Experimental investigation on heat transfer characteristics on target wall in a trapezoid duct with incline impingement jets

A simplified trapezoidal duct was built up to imitate the internal cooling cavities utilized near the leading edge. An experimental research on the impingement cooling in the trapezoidal duct was conducted to understand the flow fields in the duct and heat transfer characteristics on the target wall. The experimental data of the heat transfer was analyzed combining with that of the flow field. It is helpful to understand the heat transfer mechanism inside such a kind of confined channel. It can also provide some useful information for the design of a more effective internal cooling structure. The temperature on the target wall was measured by the thermocouples. The effects of the impingement angle, the cross flow and the impingement Reynolds number on the Nusselt number on the target wall were considered. Important results of the research include: the lower impingement jets impinge the target wall effectively, the higher impingement jets fail. The increase of the impingement angle enhances the impingement cooling of the lower impingement jets but has no effect on those at higher position. A strong cross flow severely impairs the heat transfer on the target wall, but the increase of the impingement Reynolds number improves the heat transfer ability evidently on the entire target wall. The data of the heat transfer experiment agrees well with the flow field analysis shown in the previous research.