Drag Reduction for Spike Attached to Blunt-Nosed Body at Mach 6

Abstract

A HIGH-SPEED flow over a blunt body generates a bow shock wave in front of it, which causes a rather high surface pressure and, as a result, high aerodynamic drag. The surface pressure on the blunt body can be substantially reduced if a conical shock wave is generated by attaching a forward-facing spike. Thus, the introduction of the spike decreases the drag and increases the lift coefficient. The spike produces a region of recirculating separated flow that shields the blunt-nosed body from the incoming flow. The applicability of the spike is limited due to the possible appearance offlowoscillations in the separation region, which may reduce its positive effects and may cause aerodynamic disturbances during the flight [1]. Many experimental studies focused their attention on the influence of the spike’s length on the aerodynamic characteristics of blunt bodies for various angles of attack at some transonic [2], supersonic [3–5], or even hypersonic [6–8] speeds. This Note contributes to the experimental study of the fluid flow structure and aerodynamic characteristics of a spike attached to blunt body atMach 6. This Note analyzes the aerodynamic effects of the spike attached to the blunt body by using schlieren flow visualization and measured aerodynamic forces and moments. This Note briefly describes the experimental results of the research on a hemispherical blunt nose body with and without spike at L=D ratio of 1.5 and 2 (where L is the spike length and D is cylinder diameter), and angle of attack from 0 to 8 deg, with a 1 deg step. An in-depth description of the experiment conditions and results may be found in [9].