A Numerical Investigation on the Development of an Embedded Streamwise Vortex in a Turbulent Boundary Layer With Spanwise Pressure Gradient

Abstract

It is the aim of this article to investigate numerically the effects of spanwise pressure gradient on an embedded streamwise vortex in a turbulent boundary layer. The governing equations were discretized by the finite volume method and SIMPLE algorithm was used to couple between pressure and velocity. The LRR model for Reynolds stresses was utilized to predict the anisotropy of turbulence effectively. The validation was done for two cases: one is the development of a streamwise vortex embedded in a pressure-driven, three-dimensional turbulent boundary layer. The other involves streamwise vortex pairs embedded in a turbulent boundary layer without the spanwise pressure gradient. In the case of the former, the predicted results were compared with Shizawa and Eaton’s experimental data. In the latter case, the calculated results were compared against the experimental data of Pauley and Eaton. We performed numerical simulations for three cases with different values of spanwise pressure gradient. As a result, the primary streamwise vortex with spanwise pressure gradients decays more rapidly than the case with no pressure gradients, as the spanwise pressure gradient increases. This indicates that the spanwise pressure gradient may play an important role on mean and turbulent structures. In particular, it can be seen that the increase of pressure gradient enhances a level of turbulent normal stresses.

Investigation of Staggered Labyrinth Tip Shroud on Flow Mechanism of Low-Pressure Turbine

“…At the location of A2, the reentering flowrate in cavity inlet gap reaches the highest. It is noticeable that there is little difference on the positive static pressure gradient that drives the radial movement of reentering flow in both figure 13 (c) and (d), indicating the reentering flow is mainly driven by the counter toroidal vortex, which begins to dissipate under the circumstances that the radial pressure gradien becomes neglectable, based on the model of numerical investigation by (Lee, 2001). In figure 13 (c), with the circumferential position increased, counter toroidal vortex keeps expanding by inhaling the ingestion mass flow together with the axial movement of twin cavity vortices core.…”