893
893
May 6, 2010
05/10
by
Brennan, J. A
texts
eye 893
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Discharge coefficients of orifice flow of liquid hydrogen and nitrogen into vacuum
Topics: COEFFICIENTS, DUCTED FLOW, LIQUID HYDROGEN, LIQUID NITROGEN, ORIFICE, DISCHARGE COEFFICIENT, DUCTED...
216
216
Jun 27, 2010
06/10
by
Dugan, J. V., Jr.; Rose, J. R
texts
eye 216
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Simple argon model atoms used for calculating electron number densities for argon plasma discharges
Topics: CONDUCTING FLUIDS, ELECTROMAGNETIC PUMPS, COOLANTS, DUCTED FLOW, ELECTRIC GENERATORS, FARADAY...
396
396
Jul 12, 2010
07/10
by
Liang, P. Y
texts
eye 396
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The Advanced Rocket Injector/Combustor Code (ARICC) that has been developed to model the complete chemical/fluid/thermal processes occurring inside rocket combustion chambers are highlighted. The code, derived from the CONCHAS-SPRAY code originally developed at Los Alamos National Laboratory incorporates powerful features such as the ability to model complex injector combustion chamber geometries, Lagrangian tracking of droplets, full chemical equilibrium and kinetic reactions for multiple...
Topics: GAS DYNAMICS, HIGH TEMPERATURE GASES, SPACE SHUTTLE MAIN ENGINE, DUCTED FLOW, FLOW GEOMETRY, NOZZLE...
1,060
1.1K
Jul 11, 2010
07/10
by
Walter, R. J
texts
eye 1,060
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Cyclic-load crack growth measurements were performed on ASME SA-105 Grade 2 steel specimens exposed to 10,000- and 15,000-psi hydrogen and to 5000-psi helium, all at ambient temperatures. The cyclic-load crack growth rate was found to be faster in high-pressure hydrogen than in helium. Cyclic-load crack growth rates in this steel were not reduced by preloading in air to a stress intensity of 1.5 times the cyclic K sub max in hydrogen. There are indications that holding under load in hydrogen,...
Topics: ACOUSTIC MEASUREMENT, ENGINE NOISE, SUPERSONIC TRANSPORTS, TURBOFAN ENGINES, AFTERBURNING, DUCTED...
195
195
Jul 6, 2010
07/10
by
Kalinina, N. N
texts
eye 195
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The effect of mountains in the propagation path on the propagation of radio waves by meteors is discussed. The results are compared with propagation paths across plains.
Topics: AIR FLOW, FLOW CHARACTERISTICS, JET MIXING FLOW, SUBSONIC FLOW, DUCTED FLOW, FLOW EQUATIONS,...
419
419
May 31, 2011
05/11
by
Hanson, Curtis E.; Ryan, Jack; Allen, Michael J.; Jacobson, Steven R
texts
eye 419
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The first flight test phase of the NASA Dryden Flight Research Center Autonomous Formation Flight project has successfully demonstrated precision autonomous station-keeping of an F/A-18 research airplane with a second F/A-18 airplane. Blended inertial navigation system (INS) and global positioning system (GPS) measurements have been communicated across an air-to-air telemetry link and used to compute relative-position estimates. A precision research formation autopilot onboard the trailing...
Topics: JET MIXING FLOW, ENERGY TRANSFER, DUCTED FLOW, CROSS FLOW, COMBUSTION, SUBSONIC FLOW, INJECTION,...
293
293
May 22, 2011
05/11
by
NON
texts
eye 293
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Presented are the statements of Bill D. Colvin, Inspector General of NASA, before the Subcommittee on Legislation and National Security, Committee on Government Operations, U.S. House of Representatives, on the audit and investigative oversight work the NASA office of Inspector General performs at the agency and among its contractors and how this work relates to NASA's efforts at management and procurement reform. The testimony is divided into the following major areas: procurement oversight,...
Topics: CROSS FLOW, STATIC PRESSURE, DUCTED FLOW, FLOW DISTRIBUTION, INLET FLOW, VORTEX GENERATORS,...
337
337
Jun 11, 2011
06/11
by
Meyers, James F
texts
eye 337
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The development of Doppler global velocimetry is described. Emphasis is placed on the modifications necessary to advance this nonintrusive laser based measurement technique from a laboratory prototype to a viable wind tunnel flow diagnostics tool. Several example wind tunnel flow field investigations are described to illustrate the versatility of the technique. Flow conditions ranged from incompressible to Mach 2.8 with measurement distances extending from 1 to 15 m.
Topics: THREE DIMENSIONAL FLOW, NAVIER-STOKES EQUATION, NUMERICAL ANALYSIS, INCOMPRESSIBLE FLOW, INVISCID...
259
259
Jun 1, 2011
06/11
by
Ambartsumyan, S. A
texts
eye 259
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This paper considers a sufficiently thin shallow shell of nonzero Gaussian curvature. It also presents a system of symmetrically constructed differential equations, constructed by the mixed method through the stress function and the displpacement function.
Topics: PERTURBATION, SERIES (MATHEMATICS), SHOCK WAVES, COORDINATES, UNSTEADY FLOW, DUCTED FLOW,...
561
561
May 22, 2011
05/11
by
Landis, Geoffrey A
texts
eye 561
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If even a very small fraction of the hundred billion stars in the galaxy are home to technological civilizations which colonize over interstellar distances, the entire galaxy could be completely colonized in a few million years. The absence of such extraterrestrial civilizations visiting Earth is the Fermi paradox. A model for interstellar colonization is proposed using the assumption that there is a maximum distance over which direct interstellar colonization is feasible. Due to the time lag...
Topics: COMPUTATIONAL FLUID DYNAMICS, DUCTED FLOW, DUCTS, DYNAMIC STRUCTURAL ANALYSIS, FINITE ELEMENT...
320
320
Aug 2, 2010
08/10
by
Larocca, Francesc
texts
eye 320
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The research activities in Italy on inverse design and optimization are reviewed. The review is focused on aerodynamic aspects in turbomachinery and wing section design. Inverse design of blade rows and ducts of turbomachinery in subsonic and transonic regime are illustrated by the Politecnico di Torino and turbomachinery industry (FIAT AVIO).
Topics: AERODYNAMICS, COMPUTER AIDED DESIGN, FINITE DIFFERENCE THEORY, DESIGN ANALYSIS, DUCTED FLOW, DUCTS,...
335
335
Jul 12, 2010
07/10
by
NON
texts
eye 335
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A variety of topics relevant to global modeling and simulation are presented. Areas of interest include: (1) analysis and forecast studies; (2) satellite observing systems; (3) analysis and forecast model development; (4) atmospheric dynamics and diagnostic studies; (5) climate/ocean-air interactions; and notes from lectures.
Topics: DUCTS, LIQUID OXYGEN, SPACE SHUTTLE MAIN ENGINE, FLOW STABILITY, FLOW VELOCITY, FLOWMETERS, VANES,...
A computerized acoustic attenuation prediction procedure has been developed to evaluate acoustically lined ducts for various geometric and environmental parameters. The analysis procedure is based on solutions to the acoustic wave equation, assuming uniform airflow on a duct cross section, combined with appropriate mathematical lining impedance models. The impedance models included in the analysis procedure are representative of either perforated sheet or porous polyimide impregnated fiberglass...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC ATTENUATION, DUCTED FLOW, BOUNDARY LAYER FLOW,...
The differential equations governing the propagation of sound in a variable area duct or nozzle carrying a one dimensional subsonic compressible fluid flow are derived and put in state variable form using acoustic pressure and particle velocity as the state variables. The duct or nozzle is divided into a number of regions. The region size is selected so that in each region the Mach number can be assumed constant and the area variation can be approximated by an exponential area variation....
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC ATTENUATION, DUCTED FLOW, NOZZLE GEOMETRY, SOUND...
154
154
Sep 20, 2010
09/10
by
Kyriakopoulos, K. J.; Saridis, G. N
texts
eye 154
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An efficient method for computing the minimum distance and predicting collisions between moving objects is presented. This problem has been incorporated in the framework of an in-line motion planning algorithm to satisfy collision avoidance between a robot and moving objects modeled as convex polyhedra. In the beginning the deterministic problem, where the information about the objects is assumed to be certain is examined. If instead of the Euclidean norm, L(sub 1) or L(sub infinity) norms are...
Topics: DUCTED FLOW, DISTORTION, FLOW VISUALIZATION, SEPARATED FLOW, DUCTS, PRESSURE RECOVERY, PRESSURE...
384
384
Aug 2, 2010
08/10
by
Rinsland, Curtis P.; Seals, Robert K., Jr.; Smith, Mary Ann H.; Goldman, Aaron; Murcray, David G.; Murcray, Frank J
texts
eye 384
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The objective is the comprehensive analysis of high resolution atmospheric spectra recorded in the middle-infrared region to obtain simultaneous measurements of coupled parameters (gas concentrations of key trace constituents, total column amounts, pressure, and temperature) in the stratosphere and upper troposphere. Solar absorption spectra recorded at 0.002 and 0.02 cm exp -1 resolutions with the University of Denver group's balloon-borne, aircraft borne, and ground-based interferometers and...
Topics: AIRCRAFT DESIGN, DUCTED FLOW, INDUSTRIES, ITALY, FLOW DISTRIBUTION, OPTIMIZATION, SUBSONIC FLOW,...
244
244
Jul 9, 2010
07/10
by
Huck, F. O.; Katzberg, S. J.; Jobson, D. J.; Fales, C. L., Jr
texts
eye 244
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In addition to imaging the surrounding terrain, planetary lander cameras may also be used to survey the stars to aid in locating the lander site. The response of the facsimile camera, which was selected for the Viking lander missions to Mars, to a radiant point source is formulated and shown to result in a statistical rather than deterministic signal. The signal statistics are derived and magnitudes are evaluated for the brighter visual and red stars. The probability of detecting the resultant...
Topics: AERODYNAMIC CHARACTERISTICS, AIRCRAFT PERFORMANCE, CONTROL SURFACES, DUCTED FLOW, JET FLAPS, SPLIT...
Under certain conditions, inlets with a Borda type geometry were shown to exhibit sufficiently strong separation effects to permit the working fluid to flow through the duct as if it were a free jet. Mass limiting flow data and associated pressure profiles for tubes of 14, 53, 64, 73, and 105 L/D with a Borda type inlet were taken to determine bounds of the free jet phenomena. For a given tube roughness, the limits appear to be one dimensional and dependent only on inlet stagnation conditions....
Topics: NASA Technical Reports Server (NTRS), DUCTED FLOW, FREE JETS, HEAT TRANSFER, HYDRODYNAMICS,...
192
192
May 23, 2011
05/11
by
Roush, Ted L.; Cruikshank, Dale P.; Pollack, James B.; Young, Eliot F.; Bartholomew, Mary J
texts
eye 192
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The spectral geometric albedos of Charon and Pluto are derived at near-infrared wavelengths (1.4-2.5 jAm) from measurements obtained in 1987. Comparisons of these to theoretical calculations are used to place constraints on the identity and relative abundances of surface ices on Charon. These compari- sons suggest that widespread regions of pure CH4 ice do not occur on Charon and that if CH4 is abundant on Charon then it is large grained (-5 mm) and is likely mixed at the granular level with...
Topics: JET MIXING FLOW, DUCTS, CONFINEMENT, THREE DIMENSIONAL FLOW, ORIFICES, MASS FLOW, GAS TURBINE...
Analytical capabilities for modeling hot gas flow on the fuel side of the Space Shuttle Main Engines are developed. Emphasis is placed on construction and documentation of a computational grid code for modeling an elliptical two-duct version of the fuel side hot gas manifold. Computational results for flow past a support strut in an annular channel are also presented.
Topics: NASA Technical Reports Server (NTRS), DUCTED FLOW, FLOW DISTRIBUTION, FLOW GEOMETRY, SPACE SHUTTLE...
The resonance expansion method, developed to study the propagation of sound in rigid rectangular ducts is applied to the case of slightly soft ducts. Expressions for the generation and decay of various harmonics are obtained. The effect of wall admittance is seen through a dissipation function in the system of nonlinear differential equations, governing the generation of harmonics. As the wall admittance increases, the resonance is reduced. For a given wall admittance this phenomenon is...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC DUCTS, DUCTED FLOW, SOUND PROPAGATION, DIFFERENTIAL...
249
249
Sep 20, 2010
09/10
by
Langston, J.; Krack, K.; Reupke, W
texts
eye 249
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The Multimission Three-Axis Stabilized Spacecraft (MTASS) Flight Dynamics Support System (FDSS) has been developed in an effort to minimize the costs of ground support systems. Unlike single-purpose ground support systems, which attempt to reduce costs by reusing software specifically developed for previous missions, the multimission support system is an intermediate step in the progression to a fully generalized mission support system in which numerous missions may be served by one general...
Topics: COMPUTATIONAL FLUID DYNAMICS, TWO DIMENSIONAL FLOW, DATA ACQUISITION, DUCTED FLOW, PRESSURE...
Experiments were performed on a pilot model duct system in order to explore its aerodynamic characteristics. The model was scaled from a design projected for the high speed operation mode of the Aircraft Noise Reduction Laboratory. The test results show that the model performed satisfactorily and therefore the projected design will most likely meet the specifications.
Topics: NASA Technical Reports Server (NTRS), DIFFUSERS, DUCTED FLOW, SCALE MODELS, SUBSONIC FLOW,...
A brief review of some fundamental aspects of sound arising from turbulent boundary layers, noise due to flow past a single discontinuity (trailing edge), noise from airfoils operating in turbulent flow, and noise due to rigid flow discontinuities (spoilers) immersed in rigid ducts is presented. Emphasis is on dipole-like sound fields associated with turbulent flow past a trailing edge, rigid bodies in turbulence and in-duct spoilers. Representative available data are reviewed and evaluated in...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, AIR FLOW, AIRCRAFT NOISE, BOUNDARY LAYER...
Fan noise including its generation, radiation characteristics, and suppression by acoustic treatment is studied. In fan noise generation, results from engine and fan experiments, using inflow control measures to suppress noise sources related to inflow distortion and turbulence, are described. The suppression of sources related to inflow allows the experiments to focus on the fan or engine internal sources. Some of the experiments incorporated pressure sensors on the fan blades to sample the...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, NOISE GENERATORS, NOISE REDUCTION, TURBOFANS,...
A pilot multinozzle and duct were tested at ambient enthalpy to evaluate the suitability of such apparatus for testing thermal protection system panels mounted in the sidewalls of the duct downstream of the nozzle array. The flow field in the duct was complex: effects of wakes and shock waves from the nozzle dominated the flow field; the wakes continually mixed with the surrounding fluid; the boundary layer on the sidewalls of the duct was nonuniform; and near the exit of the duct the sidewall...
Topics: NASA Technical Reports Server (NTRS), DUCTED BODIES, GASDYNAMIC LASERS, NOZZLE GEOMETRY, BOUNDARY...
Study focuses on physical mechanism of waves in fluid such as air. Strong interaction between energy of wave and fluid particle motion causes energy of wave to be dissipated. Dissipation depends not only on momentum, time-rate, and force, but also upon nature and magnitude of entropic-flow effects.
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, AIRCRAFT NOISE, DUCTED FLOW, ENGINE NOISE,...
Simple formulas for calculating acoustic reflection and transmission coefficients for converging-diverging ducts are derived; they extend the method of Cho and Ingard to arbitrary, slowly varying ducts. These formulas involve two parameters. The first is a function of duct shape and the second is the ratio of the duct radius downstream of the throat to that upstream of the throat to the upstream of the throat. An extension of the method to include mean flow is made for symmetric ducts.
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC PROPAGATION, CONVERGENCE, DUCT GEOMETRY, DUCTS, WAVE...
The Green's function relating the radiated pressure field to the fluctuating forces on rotor or stator blades is developed in the presence of dissipation due to turbulent velocity fluctuations and sound speed fluctuations. The resonances in the output power spectrum which would occur at the cut-off frequencies in the absence of dissipation should be removed and smeared out by the incorporation of dissipation. Wave number dependence is developed for an effective eddy viscosity due to the...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC PROPERTIES, ENGINE NOISE, NOISE PROPAGATION, ROTOR...
A clearer understanding of the interactions of the hot gas flow with the structure in the duct system, the flow passages of the rotating machinery, and the thrust chamber nozzle is sought for the purpose of finding ways and means to increase the life and performance of the systems. The objective of the transient nozzle test is to understand the shock-boundary layer interactions during transient flow and the resulting large side forces acting on the nozzle skirt. The Fluctuating Pressures in...
Topics: NASA Technical Reports Server (NTRS), GAS DYNAMICS, HIGH TEMPERATURE GASES, SPACE SHUTTLE MAIN...
The objective of this investigation is the experimental evaluation of the influence of inlet turbulence intensity on secondary flow development in a turning duct. The existing 25.4 cm square turning duct (90) facility is being utilized to investigate of bulk turbulence levels on secondary flow development. The large scale duct flow facility allows detailed mean velocity and turbulence quantities to be measured at several streamwise planes in the curved duct. Non-intrusive laser velocimetry is...
Topics: NASA Technical Reports Server (NTRS), BOUNDARY LAYERS, DUCTED FLOW, FLOW DISTRIBUTION, SECONDARY...
The apparatus includes a supply duct coupled to a source of supply air for carrying the supply air therethrough. A return duct is coupled to the supply duct for carrying return conditioned air therethrough. A temperature reducing device is coupled to the supply duct for decreasing the temperature of the supply and return conditioned air. A by-pass duct is coupled to the supply duct for selectively directing portions of the supply and return conditioned air around the temperature reducing...
Topics: NASA Technical Reports Server (NTRS), AIR CONDITIONING, DUCTS, EQUIPMENT, HUMIDITY, TEMPERATURE...
All publications and presented speeches are listed that discuss the various aspects of perturbed wave propagation and noise generation in ducts with varying cross sections.
Topics: NASA Technical Reports Server (NTRS), DOCUMENTS, DUCTED FLOW, NOISE GENERATORS, TURBULENT FLOW,...
An overview of the NASA/GE Highly-Loaded Turbine Research Program at the NASA Glenn Research Center is presented. The program is sponsored by the Subsonic Fixed Wing Project of the Fundamental Aeronautics Program. The goals of the turbine research program are presented along with their relationship to the higher-level program goals. Two turbine research programs are described; the highly-loaded, single-stage high pressure turbine (HPT) and the highly loaded low pressure turbine (LPT). The HPT...
Topics: NASA Technical Reports Server (NTRS), LOW PRESSURE, HIGH PRESSURE, PRESSURE RATIO, TURBINES, DUCTED...
This paper establishes a numerical method for the solution of three-variable problems and is applied here to rotational flows through ducts of various cross sections. An iterative scheme is developed, the main feature of which is the addition of a duplicate variable to the forward component of velocity. Two forward components of velocity result from integrating two sets of first order ordinary differential equations for the streamline curvatures, in intersecting directions across the duct. Two...
Topics: NASA Technical Reports Server (NTRS), DUCTED FLOW, FLOW EQUATIONS, FLOW THEORY, TURBOMACHINERY,...
A parametric study was made of duct-burning turbofan and suppressed dry turbojet engines installed in a supersonic transport. A range of fan pressure ratios was considered for the separate-flow-fan engines. The turbofan engines were studied both with and without jet noise suppressors. Single- as well as dual-stream suppression was considered. Attention was concentrated on designs yielding sideline noises of FAR 36 (108 EPNdB) and below. Trades were made between thrust and wing area for a...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC MEASUREMENT, ENGINE NOISE, SUPERSONIC TRANSPORTS,...
501
501
Jun 1, 2011
06/11
by
Klos, Jacob; Palumbo, Daniel L
texts
eye 501
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A method to intended for measurement of the insertion loss of an acoustic treatment applied to an aircraft fuselage in-situ is documented in this paper. Using this method, the performance of a treatment applied to a limited portion of an aircraft fuselage can be assessed even though the untreated fuselage also radiates into the cabin, corrupting the intensity measurement. This corrupting noise in the intensity measurement incoherent with the panel vibration of interest is removed by correlating...
Topics: ACOUSTIC IMPEDANCE, THREE DIMENSIONAL FLOW, FREQUENCY DISTRIBUTION, FLOW RESISTANCE, AIRCRAFT...
A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution tends not to oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude. Example solutions indicate that stepped noise source profiles have much higher attenuation than plane...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC MEASUREMENT, ACOUSTIC PROPERTIES, DUCTED FLOW, SOUND...
193
193
Jul 26, 2010
07/10
by
Lamkin, Stephen L
texts
eye 193
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No Abstract Available
Topics: CONVERGENCE, CONTINUITY EQUATION, FLOW DISTRIBUTION, ITERATION, STOKES FLOW, DUCTED FLOW, FINITE...
372
372
May 30, 2011
05/11
by
NON
texts
eye 372
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Advances in turbulence modeling are needed in order to calculate high Reynolds number flows near the onset of separation and beyond. To this end, the participants in this workshop made the following recommendations. (1) A national/international database and standards for turbulence modeling assessment should be established. Existing experimental data sets should be reviewed and categorized. Advantage should be taken of other efforts already under-way, such as that of the European Research...
Topics: DETONATION WAVES, CURRENT DENSITY, DIRECT CURRENT, DUCTED FLOW, DUCTS, ELECTRICAL RESISTIVITY,...
A brief description of the radial turbine and its analysis needs is followed by discussions of five analytical areas; design geometry and performance, off design performance, blade row flow, scroll flow, and duct flow. The functions of the programs, areas of applicability, and limitations and uncertainties are emphasized. Both past contributions and current activities are discussed.
Topics: NASA Technical Reports Server (NTRS), AXIAL FLOW TURBINES, DESIGN ANALYSIS, DUCTED FLOW, ENGINE...
The radiation of sound from an inlet as a function of flow velocity, frequency, duct mode structure, and inlet geometry was examined by using a spinning mode synthesizer to insure a given space-time structure inside the duct. Measurements of the radiation pattern (amplitude and phase) and of the pressure reflection coefficient were obtained over an azimuthal wave number range of 0 to 6 and a frequency range up to 5000 Hz for an unflanged duct and a bellmouth. The measured radiated field and...
Topics: NASA Technical Reports Server (NTRS), ENGINE INLETS, ENGINE NOISE, NOISE PROPAGATION, DUCTED FLOW,...
A hemispherical head flow direction sensor was tested in a wind tunnel to evaluate its effectiveness for measuring dynamic duct flow direction angles of plus and minus 27 degrees. The tests were conducted at Reynolds numbers of 3.8 million per meter (1.0 million per foot) and 4.92 million per meter (1.5 million per foot) and at Mach numbers from 0.30 to 0.70. The design criteria for the probe are discussed and the wind tunnel results are presented. Three techniques for deriving the flow angles...
Topics: NASA Technical Reports Server (NTRS), DUCTED FLOW, FLOW DIRECTION INDICATORS, FLOW DISTRIBUTION,...
A procedure for designing ducts for subsonic and transonic speeds is described. Examples discussed are a wind-tunnel contraction cone, a supersonic nozzle, and a diffuser. A listing of the computer program is included. The streamline curvature equations represent a form of the exact, compressible, inviscid flow equations. The method is applicable from low subsonic to supersonic speeds.
Topics: NASA Technical Reports Server (NTRS), AIR FLOW, COMPRESSIBLE FLOW, DUCTED FLOW, FLOW GEOMETRY,...
A finite-difference procedure for computing the turbulent, swirling, compressible flow in axisymmetric ducts is described. Arbitrary distributions of heat and mass transfer at the boundaries can be treated, and the effects of struts, inlet guide vanes, and flow straightening vanes can be calculated. The calculation procedure is programmed in FORTRAN 4 and has operated successfully on the UNIVAC 1108, IBM 360, and CDC 6600 computers. The analysis which forms the basis of the procedure, a...
Topics: NASA Technical Reports Server (NTRS), AXISYMMETRIC FLOW, COMPRESSIBLE FLOW, DUCTED FLOW, FINITE...
The objective of the program was to determine a wave rotor demonstrator engine concept using the Allison 250 series engine. The results of the NASA LERC wave rotor effort were used as a basis for the wave rotor design. A wave rotor topped gas turbine engine was identified which incorporates five basic requirements of a successful demonstrator engine. Predicted performance maps of the wave rotor cycle were used along with maps of existing gas turbine hardware in a design point study. The effects...
Topics: NASA Technical Reports Server (NTRS), ROTORS, TURBINES, SHAFTS (MACHINE ELEMENTS), GAS TURBINE...
316
316
Jun 9, 2011
06/11
by
Kleb, William L.; Wood, William A.; vanLeer, Bra
texts
eye 316
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A new method has been developed to accelerate the convergence of explicit time-marching, laminar, Navier-Stokes codes through the combination of local preconditioning and multi-stage time marching optimization. Local preconditioning is a technique to modify the time-dependent equations so that all information moves or decays at nearly the same rate, thus relieving the stiffness for a system of equations. Multi-stage time marching can be optimized by modifying its coefficients to account for the...
Topics: SUPERSONIC COMBUSTION RAMJET ENGINES, MATHEMATICAL MODELS, DUCTED FLOW, COMPUTATIONAL FLUID...
344
344
Sep 20, 2010
09/10
by
Orme, John S.; Gilyard, Glenn B
texts
eye 344
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Integrated engine-airframe optimal control technology may significantly improve aircraft performance. This technology requires a reliable and accurate parameter estimator to predict unmeasured variables. To develop this technology base, NASA Dryden Flight Research Facility (Edwards, CA), McDonnell Aircraft Company (St. Louis, MO), and Pratt & Whitney (West Palm Beach, FL) have developed and flight-tested an adaptive performance seeking control system which optimizes the quasi-steady-state...
Topics: AERODYNAMIC CHARACTERISTICS, SEPARATED FLOW, STATIC PRESSURE, VELOCITY DISTRIBUTION, VORTICES,...
Results of supersonic mixing and combustion tests performed with two simple strut injector configurations, one with parallel injectors and one with perpendicular injectors, are presented and analyzed. Good agreement is obtained between static pressure measured on the duct wall downstream of the strut injectors and distributions obtained from one-dimensional calculations. Measured duct heat load agrees with results of the one-dimensional calculations for moderate amounts of reaction, but is...
Topics: NASA Technical Reports Server (NTRS), ENGINE TESTS, FUEL INJECTION, SUPERSONIC COMBUSTION, DUCTED...
The method of weighted residuals in the form of a modified Galerkin method with boundary residuals was developed for the study of the transmission of sound in nonuniform ducts carrying a steady, compressible flow. In this development, the steady flow was modeled as essentially one dimensional but with a kinematic modification to force tangency of the flow at the duct walls. Three forms of the computational scheme were developed using for basis functions (1) the no-flow uniform duct modes, (2)...
Topics: NASA Technical Reports Server (NTRS), COMPRESSIBLE FLOW, NONUNIFORM FLOW, SOUND TRANSMISSION,...
