气膜冷却式隔热屏壁温的数值计算方法

本文对气膜冷却式加力燃烧室隔热屏壁面温度计算方法进行了研究，给出了复杂边界条件下隔热屏二维稳态热传导模型．该计算模型考虑了壁面内纵向导热、射精段的径向导热、壁面材料的导热系数和冷却空气物性参数随温度变化等因素对垒温的影响．以具有代表性的ＳｐｅｙＭＫ－２０２发动机加力燃烧室隔热屏为例进行了计算，得到整个隔热屏壁面温度沿轴向的分布曲线．

Numeri cal Method for Calculating Wall Temperature of Film-Cooled Heat Shield

The one-dimensional radial heat--transfCr model bas been widely used in the wall temperature estimation of beat shields in afterburners for many years 1-4].No better model,to the authors best knowledge, bas appeared in the open literature. The construction of heat shield bas developed from single layerwall to two-layer film-cooled wall. Estimation of wall tcmpeerature by the now still widely used modelappears to be more and more inadequate to give satisfactory engineering accuracy.ID this paper the authors present a two-dimensional method that apperas to give satisfactory engineering accuracy. The authors start from a previous paper by the first author et al 5].The main combushon chamber dealt with in Ref.5]is much simpler in construction than aftcrburncr. In order to make thetwo-dimensional model and method applicable to aftcrburner, much careful work has to be done.The authors take into consideration the complexity of the structure of aftcTburner and establish atWo-dimensional heat conductive model. Compared with the now widely used model, the authors'modelshows two important improvements:(1)The authors'model considers the longitudial conduction in the wall, the radial conduction in concoct part of film-cooled sections,and the variations with temperature of thermal conductivity of wall material aDd of physical propertics of cooling air.(2) The beat balance equations(20),(21)are set up respectively for the secondary cooling air and forcooling air in two-layer wall.Thus the rise in temperature of the cooling air can be predicted.As an example the heat shield wall temperature of Spey MK--202 engine with two--layer wall arc cabculated. The authors like to emphasize that two significant and reasonable conclusions can be drawn fromthe authors' calculations. These two reasonable conclusions can not be drawn when calculating with thenow still widely used model. The tWo reasonable conclusions arc:(1)The maxium wall temperature of each fial-cooled section appears between the middle part andthe end of the section, not at the cud point of the section. There is a low temperature region in cooling slotsection. The external-lnycr wall temperature of the two-layer heat shield is much lower than theinternal-layer wall temperature.(2)The temperature of cooling air between the tWo layer walls increases rather fast,which should beconsidered when calculating the tompcrature of the heat shield