Session: 12-03: Film Cooling Computational Studies (I)

Paper Number: 151761

Multiscale Data-Driven RANS Closure for Trailing Edge Cutback Film Cooling Flows 

This paper addresses the steady Reynolds-Averaged Navier-Stokes (RANS) simulation of turbomachinery flows with spectral overlap. A multiscale RANS closure model is proposed and applied to trailing edge cutback film cooling flows, featuring deterministic vortex shedding and its interaction with the stochastic turbulence scales. The model consists of three transport equations that solve the deterministic kinetic energy $k_d$, stochastic kinetic energy $k_s$, and stochastic specific energy dissipation rate $\omega$, hence referred to as $k^2-\omega$ model. The key terms are the deterministic anisotropy tensor $a_{d,ij}$ that controls the production of deterministic unsteadiness, the deterministic length scale $L_d$ that controls the deterministic-to-stochastic energy transfer, and the deterministic Prandtl number $Pr_d$ that controls the deterministic heat flux, all of which are closed by data-driven algebraic models with high-fidelity simulation data. The model is trained on one geometry under two operating conditions, and it is tested in a range of unseen geometries with different trailing edge thicknesses and wall inclination angles under different operating conditions. Results show that the $k^2-\omega$ model predicts the near-wake velocity and temperature field with sufficient accuracy. It is capable of capturing the change of wall cooling effectiveness with respect to the change of geometries and operating conditions, whereas the conventional RANS closure models fail to do so due to the inherent limitation of the Reynolds averaging process in the presence of both large-scale coherent flow structures and fine-scale turbulence. The presented model is a useful tool for future aerothermal design of turbine cutback trailing edges.

Presenting Author: Xiao He Imperial College London

Presenting Author Biography: Dr. Xiao He is a Research Associate at Department of Aeronautics, Imperial College London.

Authors:

Xiao He Shanghai Jiao Tong University
Francesco Montomoli Imperial College London
Vittorio Michelassi Baker Hughes
Andrea Panizza Baker Hughes
Leonardo Pulga Baker Hughes