Shock Wave Modification by a Plasma Spike: Experiment and Theory

Kuo, Spencer

doi:10.1238/physica.regular.071a00535

Cited by 9 publications

(7 citation statements)

References 17 publications

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“…In experiments, at the time when the gas pressure around the body significantly drops, recordings also show that the image of the front part of the shock wave becomes blurred or invisible and the deflection signals appear weaker and widened with time (shock "dispersion" and "disappearance") [10,12]. As was seen above, continuous stretching of the shock front during its advancement through the plasma transforms it from being nearly normal into an inclined one.…”

Section: Pressure Drop and Drag Reductionmentioning

confidence: 82%

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Wave Drag Modification in the Presence of Discharges

Markhotok¹

2021

Aerodynamics

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A phenomenological model of wave drag modification following the thermal energy deposition in a hypersonic flow is presented. While most of the previous research was concentrated on finding optimal gas parameter values and the amount of energy, this work points at closer attention to the effect of the parameter distribution and the geometry of experimental arrangements. The approach discussed here is to fill the gap in the understanding of the complex mechanism of the flow transformation leading to the wave drag reduction. Analytical expressions used in the model identify a number of adjustment parameters that can be used to optimize thermal energy input and thus achieve fundamentally lower drag values than that of conventional approaches.

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Section: Pressure Drop and Drag Reductionmentioning

confidence: 82%

“…The "physical spikes" representing an artificial sharpening of the front region of a blunt body can reduce the drag up to 30-45% [10]. It works through the replacement of nearly normal shock wave with a weaker, oblique shock structure.…”

Section: Introductionmentioning

confidence: 99%

Wave Drag Modification in the Presence of Discharges

Markhotok¹

2021

Aerodynamics

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“…To deflect the incoming flow effectively, it favors that plasma is generated in the region upstream of the baseline shock front and has a symmetrical spatial distribution with respect to the axis of a cone [23]. In the following discussion, a symmetrically distributed plasma generated in front of the base-line shock [22] [23] [24] [25] as the plasma deflector is assumed.…”

Section: Plasma Deflectionmentioning

confidence: 99%

Shock Wave Mitigation by Air Plasma Deflector

Kuo¹

2018

AAST

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When the spacecraft flies much faster than the sound speed (~1200 km/h), the airflow disturbances deflected forward from the spacecraft cannot get away from the spacecraft and form a shock wave in front of it. Shock waves have been a detriment for the development of supersonic aircrafts, which have to overcome high wave drag and surface heating from additional friction. Shock wave also produces sonic booms. The noise issue raises environmental concerns, which have precluded routine supersonic flight over land. Therefore, mitigation of shock wave is essential to advance the development of supersonic aircrafts. A plasma mitigation technique is studied. A theory is presented to show that shock wave structure can be modified via flow deflection. Symmetrical deflection evades the need of exchanging the transverse momentum between the flow and the deflector. The analysis shows that the plasma generated in front of the model can effectively deflect the incoming flow. A non-thermal air plasma, generated by on-board 60 Hz periodic electric arc discharge in front of a wind tunnel model, was applied as a plasma deflector for shock wave mitigation technique. The experiment was conducted in a Mach 2.5 wind tunnel. The results show that the air plasma was generated symmetrically in front of the wind tunnel model. With increasing discharge intensity, the plasma deflector transforms the shock from a welldefined attached shock into a highly curved shock structure with increasing standoff distance from the model; this curved shock has increased shock angle and also appears in increasingly diffused form. In the decay of the discharge intensity, the shock front is first transformed back to a well-defined curve shock, which moves downstream to become a perturbed oblique shock; the baseline shock front then reappears as the discharge is reduced to low level again. The experimental observations confirm the theory. The steady of the incoming flow during the discharge cycle is manifested by the repeat of the baseline shock front.

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“…Symmetrically distributed plasma in front of the base-line shock, acting as a spike to deflect the flow [14][15][16], will be incorporated into the formulation of the theory for interpreting the experimental observations. This plasma spike is introduced at a location in front of the model by an on-board electrical discharge, which is triggered by a negative voltage applied between the grounded body of the cone and the tip of the cone located at z = 0, which is insulated from the body.…”

Section: Plasma Spike and Flow Deflectionmentioning

confidence: 99%

Nonthermal Plasma Mitigation of Shock Wave in Supersonic Airflow~!2009-04-01~!2009-05-11~!2009-07-16~!

Kuo¹

2009

TOPPJ

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A non-thermal technique using a plasma spike, generated by 60 Hz periodic electric discharge, for shock wave mitigation is presented. The experiments were conducted in a Mach 2.5 wind tunnel. A plasma spike was generated in front of a wind tunnel model; it led to a transformation of the shock from a well-defined attached shock into a highly curved shock structure, which had increased shock angle and also appeared in diffused form. As seen in a sequence with increasing discharge intensity, the shock in front of the model moved upstream to become detached with increasing standoff distance from the model and was eliminated near the peak of the discharge. The power measurements excluded the heating effect as a possible cause of the observed shock wave modification. A theory using a cone model as the shock wave generator is presented to explain the observed plasma effect on shock wave. The analysis has shown that the plasma generated in front of the model can effectively deflect the incoming flow; such a flow deflection modifies the structure of the shock wave generated by the cone model, as shown by the numerical results, from a conic shape to a curved one. The shock front moves upstream with a larger shock angle, matching well with that observed in the experiment.

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Shock Wave Modification by a Plasma Spike: Experiment and Theory

Cited by 9 publications

References 17 publications

Wave Drag Modification in the Presence of Discharges

Wave Drag Modification in the Presence of Discharges

Shock Wave Mitigation by Air Plasma Deflector

Nonthermal Plasma Mitigation of Shock Wave in Supersonic Airflow~!2009-04-01~!2009-05-11~!2009-07-16~!

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