Large eddy simulation of a low pressure turbine cascade with turbulent end wall boundary layers

TL;DR

This paper demonstrates the use of high-order discontinuous Galerkin large eddy simulation to accurately model flow in a low pressure turbine cascade, validating against experimental data and capturing complex flow features.

Contribution

First implicit large eddy simulation of a low pressure turbine with realistic boundary conditions using a high order discontinuous Galerkin method, validated against experimental results.

Findings

Blade loading and pressure losses match experiments

Simulation reproduces secondary flow structures and loss distribution

Effective boundary condition modeling for turbine flows

Abstract

We present first results of an implicit large eddy simulation of the MTU T161 low pressure turbine at a Reynolds number of 90,000 and Mach number of 0.6, both based on isentropic exit conditions, using a high order discontinuous Galerkin method. The aim is to validate the numerical setup with respect to available experimental data. We discuss the steps taken to create realistic inflow boundary conditions in terms of end wall boundary layer thickness and free stream turbulence intensity. This is achieved by tailoring the input distribution of Reynolds stresses and turbulent length scale to a Fourier series based synthetic turbulence generator. Both blade loading and total pressure losses at midspan show excellent agreement with the measurements. Following a short discussion of the secondary flow structures emerging due to the interaction of the incoming boundary layer and the turbine blade, we show that this simulation is also able to reproduce loss distribution behind the blade over the whole channel height.