基于自适应网格的超声速液体射流破碎过程研究

Study on the Breaking Process of Liquid Jet in Supersonic Flow Based on Adaptive Mesh

关键词:  超声速气流  液体射流  自适应网格  反转漩涡对  二次激波

Key words:  Supersonic flow  Liquid jet  Adaptive mesh  Reversal vortex repair  Secondary shock

摘要:

为研究超声速气流中液体横向射流的破碎过程，采用脉冲背景光方法和VOF方法开展了实验研究和数值研究。为提高液体横向射流中气液界面和气流场特征捕捉的精确性，采用自适应网格技术对于气液界面、激波出现位置进行网格细化，计算得到了较为精细的气液界面、激波特征及涡系结构。研究结果表明：在低成本仿真模拟条件下，利用自适应网格计算得到的射流轨迹和轮廓与实验吻合较好，射流轨迹的最大误差为10%；射流初始段在超声速气流条件下，仍然存在一段高度约为1.9倍喷孔直径且圆柱形态保持较好的连续光滑液柱。随着喷注压降的升高，液柱的长度逐渐增加；主流气体流经液柱发生三维绕流，在射流附近和近壁面区域形成不断演化的反转涡对，反转涡对的形成加速了液体射流一次破碎过程。

Abstract:

To study the breaking process of transverse liquid jet in supersonic flow. Experimental and numerical studies were carried out by pulsed background light imaging and volume of fluid method. In order to improve the accuracy of gas-liquid interface and gas field characteristics in liquid transverse jet. An adaptive mesh was used to refine the mesh where the shock waves appeared at the gas-liquid interface, the more detailed shock wave characteristics, vortex structure and gas-liquid interface are obtained by simulation. The study shows that the jet trajectory obtained by adaptive grid calculation is in good agreement with the experiment under the condition of low cost simulation. The penetration depth of simulation is in good agreement with the experimental results, the maximum error of jet trajectory is 10%. In the initial section of the jet flow, under the condition of supersonic flow, there is still a section of smooth liquid column with a height of 1.9 times of the nozzle diameter and a good cylindrical shape. With the increase of the pressure drop, the length of the continuous smooth liquid column increases gradually. The mainstream gas flows through the liquid column in three-dimensional and forms inversion vortex pairs both in the jet region and the wall region, accelerating the primary breaking process of liquid jet flow.