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 CompositeIsolator after Thermal Ablation

关键词:  隔离段  激波串  畸变  不平度

Key words:  Isolator  Shock train  Distortion  Unevenness

摘要:

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+4[hs/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%。

Abstract:

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/Dhy] is 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+4[hs/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%.