Abstract
In order to increase the thermal efficiency, combustion are designed to operate at higher temperature, which requires highly efficient cooling structures for combustion walls. Impingement is an effective structure to enhance the convective heat transfer in the combustion cooling. In the present study, two array impingement cooling structures with cross-flow are presented, and the heat transfer characteristics are obtained experimentally. The heat transfer performance of the impingement cooling structures are studied by using the transient liquid crystal thermography technique for turbulent flow in rectangular channels within the Reynolds number range from 75,000 to 125,000. The impingement hole diameters of the two test pieces were 12mm and 11mm, respectively. The impingement distances-to-hole diameter ratios (z/d) were 1.25 and 2, and the dimensionless hole spacing (x/d) was 2.5 and 2.727. It is found that crossflow shifts the jet downstream, resulting in asymmetric flow, the heat transfer coefficient upstream of the jet weakens, and the shape of stagnation area transitions from circular to hoof-shaped. The cross-flow disturbance accelerates the diffusion of the jet, which makes the distribution of the Nusselt number on the target more uniform, and the overall heat transfer on the target is enhanced. With the change of cross-flow intensity, there are differences in the influence of heat transfer on target under different impact geometries.
