Research On Heat Transfer Characteristics Of Jet Impingement Inside Semi-confined Rib-roughed 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 followings:The thermal visualizations of jet impingement cooling with single or double row holes inside semi-confined channel are studied by numerical method and then the impingement cooling heat transfer coefficients are deduced. The effects of both flow and geometry parameters on convective heat coefficients are obtained. The results show that: for a single row impingement, the impingement cooling effectiveness is enhanced with the increase of impinging Reynolds number and the decrease of hole space to diameter ratio, and when the jet-to-surface spacing equals to 1 and 2, relatively the same convective heat coefficients are obtained, better than the case that when the jet-to-surface spacing equals to 3; for double rows impingement cooling, the effective cooling area is expanded with the increase of row space.Then the thermal visualizations of jet impingement cooling with single row holes inside semi-confined rib-roughed channel are investigated by both numerical and experimental methods. The effects of flow and geometry parameters on convective heat coefficients are also obtained. Comparing the data obtained by the two methods, the results show that: the impingement cooling effectiveness of ribbed surface is affected extremely by the jet-to-surface spacing, and the best effectiveness is achieved under the jet-to-surface space equaling to 1; The rib pattern also plays great impact on cooling effectiveness, in present research scope the V-shaped ribs perform best.In order to determine the discharge coefficient for jet impingement cooling with single row holes inside semi-confined channel, an experimental investigation is performed and the influence factors are analyzed.