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现有的气泡 -液体两相流动的数值模拟中 ,或者不考虑湍流 ,或者仅仅考虑液体湍流 ,但是直接模拟和PIV测量结果都表明气泡由于尾迹的作用有强烈的湍流脉动 .本文首次推导和封闭了同时模拟气泡湍流脉动和液体湍流脉动的二阶矩输运方程两相湍流模型 ,并在此基础上建立了代数应力气泡 -液体两相湍流模型 .用代数应力模型模拟了二维矩形断面鼓泡床内气泡 -液体两相流动 .预报结果给出了气泡和液体两相速度场、两相Reynolds应力及湍动能分布和气泡体积分数分布 .模拟结果与PIV测量结果符合很好 ,表明了模型的合理性 .研究结果表明 ,原先静止的液体在气泡因浮力而产生的上升运动的作用下产生回流流动 ,而气泡则只有上升运动 .气泡速度始终大于液体速度 .在床内气泡湍流脉动确实始终很强烈 .液体则由于气泡的作用以及自身速度梯度产生的双重作用而发生湍流脉动 .气泡的脉动显著地大于液体的脉动 .两相湍流脉动都是各向异性的 ,而且气泡湍流脉动的各向异性比液体的更强烈
The existing numerical simulation of bubble-liquid two-phase flow, either without considering turbulence, or only considering liquid turbulence, both the direct simulation and PIV measurements show that the bubble has a strong turbulent ripple due to the wake effect.This paper first derives and closes A two-phase turbulent model of the second moment transport equation is presented to simulate both the turbulent pulsation of the bubble and the pulsation of the liquid turbulent flow. On this basis, the algebraic stress bubble-liquid two-phase turbulence model is established. The algebraic stress model is used to simulate the two- Bubble-liquid two-phase flow in bubble bed.The prediction results show the velocity fields of two phases of bubbles and liquids, the distribution of stress and turbulent kinetic energy and the distribution of bubble volume fraction of two-phase Reynolds.The simulation results are in good agreement with the PIV measurements, indicating that the model The results show that the previously stationary liquid produced a backflow under the ascending motion of the bubble due to the buoyancy while the bubble only moved upward.The bubble velocity was always greater than the liquid velocity.The turbulent pulsation of the bubble in the bed did indeed Very strong liquid due to the role of bubbles and their own speed gradient dual role Turbulent fluctuation occurs pulsating bubble is significantly greater than the pulsation of the liquid two-phase turbulent fluctuations are anisotropic, the anisotropy and the turbulent pulsating bubble more strongly than the liquid