Experimental study of interaction between supersonic duct flow and jets surrounded by the porous cavity

摘要

In the experiments, the effect of the combination of jets and a porous cavity on the flow field is studied by means of visualization of schlieren method and the measurements of wall static pressures and the flow direction in the cavity with the thermal tuft probe which is introduced in this paper. These measurements are performed simultaneously, which allow us to evaluate the effect of the jets and the porous cavity. Three cases for the jet arrangements are tested in this experiments. That is (1) no-jets issued only with a porous wall as a reference, (2) a single jet at the middle of the porous region, and (3) three jets in the porous region aligned spanwise to the main flow. As a result, the thermal tuft probe in the cavity is found to be non-disturbing detecting device to the whole flow field according to the shock locations and the wall static pressure measurements. It is also found that the flow direction in the cavity is greatly influenced by the starting shock wave and jet arrangements. The flow direction at the measurement positions in the cavity is always opposite to the main flow, as long as the starting shock wave is located upstream region of the porous wall for all jet patterns as well as the no-jets case. Moreover, in case that the starting shock wave exists downstream of the porous region, that is, the state of the main flow in the porous wall region is supersonic state, the flow direction in the cavity continues to be opposite to the main flow for a single jet issued at the middle of the porous wall. The results in this paper show that the combination of the jets and the porous cavity affects the shock positions and the flow direction in the cavity, which could be one of the promising techniques for the control of the flow field.