微喷管流场及其推力性能数值模拟

Simulations of Flow Field and Thrust Performance in Micronozzle

采用连续介质模型和分子运动模型系统地研究了二维微喷管内的流场及推力特性,重点考察了连续介质模型的适用性、微喷管工作条件和几何结构对流场结构和喷管性能的影响。研究结果表明,在努森数不大时,两种方法的结果基本符合。当努森数大于0.045时,连续介质模型与分子运动模型模拟结果差异较大。微喷管的推力和喉部雷诺数与喷管的入口压力、喉部宽度近似成线性变化;微喷管收缩角、扩张角给定时,其扩张段的长度仅影响推进性能,对流场结构影响较小。在喉部尺寸和扩张比一定时,扩张角为22度的微喷管推进性能最佳。

Both the continuum and kinetic models are applied to study flow field and thrust performance of 2D micronozzle in detail, with emphasizing on investigating the validity of continuum model, the effects of operating condition and configuration on micronozzle thrust performance, h is found that when Knudsen is less than 0. 0045, both continuum and kinetic models work to predict flow characteristics inside micronozzles. When Knudsen number exceeds 0. 0045, results of the continuum model obviously deviate from these of the kinetic. Thrust and Reynolds number of throat in micronozzle is appropriately linear with the inlet pressure and throat width. When the convergence and divergence angles of nozzle are fixed, thrust performance is affected by the length of divergence while the flow structure is not so sensitive. When the throat width and area ratio are given, the best divergence angle is 22°.