Shock wave is a detriment in the development of supersonic aircrafts; it increases
flow drag as well as surface heating from additional friction; it also initiates sonic
boom on the ground which precludes supersonic jetliner to fly overland. A shock
wave mitigation technique is demonstrated by experiments conducted in a Mach 2.5
wind tunnel. Non-thermal air plasma generated symmetrically in front of a wind
tunnel model and upstream of the shock, by on-board 60 Hz periodic electric arc
discharge, works as a plasma deflector, it deflects incoming flow to transform the
shock from a well-defined attached shock into a highly curved shock structure. In a
sequence with increasing discharge intensity, the transformed curve shock increases
shock angle and moves upstream to become detached with increasing standoff distance
from the model. It becomes diffusive and disappears near the peak of the discharge.
The flow deflection increases the equivalent cone angle of the model, which
in essence, reduces the equivalent Mach number of the incoming flow, manifesting
the reduction of the shock wave drag on the cone. When this equivalent cone angle
exceeds a critical angle, the shock becomes detached and fades away. This shock
wave mitigation technique helps drag reduction as well as eliminates sonic boom.
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Kuo, S.P., Kalkhoran, I.M., Bivolaru, D. and Orlick, L. (2000) Observation of Shock Wave Elimination by a Plasma in a Mach-2.5 Flow. Physics of Plasmas, 7, 1345-1348.
Sun, Q., Cheng, B.Q., Li, Y.H., Kong, W.S., Li,J., Zhu, Y.F. and Jin, D. (2013) Computational and Experimental Analysis of Mach 2 Air Flow over A Blunt Body with Plasma Aerodynamic Actuation. Science China Technological Sciences, 56, 795-802.