Flow contamination and flow quality in arc heaters used for hypersonic testing

MacDermott, W N; Horn, Dennis D.; Fisher, C. F.

doi:10.2514/6.1992-4028

Cited by 12 publications

(5 citation statements)

References 4 publications

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“…At a pressure of about 100 atm, the diameter of the current path is only about 10% of the constrictor diameter. 4 At a higher pressure, the current extinguishes. The maximum operating pressure is set by this phenomenon to be about 200 atm.…”

Section: Construction and Operationmentioning

confidence: 97%

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Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

Park

1997

Journal of Thermophysics and Heat Transfer

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The methods of making more accurate measurements in arcjet wind tunnels in the real-gas regime than have been achieved up to the present time are explored by reviewing, comparing, and interpreting the existing experimental methodologies and obtained data. The inaccuracies of the conventional method of determining enthalpy and ow uniformity are rst pointed out. The extent and consequences of ow contamination by copper vapor are next examined. Then the data obtained through spectroscopic determination of ow enthalpies, Doppler velocimetry using laser-induced uorescence, and species concentration determination using mass spectrometry are reviewed. The discrepancies between the measured and calculated ow velocities and species concentrations are pointed out and a possible explanation is given.Nomenclature A = nozzle cross-sectional area, m 2 C p = speci c heat at constant pressure C v = speci c heat at constant volume D = diameter of constrictor, m d = diameter of model, m H = enthalpy, J/kg h i = chemical energy of species i, J/mol L = length of constrictor, m n i = species concentration, mol/kg p = pressure, Pa q Ç = stagnation-point heat transfer rate, W/m 2 r = radial distance, m T = heavy particle temperature, K T e = electron temperature, K T v = vibrational temperature, K U = freestream velocity, m/s u = velocity in radial direction, m/s v = vibrational quantum number y = distance normal to wall, m = speci c heat ratio C p /C v = density, kg/m 3 = vibrational energy, J/kg Subscripts av = average c = centerline e = boundary-layer edge s = pitot total 0 = reservoir = freestream * = nozzle throat

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Section: Construction and Operationmentioning

confidence: 97%

“…When operated at a pressure of about 100 atm in the constrictor, an arcjet tunnel produces copper vapor to a concentration of about 200 ppm by mass, or about 100 ppm by mole. 4 At a lower pressure, the copper concentration is less.…”

Section: Copper Vapormentioning

confidence: 98%

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

Park

1997

Journal of Thermophysics and Heat Transfer

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“…1,14,15 To generate the necessary high enthalpy flow, a portion of the incoming A air is heated by an electric arc to a bulk temperature of approximately 4000 K and as a result, nitric oxide is formed. 16,17,18 Figure 1 shows a schematic of the facility. There are three primary facility components upstream of the test section: the arc heater, the plenum and the nozzle.…”

Section: A Arc Heated Scramjet Test Facilitymentioning

confidence: 99%

Characterization of the NASA Langley Arc Heated Scramjet Test Facility using NO PLIF

Kidd

Narayanaswamy

Danehy

et al. 2014

30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference

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The nitric oxide planar laser-induced fluorescence (NO PLIF) imaging was used to characterize the air flow of the NASA Langley Arc Heated Scramjet Test Facility (AHSTF) configured with a Mach 6 nozzle. The arc raises the enthalpy of the test gas in AHSTF, producing nitric oxide. Nitric oxide persists as the temperature drops through the nozzle into the test section. NO PLIF was used to qualitatively visualize the flowfield at different experimental conditions, measure the temperature of the gas flow exiting the facility nozzle, and visualize the wave structure downstream of the nozzle at different operating conditions. Uniformity and repeatability of the nozzle flow were assessed. Expansion and compression waves on the free-jet shear layer as the nozzle flow expands into the test section were visualized. The main purpose of these experiments was to assess the uniformity of the NO in the freestream gas for planned experiments, in which NO PLIF will be used for qualitative fuel-mole-fraction sensitive imaging. The shot-to-shot fluctuations in the PLIF signal, caused by variations in the overall laser intensity as well as NO concentration and temperature variations in the flow was 20-25% of the mean signal, as determined by taking the standard deviation of a set of images obtained at constant conditions and dividing by the mean. The fluctuations within individual images, caused by laser sheet spatial variations as well as NO concentration and temperature variations in the flow, were about 28% of the mean in images, determined by taking standard deviation within individual images, dividing by the mean in the same image and averaged over the set of images. Applying an averaged laser sheet intensity correction reduced the within-image intensity fluctuations to about 10% suggesting that the NO concentration is uniform to within 10%. There was no significant difference in flow uniformity between the low and high enthalpy settings. While not strictly quantitative, the temperature maps show qualitative agreement with the computations of the flow.

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“…Studies have found that the level of contamination from the AEDC HI segmented heater has a negligible effect on most types of hypersonic testing. 5 The H3 arc heater is expected to have the same low contamination concentrations as HI.…”

Section: Large Arc Heater Development: H3mentioning

confidence: 99%

High-pressure arc heater development and modeling - Status and requirements

Felderman

Chapman

Jacocks

et al. 1996

Journal of Propulsion and Power

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An arc heater development program has been undertaken to develop a large, high-pressure, highpower arc heater capability. A large, state-of-the-art segmented arc heater (H3) has operated successfully and is scheduled to be fully operational at chamber pressures up to 100 atm with a total power of 60 MW in 1996. The H3 arc heater is a 50% geometric scale-up of the existing HI segmented arc heater and is designed to operate at 2.25 times the power of HI. Additionally, an extensive analytical capability to assist in the design and development of segmented arc heaters has been developed. Available modeling techniques are reviewed, current modeling efforts are discussed, and areas needing additional effort are identified. Scaling laws/performance correlations have been used extensively and first-generation performance codes have been available for some 20 years. The basic components of a three-dimensional arc heater code have been developed, extending a three-dimensional Navier-Stokes code by incorporating electromagnetic effects and a multidimensional radiation model. A near-electrode model has been developed for the interface between the flowing air and the solid electrode surface. Water-tunnel vortexbreakdown studies have been carried out to aid in understanding vortex behavior. Additional modeling work required to improve our understanding of arc heater phenomenology include continued development of the three-dimensional code, extension of the near-electrode model to include nonequilibrium effects, and improved modeling for arc path prediction. Nomenclaturea -speed of sound B = magnetic field c = speed of light E = electric field H Q = total enthalpy / = total current J = current density PO = pitot pressure Re = Reynolds number Re m = magnetic Reynolds number T = temperature v = velocity 8 = divergence of magnetic field fj, = viscosity coefficient /A O = vacuum permeability p = density a = electrical conductivity cr sb = Stephan-Boltzmann constant Subscripts m = magnetic component r -radiation component v = viscous component oo = freestream conditions E

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Flow contamination and flow quality in arc heaters used for hypersonic testing

Cited by 12 publications

References 4 publications

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

Characterization of the NASA Langley Arc Heated Scramjet Test Facility using NO PLIF

High-pressure arc heater development and modeling - Status and requirements

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