NASA Scientific and Technical Aerospace Reports

20040074155 Air Force Inst. of Tech., Wright-Patterson AFB, OH
An Analysis of Coast Guard HH-65 Engine Reliability: A Comparison of Malfunctions to Component Removals
Corttrell, Donna L.; Mar. 2004; 116 pp.; In English; Original contains color illustrations
Report No.(s): AD-A422618; AFIT/GIR/ENC/04-01; No Copyright; Avail: CASI; A06, Hardcopy
The Coast Guard HH-65 helicopter experienced 3 tin- flight loss of power incidents during FY 2003 and 21 during the
first two months of FY 2003, Concurrent with this apparent decrease in reliability, the Coast Guard seeks ways to expand the
HH-65’s Airborne Use of Force capabilities as a result of the September 11th, 2001 tenorists’ attacks,
DTIC
Armed Forces (United States); Helicopters; Malfunctions
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AIRCRAFT PROPULSION AND POWER
Includes primary propulsion systems and related systems and components, e.g., gas turbine engines, compressors, and fuel systems;
and onboard auxiliary power plants for aircraft. For related information see also 20 Spacecraft Propulsion and Power; 28 Propellants
and Fuels; and 44 Energy Production and Conversion.
20040070781 NASA Glenn Research Center, Cleveland, OH, USA
New Reduced Two-Time Step Method for Calculating Combustion and Emission Rates of Jet-A and Methane Fuel
With and Without Water Injection
Molnar, Melissa; Marek, C. John; April 2004; 78 pp.; In English
Contract(s)/Grant(s): WBS 714-20-10
Report No.(s): NASA/TM-2004-213046; E-14483; No Copyright; Avail: CASI; A05, Hardcopy
A simplified kinetic scheme for Jet-A, and methane fuels with water injection was developed to be used in numerical
combustion codes, such as the National Combustor Code (NCC) or even simple FORTRAN codes that are being developed
at Glenn. The two time step method is either an initial time averaged value (step one) or an instantaneous value (step two).
The switch is based on the water concentration in moles/cc of 1x10(exp -20). The results presented here results in a correlation
that gives the chemical kinetic time as two separate functions. This two step method is used as opposed to a one step time
averaged method previously developed to determine the chemical kinetic time with increased accuracy. The first time averaged
step is used at the initial times for smaller water concentrations. This gives the average chemical kinetic time as a function
of initial overall fuel air ratio, initial water to fuel mass ratio, temperature, and pressure. The second instantaneous step, to be
used with higher water concentrations, gives the chemical kinetic time as a function of instantaneous fuel and water mole
concentration, pressure and temperature (T4). The simple correlations would then be compared to the turbulent mixing times
to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and
rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates were then used to calculate the
necessary chemical kinetic times. Chemical kinetic time equations for fuel, carbon monoxide and NOx were obtained for Jet-A
fuel and methane with and without water injection to water mass loadings of 2/1 water to fuel. A similar correlation was also
developed using data from NASA’s Chemical Equilibrium Applications (CEA) code to determine the equilibrium
concentrations of carbon monoxide and nitrogen oxide as functions of overall equivalence ratio, water to fuel mass ratio,
pressure and temperature (T3). The temperature of the gas entering the turbine (T4) was also correlated as a function of the
initial combustor temperature (T3), equivalence ratio, water to fuel mass ratio, and pressure.
Author
Jet Engine Fuels; Methane; Water Injection; Reaction Kinetics; Combustion Chambers; Emission; Mathematical Models
20040073436 NASA Glenn Research Center, Cleveland, OH, USA
Measurement of Initial Conditions at Nozzle Exit of High Speed Jets
Panda, J.; Zaman, K. B. M. Q.; Seasholtz, R. G.; May 2004; 18 pp.; In English; Seventh Aeroacoustics Conference, 28-30
May 2001, Maastricht, Netherlands
Report No.(s): NASA/TM-2004-212392; AIAA Paper 2001-2143; E-13969; No Copyright; Avail: CASI; A03, Hardcopy
The time averaged and unsteady density fields close to the nozzle exit (0.1 less than or = x/D less than or = 2, x:
downstream distance, D: jet diameter) of unheated free jets at Mach numbers of 0.95, 1.4, and 1.8 were measured using a
molecular Rayleigh scattering based technique. The initial thickness of shear layer and its linear growth rate were determined
from time-averaged density survey and a modeling process, which utilized the Crocco-Busemann equation to relate density
profiles to velocity profiles. The model also corrected for the smearing effect caused by a relatively long probe length in the
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