Drag Reduction of a Hemispherical Body Adopting Spike at Supersonic Speed

Abstract

Use of spike on a hemispherical body changes the flow field and hence the aerodynamic drag. Experimental and computational studies have been made to obtain the flow field around a hemispherical body with spikes at a supersonic Mach number of 2. The effect of shape of spike tip and length has been studied. Experiments consisted of shadowgraph flow visualisation and measurement of drag. Computations have been made adopting structured grid and k-ω turbulence model using commercial software Fluent. It is observed that use of a sharp spike itself reduces the drag significantly. However the use of a hemispherical head spike further reduces the drag. Contribution of different components towards drag indicate that the increase in length of a spike do not change the spike contribution. However the flow field on main body is altered which leads to reduction in drag with change in length. Estimated drag generally found to be higher in comparison to measured value, however the trend is almost similar.