旋流燃烧室对固体燃料冲压发动机药柱表面传热以及燃速的影响

Investigation on heat transfer of solid fuel surface and regression rate of solid fuel ramjet effect by swirl flow

为研究旋流燃烧室对固体燃料冲压发动机(SFRJ)药柱表面传热以及燃速的影响,以高密度聚乙烯(HDPE)为燃料,对旋流和无旋工况下的固体燃料冲压发动机进行了连管实验研究,并且编制了二维轴对称湍流燃烧仿真程序,采用流固耦合传热的方法以及非定常时间推进方式,对实验工况进行了数值模拟。结果表明:①药柱表面热流密度对燃速有显著影响,在回流区与附着点处,药柱表面的对流换热能力要明显优于再发展区;②在旋流工况下,在离心力与切向速度的作用下,使热解产物在药柱表面附近区域停留时间更长,有助于热解产物的充分反应,并且明显增强药柱表面对流换热能力,与无旋工况相比,提高幅度可达100%,并且在旋流工况下发动机可更快建立自持燃烧;③通过实验研究发现,旋流的引入提高发动机的燃速有积极作用,增幅可达26%,但会导致固体燃料冲压发动机补燃室压强出现周期性振荡。

In order to investigate the heat transfer of solid fuel surface and regression rate of solid fuel ramjet(SFRJ)effect by swirl flow,high-density polyethylene(HDPE)was used as fuel of SFRJ,the experiments were conducted by using connected pipe facility.And a two-dimensional axisymmetric turbu1 ent f1 ow and combustion program was developed,the heat transfer between fluid and solid domains was considered,and unsteady time method was used to simulate the case of experiment.The results indicated that the heat transfer in recirculation zone and reattachment point was higher than that in redevelopment zone,and the heat transfer of fuel surface had an appreciable effect on regression rate.Due to the function of centrifugal force and tangential velocity provided by swirl flow,this can lead to the long residence of pyrolysis of HDPE,and has positive effect on the combustion efficiency near the fuel surface.Moreover,the swirl flow can also increase the ability of heat transfer of fuel surface,the heat transfer coefficient was 100%higher than that of non-swirl flow.Compared with non-swirl flow,the combustion achieved for stability could be faster with swirl flow.The experimental result indicate that the introduction of swirl flow has a positive effect on improving the regression rate of SFRJ about 26%,but it can also lead to periodic oscillation of the pressure after burning chamber.