Study of a non-reacting hypersonic flow over an external cavity with flow injection using DSMC method

Abstract

In the current study, a DSMC solver is utilized to study a rarefied external cavity flow. The main focus of this research is mainly on the properties of flow near the rear wall of the cavity. It is observed that the flow temperature near the wall increases by increasing the free stream Mach number. Also, the cavity length-to-depth (L/D) ratio affects the flow structure dramatically in a constant Mach number. Injection from the rear wall of the cavity is studied. Results show that injection does not affect cavity vortex location. Local density and x-velocity increase is observed at the point of injection. Nonmonotonic y-velocity behavior is seen as a result of cavity vortex interaction with low-momentum injection fluid. Dimensionless temperature is decreased significantly due to injection. So, it can be treated as a remedy to decrease surface heat transfer coefficient. No significant impact is seen on the wall pressure coefficient and friction coefficient due to injection. The average number flux is increased due to injection. Higher L/D ratios result in a higher average heat transfer coefficient while having lower gradients along the wall. Enhancing the injection velocity would decrease the heat transfer coefficient and promotes cooling effects. Cold-to-hot heat transfer occurs inside the cavity and heat flux lines show that injection, decreases the flow temperature inside the cavity near the rear wall in comparison with no injection case.