Rearrangement of the bow shock shape using a ?hot spike?

Nemchinov, I. V.; Artem'ev, V. I.; Bergelson, Vitaly; Khazins, V. M.; Орлова, Т. И.; Rybakov, V. A.

doi:10.1007/bf01414630

Cited by 25 publications

(17 citation statements)

References 9 publications

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“…Such an aerospike generally protrudes well ahead of the vehicle nose, creating its own shock wave, and significantly reduces the drag on the vehicle. This technique is still being investigated, for example, by Guy et al 2 and by Nemchinov et al, 3 who took it even further by looking at shock interaction with a heated "hot" spike. Other mechanical methods of affecting the shock wave have also been researched over the decades, including counterpropagating streams of gas, 4,5 heated/reacting/ionized gas, 6 and liquid (e.g., water) and even using an ablative aerospike (e.g., Teflon TM ) to deposit its degradation products into the flow.…”

Section: B Past Workmentioning

confidence: 99%

Computational Study of Shock Mitigation and Drag Reduction by Pulsed Energy Lines

2006

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A series of numerical experiments were performed in which energy was deposited ahead of a cone traveling at supersonic/hypersonic speeds. The angle of attack was zero, and the cone half-angles ranged from 15 to 45 deg. The Mach numbers simulated were 2, 4, 6, and 8. The energy was deposited instantaneously along a finite length of the cone axis, ahead of the cone's bow shock, causing a cylindrical shock wave to push air outward from the line of deposition. The shock wave would sweep the air out from in front of the cone, leaving behind a low-density column/tube of air, through which the cone (vehicle) propagated with significantly reduced drag. The greatest drag reduction observed was 96%. (One-hundred percent drag reduction would result in the complete elimination of drag forces on the cone.) The propulsive gain was consistently positive, meaning that the energy saved as a result of drag reduction was consistently greater than the amount of energy "invested" (i.e., deposited ahead of the vehicle). The highest ratio of energy saved/energy invested was approximately 6500% (a 65-fold "return" on the invested energy). We explored this phenomenon with a high-order-accurate multidomain weighted essentially nonoscillatory finite difference algorithm, using interpolation at subdomain boundaries. This drag-reduction/shock-mitigation technique can be applied locally or globally to reduce the overall drag on a vehicle.

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Section: B Past Workmentioning

confidence: 99%

Computational Study of Shock Mitigation and Drag Reduction by Pulsed Energy Lines

2006

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“…The sine of the angle between the oblique shock wave and the thermal layer is approximately proportional to the ratio of the speed of sound in the ambient gas to that in the thermal layer (Bergel'son et al 1987). The process of the shock wave interaction with the thermal layer was fairly well investigated recently (see: Nemchinov et al 1994;Shuvalov 1999). With sufficiently high free-stream Mach numbers, the flowfield is nonstationary, and a recirculation zone, a vortex, a system of inner shock waves and contact boundaries develops within the precursor.…”

Section: Numerical Solutions Of the Test Problemmentioning

confidence: 99%

“…A small particle, a thin thermal layer or a thin cylindrical hot spike placed upwind of the shock can cause disturbances (see, for example: Holden et al 1976;Glovacki et al 1985;Mirels 1988;Nemchinov et al 1994). The shock wave moves faster along the thermal layer and a large-scale vortex develops behind the oblique shock wave.…”

Section: Introductionmentioning

confidence: 99%

Vortical regime of the flow behind the bow shock wave

Svetsov

2001

Shock Waves

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A new nonstationary regime of the flow around a step and a cylinder was found to exist at high free-stream Mach numbers for gas specific heat ratios below 1.2. The main features of the flow are strong vortices in the shock-compressed region with supersonic reversal velocities at the body face. The bow shock wave takes on a complicated shape, fluctuating in time. The vortical regimes can result from local heterogeneities in the free stream. The case of the heterogeneity is studied in this paper in the form of a thin thermal layer of limited length. The vortical regime remains in existence after the source of disturbances is removed. The results have been obtained through computer simulations through the use of Eulerian hydrodynamic equations and by way of several numerical methods: FLIC, Godunov's scheme, TVD, and PPM. The influence of viscosity on the development of the vortical regime has been studied by computer solving the Navier-Stokes equations.

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“…Various methods of quasi-steady periodic pulsed 1, 2 or DC-discharge energy deposition [3][4][5][6][7] have been investigated for blunt body wave drag reduction and flight control purposes in super-and hypersonics during the last decades. Mainly focused laser/microwave pulses or electrostatic discharge devices are suitable to ignite a plasma which provokes an intense energy deposition.…”

Section: Introductionmentioning

confidence: 99%

Wave Drag Reduction of Blunt Bodies Using Laser Sustained Energy Deposition In Argon Atmosphere

Sperber

Schmid

Eckel

et al. 2012

6th AIAA Flow Control Conference

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Laser-induced energy deposition has been proposed for an effective flow control concept in super-and hypersonic transportation. Especially for blunt bodies the strength of the normal shock waves can be significantly mitigated by a modification of the gas temperature commonly generated by spark-discharge or repetitive laser-induced gas breakdown. The paper presents experimental and computational results of a laser-induced, non-repetitive gas heating concept in supersonic argon flow. Ignited by the gas breakdown of a Q-switched Nd:YAG laser a focused continuous wave CO2 laser sustains a plasma. The pressure distribution of a miniature hemisphere is measured by four static pressure taps and determines a drag reduction of up to 55 % for the Mach number 2.1 and of up to 60 % for the Mach number 2.7 using an average pulse power of up to 5.4 kW for a typical duration of 700 µs.

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Rearrangement of the bow shock shape using a ?hot spike?

Cited by 25 publications

References 9 publications

Computational Study of Shock Mitigation and Drag Reduction by Pulsed Energy Lines

Computational Study of Shock Mitigation and Drag Reduction by Pulsed Energy Lines

Vortical regime of the flow behind the bow shock wave

Wave Drag Reduction of Blunt Bodies Using Laser Sustained Energy Deposition In Argon Atmosphere

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