Numerical Investigation of Hypersonic Flow Past a Spherically Blunted Nose Cone

This paper numerically investigates the flow past a spherically blunted nose cone at a hypersonic Mach number of 5.8. The present study focuses in determining the flow/shock characteristics of the nose cone such as pressure coefficient, shock detachment distance and location and shape of bow shock formed ahead of the spherically blunted nose cone etc. The shock detachment distance, pressure coefficient, location and shape of bow shock in spherically blunted cones have numerous applications in the design of high speed aerodynamic vehicles such as space shuttles, missiles, rockets etc. The design of geometric parameters in hypervelocity vehicles are very important and are highly challenging for improving its performance and hence to alleviate the aerodynamic heating. The key parameters that play a significant role in affecting the aerodynamic characteristics of nose cone are semi-cone angle, bluntness ratios etc. Therefore, the present study focuses to investigate the effect of semi-cone angles of 5° and 20° and bluntness ratios of 0.4 and 0.8, in order to understand the aerodynamic performance characteristics of the spherically blunted nose cones. The velocity vector shows the flow direction which indicate clearly the deceleration near the nose, re-acceleration through the sideways of the nose cone as well the formation of recirculation zone behind the cone base. The shape and location of the bow shock formed ahead of the nose as well as the shock detachment distance is shown with the help of the Mach number contour. It is observed that the pressure coefficient decreases rapidly up to a certain distance along the wall and thereafter it remains almost constant for both the bluntness ratios (0.4 and 0.8) and semi cone angles (5° and 20°). It is observed that there is no significant variation in the shock detachment distance observed for both the bluntness ratios (0.4 and 0.8) and semi cone angles (5° and 20°) studied. In general, it is observed that increase in temperature is more for small semi cone angles and bluntness ratios and it decreases for higher bluntness ratios and cone angles. The increase in temperature may be due to viscous dissipation which arises due to curved shocks which makes the flow rotational due to the existence of large entropy gradients. A minimum temperature is achieved for a bluntness ratio of 0.8 and 20° semi cone angle. Thus, this paper sufficiently demonstrates the effect of different bluntness ratios and semi cone angles on the aerodynamic as well as heating characteristics of a spherically blunted nose cone.