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  • 1
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    Simplified Approach to Predicting Rough Surface Transition (2009)
    In:  Other Sources
    Details
    Publication Date: 2018-06-06
    Description: Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consistent with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparisons are presented with published experimental data. Some of the data are for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach taken in this analysis is to treat the roughness in a statistical sense, consistent with what would be obtained from blades measured after exposure to actual engine environments. An approach is given to determine the equivalent sand grain roughness from the statistics of the regular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test conditions. Additional comparisons are made with experimental heat transfer data, where the roughness geometries are both regular and statistical. Using the developed analysis, heat transfer calculations are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.
    Keywords: Aircraft Propulsion and Power
    Type: Journal of Turbomachinery; Volume 131; Issue 4; 041020-1 - 041020-11
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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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
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Infrared Low-Temperature Turbine Vane Rough Surface Heat Transfer Measurements (2001)
    In:  Other Sources
    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 percent. 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: Aircraft Propulsion and Power
    Type: Paper-2000-GT-216 , Journal of Turbomachinery; 123; 168-177|45th International Gas Turbine and Aeroengine Congress and Exhibition; Mar 08, 2000 - Mar 11, 2000; Munich; Germany
    Format: text
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  • 4
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    Three-Dimensional Flow Field Measurements in a Transonic Turbine Cascade (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Three-dimensional flow field measurements are presented for a large scale transonic turbine blade cascade. Flow field total pressures and pitch and yaw flow angles were measured at an inlet Reynolds number of 1.0 x 10(exp 6) and at an isentropic exit Mach number of 1.3 in a low turbulence environment. Flow field data was obtained on five pitchwise/spanwise measurement planes, two upstream and three downstream of the cascade, each covering three blade pitches. Three-hole boundary layer probes and five-hole pitch/yaw probes were used to obtain data at over 1200 locations in each of the measurement planes. Blade and endwall static pressures were also measured at an inlet Reynolds number of 0.5 x 10(exp 6) and at an isentropic exit Mach number of 1.0. Tests were conducted in a linear cascade at the NASA Lewis Transonic Turbine Blade Cascade Facility. The test article was a turbine rotor with 136 deg of turning and an axial chord of 12.7 cm. The flow field in the cascade is highly three-dimensional as a result of thick boundary layers at the test section inlet and because of the high degree of flow turning. The large scale allowed for very detailed measurements of both flow field and surface phenomena. The intent of the work is to provide benchmark quality data for CFD code and model verification.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107388 , NAS 1.15:107388 , ARL-TR-1252 , E-10584 , Gas Turbine and Aeroengine Congress; Jun 10, 1996 - Jun 13, 1996; Birmingham; United Kingdom
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Endwall Heat Transfer Measurements in a Transonic Turbine Cascade (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Turbine blade endwall heat transfer measurements are given for a range of Reynolds and Mach numbers. Data were obtained for Reynolds numbers based on inlet conditions of 0.5 and 1.0 x 106, for isentropic exit Mach numbers of 1.0 and 1.3, and for freestream turbulence intensities of 0.25% and 7.0%. Tests were conducted in a linear cascade at the NASA Lewis Transonic Turbine Blade Cascade Facility. The test article was a turbine rotor with 136' of turning and an axial chord of 12.7 cm. The large scale allowed for very detailed measurements of both flow field and surface phenomena. The intent of the work is to provide benchmark quality data for computational fluid dynamics (CFD) code and model verification. The flow field in the cascade is highly three-dimensional as a result of thick boundary layers at the test section inlet. Endwall heat transfer data were obtained using a steady-state liquid crystal technique.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107387 , E-10583 , NAS 1.15:107387 , ARL-TR-1253 , Gas Turbine and Aeroengine Congress; Jun 10, 1996 - Jun 13, 1996; Birmingham; United Kingdom
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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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
    Format: text
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    NASA TECHNICAL REPORTS
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