烧蚀后C-SiC复合材料隔离段内激波串长度预测

Prediction of Shock Train Length in C-SiC Composite Isolator after Thermal Ablation

为了研究畸变气流影响下烧蚀后的C-SiC复合材料隔离段内激波串长度预测问题,设计了能够模拟进气道喉道流场畸变的隔离段直连台,并开展了马赫数2.5和3.5来流的两种不同烧蚀程度的C-SiC复合材料隔离段直连实验,获得了有效的纹影和压力数据,结合实验和理论分析,采用无量纲不平度hs/Dhy来表征烧蚀后C-SiC隔离段内壁面严重不规则粗糙特征,尝试在Waltrup公式中增加包含无量纲不平度的因子(1+4hs/Dhy),以此形成新的公式来预测烧蚀后C-SiC隔离段内激波串长度,预测精度较原来公式大幅提高,按照10%的误差带分析,修正后的Waltrup公式预测精度提高了33.3%。

In order to investigate the prediction of shock train’s length in the ablated C-SiC isolator under the influence of distorted flow,the direct connect experiment equipment which could simulate the distorted flow was designed,and experiments of two different ablated C-SiC isolators were conducted in Mach 2.5 and 3.5 flows,schlieren pictures and wall pressure were obtained. Combined with experimental and theoretical analysis,it is proposed that the dimensionless unevenness hs/Dhyis used to characterize the severe irregular roughness of the walls of ablated C-SiC isolators. In order to create a new formula to accurately predict the shock train’s length in the ablated isolator,the dimensionless factor(1+4hs/Dhy)was added to the Waltrup formula. The prediction accuracy of the new formula is significantly higher than the Waltrup formula. The accuracy is improved by 33.3% according to the error band of 10%.