Numerical investigation on vane leading edge impingement cooling performance under influences of ribs established between adjacent jets

Abstract

Numerical studies on the vane leading edge jet impingement cooling are conducted to analyzed the influence of the cylindrical ribs applied between adjacent jets. A one-way inlet coolant supply channel and a one-way exit semicircular target channel are connected through single array of 10 jet holes. The gradually accumulated cross flow greatly decreases the impingement heat transfer intensity at the target channel downstream region. Therefore, the influences of rib diameters ( Dr/ D = 0.25, 0.5, 0.75, 1.0) and three rib to jet distances ( P/ D = 1.2, 1.5, 1.8) are numerically studied to decrease the effect of the cross flow and increase the impingement heat transfer performance as well as the heat transfer uniformity. The Reynolds-averaged Navier-Stokes equations (RANS) method coupled with Realizable k–ε turbulence model are used to complete the numerical simulation, the numerical method is carefully validated. The pressure and velocity distributions are illustrated. The effects of ribs on the flow characteristics inside the semicircular target channel are discussed and three major vortical structures are captured and compared. The two heat transfer enhancement mechanisms which depend on the rib to jet distance are also analyzed in detail. Results indicate that, with the application of ribs, the area-averaged Nusselt number increases about 4.3%–11.3% and the impingement heat transfer is more uniformly distributed along the target channel axis. When pursuing a larger heat transfer enhancement and a larger performance evaluation criterion (PEC), a larger rib diameter coupled with a larger rib to downstream jet distance is preferred, the largest PEC enhancement is about 8.1%.