关键词: 边界层转捩, 转捩模式, 柔性减速器, 高超声速, 气动热

Abstract:

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-γ model 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-γ model to assess and verify its performance for complicated transition nature. Furthermore， the transition prediction mechanisms of the improved k-ω-γ model are carefully dissected. Results show that the improved k-ω-γ could 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-γ model for complex configurations， and can provide reference for the development of the transition prediction method for flow transition induced by multiple instability coupling.

Key words: boundary layer transition, transition model, flexible decelerator, hypersonic, aerothermodynamic