turbine vane heat transfer for a rough surface over a wide range of test conditions with experimental data. Predictions were made for the entire vane surface. However, measurements were made only over the suction surface of the vane, and the leading edge region of the pressure surface. Comparisons are shown for a wide range of test conditions. Inlet pressures varied between 3 and 15 psia, and exit Mach numbers ranged between 0.3 and 0.9. Thus, while a single roughened vane was used for the tests, the effective rougness,(k(sup +)), varied by more than a factor of ten. Results were obtained for freestream turbulence levels of 1 and 10%. Heat transfer predictions were obtained using the Navier-Stokes computer code RVCQ3D. Two turbulence models, suitable for rough surface analysis, are incorporated in this code. The Cebeci-Chang roughness model is part of the algebraic turbulence model. The k-omega turbulence model accounts for the effect of roughness in the application of the boundary condition. Roughness causes turbulent flow over the vane surface. Even after accounting for transition, surface roughness significantly increased heat transfer compared to a smooth surface. The k-omega results agreed better with the data than the Cebeci-Chang model. However, the low Reynolds number k-omega model did not accurately account for roughness when the freestream turbulence level was low. The high Reynolds number version of this model was more suitable when the freestream turbulence was low.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2000-210219 , E-12338 , NAS 1.15:210219 , ASME-2000-GT-0217 , International Gas and Turbine and Aeroengine Technical Congress; May 05, 2000 - May 08, 2000; Munich; Germany
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  • 3
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    Infrared Low Temperature Turbine Vane Rough Surface Heat Transfer Measurements (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Turbine vane heat transfer distributions obtained using an infrared camera technique are described. Infrared thermography was used because noncontact surface temperature measurements were desired. Surface temperatures were 80 C or less. Tests were conducted in a three vane linear cascade, with inlet pressures between 0.14 and 1.02 atm., and exit Mach numbers of 0.3, 0.7, and 0.9, for turbulence intensities of approximately 1 and 10%. Measurements were taken on the vane suction side, and on the pressure side leading edge region. The designs for both the vane and test facility are discussed. The approach used to account for conduction within the vane is described. Midspan heat transfer distributions are given for the range of test conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2000-210220 , NAS 1.15:210220 , E-12339 , ASME-2000-GT-0216 , 45th International Gas Turbine and Aeroengine Technical Congress; May 08, 2000 - May 11, 2000; Munich; Germany
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  • 4
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    Prediction of Relaminarization Effects on Turbine Blade Heat Transfer (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An approach to predicting turbine blade heat transfer when turbulent flow relaminarizes due to strong favorable pressure gradients is described. Relaminarization is more likely to occur on the pressure side of a rotor blade. While stators also have strong favorable pressure gradients, the pressure surface is less likely to become turbulent at low to moderate Reynolds numbers. Accounting for the effects of relaminarization for blade heat transfer can substantially reduce the predicted rotor surface heat transfer. This in turn can lead to reduced rotor cooling requirements. Two-dimensional midspan Navier-Stokes analyses were done for each of eighteen test cases using eleven different turbulence models. Results showed that including relaminarization effects generally improved the agreement with experimental data. The results of this work indicate that relatively small changes in rotor shape can be utilized to extend the likelihood of relaminarization to high Reynolds numbers. Predictions showing how rotor blade heat transfer at a high Reynolds number can be reduced through relaminarization are given.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2001-210978 , NAS 1.15:210978 , E-12832 , Rept-2001-GT-0162 , 2001 Turbo Expo; Jun 04, 2001 - Jun 07, 2001; New Orleans, LA; United States
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  • 5
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    Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment (2009)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.
    Keywords: Lunar and Planetary Science and Exploration
    Type: 09-RC-219-AAS-DPS , 41st Annual Meeting of the AAS Division for Planetary Sciences; Oct 04, 2009 - Oct 09, 2009; Fajardo; Puerto Rico
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