冲击冷却局部换热特性的实验研究

木文研究了用单排圆射流冲出冷却的方法来模拟涡轮叶片前缘的局部换热特性。通过对大量实验数据的分析研究,发现局部换热系数的分布曲线是一个分段函数:驻点区为高斯分布函数,壁射流区为幂函数分布。文中还分析了射流雷诺数、射流孔与试验靶之间的无因次距离、冲击管和试验靶的无因次结构尺寸等对局部换热系数及其分布的影响。最后,用最小二乘法整理出一组描述冲击冷却局部换热特性的经验公式。这些公式对冲击冷却叶片的设计具有一定的工程实用参考价值。

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.