旋流燃烧室构型对固体燃料冲压发动机自持燃烧性能影响

Effects of Combustion Chamber Configuration on Characteristic of Solid Fuel Ramjet Self-Sustaining Combustion in Swirl Flow

关键词:  固体燃料冲压发动机  相对台阶高度  旋流数  火焰稳定  自持燃烧

Key words:  Solid fuel ramjet  Relative step height  Swirl number  Flame stability  Self-sustaining combustion

摘要:

为研究燃烧室构型对引入旋流的固体燃料冲压发动机(SFRJ)燃烧特性的影响，通过改变药柱内径以改变相对台阶高度，利用高密度聚乙烯(HDPE)为固体燃料，对4种不同相对台阶高度的冲压发动机进行了旋流和直流连管实验，其中旋流工况的旋流数为0.6。利用Fortran语言编制CFD计算程序，对其中多个旋流工况进行了数值模拟，利用相关实验验证了计算程序的可靠性。仿真以及实验结果表明，在旋流工况下，相对台阶高度对火焰稳定以及燃烧特性有显著影响，当相对台阶高度为1.5时，旋流工况下发动机无法自持燃烧；在1.75相对台阶高度工况下，药柱表面热流密度与燃速均高于其他工况，且药柱平均燃速以及药柱表面热流密度会随相对台阶高度的升高而降低，最终趋于平缓；相对台阶高度的改变对特征速度与推力的作用不大，而在无旋工况下，特征速度和推力则随相对台阶高度的增加而增加。

Abstract:

In order to study the effects of combustion chamber configuration on characteristic of solid fuel ramjet(SFRJ) self-sustaining combustion in swirl flow working condition， high density polyethylene(HDPE) were used as solid fuel， and relative step height were used as experimental variables by changing internal diameter of solid fuel， four groups of experiments were conducted in different relative step height， each group of experiments contains two sets of experiment in both swirl-flow and non-swirl-flow working condition， swirl number of swirl flow working condition were 0.6. A CFD code was developed to simulate the swirl flow conditions by using Fortran. And the reliability of this program is verified by experiments. The main results obtained from experiment results and simulation results show that the combustion characteristic and the flame stability are highly influenced by relative step height. For the engine of 1.5 relative step height in swirl-flow working condition， self-sustaining combustion were failed. For 1.75 relative step height in swirl-flow working condition， the heat flux along the surface and regression rate of HEPE are higher than other working condition， and the average regression rate and heat flux along the HDPE surface decrease with the increase of relative step height， but the decrease trend is flat gradually， the change of relative step height has no effect on characteristic velocities and thrust. On the non-swirl-flow working condition， the characteristic velocities and the thrust increased with the increasing of relative step height.