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Evidence of longitudinal vortices evolved from distorted wakes in a turbine passage. (English) Zbl 0997.76032
Summary: Two types of longitudinal vortices are found to arise from distorted, migrating wakes convecting through a low-pressure turbine stator passage. The primary vortices emerge within the free stream as the wake is subjected to irrotational strains. Their axes align approximately with the local mean wake velocity. They are dragged over the surface and induce secondary vortices near the wall, which have the sense of rotation opposite to the primary vortices. Although they form on the concave side, these secondary vortices are neither produced nor sustained by Görtler instability; rather, they are a consequence of severely straining the passing wakes. Evidence is drawn from a numerical simulation of the unsteady, incompressible flow through a turbine stator passage with and without upstream turbulent wakes. The computations were performed with 2.5 and \(5.7 \times 10^7\) grid points on a parallel computer.

MSC:
76F25 Turbulent transport, mixing
76F65 Direct numerical and large eddy simulation of turbulence
76D25 Wakes and jets
76U05 General theory of rotating fluids
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