固体推进剂药浆立式混合过程SPH方法研究

SPH Method for Vertical Mixing Process of the Solid Propellant Slurry

立式混合机内桨叶的行星运动可有效促进物料不同组分间的分散循环和均质分布,故已应用于固体推进剂药浆的制备过程。然而,混合机内的复杂界面及其运动导致药浆内部的混合机理与流变特性难以采用传统的方法进行研究。针对层流流动下推进剂药浆与桨叶耦合过程,基于光滑粒子法(Smoothed Particle Hydrodynamics,SPH),连续体被离散为若干携带物理量的守恒质点。结合Herschel-Bulkley(HB)本构模型,发展了适用于非牛顿流体状态下推进剂药浆混合过程的无网格方法。将数值模拟和实验进行对比,验证所提出模型的准确性。通过探究桨叶运动参量与功率消耗的相关性,分析了几何构型、转动模式对药浆混合均匀程度及叶轮扭矩负载的影响规律。研究结果表明,若剪切速率指数n为0.47时,液体在非牛顿流动状态下,模拟结果相对文献实验结果的平均误差约为4.98%,故两者具有良好的一致性。行星叶轮搅拌2.65 s后,其混合均匀性指数相比于中心、偏心叶轮依次提高了8.9%和7.3%。而雷诺数Re=1时,公转半径在0.11D_(w)~0.23D_(w)范围内,扭矩的最大增幅可达38.4%。

The planetary motion of impeller in the vertical mixer can effectively promote the dispersed circulation and homogeneous distribution of different material components,which has been employed in the preparation procedure of solid propellant slurry.However,the mixer involves complex interfaces and motions that it is difficult to study the mixing mechanism and rheo-logical property of slurries by traditional methods.Based on the smoothed particle hydrodynamics(SPH),the continuum was discretized into the conserved particles with physical quantities for simulating the interaction between the propellant slurry and blades under laminar flow.A meshless method for the mixing process of propellant slurries in non-Newtonian fluid state was developed by combining the Herschel-Bulkley(HB)constitutive model.The numerical simulations were compared with the experiments to verify the accuracy of the proposed model.The correlations of the blade motion parameters and power consumption were explored.The effects of geometric configurations and rotation modes on the mixing uniformity of slurries and the torque loads of impellers were analyzed.Research findings indicate that the simulation and literature experiment results have a good agreement that the average relative error between them is around 4.98%in the non-Newtonian fluid with shear rate index n=0.47.The mixing uniformity index of planetary impellers increased by 8.9%and 7.3%respectively than those of central and eccentric impellers after stirring for 2.65 s.The maximum amplification in torque can reach 38.4%within the revolution radius range of 0.11D_(w)-0.23D_(w)at Reynolds number Re=1.