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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Results of tests of Insta-Foam Thermal Protection System (TPS) material for protection of equipment inside the SRB aft skirt

The objective of these tests was to determine whether Insta-Foam can be used successfully to protect items inside the solid rocket booster aft skirt during reentry. On some of the early Space Shuttle flights the aft skirt heat shield curtain failed during reentry. This allowed the hot gases to damage some of the equipment, etc., inside the skirt. For example, some of the propellant lines were overheated and ruptured and some of the NSI (nozzle severance) cables were damaged. It was suggested that the Insta-Foam thermal protection system be sprayed over these lines, etc., to protect them during future flights in case of a curtain failure. The tests presented were devised and run to check out the feasibility of this idea.

Dean, W. G.↗
NASA NTRS1985

A three-dimensional Navier-Stokes/Euler code for blunt-body flow computations

The formulation computation method of an improved version of the three-dimensional Navier-Stokes/Euler computation algorithm of Li (1981) for the numerical simulation of blunt-body reentry flows are discussed, and results for five sample problems are presented graphically. The vector notation of the coordinate systems is defined; the governing equations are presented in full; the Jacobian matrices and damping terms of the factorization technique (based on the alternating-direction implicit procedure of Beam and Warming, 1978) are explained; and the capabilities, limitations and proper use of the code are summarized. Examples presented include the equilibrium-flow problem for Shuttle-orbiter reentry at Mach 22 and angle of attack 40.8 deg and the perfect-gas problem of an aerobraking orbital-transfer vehicle with an ellipsoidal/60-deg cone and a toroidal sonic shoulder. The advantages of the improved code in terms of accuracy and computation time are indicated.

Li, C. P.↗
NASA NTRS1985

Vapor deposited emittance/catalysis coatings for superalloys in heatshield applications

Statically oxidized Inconel 617 and MA 956 superalloys were prepared with vapor deposited aluminosilicate layers and exposed to temperatures which simulated reentry conditions. The aluminosilicate layers were 1-2 microns thick. The trials consisted of exposures to 1500-2300 F heat while surface temperatures were monitored with pyrometers. Analyses were then performed of the catalytic activity, oxidation phenomena, and radiative properties after thermal cycling the specimens for 8 hr. Both alloys were found to be catalytic to the recombination processes of dissociated species in the reentry environment. The coatings reduced the catalytic activity by 40 percent for both alloys but did not change the emittance. An enhanced Cr depletion zone was detected in the Inconel samples, implying that the coating did not prevent diffusion loss of Cr. The coated MA 956, on the other hand, gained weight over the course of the trials.

Clark, R. K.↗
NASA NTRS1985

Space Shuttle Main Engine nozzle thermal protection system

Two of the three Space Shuttle Main Engine (SSME) nozzles are exposed to significant reentry aeroheating loads. To ensure reusability of the Nozzle Assembly, the nozzle primary structure must not exceed specific temperature limits. Due to the thermal, pressure, and dynamic flexing of the nozzle during a mission cycle, an appropriate insulating system must have significant flexibility. Recent missions have demonstrated nozzle reentry aeroheating rates and heat loads much higher than predictions, higher than the capability of the original insulating system. A new insulating system has been developed using similar materials in an aerodynamically 'smooth' shape to both reduce the incoming heating and increase radiation cooling.

Nordlund, R. M.↗
NASA NTRS1986

Addressing the hypersonic simulation problem

The hypersonic simulation problem is solved by the meshing of bench-marked experimental data with results from validated computational fluid dynamic codes. The example presented is for the reentry of the Space Shuttle Orbiter. Mach number effects were assessed by parametrically varying free-stream Mach number and angle of attack in a series of inviscid, perfect-gas computations carried out on a modified Orbiter geometry. Real-gas effects were determined by making calculations at specific points of the reentry trajectory using equilibrium air thermodynamics and comparing with corresponding perfect-gas computations. Viscous computations were also made for both the basic Orbiter body and control surfaces. A methodology is developed that permits the extrapolation of wind tunnel data to flight situations, providing a solution to the hypersonic simulation problem.

Griffith, B. J.↗
NASA NTRS1986

Experimental evaluation of wall Mach number distributions of the octagonal test section proposed for NASA Lewis Research Center's altitude wind tunnel

Wall Mach number distributions were determined over a range of test-section free-stream Mach numbers from 0.2 to 0.92. The test section was slotted and had a nominal porosity of 11 percent. Reentry flaps located at the test-section exit were varied from 0 (fully closed) to 9 (fully open) degrees. Flow was bled through the test-section slots by means of a plenum evacuation system (PES) and varied from 0 to 3 percent of tunnel flow. Variations in reentry flap angle or PES flow rate had little or no effect on the Mach number distributions in the first 70 percent of the test section. However, in the aft region of the test section, flap angle and PES flow rate had a major impact on the Mach number distributions. Optimum PES flow rates were nominally 2 to 2.5 percent wtih the flaps fully closed and less than 1 percent when the flaps were fully open. The standard deviation of the test-section wall Mach numbers at the optimum PES flow rates was 0.003 or less.

Harrington, Douglas E.↗
NASA NTRS1987

Users of middle atmosphere models remarks

The procedure followed for shuttle operations is to calculate descent trajectories for each potential shuttle landing site using the Global Reference Atmosphere Model (GRAM) to interactively compute density along the flight path 100 times to bound the statistics. The purpose is to analyze the flight dynamics, along with calculations of heat loads during reentry. The analysis program makes use of the modified version of the Jacchia-70 atmosphere, which includes He bulges over the poles and seasonal latitude variations at lower altitudes. For the troposphere, the 4-D Model is used up to 20 km, Groves from 30 km up to 90 km. It is extrapolated over the globe and faired into the Jacchia atmosphere between 90 and 115 km. Since data on the Southern Hemisphere was lacking, what was done was that the data was flipped over and lagged 6 months. Sometimes when winds are calculated from pressure data in the model there appear to be discontinuities. Modelers indicated that the GRAM was not designed to produce winds, but good wind data is needed for the landing phase of shuttle operations. Use of atmospheric models during reentry is one application where it is obvious that a single integrated atmosphere model is required.

Gamble, Joe↗
NASA NTRS1987

Experimental evaluation of blockage ratio and plenum evacuation system flow effects on pressure distribution for bodies of revolution in 0.1 scale model test section of NASA Lewis Research Center's proposed altitude wind tunnel

An experimental investigation was conducted in the slotted test section of the 0.1-scale model of the proposed Altitude Wind Tunnel to evaluate wall interference effects at tunnel Mach numbers from 0.70 to 0.95 on bodies of revolution with blockage rates of 0.43, 3, 6, and 12 percent. The amount of flow that had to be removed from the plenum chamber (which surrounded the slotted test section) by the plenum evacuation system (PES) to eliminate wall interference effects was determined. The effectiveness of tunnel reentry flaps in removing flow from the plenum chamber was examined. The 0.43-percent blockage model was the only one free of wall interference effects with no PES flow. Surface pressures on the forward part of the other models were greater than interference-free results and were not influenced by PES flow. Interference-free results were achieved on the aft part of the 3- and 6-percent blockage models with the proper amount of PES flow. The required PES flow was substantially reduced by opening the reentry flaps.

Burley, Richard R.↗
NASA NTRS1987

Methods for extracting aerodynamic accelerations from Orbiter High Resolution Accelerometer Package flight data

This report presents a process for extracting the aerodynamic accelerations of the Shuttle Orbiter Vehicle from the High Resolution Accelerometer Package (HiRAP) flight data during reentry. The methods for obtaining low-level aerodynamic accelerations, principally in the rarefied flow regime, are applied to 10 Orbiter flights. The extraction process is presented using data obtained from Space Transportation System Flight 32 (Mission 61-C) as a typical example. This process involves correcting the HiRAP measurements for the effects of temperature bias and instrument offset from the Orbiter center of gravity, and removing acceleration data during times they are affected by thruster firings. The corrected data are then made continuous and smooth and are further enhanced by refining the temperature bias correction and removing effects of the auxiliary power unit actuation. The resulting data are the current best estimate of the Orbiter aerodynamic accelerations during reentry and will be used for further analyses of the Orbiter aerodynamics and the upper atmosphere characteristics.

Thompson, J. M.↗
NASA NTRS1987

Spectroscopic investigations and measurements of certain ARC jet parameters

The NASA/JSC Atmospheric Reentry Materials and Structures Evaluation Facility (ARMSEF) was intensively and extensively involved in ground testing of spacecraft materials and thermal protection systems (TPS) in simulated reentry conditions. Ground experiments on surface catalytic efficiency of such TPS requires a knowledge of the flow system in the arc jet. In the work described, spectroscopic diagnostic techniques are used to determine the free stream constituents. Specifically, the emission spectrum of the free stream constituents was obtained and the species therein identified. A laser system was added on, which will give the added capacity of studying the arc jet flow using Laser Raman Spectroscopy (LRS). The LRS technique will complement information obtained from the emission spectra. A short list of further work that can be done in the area of spectroscopic investigations on the arc jet is mentioned.

Murty, Vedula S.↗
NASA NTRS1988

Shuttle high resolution accelerometer package experiment results - Atmospheric density measurements between 60-160 km

Indirect or inferred values of atmospheric density encountered by the Shuttle Orbiter during reentry have been calculated from acceleration measurements made by the High Resolution Accelerometer Package (HiRAP) and the Orbiter Inertial Measurement Unit (IMU) liner accelerometers. The atmospheric density data developed from this study represent a significant gain with respect to the body of data collected to date by various techniques in the altitude range of 60 to 160 km. The data are unique in that they cover a very wide horizontal range during each flight and provide insight into the actual density variations encountered along the reentry flight path. The data, which were collected over about 3 years, are also characterized by variations in solar activity, geomagnetic index, and local solar time. Comparison of the flight-derived densities with various atmospheric models have been made, and analyses have attempted to characterize the data and to show correlation with selected physical variables.

Blanchard, R. C.↗
NASA NTRS1988

Navier-Stokes simulation of 3-D hypersonic equilibrium air flow

A computationally efficient three-dimensional conservative supracharacteristic Navier-Stokes method has been extended to simulate complex external chemically reacting flows of hypersonic reentry vehicles at angle-of-attack. Numerical simulation results of the flow around a sphere-cone-cone-flare reentry vehicle at 10 deg angle-of-attack are presented, in addition to the results of a well-validated two-dimensional code with which the 0-deg axisymmetric flow has been computed. A method for obtaining compositions of species in equilibrium ionized air is proposed.

Nagaraj, N.↗
NASA NTRS1989

Thermal Stresses In Space-Shuttle Wing

Combined thermal deformations of wing-skin panel and TPS would not tear SIP layer. Report presents analysis of thermal stresses induced in skin panel, thermal-protection system (TPS), and strain-isolation pad (SIP) of Space Shuttle orbiter. Purpose of analysis to determine whether any part of above mentioned structures overstressed and overdeformed under reentry heating, assuming one TPS tile lost at end of reentry heating.

Ko, William L.↗
NASA NTRS1989

Arc jet diagnostics tests

Two objectives were addressed during a 10 week 1988 NASA/ASEE summer faculty fellowship at the Johnson Space Center Atmospheric Reentry Materials Structures Evaluation Facility (ARMSEF). These objectives were the evaluation of mass spectrometry for the measurement of atomic and molecular species in an arc jet environment, and the determination of atomic recombination coefficients for reaction cured glass (RCG) coated high temperature surface insulation (HRSI) materials subjected to simulated reentry conditions. Evaluation of mass spectrometry for the measurement of atomic and molecular species provided some of the first measurements of point compositions in arc jet tunnel environments. A major objective of this project centered around the sampling residence time. A three staged vacuum sampling system pulled the molecules and atoms from the arc jet to a quadrupole ionization mass spectrometer in 400 milliseconds. Conditions investigated included a composition survey across the nozzle exit at 3 cm z-distance from the nozzle exit for 3 different currents. Also, a point composition survey was taken around a shock created by the presence of a blunt body.

Willey, Ronald J.↗
NASA NTRS1988

Simulation of launch and re-entry acceleration profiles for testing of Shuttle and unmanned microgravity research payloads

A procedure was developed for the simulation of the launch and reentry acceleration profiles of the Space Shuttle (3.3 and 1.7 g maximum, respectively) and of two versions of NASA's proposed materials research Reusable Reentry Satellite (RRS) (8 and 4 g maximum, respectively). With a 7-m centrifuge, the time dependence of five different acceleration episodes was simulated for payload masses up to 59 kg. Test results obtained for the Materials Dispersion Apparatus, a commercial low-cost payload device, are presented.

Cassanto, J. M.↗
NASA NTRS1989

An artificial gravity demonstration experiment

An artificial gravity experiment which is tethered to a Delta second stage and which uses the Small Expendable Deployer System is proposed. Following tether deployment, the Delta vehicle performs the required spin-up maneuver and can then be passivated. A surplus reentry vehicle houses the artificial gravity life science experiments. When the experiments are completed, the reentry phase of the experiment is initiated by synchronizing the spin of the configuration with the required deorbit impulse.

Rupp, C.↗
NASA NTRS1989

Influence of flowfield and vehicle parameters on engineering aerothermal methods

The reliability and flexibility of three engineering codes used in the aerosphace industry (AEROHEAT, INCHES, and MINIVER) were investigated by comparing the results of these codes with Reentry F flight data and ground-test heat-transfer data for a range of cone angles, and with the predictions obtained using the detailed VSL3D code; the engineering solutions were also compared. In particular, the impact of several vehicle and flow-field parameters on the heat transfer and the capability of the engineering codes to predict these results were determined. It was found that entropy, pressure gradient, nose bluntness, gas chemistry, and angle of attack all affect heating levels. A comparison of the results of the three engineering codes with Reentry F flight data and with the predictions obtained of the VSL3D code showed a very good agreement in the regions of the applicability of the codes. It is emphasized that the parameters used in this study can significantly influence the actual heating levels and the prediction capability of a code.

Wurster, Kathryn E.↗
NASA NTRS1989

Aerospace Vehicle Design, Spacecraft Section. Volume 1: Project Groups 3-5

Three groups of student engineers in an aerospace vehicle design course present their designs for a vehicle that can be used to resupply the Space Station Freedom and provide an emergency crew return to earth capability. The vehicle's requirements include a lifetime that exceeds six years, low cost, the capability for withstanding pressurization, launch, orbit, and reentry hazards, and reliability. The vehicle's subsystems are analyzed. These subsystems are structures, communication and command data systems, attitude and articulation control, life support and crew systems, power and propulsion, reentry and recovery systems, and mission management, planning, and costing.

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