Session: 34-01 High-fidelity CFD – turbines

Paper Number: 151494

Evaluation of Lattice-Boltzmann Method Simulations for a 1-1/2 Stage Transonic Turbine With an Aggressive Interturbine Transition Duct 

The predictive accuracy of the lattice-Boltzmann method very large eddy simulation (LBM-VLES) approach was evaluated for a 1-1/2 stage transonic turbine with an aggressive interturbine transition duct (ITD). As the geometry was not publicly available, efforts were undertaken to reverse-engineer the geometry of the transonic high pressure (HP) vane/blade rows and the low pressure (LP) vane row of the Transonic Test Turbine rig at the Institute for Thermal Turbomachinery at Graz University of Technology in Styria, Austria in its single HP stage aero design point (ADP1), aggressive ITD (C4) configuration. The reverse-engineering process was guided by conducting steady Reynolds-Averaged Navier-Stokes (RANS) simulations using the ANSYS CFX solver with the goal of matching published bulk performance metrics and radial flow distributions for this rig.

The unsteady LBM-VLES simulation approach (implemented using the commercial PowerFLOW solver developed by Dassault Systèmes Simulia Corp.) involved documenting the sensitivity of calculated bulk performance and mean radial distributions to the grid resolution, with the cell count varying from 245 million to 1.1 billion voxels (Cartesian grid elements). Particular attention was paid to grid refinement within the tip clearance of the unshrouded HP blades and the evolution of resolved turbulence along the ITD casing as the tip clearance vortices propagated downstream. Two different HP blade tip clearances were simulated (1.5% and 2.4% of the blade span), and the sensitivity to the varying tip clearance was evaluated in terms of flow field evolution through the ITD and downstream LP vane row, with comparisons against RANS simulations and published rig test data.

Overall, the authors found that LBM-VLES simulations were a suitable approach for predicting the performance and unsteady loss mechanisms of a 1-1/2 stage transonic turbine coupled to an aggressive ITD, at a computational cost compatible with industrial design cycles. To the authors’ knowledge, this publication represents a novel application of the lattice-Boltzmann method, in terms of both the transonic operating regime of the HP stage and its coupling to an aggressive ITD.

Presenting Author: Matthew Langford Techsburg, Inc.

Presenting Author Biography: Matt Langford is the Chief Engineer at Techsburg, Inc. (located in Christiansburg VA), where he has worked since 2003. His technical focus over that time has been on aerodynamics and aeroacoustics of aircraft propulsion systems, including fans, propellers, vertical lift, and gas turbines. He has split time between experimental and computational projects, but efforts since 2020 have focused on unsteady computational fluid dynamics and computational aeroacoustics using the lattice-Boltzmann method.

Authors:

Matthew Langford Techsburg, Inc.
Stephen Guillot Techsburg, Inc.
Eric Monson Solar Turbines Incorporated
Andrew Lombardi Solar Turbines Incorporated
Gregory Heitland Solar Turbines Incorporated