Conditions and a Physical Mechanism for Plasma Mitigation of Shock Wave in a Supersonic Flow

Kuo, Spencer

doi:10.1088/0031-8949/70/2-3/014

Cited by 10 publications

(3 citation statements)

References 21 publications

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“…The results extracted from the videotapes of the shadow image of the flow and the airglow images of the plasma provide crucial information on the correlation between plasma distribution and modification of shock structure. It was shown [20] that significant plasma effect on the shock wave appeared under two conditions: (i) the plasma is generated in the region upstream of the baseline shock front and (ii) the plasma has a symmetrical spatial distribution with respect to the axis of the model. This conclusion is exemplified by comparing the two sets of video graphs presented in figure 2.…”

Section: Resultsmentioning

confidence: 99%

On plasma mitigation of shock waves

Kuo¹

2006

Phys. Scr.

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Experiments were conducted in a Mach 2.5 wind tunnel to explore the modification effect on the shock wave structure by a plasma spike generated by an on-board 60 Hz electric discharge in front of a 60° cone-shaped model, which was used as a shock wave generator. Modification of the shock by the plasma spike from an attached conic shock into a highly curved shock structure, which has increased shock angle and also appears in diffused form, is demonstrated. Due to the cyclic nature of the generated plasma an unsteady shock motion during one discharge period was observed. As shown in a sequence with increasing discharge intensity, the shock in front of the model moves upstream to become detached with increasing standoff distance from the model and with increasing dispersion in the spatial distribution of the shock front. Experimental results exclude the heating effect as a possible cause of the observed shock wave modification. A theory also using a cone model as the shock wave generator is presented to explain the observed plasma effect on the shock wave. Analysis shows that the plasma spike can effectively deflect the incoming flow before the flow reaches the cone model; such a flow deflection modifies the structure of the shock wave generated by the cone model from conic shape to a curved one. The shock front moves upstream with a larger shock angle, consistent with the experimental results.

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Section: Resultsmentioning

confidence: 99%

On plasma mitigation of shock waves

Kuo¹

2006

Phys. Scr.

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“…The considered physical mechanism is to symmetrically deflect the flow by a symmetrically distributed plasma spike in front of the baseline shock. Plasma electrons are kept in place in front of the tip of the wedge by the local electric field to act as a spike to deflect the flow [23]. The transverse perturbation in neutral particles' momentum is distributed symmetrically in opposite directions.…”

Section: Discussionmentioning

confidence: 99%

Shock Wave Modification by a Plasma Spike: Experiment and Theory

Kuo¹

2005

Phys. Scr.

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Experiments were conducted in a Mach 2.5 wind tunnel to explore the modification effect on the shock wave structure by a plasma spike generated by an on-board 60 Hz electric discharge in front of a 60 • cone-shaped model, which is used as a shock wave generator. Due to cyclic nature of the generated plasma an unsteady shock motion during one discharge period was observed. The pronounced influence of plasma on the shock structure is clearly demonstrated by the result, at the peak of the discharge, showing a transformation of the shock from a well defined attached shock into a classic highly curved bow shock structure, which also appears in diffused form. Experimental results exclude the heating effect as a possible cause of the observed shock wave modification. A theory using a wedge model as the shock generator is developed to introduce a non-heating mechanism responsible for the observed plasma effect on shock waves. Analysis shows that the plasma spike can effectively deflect the incoming flow before the flow reaches the wedge; consequently the shock structure in the interaction region is modified from an oblique one to a slightly curved one. The shock front moves upstream with a larger shock angle, consistent with the experimental results.

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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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Conditions and a Physical Mechanism for Plasma Mitigation of Shock Wave in a Supersonic Flow

Cited by 10 publications

References 21 publications

On plasma mitigation of shock waves

On plasma mitigation of shock waves

Shock Wave Modification by a Plasma Spike: Experiment and Theory

Shock Wave Mitigation by Air Plasma Deflector

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