摘要
为计算有分离三维边界层的特性,探索适用的应力模式,对无限展长的后掠翼(x=35°),选择了几种湍流应力模式进行计算,井对结果作了分析。所采用的应力模式有代数模式,它包括常用的Cebeci-Smith(C-5)模式、Baldwin-Lomax(B-L)模式、修正外区涡粘性系数的C-S模式修正形式以及北京航空航天大学近年研究的修正由压强梯度和湍能非平衡引起影响的模式。所采用的还有考虑壁面效应的低Re数k-ε双方程模式,对此取效果较好的Chien(CH)、Lam-Bremhorst(LB)和Laundcr-Sharma(LS)三种。与实验值的比较表明,在接近分离线时,用上述各模式的平均速度和摩阻系数计算值都不够准确,但在分离线前较远处,本文提到的北肮模式的计算准确度较高。对湍流应力剖面的计算也以北航模式为较佳。此外,除了修正外区涡粘性系数的模式外,其它各模式均使计算可推进到实验分离点的下游,尚不足以预测分离。
In ordcr to understand the effect of modelling the turbu-lent stresses on prediction of the behavior of 3-D turbulent boundary layer with separation, some commonly used turbulence models were se-lected in computation.They、were to include the algebraic turbulence models such as Ccbeci Smith(C-S) model, Baldwin-Lomax (B-L) model,revised C-S model with the turbulent viscosity modified in the outer region and the newly developed BUAA model having taken the effects of high pressure gradient and local non equilibrium into consideration, along with the low Reynolds number k-ε models like Chien (CH),Lam-Bremhorst(LB)and Launder-Sharma(LS),all claimed to be more efficient than others in predicting the near-wall turbulent flow. Computations were focused on the 3-D turbulent boundary layer de-veloped on an infinitely spanned wing having a sweep-back angle x=35°,towhich available experimental results are sufficient for the evaluation of computational results.Data comparison shows that for all mentioned models,the predictional accuracy of the mean velocitv and friction coefficent de-creases when approaching to the separation line,although it may be accurate enough at positions further ahead of the separation. Among them,the model proposed by BUAA seems to be the best,especially for the prcdiction of turbulent stresses.Nevertheless,the computation could proceed down-stream after the experimentally determined separation line,except by using the modified C-S model,therefore the mentioned models are still inconvenient for predicting the start of flow separation.
出处
《空气动力学学报》
CSCD
北大核心
1994年第2期130-138,共9页
Acta Aerodynamica Sinica
基金
国家自然科学基金
关键词
边界层
湍流模式
分离
三维计算
boundary layer,turbulence modelling,separation,3-Dcomputation.