Nonequilibrium and equilibrium shock front radiation measurements

Sharma, Surendra P.; Gillespie, Walter D.

doi:10.2514/3.259

Cited by 92 publications

(41 citation statements)

References 3 publications

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“…Sharma et al [3] measured the vibrational and rotational temperatures behind a normal shock wave in a shock tube spectroscopically. The results were compared with a calculation made using the two-temperature model.…”

Section: Unsolved Problemsmentioning

confidence: 99%

“…A normal shock wave was produced in a shock tube to a speed of up to 11 km/s occurring during the Apollo's entry flight, and the . Radiation intensity behind a normal shock wave [3] intensity of the radiation emitted by the hot gas behind the shock wave was measured. Surprisingly, the radiation was strongest at a short distance behind the shock wave as shown in Figure 4 [3].…”

Section: Past Accomplishmentsmentioning

confidence: 99%

“…Radiation intensity behind a normal shock wave [3] intensity of the radiation emitted by the hot gas behind the shock wave was measured. Surprisingly, the radiation was strongest at a short distance behind the shock wave as shown in Figure 4 [3]. The peak intensity was much larger than that in equilibrium.…”

Section: Past Accomplishmentsmentioning

confidence: 99%

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Hypersonic Aerothermodynamics: Past, Present and Future

Park¹

2013

International Journal of Aeronautical and Space Sciences

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This is a written version of the keynote speech delivered at the International Symposium on Hypersonic Aerothermodynamics -Recent Advances held in Bangalore, India, from December 6 th to 10 th , 2012. In this document, what was accomplished in the past, the present status, and what is expected in the future in the field of hypersonic aerothermodynamics are reviewed. Solved problems are categorized into four items; unsolved problems into twelve items, and emerging problems into four items. Removing one degree uncertainty in trim angle of attack, studying the thermochemical phenomena in a hydrogen-heliummethane mixture, and entry flights of meteoroids are cited as the tasks for the future.

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Section: Unsolved Problemsmentioning

confidence: 99%

Section: Past Accomplishmentsmentioning

confidence: 99%

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Hypersonic Aerothermodynamics: Past, Present and Future

Park¹

2013

International Journal of Aeronautical and Space Sciences

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“…Moser and Hindelang employed infrared diode laser absorption spectroscopy tuned to specific ro-vibrational transitions for a NO-Ar gas mixture. At shock velocities of 6:2 km=s, Sharma and Gillespie conducted rotational and vibrational temperature measurements behind a normal shock [18], which sought to advance previous nonequilibrium relaxation region measurements by Allen et al [19][20][21]. In each of these cases, nitrogen was the test gas.…”

Section: Introductionmentioning

confidence: 99%

NO and OH Spectroscopic Vibrational Temperature Measurements in a Post-Shock Relaxation Region

et al. 2010

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In this paper, spatial temperature profiles are examined in the nonequilibrium relaxation region behind a stationary shock wave in a hypervelocity air Mach 7.42 freestream. The normal shock wave is established through a Mach reflection from an opposing wedge arrangement in an expansion tube facility. Schlieren images confirm that the shock configuration is steady and the location is repeatable. Emission spectroscopy is used to identify dissociated species and to make vibrational temperature measurements using both the nitric oxide and the hydroxyl radical A-X band sequences. Temperature measurements are presented at selected locations behind the normal shock. LIFBASE is used as the simulation spectrum software for OH temperature-fitting; however, the need to access higher vibrational and rotational levels for NO leads to the use of an in-house developed algorithm. For NO, results demonstrate the contribution of higher vibrational and rotational levels to the spectra at the conditions of this study. Very good agreement is achieved between the experimentally measured NO vibrational temperatures and calculations performed using an existing state-resolved, three-dimensional forced-harmonic oscillator thermochemical model. The measured NO vibrational temperatures are significantly higher than the OH temperatures.

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“…Much research has been conducted to both theoretically and experimentally investigate these phenomena. [1][2][3][4] As a result, several thermochemical models for re-entry calculations have been developed and applied to the design of re-entry vehicles. [5][6][7][8] Recently, a series of shock tube experiments were conducted by Yamada et al 9,10) to validate the two-temperature model for the super-orbital re-entry flight conditions encountered by the Hayabusa re-entry capsule.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis on the Nonequilibrium Phenomena of the Electronic Excitation Process behind Hypersonic Shock Waves

Yamada

Takayanagi

Suzuki

et al. 2013

Trans. Japan Soc. Aero. S Sci.

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In this study, the nonequilibrium phenomena of the electronic excitation process behind hypersonic shock waves have been investigated through numerical analysis. In the analysis, the three-temperature model is employed and temperature profiles are computed along the distance from the shock front. In the three-temperature model, the translationalrotational, vibrational and electron-electronic excitation temperatures are separately described and the relaxation processes for each energy mode are considered. Numerical calculations are conducted under the conditions corresponding to the shock tube experiments conducted in our previous study and the results are compared with the experimental data. It is found that the calculated and measured vibrational temperature profiles are in good agreement. In contrast, the calculated electronic excitation temperature is much lower than the measured one, revealing the discrepancy in the modeling of the electronic excitation temperature. To investigate the effect of electron behavior, parametric studies are conducted using the three-temperature model. The calculated temperatures agree well with the measured temperatures by considering the electrons in the region ahead of the shock wave. This result suggests that the effect of electron behavior is significant for hypersonic shock waves and a detailed model to describe the nonequilibrium phenomena is needed.

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Nonequilibrium and equilibrium shock front radiation measurements

Cited by 92 publications

References 3 publications

Hypersonic Aerothermodynamics: Past, Present and Future

Hypersonic Aerothermodynamics: Past, Present and Future

NO and OH Spectroscopic Vibrational Temperature Measurements in a Post-Shock Relaxation Region

Numerical Analysis on the Nonequilibrium Phenomena of the Electronic Excitation Process behind Hypersonic Shock Waves

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