On the Structure of an Impact Jet with Flow Swirling and Combustion

The PIV and PLIF OH techniques were used to experimentally study the structure of a jet impinging on a flat obstacle with swirling and combustion of a propane–air mixture with an equivalence ratio of 0.7 for a nozzle–obstacle distance H/d = 1 and 3 and in the absence of the obstacle. The swirl ratio was 0.41 and 1.0, and the Reynolds number was 5 000. It is concluded that for both values of the swirl ratio, the presence of the impact surface leads to the formation of an extended central cone-shaped recirculation zones. For H/d = 3 and 2, the OH fluorescence intensity near the impact surface and inside the recirculation zone is significantly reduced. This effect may be caused by a decrease in the temperature of combustion products in the recirculation zone, including in the vicinity of the flame front.