Supersonic Drag Reduction over a Blunt-Body by Combination of Conical Spike and Energy Deposition

Abstract

Drag reduction performance over a blunt-body by a combination of a conical spike and repetitive energy depositions is investigated. Experiments are conducted in a Mach 2 supersonic flow in an in-draft wind tunnel, varying the length and the apex angle of the spike on a flat head body and the repetitive frequency of laser pulse energy depo-sitions from 0 to 60 kHz. Computational fluid dynamics calculations are done to diagnose the flow fields. Comparison is made between the experiment and calculation with respect to visualized flow fields and to the drag. When the length of the spike is shorter than the shock stand-off distance over the body without the spike, the effect of the spike is significant in low repetitive frequencies of up to 40 kHz. In even higher repetitive frequencies, the impact of the spike becomes weak; the drag reduction is primarily attributed to energy deposition. D D 0 @@@@@@@@@@@@@@@@@@@@ d d 0 E 1 f l M P q 0 1 (r, z)2 r 0 s t u ∆D δ η η a * 1 C ⃝ 2014 25 10 3 * 2 * 3 θ λ σ τ 1 1. 1 18) ∆D/D 0 1) η ∆D D 0 = D − D 0 D 0 (1) η = u × (−∆D) P (2) η ∆D/D 0 < 0 η > 1 Tret'yakov 2) M = 2.0 CO 2 100 kHz ∆D/D 0 = 45% η < 1 Kim 3) M = 1.92 Nd:YVO 4 80 kHz