Modeling of laminar-turbulent transition in a turbine rear structure

Abstract

The turbine rear structure (TRS) of modern aircraft gas turbine engines have several significant role, one of which is de-swirling the outlet flow coming from the Low Pressure Turbine (LPT) located upstream. Furthermore, the Outlet Guide Vane (OGV) in the TRS provides a structural support between the aft bearing support and main engine case. Other than de-swirling the flow, the TRS-OGV is mechanically and thermally loaded due to the hot outlet gases coming from LPT, which requires the OGV to be designed robustly. The TRS facility in Chalmers University, has a capability of operating over a wide range of Reynolds number, which allows several modes of transition, which in turn affects the aerodynamic and aerothermal performance. This thesis presents a tuned case-specific numerical investigation on the laminar-turbulent transition flow structures in the Turbine Rear Structure- Outlet Guide Vane (TRS OGV). The work includes the processes and results of matching the laminar turbulent transition in the TRS OGV using RANS-CFD with SST k-ω turbulence model and the Langtry-Menter γ-θ transition model. Experimental data for a certain case was used for ambient and boundary conditions for the inlet, outlet, turbulence decay and surface heat transfer. The numerical results obtained, match the experimental verification data considerably well.