| An experimental investigation was carried out to determine the effects of the number of unblocked cross-over holes and different flow arrangements on heat transfer coefficients in impingement cooling over a curved surface, simulating the leading-edge cooling cavity of an airfoil. A jet plate through which impingement took place divided the test section to two main parts; the supply channel through which the flow was directed into the test section and the leading-edge channel were the targeted surface was installed. Experimental results were obtained for five cases: (1) nine cross-over holes, (2) eight cross-over holes, (3) seven cross-over holes, (4) six cross-over holes and (5) five cross-over holes. The different flow arrangements tested were: (1) flow entering from one side of supply channel and leaves from the opposite side of the L.E channel (parallel), (2) flow entering from one side of the supply channel and leaves from the same side of the L.E channel (circular), (3) flow entering from one side of the supply channel and leaves from both side of L.E channel (both-end-open), (4) flow entering the test section from both side of the supply channel and leaves from both sides of L.E channel. The nine, eight and five unblocked holes were tested for parallel, circular, both-end-open and 2-inlet-2-outlet flow arrangement, while the six and seven unblocked holes were tested for parallel, circular and both-end-open flow arrangements.;Most of the data available in the open literature are for jets impinging over different geometry surfaces and for different surface texture. Therefore, the present investigation includes a new geometry to study the airfoil leading-edge cooling, which is the study of the effect of different flow arrangement and different number of cross-over-holes.;The results showed that, on the target surface, the heat transfer coefficients increased with increasing the number of blocked holes. This led to the increasing of the jet Reynolds number. Also the 2-inlet-2-outlet flow arrangement resulted in a higher transfer coefficient over the rest of the flow arrangements. |
