Experiment Study Of Convective Heat Transfer And Discharge Coefficient Of Jet Impingement Inside Semi-confined Channel

Jet impingement cooling is an advantage method in heat transfer enhancement owing to its extremely high local heat transfer coefficient and simple structure. As regard as the combustor flame tube cooling structure is concerned, the impingement-converse convection-film composite cooling is an effective method, in this composite cooling structure, the impingement cooling problem could be modeled as impingement inside semi-confined channel. The main research contents are the following.The thermal visualizations of jet impingement cooling with single or double row holes inside semi-enclosed channel are measured by using infrared camera and then the impingement cooling heat transfer coefficients are deduced. The effects of flow and geometry parameters on convective heat coefficients are obtained. The results show that: for a single row normal impingement, the impingement cooling effectiveness is enhanced with the increase of impinging Reynolds number or the decrease of hole space to diameter ratio, and the best effectiveness is achieved under the jet-to-surface spacing equals to 2; when the jet is oblique to the confined wall, the cooling effectiveness is weaken especially under the jet-to-surface spacing ratio is greater than 2; for double rows normal impingement cooling, the cooling effectiveness of rear row jet is weaker than the front row under lower impinging Reynolds number or bigger jet-to-surface spacing. Then the thermal visualizations of jet impingement cooling with single or double row holes inside semi-enclosed ribbed channel are measured by using infrared camera and the effects of flow and geometry parameters on convective heat coefficients are obtained. The results show that: the impingement cooling effectiveness of ribbed surface is affected greatly by the jet-to-surface spacing, and the best effectiveness is achieved under the jet-to-surface spacing equals to 1. The correlation formulas of impingement heat transfer characteristics to the parameters are finally concluded and in good agree with the experiment data.