井底边界条件下单喷嘴射流流场的数值模拟

NULMIRICAL SIMULATION OF TURBULENT AXISYMMETRIC IMPINGING JET FLOWFIELDS

用数值模拟的方法研究了符合井底边界条件的轴对称单喷嘴淹没非自由射流流场，给出了不同喷嘴直径、不同喷速、不同喷距下的流场矢量图，并研究了上述工况下的射流轴心速度衰减规律。结果表明，除射流区、撞击区、漫流区、返回区之外，还存在一明显的回流旋涡区，射流出口雷诺数对轴心速度衰减的影响很小，而漫流的存在使得射流轴心速度在靠近井底的区域内受到很大程度的影响．数值模拟结果和有关实验数据有较好的一致性。

A numeri cal simulation of the characteristics of a turbulent submergedaxisymmetric impinging jet onto well bottom is made,Ahybrid fin ite difference method isused to solve the Reynolds-averaged Navier-Stokes equati ons(RANS)wi th the standard k-εturbulent model.and the constant C_1 of the turbulent model is optimized; The decay ofcentcrline velocity is insensitive to nozzle Reynolds number and the dlmcnsionless potentia]core length of impinging jet is about4.0～5.0 times of diameter of nozzle. Numerical resultsshow that the centerline velocity of impinging jet is almost the same as that of free jet.but itdecays to zero very quickly near the impingement region of well bottom. In addition,thecrossflow behavior under different conditions (nozzle diameter.nozzle exit velocity,distancefrom the nozzle to the end of well bottom) is studied.The numerical resul ts agree well withthose of experiments.