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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Arc Jet Testing: A Short Course

This course will cover an overview of the Entry Systems and Technology Division (TS) at NASA Ames Research Center (ARC) and descriptions of the extensive arc jet testing complex managed within the branch. After a quick look at the Earth and Planetary Entry projects supported by TS, along with the inventions and software developed within the division, a description of the entry environments to which thermal protection systems (TPS) are exposed will be discussed. The question of "How do we insure TPS survival?" will be answered with descriptions of the various test facilities across the agency and beyond and their applicability. The Ames Arc Jet Complex will then be described, starting with how an arc heater works, adding in the associated infrastructure required to run an arc heater, and the capabilities of each of the test tunnels. Finally, examples of TPS test articles will round out the course.

ablative materials↗
NASA NTRSDate not supplied

On Characterization of Flow Disturbances in Arc-Jet Testing

This paper reports computational simulations and analysis of flow characterization tests in high enthalpy arc-jet facilities at NASA Ames Research Center. Flow disturbances and their characterization are presented through case studies, and their implications for testing are discussed. The case studies include free-jet test configurations from three different arc heaters and nozzles: the 60-MW IHF 30-inch conical nozzle, the 10-MW TP3 15-inch conical nozzle, and the 20-MW AHF 12-inch conical nozzle. For all cases, test articles are placed in the jet exiting the conical nozzle, and the existence of a flow disturbance is confirmed through flow survey data using pitot pressure and heat flux probes and accompanying analysis. The paper focuses on cases where the effects of the disturbances on test article surface quantities are important. The present analysis comprises computational fluid dynamics simulations of the nonequilibrium flowfield in the facility nozzles and test box, including the models tested. Comparisons of computations with the experimental measurements are presented. The computations that reproduce the probe sweep data approximately are essential to interpret the arc-jet test data accurately, while providing insights into several observed calorimeter anomalies caused by flow disturbances.

Arc-jet testing↗
NASA NTRSDate not supplied

On Characterization of Flow Disturbances in Arc-Jet Testing

This paper reports computational simulations and analysis of flow characterization tests in high enthalpy arc-jet facilities at NASA Ames Research Center. Flow disturbances and their characterization are presented through case studies, and their implications for testing are discussed. The case studies include free-jet test configurations from three different arc heaters and nozzles: the 60-MW IHF 30-inch conical nozzle, the 10-MW TP3 15-inch conical nozzle, and the 20-MW AHF 12-inch conical nozzle. For all cases, test articles are placed in the jet exiting the conical nozzle, and the existence of a flow disturbance is confirmed through flow survey data using pitot pressure and heat flux probes and accompanying analysis. The paper focuses on cases where the effects of the disturbances on test article surface quantities are important. The present analysis comprises computational fluid dynamics simulations of the nonequilibrium flowfield in the facility nozzles and test box, including the models tested. Comparisons of computations with the experimental measurements are presented. The computations that reproduce the probe sweep data approximately are essential to interpret the arc-jet test data accurately, while providing insights into several observed calorimeter anomalies caused by flow disturbances.

Arc-jet testing↗
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 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 NTRS2002

Enthalpy By Energy Balance for Aerodynamic Heating Facility at NASA Ames Research Center Arc Jet Complex

The NASA Ames Research Center (ARC) Arc Jet Facilities' Aerodynamic Heating Facility (AHF) has been instrumented for the Enthalpy By Energy Balance (EB2) method. Diagnostic EB2 data is routinely taken for all AHF runs. This paper provides an overview of the EB2 method implemented in the AHF. The chief advantage of the AHF implementation over earlier versions is the non-intrusiveness of the instruments used. For example, to measure the change in cooling water temperature, thin film 1000 ohm Resistance Temperature Detectors (RTDs) are used with an Anderson Current Loop (ACL) as the signal conditioner. The ACL with 1000 ohm RTDs allows for very sensitive measurement of the increase in temperature (Delta T) of the cooling water to the arc heater, which is a critical element of the EB2 method. Cooling water flow rates are measured with non-intrusive ultrasonic flow meters.

Hightower, T. Mark↗
NASA NTRS1963

THIRTY DAY ENDURANCE TEST OF A 30KW ARC JET ENGINE

Details are presented on a 30-day run of a radiation cooled thermal arc jet engine. The engine performed satisfactorily throughout the test period, maintaining a thrust of 250 grams and a propellant specific impulse greater than 1000 seconds a t an input power level of 30 kilowatts. The resulting propulsive efficiency was greater than 40 percent. Visual examination of the arc discharge through a quartz constrictor indicates that there is a smooth, constant diameter, bright core extending from the cathode completely through the constrictor to the cathode. Photographic observations on the arc discharge, using a red filter, indicate that the center of the column is darker than the outside: and this, in turn, suggests that the maximum core temperature is greater than 20,000°K. Calculations on the energy flow rate through a fully developed laminar column, combined with the experimental observation that the longitudinal energy flux gradient along the column is small, suggest that there may be a region of high volumetric energy release in the vicinity of the cathode tip.

Arc jet↗
NASA NTRS2017

CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad/Separation Bolt Wedge Tests

This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Panel test articles included a metallic separation bolt imbedded in the compression-pad and heat shield materials, resulting in a circular protuberance over a flat plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the non-equilibrium flow field in the facility nozzle, test box, and flow field over test articles, and comparisons with the measured calibration data.

TPS↗
NASA NTRS2017

CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad/Separation Bolt Wedge Tests

This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Each panel test article included a metallic separation bolt imbedded in Orion compression-pad and heatshield materials, resulting in a circular protuberance over a flat plate. The protuberances produce complex model flowfields, containing shock-shock and shock-boundary layer interactions, and multiple augmented heating regions on the test plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the nonequilibrium flowfield in the facility nozzle, test box, and flowfield over test articles, and comparisons with the measured calibration data.

CFD↗
NASA NTRS2017

CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad Separation Bolt Wedge Tests

This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Each panel test article included a metallic separation bolt imbedded in Orion compression-pad and heatshield materials, resulting in a circular protuberance over a flat plate. The protuberances produce complex model flowfields, containing shock-shock and shock-boundary layer interactions, and multiple augmented heating regions on the test plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the non-equilibrium flow field in the facility nozzle, test box, and flow field over test articles, and comparisons with the measured calibration data.

CFD↗
NASA NTRS2011

Enthalpy Distributions of Arc Jet Flow Based on Measured Laser Induced Fluorescence, Heat Flux and Stagnation Pressure Distributions

The centerline total enthalpy of arc jet flow is determined using laser induced fluorescence of oxygen and nitrogen atoms. Each component of the energy, kinetic, thermal, and chemical can be determined from LIF measurements. Additionally, enthalpy distributions are inferred from heat flux and pressure probe distribution measurements using an engineering formula. Average enthalpies are determined by integration over the radius of the jet flow, assuming constant mass flux and a mass flux distribution estimated from computational fluid dynamics calculations at similar arc jet conditions. The trends show favorable agreement, but there is an uncertainty that relates to the multiple individual measurements and assumptions inherent in LIF measurements.

Suess, Leonard E.↗
NASA NTRS2010

Evaluation of the NASA Arc Jet Capabilities to Support Mission Requirements

NASA accomplishes its strategic goals through human and robotic exploration missions. Many of these missions require launching and landing or returning spacecraft with human or return samples through Earth's and other planetary atmospheres. Spacecraft entering an atmosphere are subjected to extreme aerothermal loads. Protecting against these extreme loads is a critical element of spacecraft design. The safety and success of the planned mission is a prime concern for the Agency, and risk mitigation requires the knowledgeable use of thermal protection systems to successfully withstand the high-energy states imposed on the vehicle. Arc jets provide ground-based testing for development and flight validation of re-entry vehicle thermal protection materials and are a critical capability and core competency of NASA. The Agency's primary hypersonic thermal testing capability resides at the Ames Research Center and the Johnson Space Center and was developed and built in the 1960s and 1970s. This capability was critical to the success of Apollo, Shuttle, Pioneer, Galileo, Mars Pathfinder, and Orion. But the capability and the infrastructure are beyond their design lives. The complexes urgently need strategic attention and investment to meet the future needs of the Agency. The Office of Chief Engineer (OCE) chartered the Arc Jet Evaluation Working Group (AJEWG), a team of experienced individuals from across the Nation, to capture perspectives and requirements from the arc jet user community and from the community that operates and maintains this capability and capacity. This report offers the AJEWG's findings and conclusions that are intended to inform the discussion surrounding potential strategic technical and investment strategies. The AJEWG was directed to employ a 30-year Agency-level view so that near-term issues did not cloud the findings and conclusions and did not dominate or limit any of the strategic options.

Calomino, Anthony↗
NASA NTRS2002

Graphite Ablation and Thermal Response Simulation Under Arc-Jet Flow Conditions

The Two-dimensional Implicit Thermal Response and Ablation program, TITAN, was developed and integrated with a Navier-Stokes solver, GIANTS, for multidimensional ablation and shape change simulation of thermal protection systems in hypersonic flow environments. The governing equations in both codes are demoralized using the same finite-volume approximation with a general body-fitted coordinate system. Time-dependent solutions are achieved by an implicit time marching technique using Gauess-Siedel line relaxation with alternating sweeps. As the first part of a code validation study, this paper compares TITAN-GIANTS predictions with thermal response and recession data obtained from arc-jet tests recently conducted in the Interaction Heating Facility (IHF) at NASA Ames Research Center. The test models are graphite sphere-cones. Graphite was selected as a test material to minimize the uncertainties from material properties. Recession and thermal response data were obtained from two separate arc-jet test series. The first series was at a heat flux where graphite ablation is mainly due to sublimation, and the second series was at a relatively low heat flux where recession is the result of diffusion-controlled oxidation. Ablation and thermal response solutions for both sets of conditions, as calculated by TITAN-GIANTS, are presented and discussed in detail. Predicted shape change and temperature histories generally agree well with the data obtained from the arc-jet tests.

Chen, Y.-K.↗
NASA NTRS2020

3.6 Arc Jet Test Facilities

Among all the ground test facilities that have been developed over the past 7 decades for testing TPS, arc jet ranks as the most flight relevant and extensively used test facility in the history of TPS development in the US. Arc Jet facilities played, and continue to play, a critical role not only in the early screening and selection of TPS materials, but more importantly, in the flight vehicle integrated development and in the flight qualification.

Ethiraj Venkatapathy↗