喷嘴内液固两相射流流场的数值模拟

基于连续介质理论,考虑了液固两相间的相互作用,给出了喷嘴流道内液固两相射流的控制方程,利用标准的k-ε两方程模型对磨料射流喷嘴内流场进行了数值模拟研究,并对模型中的主要参数进行了优选。研究结果表明,水与磨料颗粒之间存在速度滑移,在相间力的作用下磨料颗粒一直作加速运动,颗粒速度逐渐趋向水的速度;进入喷嘴收缩段后,水与磨料颗粒同时得到加速,但由于惯性力的作用,达到相同速度磨料颗粒的加速过程要长;进入直柱段后,液相速度继续增加至最大速度,此后缓慢降低,而磨料颗粒在整个直柱段内一直加速,液固两相的速度差逐渐减小,直至从喷嘴喷出;喷嘴出口处液固两相的速度剖面近似为抛物线形,在喷嘴截面中心处速度最大,沿径向逐渐减小,离壁面越近,速度降低的幅度越明显。与前人的研究结果对比发现,模拟所得的结果是正确的。

Numerical simulation on fluid-particle two-phase jet flow field in nozzle

Based on the continuum theory,the control equations for the fluid-particle two-phase jet in the nozzle were established in consideration of fluid-particle interactions.The numerical simulation was conducted using standard two-equation model,in which the main constants were optimized.The results show that there exists velocity slip between water and abrasive particles.Under the condition of inter-phase force,abrasive particles are accelerated all the way which shows the inclination to follow the water.In the convergent section of the nozzle,both water and abrasive particles are accelerated and it takes a long time for abrasive particles to be accelerated because of the inertia force.In the straight tube section of the nozzle,water continues to be accelerated and reaches its maximum velocity and then decreases slowly.Abrasive particles are accelerated all the way and the velocity difference between water and abrasive particles decreases.At the nozzle exit,the velocity profiles of water and abrasive particles are parabolic with maximum velocities at the center and decrease in the radial direction.The more close to the wall,the more obvious velocity decreases.Compared with former conclusions,the results are found to be correct.