EXPERIMENTAL INVESTIGATION OF LOCAL HEAT TRANSFER CHARACTERISTICS BY IMPINGEMENT COOLING

The simulation of the local heat transfer characteristics of the leading edge region of a turbine blade by impingement cooling of concave surface with a row of circular air jets has been investigated experimentally.The effects of Reynolds number, the dismensionless distance between the jet and the target, the compound geometrical configurations both of the impingement tube and target on the local heat transfer coefficients are discussed. The special distributions of local heat transfer coefficients are also analyzed.It is found from a large amount of experiments that the heat transfer coefficientdistribution is not a simple Guass function. The Guass function fits the experimental data satisfactorily only at the stagnation region,while the local heat transfer coefficients in t.he jet region at the wall can be expressed in exponent functions. A set of empirical formulas which describe the distribution of the local heat transfer coefficients by impingement cooling have been obtained from the experimentaldata by means of least square approach.