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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Experimental study of flow due to an isolated suction hole and a partially plugged suction slot

Details for construction of a model of a partially plugged, laminar flow control, suction slot and an isolated hole are presented. The experimental wind tunnel facility and instrumentation is described. Preliminary boundary layer velocity profiles (without suction model) are presented and shown to be in good agreement with the Blasius laminar profile. Recommendations for the completion of the study are made. An experimental program for study of transition on a rotating disk is described along with preliminary disturbance amplification rate data.

Goglia, G. L.↗
NASA NTRS1980

Time dependent difference theory for sound propagation in axisymmetric ducts with plug flow

The time dependent governing acoustic-difference equations and boundary conditions are developed and solved for sound propagation in an axisymmetric (cylindrical) hard wall duct with a plug mean flow and spinning acoustic modes. The analysis begins with a harmonic sound source radiating into a quiescent duct. This explicit iteration method then calculates stepwise in real time to obtain the transient as well as the 'steady' state solutions of the acoustic field. The time dependent finite difference analysis has two advantages over the steady state finite difference and finite element techniques: (1)the elimination of large matrix storage requirements, and (2)shorter solution times under most conditions.

Baumeister, K. J.↗
NASA NTRS1980

A unique coannular plug nozzle jet noise prediction procedure

The work presents a method for predicting jet mixing and shock noise spectra from coannular plug nozzles operated in the inverted velocity profile mode. It is shown that the jet mixing noise prediction method is based on the physics of the flow and its noise radiating characteristics, modeling the source spectrum, eddy convection, and fluid shrouding in a simplistic fashion. Further, the shock noise prediction procedure is described, noting that it is an extension of the Fisher-Harper-Bourne method for conical nozzles. Finally, it is concluded that the method has the potential of being extended to suppressors of complex geometries.

Bhutiani, P. K.↗
NASA NTRS1980

Time dependent difference theory for sound propagation in axisymmetric ducts with plug flow

The time dependent governing/acoustic-difference equations and boundary conditions are developed and solved for sound propagation in an axisymmetric (cylindrical) hard wall duct with a plug mean flow and spinning acoustic modes. The analysis begins with a harmonic sound source radiating into a quiescent duct. This explicit iteration method then calculates stepwise in real time to obtain the transient as well as the 'steady' state solutions of the acoustic field. The time dependent finite difference analysis has two advantages over the steady state finite difference and finite element techniques: (1) the elimination of large matrix storage requirements, and (2) shorter solution times under most conditions.

Baumeister, K. J.↗
NASA NTRS1985

Close-Out Plugs

Externally-applied circular plug seals holes in walls up to 0.44 (12 mm) in diameter.

Adams, T.↗
NASA NTRS1984

Separator plugs for liquid helium

Work performed during Summer 1984 (from June to Sept. 30) in the area of porous media for use in low temperature applications is discussed. Recent applications are in the area of vapor - liquid phase separation, pumping based on the fountain effect and related subsystems. Areas of potential applications of the latter are outlined in supplementary work. Experimental data have been developed. The linear equations of the two-fluid model are inspected critically in the light of forced convection evidence reported recently. It is emphasized that the Darcy permeability is a unique throughput quantity in the porous media application areas whose use will permit meaningful comparisons of data not only in one lab but also within a group of labs doing porous plug studies.

Lee, J. M.↗
NASA NTRS1987

Pin Inserts for Plug Welds

Leakage through minute cracks eliminated. Electron-beam-welded pins reinforce material around coolant holes during plug welding and subsequent remachining. Pins removed in final machining of 0.188-in diameter hole.

Penninger, Michael↗
NASA NTRS1986

Determination of the Darcy permeability of porous media including sintered metal plugs

Sintered-metal porous plugs with a normal size of the order of 1-10 microns are used to evaluate the Darcy permeability of laminar flow at very small velocities in laminar fluids. Porous media experiment results and data adduced from the literature are noted to support the Darcy law analog for normal fluid convection in the laminar regime. Low temperature results suggest the importance of collecting room temperature data prior to runs at liquid He(4) temperatures. The characteristic length diagram gives a useful picture of the tolerance range encountered with a particular class of porous media.

Frederking, T. H. K.↗
NASA NTRS1990

Convective heat flow in space cryogenics plugs - Critical and moderate He II heat flux densities

Plug flow rates of entropy, heat and normal fluid in phase separators and in zero net mass flow systems are, to some extent, quite similar. A simplified analysis of critical conditions is presented in agreement with data trends. A critical temperature gradient arises on the basis of the He II two-fluid model at the stability limit constraining the thermohydrodynamics of the system. Thus, the question of critical thermodynamic fluctuations associated with nucleation versus the possibility of critical gradients in externally imposed parameters is answered in favor of the latter route toward turbulence. Furthermore, a similarity equation is presented which incorporates size dependent rates for moderate heat flow densities observed in experiments.

Yuan, S. W. K.↗
NASA NTRS1989

A combined Eulerian-Lagrangian two-phase analysis of the SSME HPOTP nozzle plug trajectories

As a result of high cycle fatigue, hydrogen embrittlement, and extended engine use, it was observed in testing that the trailing edge on the first stage nozzle plug in the High Pressure Oxygen Turbopump (HPOTP) could detach. The objective was to predict the trajectories followed by particles exiting the turbine. Experiments had shown that the heat exchanger soils, which lie downstream of the turbine, would be ruptured by particles traveling in the order of 360 ft/sec. An axisymmetric solution of the flow was obtained from the work of Lin et. al., who used INS3D to obtain the solution. The particle trajectories were obtained using the method of de Jong et. al., which employs Lagrangian tracking of the particle through the Eulerian flow field. The collision parameters were obtained from experiments conducted by Rocketdyne using problem specific alloys, speeds, and projectile geometries. A complete 3-D analysis using the most likely collision parameters shows maximum particle velocities of 200 ft/sec. in the heat exchanger region. Subsequent to this analysis, an engine level test was conducted in which seven particles passed through the turbine but no damage was observed on the heat exchanger coils.

Garcia, Robert↗
NASA NTRS1991

Some preliminary results of brush seal/rotor interference effects on leakage at zero and low RPM using a tapered-plug rotor

Some preliminary brush seal leakage results for ambient temperature air are presented. Data for four nominal brush rotor radial clearances of -0.09, -0.048, -0.008, and 0.035 mm were taken by using a tapered plug rotor at 0 and 400 rpm with rotor runout of 0.127 mm peak to peak. The brush seal nominal bore diameter was 38 mm with 0.05 mm bristles at 200 bristles/mm of circumference and a 0.61 mm fence height. Leakages were greater than predicted, but agreement was reasonable. Leakage rates were not significantly altered by hysteresis or inlet flow variations. Visualization studies showed that the bristles followed the 400 rpm excitation, and loading studies indicated that bristles slid relative to one another.

Hendricks, R. C.↗
NASA NTRS1991

Plug-type heat flux gauge

A plug-type heat flux gauge formed in a material specimen and having a thermoplug integrally formed in the material specimen, and a method for making the same are disclosed. The thermoplug is surrounded by a concentric annulus, through which thermocouple wires are routed. The end of each thermocouple wire is welded to the thermoplug, with each thermocouple wire welded at a different location along the length of the thermoplug. The thermoplug and concentric annulus may be formed in the material specimen by electrical discharge machining and trepanning procedures.

Liebert, Curt H.↗
NASA NTRS1991

Some preliminary results of brush seal/rotor interference effects on leakage at zero and low rpm using a tapered-plug rotor

Some preliminary brush seal leakage results for ambient-temperature air are presented. Data for four nominal brush-rotor radial clearances of -0.09, -0.048, -0.008, and 0.035 mm were taken by using a tapered plug rotor at 0 and 400 rpm with rotor runout of 0.127 mm peak to peak. The brush seal nominal bore diameter was 38 mm with 0.05-mm bristles at 200 bristles/mm of circumference and a 0.61-mm fence height. Leakages were greater than predicted, but agreement was reasonable. Leakage rates were not significantly altered by hysteresis or inlet flow variations. Visualization studies showed that the bristles followed the 400-rpm excitation, and loading studies indicated that bristles slid relative to one another.

Hendricks, R. C.↗
NASA NTRS1992

Miniature high temperature plug-type heat flux gauges

The objective is to describe continuing efforts to develop methods for measuring surface heat flux, gauge active surface temperature, and heat transfer coefficient quantities. The methodology involves inventing a procedure for fabricating improved plug-type heat flux gauges and also for formulating inverse heat conduction models and calculation procedures. These models and procedures are required for making indirect measurements of these quantities from direct temperature measurements at gauge interior locations. Measurements of these quantities were made in a turbine blade thermal cycling tester (TBT) located at MSFC. The TBT partially simulates the turbopump turbine environment in the Space Shuttle Main Engine. After the TBT test, experiments were performed in an arc lamp to analyze gauge quality.

Liebert, Curt H.↗
NASA NTRS1992

Method of producing a plug-type heat flux gauge

A method of making a plug-type heat flux gauge in a material specimen in which a thermoplug is integrally formed in the specimen is disclosed. The thermoplug and concentric annulus are formed in the material specimen by electrical discharge machining and trepanning procedures. The thermoplug is surrounded by a concentric annulus through which thermocouple wires are routed. The end of each thermocouple wire is welded to the thermoplug, with each thermocouple wire welded at a different location along the length of the thermoplug.

Liebert, Curt H.↗
NASA NTRS1991

Progress in the measurement of SSME turbine heat flux with plug-type sensors

Data reduction was completed for tests of plug-type heat flux sensors (gauges) in a turbine blade thermal cycling tester (TBT) that is located at NASA/Marshall Space Flight Center, and a typical gauge is illustrated. This is the first time that heat flux has been measured in a Space Shuttle Main Engine (SSME) Turbopump Turbine environment. The development of the concept for the gauge was performed in a heat flux measurement facility at Lewis. In this facility, transient and steady state absorbed surface heat flux information was obtained from transient temperature measurements taken at points within the gauge. A schematic of the TBT is presented, and plots of the absorbed surface heat flux measured on the three blades tested in the TBT are presented. High quality heat flux values were measured on all three blades. The experiments demonstrated that reliable and durable gauges can be repeatedly fabricated into the airfoils. The experiment heat flux data are being used for verification of SSME analytical stress, boundary layer, and heat transfer design models. Other experimental results and future plans are also presented.

Liebert, Curt H.↗