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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1948

Altitude-Wind-Tunnel Investigation of a 4000-Pound-Thrust Axial-Flow Turbojet Engine: Analysis of Turbine Performance - 5

Performance characteristics of the turbine of a 4000-pound-thrust axial-flow turbojet engine was determined in investigations of the complete engine in the NACA Cleveland altitude wind tunnel. Characteristics are presented as functions of the total-pressure ratio across the turbine and of turbine speed and gas flow corrected to sea-level conditions. Three turbine nozzles of different areas were used to determine the area that gave optimum performance. Inasmuch as tail-pipe nozzles of different diameters were investigated in combination with the standard turbine nozzle, the effect of varying discharge conditions on turbine operation could be observed. The investigations covered a range of pressure attitudes from 5000 to 40,000 feet. The engine was investigated over the entire operable range of speeds at each altitude. At pressure altitude of 30,000 feet, the effect on turbine operation of varying the ram pressure ration over a range from 1.10 to 1.77 was evaluated. An altitude effect was apparent when turbine pressure ratio was plotted against corrected turbine speed but it was so slight as to be negligible insofar as the turbine efficiencies were concerned. A maximum turbine efficiency of slightly more than 82 percent was obtained with the configuration using the standard turbine nozzle and the low-flow compressor. This efficiency, which is somewhat lower than the actual turbine efficiency, is uncorrected for accessories drive power, bearing friction, tail-pipe pressure drop, compressor thermal radiation, and introduction of turbine-disk cooling air into the gas stream. Changes in the ram pressure ratio had a negligible effect on the turbine efficiency.

Krebs, Richard P.↗
NASA NTRS1974

Quasi-three-dimensional flow solution by meridional plane analysis

A computer program has been developed to obtain subsonic or shockfree transonic, nonviscous flow analysis on the hub-shroud mid-channel flow surface of a turbomachine. The analysis may be for any annular passage, with or without blades. The blades may be fixed or rotating and may be twisted and leaned. The flow may be axial, radial or mixed. Blade surface velocities over the entire blade are approximated based on the rate of change of angular momentum. This gives a 3-D flow picture based on a 2-D analysis. The paper discusses the method used for the program and shows examples of the type of passages and blade rows which can be analyzed. Also, some numerical examples are given to show how the program can be used for practical assistance in design of blading, annular passages, and annular diffusers.

Katsanis, T.↗
NASA NTRS1991

A computer program to perform flow and thermal analysis during pressurization of the Space Shuttle Solid Rocket Motor field joint

A computational technique for prediction of the flow and thermal environment in the SRM field joint cavities is described. The SRM field joint hardware was tested with a defect in the insulation, and due to this defect, the O-ring gland cavities are pressurized during the early part of the ignition. A computer model is developed to predict the thermal environment and flow through the simulated flaw, during the pressurization of the field joint. The transient mass, momentum, and energy conservation equations in the flow passage together with the thermodynamic equation of state are solved by a fully implicit iterative numerical procedure.

Clayton, J. Louie↗
NASA NTRS1973

Analysis of inlet flow distortion and turbulence effects on compressor stability

The effect of steady state circumferential total pressure distortion on the loss in compressor stall pressure ratio has been established by analytical techniques. Full scale engine and compressor/fan component test data were used to provide direct evaluation of the analysis. Specifically, since a circumferential total pressure distortion in an inlet system will result in unsteady flow in the coordinate system of the rotor blades, analysis of this type distortion must be performed from an unsteady aerodynamic point of view. By application of the fundamental aerothermodynamic laws to the inlet/compressor system, parameters important in the design of such a system for compatible operation have been identified. A time constant, directly related to the compressor rotor chord, was found to be significant, indicating compressor sensitivity to circumferential distortion is directly dependent on the rotor chord.

Melick, H. C., Jr.↗
NASA NTRS1974

Quasi-three-dimensional flow solution by meridional plane analysis

A computer program has been developed to obtain subsonic or shock-free transonic, nonviscous flow analysis on the hub-shroud midchannel flow surface of a turbomachine. The analysis may be for any annular passage, with or without blades. The blades may be fixed or rotating and may be twisted and leaned. The flow may be axial, radial, or mixed. Blade surface velocities over the entire blade are approximated, based on the rate of change of angular momentum. This gives a three-dimensional flow picture based on a two-dimensional analysis. This paper discusses the method used for the program and shows examples of the type of passages and blade rows which can be analyzed. Also, some numerical examples are given to show how the program can be used for practical assistance in design of blading, annular passages, and annular diffusers.

Katsanis, T.↗
NASA NTRS1977

Finite element analysis of aeroacoustic jet-flap flows

A computational analysis was performed on the steady, turbulent aerodynamic flowfields associated with a jet-blown flap. For regions devoid of flow separation, a parabolic approximation to the governing time-averaged Navier-Stokes equations was applied. Numerical results are presented for the symmetry plane flow of a slot-nozzle planar jet flap geometry, including prediction of flowfield evolution within the secondary mixing region immediately downstream of the trailing edge. Using a two equation turbulence kinetic energy closure model, rapid generation and decay of large spatial gradients in mean and correlated fluctuating velocity components within the immediate wake region were predicted. Modifications to the turbulent flow structure, as induced by porous surface treatment of the flap, were evaluated. The recirculating flow within a representative discrete slot in the surface was evaluated, using the two dimensional, time-averaged Navier-Stokes equations.

Baker, A. J.↗
NASA NTRS1977

Analysis of internal flow of J85-13 multistage compressor

Interstage data recorded on a J85-13 engine were used to analyze the internal flow of the compressor. Measured pressures and temperatures were used as input to a streamline analysis program to calculate the velocity diagrams at the inlet and outlet of each blade row. From the velocity diagrams and blade geometry, selected blade-element performance parameters were calculated. From the detailed analysis it is concluded that the compressor is probably hub critical (stall initiates at the hub) in the latter stages for the design speed conditions. As a result, the casing treatment over the blade tips has little or no effect on stall margin at design speed. Radial inlet distortion did not appear to change the flow in the stages that control stall because of the rapid attenuation of the distortion within the compressor.

Hager, R. D.↗
NASA NTRS1976

An application of the suction analog for the analysis of asymmetric flow situations

A recent extension of the suction analogy for estimation of vortex loads on asymmetric configurations is reviewed. This extension includes asymmetric augmented vortex lift and the forward sweep effect on side edge suction. Application of this extension to a series of skewed wings has resulted in an improved estimating capability for a wide range of asymmetric flow situations. Hence, the suction analogy concept now has more general applicability for subsonic lifting surface analysis.

Luckring, J. M.↗
NASA NTRS1988

Parametric and experimental analysis using a power flow approach

Having defined and developed a structural power flow approach for the analysis of structure-borne transmission of structural vibrations, the technique is used to perform an analysis of the influence of structural parameters on the transmitted energy. As a base for comparison, the parametric analysis is first performed using a Statistical Energy Analysis approach and the results compared with those obtained using the power flow approach. The advantages of using structural power flow are thus demonstrated by comparing the type of results obtained by the two methods. Additionally, to demonstrate the advantages of using the power flow method and to show that the power flow results represent a direct physical parameter that can be measured on a typical structure, an experimental investigation of structural power flow is also presented. Results are presented for an L-shaped beam for which an analytical solution has already been obtained. Furthermore, the various methods available to measure vibrational power flow are compared to investigate the advantages and disadvantages of each method.

Cuschieri, J. M.↗
NASA NTRS1977

Experiment and analysis on the flow process dynamics of the NASA-Langley eight foot transonic pressure tunnel

A dynamic response test performed in a eight foot transonic pressure tunnel is described. The dynamics of the flow process of the wind tunnel at transonic conditions were obtained. Descriptions of the test conditions, instrumentation, presentation of raw data, analysis of data, and finally, based on experimental evidences, an attempt to construct an input output relationship of the flow process from the viewpoints of control engineering are included.

Tcheng, P.↗
NASA NTRS1986

Lava flows on Mars - Analysis of small surface features and comparisons with terrestrial analogs

High-resolution images of south and west Arsia Mons, eastern Tharsis, and Memnonia Fossae on Mars are analyzed. Lava flows with different types of features, such as pressure ridges, tumuli, festoon ridges, and ring ridges, are observed. The effects of these small features on the type of eruption, mode of flow emplacement, and characteristics of the terrain over which the lavas flow are examined. The development of terrestrial pressure ridges, festoon, and ring structures is discussed and they are compared to the observed Martian features. The interior viscosity of the features are calculated using the Fink and Fletcher (1978) and Fink (1980a) models; the interior viscosity was estimated as 100 MPa sec in flow margins, ponded areas, and across flow lobes. The data reveal that south of Arsia Mons, flows containing pressure ridges are emplaced as multiple flow units from sporadic low-effusion rate eruptions, and the flows at the other three areas are large sheet flows that represent basaltic flood-type volcanism.

Theilig, E.↗
NASA NTRS1992

Scaling of low-Prandtl-number thermocapillary flows

Scaling analysis was used to study thermocapillary flows of low-Prandtl-number fluids in shallow rectangular enclosures under an imposed-heat-flux configuration. Different regimes that appear in the thermo-fluid problem are identified and the proper parameters and reference quantities that define them are obtained. Assuming that the flow is driven by thermocapillary effects and it is concluded that the extent of the region where the thermocapillary driving force is important defines the region of applicability of the scaling results.

Rivas, Damian↗
NASA NTRS1990

Particle acceleration in step function shear flows - A microscopic analysis

The transport of energetic particles in a moving, scattering fluid, which has a large shear in its velocity over a distance small compared with the scattering mean free path is discussed. The analysis is complementary to an earlier paper by Earl, Jokipii, and Morfill (1988), which considered effects of more-gradual shear in the diffusion approximation. The case in which the scattering fluid undergoes a step function change in velocity, in the direction normal to the flow is considered. An analytical, approximate calculation and a Monte Carlo analysis of particle motion are presented. It is found that particles gain energy at a rate proportional to the square of the magnitude of the velocity change.

Jokipii, J. R.↗