Transient heat transfer between a turbulent lean partially premixed flame in limit cycle oscillation and the walls of a can type combustor

Abstract

In this paper transient fluid-structure thermal analyses of the Limousine test rig have been conducted while the combustor was exposed to saturated amplitude limit cycle combustion oscillations (LCO). The heat transfer between hot combustion gases and the liner wall cooled by convection will affect thermo-acoustic instabilities, and therefore the relevance of prediction of the transient heat transfer rate in gas turbine combustors is explored. The commercial CFD code ANSYS CFX is used to analyze the problem. Fluid and solid regions are resolved simultaneously in a monolithical approach with application of a finite volume approach. Since the spatial scales of the solid temperature profiles are different in case of steady state and transient oscillatory heat transfer, special care has to be taken in the meshing strategy. It is shown that for the transient oscillatory heat transfer in to the solid in LCO operation, the mesh distribution and size of the grid in the solid part of the domain will play a very important role in determining the magnitude for the heat flow in the solid and the gas pressure fluctuations, and the grid resolution needs to be adapted to the thermal penetration depth. Moreover, compared to the calculations of only the fluid domain with adiabatic/isothermal boundary wall conditions, the results demonstrated that application of the Conjugated Heat Transfer (CHT) model leads to significant accuracy improvements in the prediction of the characteristics of the combustion instability.