【作者】 常飞；

【导师】 常海萍；

【作者基本信息】 南京航空航天大学 ， 工程热物理， 2009， 硕士

【摘要】 现代航空发动机的加力燃烧室通常装有纵向波纹隔热屏,其上开有气膜孔,可以防止燃烧室筒体的过热和震荡燃烧。本文采用商业软件Fluent对航空发动机的纵向波纹隔热屏进行数值模拟。按照孔径的大小和孔的密集程度,可分为离散孔和发散孔两种结构,本文以离散孔结构的研究为主。离散孔结构的孔径较大,且气膜孔之间的轴向和周向间距较大。对于离散孔的研究主要包含两部分内容,即离散孔结构的换热特性和离散孔结构的流量系数。流动参数对离散孔结构的换热特性的影响的研究表明:有效温比受吹风比的影响较大,并随着吹风比的增加而增加;热侧换热系数受主流雷诺数的影响较大,并随着主流雷诺数的增加而增加;冷侧换热系数则随着次流雷诺数和射流与次流密流之比的增加而增加。结构参数对离散孔结构换热特性的影响的研究表明:随着隔热屏曲率半径或者隔热屏高度的增加,隔热屏的有效温比降低;气膜孔的开孔位置越靠近波峰,冷却效果越好;波谷处不宜开孔。对离散孔气膜孔的流量系数的研究发现:越靠近波峰处的气膜孔,其流量系数越大;离散孔的流量系数随着吹风比的增加而增加,随着次流雷诺数的增加而降低,随着主流雷诺数的增加而增加;发散孔结构的孔径较小,且气膜孔之间的周向和轴向间距较小。对于发散孔对称板和发散孔非对称板结构,均在给定的冷却流量条件下,研究结构参数的改变对其冷却效果的影响,得到主要的结论如下:随着开孔率增加,冷却效果降低;随着气膜孔孔径或者轴向孔间距的增加,冷却效果降低;随着气膜孔入射角的增加,冷却效果有所降低。更多还原

【Abstract】 For modern high-powered aircraft engine, longitudinal ripple way liner is used a lot to avoid concussive combustion and the ablation by the high temperature gas. This article uses commercial software, the Fluent, to simulate the longitudinal ripple way liner. According to the diameter or density of the fim holes, the ripple way liners are divided into discrete film holes and transpiration holes. This article argues mainly in the discrete film holes.The diameter and space between holes of the discrete holes are larger than that of transpiration holes. The research on the discrete holes have two parts. That is the influence on the heat transfer and on the characteristic and on the flow characteristic.The results on the characteristic of heat transfer judged by the flow parameter are as follows. The cooling effectiveness is mainly determined by the blowing ratio and while the blowing ratio incrases, the cooling effectiveness improves a lot. The heat-exchange coefficent of the hot face increase while the the Renalt number of the mainstream increases. The heat-exchange cofficient of the cool side increases while G2/Gc or Renault number of the cooling stream increases.The results on the characteristic of heat transfer by the structure are as follows. The cooling effectiveness will arise while the radius of curvature or the height of the ripple changes. The film holes around the crest zone will do more effort on the cooling effectiveness compared with the trough zone.The results on the flux cofficient are as follows. The flux cofficient around the crest zone is larger compared with those around trough zone.The flux coefficient increases while the blowing ratio or Renault number of the mainstream increases and decreases while the Renault number of the cooling stream decreases.For the ripples with transpiration film holes,whether they are symmetrical or unsymmetrical in shape, the results are found as follows.With the fixed mass of cooling air, the cooling effectiveness will decrease when the radius of film hole or the inject angle increase.更多还原