The various flow patterns and corresponding various characteristics of local heat transfer of impingement flow are considered for the short distance between nozzle exit and target surface.In the case of the two-dimensional slot jet

the flow patterns and characteristics of local heat transfer are remarkably influenced by these factors such as the degree of turbulance development in jet

the reaction of target surface on the jets and the compressibility of jet at high velocity.The types of multi-peak distribution of local heat transfer on the target surface depend on variation of these factors.For the row of circular jets

besides the above-mentioed factors

the effect of the three-dimensional flow of jets at short distance between nozle exits and target surface

leads to makes the local heat transfer from both sides of the stagnant line drop sharper than that of the two-dimensional slot jet.