Large eddy simulation of the trenched film cooling hole with different compound angles and coolant inflow orientation effects

Abstract

The trenched-hole film cooling with different compound angles and coolant inflow orientations is investigated at the blowing ratio of M = 1.0 by large eddy simulation (LES). The compound angle (CA) is 0° and 90° which are commonly used in the actual application. The plenum inflow directions include the inflow fed from the plenum base (VP), the coolant orientation into the plenum vertical to (VV) and parallel to (PM) the mainstream flow. Results show that the compound angle of 90° generates a downstream asymmetrical vortex and increases the complexity of flow characteristics. This vortex is related to the low-speed recirculation region in the jet tube. Nevertheless, the trenched hole of CA = 90° improves the lateral coolant coverage, compared with CA = 0°. The coolant inflow orientations have been demonstrated to exert a significant effect on film cooling effectiveness for the round and shaped hole. The trench hole of CA = 0° narrows the difference of velocity distribution on the trench exit due to the redistribution of coolant in the trench. For CA = 90°, the decline of cooling effectiveness declines more obviously while the plenum inflow direction is vertical to the direction of the jet tube.