改进k-ω-γ转捩模式对不同雷诺数下HIAD的转捩预测

Transition prediction for HIAD with different Reynolds numbers by improved k-ω-γ transition model

高超声速充气式柔性减速器(HIAD)在气动力作用下会变形为波纹状,从而促进流动转捩为湍流,准确预测其转捩位置和壁面热流对热防护系统的设计至关重要。拓展了分离诱导转捩预测性能的改进k-ω-γ模式,同时具备对第1模态、第2模态、横流模态以及流动分离失稳的预测能力。本文将其应用于不同雷诺数下壁面波纹变形的HIAD边界层转捩预测,并与原始k-ω-γ模式的预测结果进行了对比,以评估和验证其对复杂转捩现象的预测性能。在此基础上,细致剖析了改进k-ω-γ模式的转捩预测机制。结果表明,改进k-ω-γ转捩模式可准确预测不同来流雷诺数下HIAD的转捩起始位置、转捩阵面形态和壁面热流分布。波纹壁面波峰处的转捩预测主要由构造的分离间歇因子猝发。而在波谷位置,第1模态、横流模态以及流动分离的贡献都很重要。以上研究显示了改进k-ω-γ模式在复杂外形中的应用潜力,可为多重不稳定耦合作用下的转捩预测方法发展提供参考。

Hypersonic Inflatable Aerodynamic Decelerator(HIAD)would become undulated under the effect of aerodynamic force,thereby facilitating the flow transition to turbulence.Accurate prediction of transition onsets and surface heat flux is of paramount importance for the design of thermal protection systems.The improved k-ω-γmodel for separation-induced transition prediction possesses predictive capability for the first-,second-,and crossflow-mode instability and flow separation instability.In this study,it is applied to the boundary layer transition prediction over HIAD with wave-like wall deformation with different Reynolds numbers,and compared with the results by the original k-ω-γmodel to assess and verify its performance for complicated transition nature.Furthermore,the transition prediction mechanisms of the improved k-ω-γmodel are carefully dissected.Results show that the improved k-ω-γcould accurately predict the transition onsets,transition shapes and wall heat flux distributions of HIAD with different incoming Reynolds numbers.The transition prediction at crests of undulating surfaces is mainly triggered by the constructed separation intermittency,while in valleys,the contributions of the first mode,crossflow mode and flow separation instabilities should be emphasized.Current research indicates the huge application potential of the improved k-ω-γmodel for complex configurations,and can provide reference for the development of the transition prediction method for flow transition induced by multiple instability coupling.