Experimental and numerical investigation on flow and heat transfer characteristics of swirl cooling with ribs

Swirl cooling is an advanced and efficient cooling method for gas turbine blade leading-edge. However, the swirl strength of coolant decreases rapidly along the swirl chamber. This paper investigated the swirl cooling with vertical ribs experimentally and numerically aiming to mitigate the effect of the low heat transfer zone and the crossflow. The experiment was carried out in an open wind tunnel where the target wall temperature was measured by infrared camera. The numerical simulations were performed by solving the 3D steady Reynolds-averaged Navier–Stokes equations (RANS). The mechanism of crossflow suppression and heat transfer enhancement of swirl cooling with ribs was revealed by comparing its simulation and measurement results with that of smooth swirl chamber under different Reynolds numbers. For smooth swirl chamber, the swirl strength decayed linearly, and the heat transfer coefficients decreased rapidly in axial direction. The circumferential velocity of the jet gradually decreased while the axial velocity increased forming the crossflow. For swirl chamber with ribs, the crossflow and downstream jets showed less interaction. The ability of the downstream jet to penetrate the main-stream and scour the target surface was strengthened and the heat transfer coefficient of the target surface near the downstream jet was enhanced.