彎管曲率及角度對S管道二次渦流之影響

The Effects of Curvature and Angle in a S-Duct to the Secondary Flows

戴昌賢(C. H. Tai) ； 蘇永平(Y. P. Su) ； 江大成(D. C. Chiang)

《中國航空太空學會學刊》 29卷3期 (1997/09) Pp. 265-277

https://doi.org/10.6124/TAASRC.199709_29(3).08

摘要

本研究以三維全納維史拓克方程式，模擬等截面S管道可壓縮流場現象。流體在彎管流場中，因曲率所造成離心力及壁面黏性效應的影響，會產生二次渦漩流(Secondary Swirl)，具有連續兩反向彎管的S管道，流場的複雜性更爲增加，其最主要特徵爲在第二彎管出口處形成一高總壓損失區，本研究將探討此低壓區之確實成因及影響因素。數值方法選用有限體積法(Finite Volume Method)，在空間方面以高階精度的van Leer Kapper scheme配合上風法(Roe's Upwind Scheme)處理空間項通量計算，另以顯式多步階法(Explicit Multi-Stage Scheme)作時間趨進(Time Marching)。所得之模擬結果指出，本流場特性爲流線曲率產生的離心力所主導，黏滯性對二次流之影響並不顯著；在第二彎管出口低總壓恢復區之大小，與流體在第一彎管所形成二次渦流的強度有密切關係。

關鍵字

S管道 ； 二次渦漩流 ； 總壓恢復 ； 紊流模式

並列摘要

In this paper, three dimensional Pull Navier-Stokes computational results are presented for compressible flow through S-duct. Secondary flows formed in bending ducts are due to the centrifugal force, generated by the streamwise curvature, and the viscous effect of walls. S-duct linked of two counter-direction bending ducts complicate the flow field phenomena, and forms a high total pressure loss region on the exit of second bend. The finite volume method coupled with explicit multi-stage and upwind flux-difference split scheme (Roe's scheme) are used to solve the governing equations which combined with 2 isotropic turbulence models. The results indicate that the features of flow through S-duct was dominated by the centrifugal force induced of the streamline curvature, and the viscous term was irremarkable for the flow as well as the range of low total pressure recovery region was strong dependent upon the intensity of secondary vortex which form in the first bend.

並列關鍵字

S-duct ； Secondary vortex ； Total pressure recovery ； Turbulence models