幂律型凝胶推进剂射流撞击雾化SPH模拟

SPH Simulation of Atomization Characteristics of Power-Law Gelled Propellant Formed by Two Impinging Jets

关键词:  幂律流体  凝胶推进剂  射流撞击雾化  光滑粒子流体动力学

Key words:  Power-law fluid  Gelled propellant  Jet impingement atomization  SPH

摘要:

为研究幂律型本构关系对于凝胶推进剂雾化的影响，应用光滑粒子流体动力学(SPH)方法进行了凝胶推进剂的射流撞击雾化仿真，并与实验结果进行了对比。推导了幂律型本构关系的SPH求解方法，发展了三维隐式SPH算法，克服了凝胶推进剂的高粘度对于时间步长的限制。制备了胶凝剂含量分别为1%，2%的两种水基凝胶推进剂模拟液并进行了6种工况的雾化实验和数值模拟，证明了本文SPH方法可以有效模拟凝胶推进剂的雾化问题。对于本文研究的工况，雾化区内模拟液的表观粘度普遍高于[10-2N?s/m2]，从撞击点至雾化区下游，模拟液的表观粘度呈震荡上升分布。分析表明，雾化区下游的高表观粘度是造成凝胶推进剂雾化生成液丝及大尺寸液滴的重要原因。

Abstract:

With the aim of finding the influences of the power-law constitutive on atomization，the atomization characteristics of gelled propellant were investigated using Smoothed Particle Hydrodynamics (SPH) and the simulation results were compared with the experimental ones. Firstly，an SPH discretization scheme for the power-law constitutive of gelled propellant was developed. Secondly，as the high viscosity of gelled propellant laid a strict restriction on the simulation time steps，a new 3D implicit SPH method，which was stable on relatively much larger time steps，was proposed. In order to validate the new SPH method，two kinds of water-based gelled propellant simulants with 1 wt%，2 wt% gallant were prepared and 6 jet impingement experiments were carried out. SPH simulations were also carried out on the same conditions. It is found that the simulation results were in consistency with the experiment ones，which proved the efficiency of the SPH method. Then，the shear rate and apparent viscosity of different conditions were numerically investigated. As to the conditions investigated in this paper，the simulants’apparent viscosities were larger than [10-2N·s/m2] in the atomization area，and from the jet impinging point to the downstream atomization area，the apparent viscosity experienced a rocky increase. Analyses show that the high apparent viscosity in the downstream atomization area was a key reason of the phenomenon that the main atomization products of gelled propellant were ligaments and large-scaled droplets.