Ballistic range tests in weakly ionized argon

Lowry, Heard; Smith, Mike; Sherrouse, Peter; Felderman, John; Drakes, J. A.; Bauer, M. L.; Pruitt, D.; Keefer, Dennis

doi:10.2514/6.1999-4822

Cited by 13 publications

(3 citation statements)

References 3 publications

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“…Lowry et al conducted shock standoff distance measurements in air, which spanned the range between that expected due to the thermal effects and that measured in the Ioffe Institute tests. As seen in figure 16, the ratio of the measured shock standoff to the sphere diameter in air at approximately 1600 m s −1 fell between that expected at 1300 K, which was the Lowry et al [18] also conducted a series of tests in argon plasma to investigate if the effects of vibrational nonequilibrium in air plasma could have impacted the flowfield around the sphere. In these experiments, the shock standoff distances were found to be consistent with the measured temperature in the discharge.…”

Section: Plasma Aerodynamics In Ballistic Range Testmentioning

confidence: 76%

Plasmas in high speed aerodynamics

Bletzinger¹,

Ganguly²,

Wie³

et al. 2005

J. Phys. D: Appl. Phys.

293

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A review is presented of the studies in the former Soviet Union and in the USA of the mutual interactions of plasmas and high speed flows and shocks. There are reports from as early as the 1980s of large changes in the standoff distance ahead of a blunt body in ballistic tunnels, significantly reduced drag and modifications of travelling shocks in bounded weakly ionized gases. Energy addition to the flow results in an increase in the local sound speed that leads to expected modifications of the flow and changes to the pressure distribution around a vehicle due to the decrease in local Mach number. The critical question was, did a plasma provide a significant energy multiplier for the system? There have been a large number of experimental studies on the influence of a weakly ionized plasma on relatively low Mach number shocks and inherently also on the influence of the shock on the plasma. This literature is reviewed and illustrated with representative examples. The convergence through more controlled experiments and improved modelling to a physics understanding of the effects being essentially due to heating is outlined. It is demonstrated that the heating in many cases is global; however, tailored experiments with positive columns, dielectric barrier discharges and focused microwave plasmas can produce very localized heating. The latter appears more attractive for energy efficiency in flow control. Tailored localized ionization and thermal effects are also of interest for high speed inlet shock control and for producing reliable ignition for short residence time combustors, and work in these areas is also reviewed.

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Section: Plasma Aerodynamics In Ballistic Range Testmentioning

confidence: 76%

Plasmas in high speed aerodynamics

Bletzinger¹,

Ganguly²,

Wie³

et al. 2005

J. Phys. D: Appl. Phys.

293

View full text Add to dashboard Cite

show abstract

“…This small shock movement was attributed to the lack of vibrational excitation of argon as opposed to air. 2 However, with the new calculations presented in this report, we must re-assess this conclusion.…”

Section: Argon Experimentsmentioning

confidence: 99%

“…2 Standoff distance ratios of between 0.22 and 0.28 were measured, as compared to a ratio of 0.24 with no plasma. This small shock movement was attributed to the lack of vibrational excitation of argon as opposed to air.…”

Section: Argon Experimentsmentioning

confidence: 99%

Effect of Internal Energy Excitation on Supersonic Blunt-Body Aerodynamics

Candler¹

2001

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Dynamics of Shock Dispersion and Interactions in Supersonic Freestreams with Counterflowing Jets

et al. 2009

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An active flow control concept using counterflowing jets to significantly modify the external flowfields and strongly weaken or disperse the shock-waves of supersonic and hypersonic vehicles to reduce the aerothermal loads and wave drag was investigated. Experiments were conducted in a trisonic blow-down wind-tunnel, complemented by pre-test computational fluid dynamics (CFD) analysis of a 2.6% scale model of Apollo capsule, with and without counterflowing jets, in Mach 3.48 and 4.0 freestreams, to assess the potential aerothermal and aerodynamic benefits of this concept. The model was instrumented with heat flux gauges, thermocouples and pressure taps, and employed five counterflowing jet nozzles (three sonic and other two supersonic with design Mach numbers of 2.44 and 2.94) and nozzle exit diameters ranging from 0.25 to 0.5 inch. Schlieren data show that at low jet flow rates of 0.05 and 0.1 lb,/sec, the interactions result in a long penetration mode (LPM) jet, while the short penetration mode (SPM) jet is observed at flow rates greater than 0. Ilb,/sec., consistent with the pre-test CFD predictions. For the LPM, the jet appears to be nearly hlly-expanded, resulting in a very unsteady and oscillatory flow structure in which the bow shock becomes highly dispersed such that it is no longer discernable. Higher speed camera Schlieren data reveal the shock to be dispersed into striations of compression waves, which suddenly coalesce to a weaker bow shock with a larger standoff distance as the flow rate reached a critical value. The pronounced shock dispersion could significantly impact the aerodynamic performance (L/D) and heat flux reduction of spacecrafk in atmospheric entry and re-entry, and could also attenuate the entropy layer in hypersonic blunt body flows. For heat transfer, the results show significant reduction in heat flux, even giving negative heat flux for some of the SPM interactions, indicating that the flow wetting the model is cooling, instead of heating the model, which could significantly impact the requirements and design of thermal protection system. These findings strongly suggest that the application of counterflowing jets as active flow control could have strong impact on supersonic and hypersonic vehicle design and performance. IntroductionOne of the technical challenges in space exploration and interplanetary missions is controlled entry and re-entry into planetary and Earth atmospheres, which requires the dissipation of considerable kinetic energy as the spacecrafk decelerates and penetrates the atmosphere. As such, effective heat load management of stagnation points and acreage heating remain a technological challenge and pose significant risk, especially for human missions.

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Ballistic range tests in weakly ionized argon

Cited by 13 publications

References 3 publications

Plasmas in high speed aerodynamics

Plasmas in high speed aerodynamics

Effect of Internal Energy Excitation on Supersonic Blunt-Body Aerodynamics

Dynamics of Shock Dispersion and Interactions in Supersonic Freestreams with Counterflowing Jets

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