Drag and heat flux reduction induced by the pulsed counterflowing jet with different waveforms on a blunt body in supersonic flows

The drag and heat flux reduction characteristics plays a very important role in the conceptual design phase and engineering realization of the aerospace vehicle. In the current study, the flow field properties around a blunt body with three different pulsed counterflowing jets in the supersonic flow with the freestream Mach number being 3.98 are investigated numerically. In this paper, there are three different kinds of pulsed jets with the sinusoidal, triangular and rectangular waveforms are established, and the periods of the pulsed jets are all set to be T = 1.0 ms. The jet nozzle is placed at the nose of the blunt body. In the numerical investigation, an axisymmetric numerical simulation model of the counterflowing jet on the supersonic vehicle nose-tip is established, and the two-dimensional axisymmetric Reynolds-averaged Navier-Stokes (RANS) equations coupled with the two equation k-co shear stress transport (SST) turbulence model are employed. The wall Stanton number distributions, as well as the surface static pressures, are extracted from the flow field structures in order to evaluate the drag and heat flux reduction characteristics. Further, the influence of the pulsed jet waveform on the drag and heat flux reduction is analyzed based on the wall Stanton number and surface pressure distributions. The obtained results show that the variations of the wall Stanton number and surface pressure distributions induced by the pulsed jet with the same period but different waveforms, all have an obvious periodicity and hysteresis phenomenon. At the same time, it is found that the drag and heat flux reduction under the triangular wave has the best effect, and the pulsed jet with the triangular wave has a better comprehensive performance than the other two waveforms.