欧拉-拉格朗日迭代固-液相变算法

Solid-liquid phase change algorithm with Euler-Lagrange iteration

在固-液相变过程中,外力可导致固体相变材料在液体相变材料中产生相对运动并严重影响相变流动传热。提出一种欧拉-拉格朗日迭代固-液相变算法,创新地将预测固体相对运动的拉格朗日迭代外置耦合于预测相变流动传热的欧拉迭代,能够稳定准确地耦合计算固-液相变的流动传热和固体相变材料的相对运动。采用本算法研究了方腔内的接触熔化过程,探讨不同糊状区系数和重力加速度对本算法的影响规律。结果表明,本算法预测液相体积分数的平均误差为4.93%,固体相对运动预测数值振荡降低51.42%。对于石蜡材料,推荐使用的糊状区系数为1010。增大重力加速度会提高熔化速率并加快相对运动,但对整体趋势影响较小。研究结果可作为相变储能装置的设计参考。

During the solid-liquid phase change process,the external force can cause relative motion of the solid phase change material within the liquid phase change material,which can seriously affect the flow and heat transfer.An Euler-Lagrange iterative solid-liquid phase change algorithm is proposed to numerically solve the above problem.The Lagrange iteration for predicting the solid relative motion is externally coupled to the Euler iteration for calculating the phase change flow and heat transfer,which can stably and accurately simulate the flow and heat transfer of the solid-liquid phase change and the relative motion of the solid phase change material.Based on the present algorithm,the close-contact melting processes in the square cavity are investigated under gravity.Furthermore,the influence of different mushy zone coefficients and gravity accelerations on this algorithm is explored.The results show that the average error of the algorithm in predicting the liquid phase volume fraction is 4.93%,and the numerical oscillation of the solid relative motion prediction is reduced by 51.42%.For paraffin materials,the mushy zone coefficient of 1010 is recommended for this algorithm.The increase of the gravity acceleration can improve the melting rate and accelerate the relative downward motion,yet has less impact on the overall trends of liquid phase fraction and solid phase relative motion.The results can be used as the theoretical guideline for the design and optimization of the efficient solid-liquid phase change energy storage devices.