基于蒙特卡罗粒子仿真方法的高空火箭发动机气体-颗粒两相稀薄羽流的流动与辐射特性研究

Rarefied gas-particle two-phase plume in which the phase of particle is liquid or solid flows from the propellant rocket of reaction control systems demanding for the maneuver and brake of hypersonic vehicles flying in the high altitude,the particulates not only impact the rarefied gas flow properties,but also make a great difference to plume radiation signature,so the prediction of the rarefied gas-particle two-phase plume flow and radiation characteristics is very important for space target recognition and penetration of hypersonic vehicles. In the microthrusters, which is used for the spacecraft such as the satellite for the attitude control, rarefied two-phase plume flow also exists, which attacts an increasing attention due to the surface contamination and heating control.The present investigation has focused on the two-phase flow in which the gas phase is continuous, and the study on the gas-particle two-phase flow in which the gas phase is noncontinuous is developing as well. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and radiation characteristics. The direct simulation Monte Carlo (DSMC) method is developed for the radiation transfer of the rarefied gas,and the DSMC simulation coupled with the Monte Carlo method is performed for the rarefied gas flow and radiation.The Monte Carlo simulation is developed for the particulate flow and radiation in the rarefied gas-particle two-phase plume. The techniques of breakdown surface generation for continuum/non-continuum coupling flow, mesh regeneration and diverse arithmetic solvers joint for continuum and non-continuum regimes are presented. A program for the numerical simulation of the gas-particle two-phase flow and radiation in the region of the rarefied gas is implemented. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristic in this project, and the basic flowfield and radiation data for spacecraft contamination and satellite heating control are provided.

当航天飞行器在气体稀薄的高空中飞行时，火箭发动机羽流中存在液态颗粒和固态颗粒，这些颗粒既对流场辐射特性起主导作用，又对航天器羽流污染分析和关键部位热负荷预估产生重要影响，为满足未来高超声速飞行器空间目标识别和突防需求，亟需精确预估高空火箭发动机气体-颗粒两相羽流的流动与辐射特性。因此，本项目针对稀薄条件下的气粒两相羽流场与辐射场，从描述粒子运动的微观层次出发，基于蒙特卡罗粒子仿真方法，研究适用于直接模拟蒙特卡罗（DSMC）方法的气体辐射模型，构造气体流动与辐射的DSMC-MC耦合算法，发展适用于Monte Carlo方法的颗粒辐射与动力学耦合模型，研究两相羽流场连续/稀薄混合流动分区、网格重构和算法搭建技术，实现稀薄条件下气粒两相羽流的流动与辐射传输的数值模拟，形成一套适用于高空火箭发动机的气粒两相羽流流动和辐射计算程序，为解决稀薄条件下气粒两相羽流的流动及辐射问题提供一种新的研究手段。

本项目重点研究了基于Monte Carlo方法的颗粒辐射与颗粒动力学耦合模型，构造了高空稀薄环境下流动与辐射的DSMC-MC耦合算法。取得的标志性成果如下：.根据非平衡结晶动力学原理，在忽略结晶中间相态假设条件下，构建了颗粒相的相变模型和颗粒辐射模型。开展了稀薄环境下两相流动中颗粒相的相变研究，研究了相变模型对流场气相以及颗粒相参数分布的影响，分析了相变模型对不同粒径颗粒的具体作用，并对流场在不同热适应系数和颗粒比热下的特性进行了描述和分析。.采用非结构网格对三维复杂流场进行描述，开展了稀薄环境下三维气粒两相流动研究。在零攻角条件下考虑稀薄来流的影响，数值模拟研究了固体火箭发动机模型高空稀薄环境下尾喷多相流场的流动结构以及颗粒相的存在对三维流场结构的影响，考察了三维条件下颗粒相的存在对气相流场的影响规律。.通过对稀薄环境下两相流场中颗粒相Al2O3的辐射模型研究，开展了稀薄环境下两相流场颗粒相辐射研究，编制了计算流场颗粒辐射的DSMC程序。通过流场计算和辐射计算的耦合，研究了颗粒相的辐射特性，分析了不同粒径颗粒在辐射模型作用下的具体表现，重点考察了颗粒发射、吸收、散射、比热以及喷管探照灯效应对流场辐射特性的影响。.主要创新点为在对高空稀薄环境下的多相羽流的流动特性数值模拟基础上，采用粒子米氏散射理论，基于颗粒动力学模式和辐射行为耦合的Monte Carlo模型，建立非灰介质的辐射场和流场的耦合算法，实现高空稀薄环境下的气粒多相羽流的流动和辐射特性数值模拟，弥补国内目前所做工作的缺陷，为高超声速飞行器的空间目标识别和突防提供基础数据。.本研究成果可用于开展高空稀薄环境下具有典型流动特征的气粒多相羽流流动和辐射的数值模拟，分析采用碳氢燃料的液体火箭发动机和包含金属添加剂的固体火箭发动机的羽流中包含的颗粒相对辐射特性、流场结构和飞行器物面气动参数的影响，可为工业设计部门提供高超声速飞行器全再入轨道的羽流干扰特性与辐射特性数据。

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