Numerical investigation of flow and heat transfer in rotating trapezoidal channel with lateral slots and dimple structure

摘要

High-efficiency trailing edge cooling technology is essential for the safe and stable operation of turbine blades. In this paper, trapezoidal trailing edge channels with lateral slots are modeled, and a variety of dimples with different sizes and arrangement densities are placed on the end walls. Flow characteristics, wall heat transfer distributions and overall heat transfer performance under stationary and rotating states are numerically investigated and effects of dimple arrangement, rotation number (Ro) and channel orientation (β) are comprehensively analyzed. The results show that, under rotating state, the Coriolis force leads to the flow separation, while dimples promote the generation and development of three-dimensional spatial vortices, and effectively suppresses the expansion of separation area. Dimples greatly improve the rotating cooling performance, and there exists a critical point of arrangement density, in which the maximum heat transfer level is obtained. A 108.2% improvement in relative Nusselt number of trailing surface can be achieved by increasing rotation number in dimple channels. And the operation condition of Ro = 0.8 and β = 15° is recommended for the cooling of trapezoidal trailing edge. Compared with rotation number, the channel orientation has a stronger effect on the flow and heat transfer performances.