粉末推进剂流化过程及高压流化机制分析

Analysis on Fluidization Process and Mechanismof Powder Propellant at High Pressure

关键词:  粉末发动机  供粉系统  均方差  流化模式  高压流化机制

Key words:  Powder engine  Powder feeding system  Standard deviation  Fluidization model  Fluidization mechanism at high pressure

摘要:

为深入探究粉末发动机推进剂供给装置内的粉末流化特性，通过搭建粉末高压流化过程的可视化实验系统，开展了0.3～5MPa压强条件下粉末流化过程和流化特征研究，并结合压强信号的均方差分析结果以及颗粒起动的各类学说，详细分析了粉末流化模式以及高压流化机制。结果表明:随压强升高，粉末表现出不同的流化模式，其中在低压(<1.5MPa)流化模式时，其流化压强均方差最小，粉末为局部波动状态；过渡阶段流化模式时，其流化压强均方差最大，不稳定气固分界面形成；而高压(>2.3MPa)流化模式时，在活塞与流化进气的双重作用下，储箱内可形成稳定的气固分界面，为粉末推进剂的稳定输送提供了有力证明；粉末的高压流化机制为颗粒斜面飞升与湍流共同作用的结果。

Abstract:

In order to research the powder fluidization characteristics of propellant feeding device with pressure?driven piston in powder engine， a visualized experimental system of powder fluidization process at high pressure was conducted， and under the conditions of pressure range 0.3～5MPa， the powder fluidization process and characteristics were investigated experimentally. Based on the standard deviation analysis of pressure signal and the kinds of particle pickup theories， the powder fluidization patter and fluidization mechanism at high pressure were also discussed in detail. The results show that powder fluidization will experience different patterns when raising the pressure， and the fluidization pattern at low pressure( lower than 1.5MPa) owns the smallest value of standard deviation， along with partial powder fluctuation. The standard deviation in the transitional phase is the biggest by comparing to the other fluidization models， and the unsteady gas-solid interface is forming. It is also found that a stable gas-solid interface will be formed by the dual actions of piston and fluidization gas in the fluidization pattern at high pressure (higher than 2.3MPa)， which provides?potent?proof?for the stable conveying of powder propellant. And the?joint?effect of particle ‘slope-soaring’ and turbulent flow forms the powder fluidization mechanism at high pressure.