水平管内螺旋流涡特性数值模拟

螺旋流是工程上常见的流动现象,具有增强湍流度、促进传热传质和提高对颗粒的携带能力等特性。该文采用雷诺应力湍流模型(RSM)对水平管内由短螺旋扭带起旋的螺旋流流动特性进行了数值模拟研究,通过激光多普勒测速仪(LDV)测速实验验证了数学模型的准确性和可靠性。结果表明,水平管内螺旋涡首先在扭带吸力面形成,且形成初期,涡量的大小受主涡影响较大,二次涡形成后,涡量大小主要受二次涡影响。在形成过程中二次涡增强了壁面附近的速度脉动,能够有效地增加介质的掺混。此外,由于二次螺旋涡的存在,使水平径向压力梯度增加,靠近壁面处的轴向速度减小,近壁处切向速度值增大1倍,且径向速度在螺旋流中不可忽略。

Numerical simulation on vortex characteristics of swirl flow in a horizontal pipe

Swirl flow was very common in engineering,which enhanced turbulence,promoted mass transfer and carried small particles.The flow characteristic of swirl flow caused by short twisted tape in the horizontal pipe was numerically simulated using the RSM turbulence model.The numerical results were in good agreements with the experimental data verifying the accuracy and reliability of the developed mathematical model.The results showed that the secondary helical vortices in the pipe formed firstly in the suction side,and early formation of spiral flow,primary vortex had a great influence on the vorticity.The vorticity was mainly affected by the secondary vortex after the secondary vortex formed.The secondary vortex strengthened the disturbance near the wall in the formation process,and could effectively increase the medium mixing.In addition,the existence of the secondary helical vortices made the horizontal radial pressure gradient increased,the axial velocity near the wall reduced,the near-wall tangential velocity value increased by one time.