Experimental and Numerical Study of Laminar-Turbulent Transition on a Low-Pressure Turbine Outlet Guide Vane

Abstract

This work presents an experimental and numerical investigation on the laminar-turbulent transition and secondary flow structures in a Turbine Rear Structure (TRS). The study was executed at engine representative Reynolds number and inlet conditions at three different turbine load cases. Experiments were performed in an annular rotating rig with a shrouded low-pressure turbine upstream of a TRS test section. The numerical results were obtained using the SST k–ω turbulence model and the Langtry-Menter γ–θ transition model. The boundary layer transition location at the entire vane suction side is investigated. The location of the onset and the transition length are measured using IR-thermography along the entire vane span. The IR-thermography approach was validated using hot-wire boundary layer measurements. Both experiments and CFD show large variations of transition location along the vane span with strong influences from endwalls and turbine outlet conditions. Both correlate well with traditional transition onset correlations near midspan and show that the transition onset Reynolds number is independent of the acceleration parameter. However, CFD tends to predict an early transition onset in the midspan vane region and a late transition in the hub region. Furthermore, in the hub region, CFD is shown to overpredict the transverse flow and related losses.

Detailed Experimental Study of the Flow in a Turbine Rear Structure at Engine Realistic Flow Conditions

“…The thick OGV oil-visualizations are presented in this paper. Similar visualizations for the regular OGV can be found in an accompanying paper [10].…”

“…It was found that the formation of this region is very sensitive to the oil-film thickness, which indicates that a laminar flow separation with further turbulent reattachment may take place. The accompanying study [10] shows that on the regular vane the laminar-turbulent transition of the boundary layer takes place in this location and that the transition occurs at strong negative values of the acceleration parameter close to the separation margin.…”

“…The design of the new rig is presented by Rojo et al [7]. Jonsson et al [8] presented the accurate measurements of the heat transfer coefficient on OGVs, which has allowed for the mapping of the laminar-turbulent transition on OGVs for a number of aerodynamic load cases and his work is further extended and compared to CFD in an accompanying paper [10]. Jonsson et al [9] illustrated the impact of surface roughness on secondary flows and pressure losses in a TRS.…”

Experimental and Numerical Flow Analysis of an Engine Realistic State-Of-The-Art Turbine Rear Structure

“…Jonsson et al extended these measurements to look at secondary flows [9] and heat-transfer [10] in more detail. Deshpande et al [11] and Jonsson et al [12] also studied surface roughness and laminar-turbulent transition in this TRS. Vikhorev et al [13] continued to experimentally investigate both thick vanes and engine mount bumps in this circular TRS.…”

Design of Chalmers new low-pressure compressor test facility for low-speed testing of cryo-engine applications

“…The parts downstream of the OGV are modular and relatively simple and cost-effective to replace. Shroud, hub and ICDs can be replaced with instrumented geometries with pressure taps as in Jonsson et al [2018] or for heat transfer studies and local transition detection as in Jonsson et al [2020b] and Jonsson et al [2020c].…”