Aero-Thermal Analysis of Rarefied Flow Over Inverse Cone Shaped Objects Using Direct Simulation Monte Carlo Analysis

Abstract

When an object undergoes atmospheric entry it experiences drag and heat load over its surface which determines its trajectory and ability to survive the hostile flow conditions. This work performs numerical analysis using direct simulation Monte Carlo (DSMC) simulations to study key flow features and properties on a cone-shaped body. The cone is created by varying the angle of extrusion ($\alpha$) of the flat-nosed face of a cylinder in positive and negative directions. Detailed analysis of the key flow features is conducted and the results of the distribution of surface heat transfer and drag coefficient on each of the negative $\alpha$ are contrasted against the results obtained for zero and positive $\alpha$ for which compressible flow physics are well defined. For $\alpha \leq 45\degree$, heat flux increases with an increase in $\alpha$ while the total drag experienced by the body decreases. Meanwhile, when $\alpha$ is increased in the negative direction an inverse cone is formed, which creates a cavity inside the body, and the body decelerates more with an increasing magnitude of $\alpha$ while the wall heat flux inside the cone remains quite low. These conditions allow the body to maintain a significantly low temperature during high-speed flow, like in the case of planetary entry, in comparison with the high temperature resulting for $\alpha \geq 0\degree$ cases. The present study also helps to improve the understanding of optimum cone-shaped space objects, from the perspective of drag and heat flux.