Behaviors of the long penetration mode with a hot counterflowing jet

Abstract

When an aircraft flies at hypersonic speeds, a large aerodynamic drag and a significant amount of aerodynamic heat are generated around it. As an active flow control technology, counterflowing jets can effectively reduce the drag and heat flux and have therefore attracted broad attentions. However, the oscillation problem that accompanies counterflowing jets remains to be studied further. The present study aims to investigate the oscillation properties of the flow around a hypersonic vehicle with a hot counterflowing jet using a numerical solver with a single-temperature multi-component chemical reaction model. A hypersonic hemispherical-nosed is selected and the solver is developed on the OpenFoam platform. The drag reduction efficiency, the flow field structure, and the flow instability characteristics for different jet temperatures are discussed in detail. It is found that a high-temperature jet can reduce the amplitude of the drag force significantly and even suppress the flow oscillation, and the drag reduction efficiency per unit mass increases with the jet temperature. For the same efficiency, a high-temperature jet has a smaller mass flow rate which may reduce the load of flight and lead to savings in space and cost. Therefore, within the allowable range of heat flux, increasing the jet temperature might be a more effective method for reducing drag and stabilizing the flow field than increasing the jet pressure ratio as usually thought. It is hoped that the present results serve to advance the application and the development of hypersonic counterflowing jet technology.