Coupled heat-transfer simulations of turbines in consideration of unsteady flows

This paper describes an approach to perform coupled heat-transfer simulations of typical design relevant problems for gas turbines. In contrast to earlier publications, unsteady flow effects are incorporated leading to a different result compared to a purely steady simulation. The approach is validated by comparing it against an analytical solution of the unsteady convective heat transfer for a one-dimensional example. The approximation of the unsteady wall temperature allows for a fast comparison of the convective heat transfer for two cases: with and without wall temperature oscillations. A range of typical parameters, material properties as well as convective conditions, are considered to estimate the validity of the presented method for the aerothermal turbine design. It is shown that the influence of the wall temperature unsteadiness on the time-averaged heat load is low for typical turbine relevant frequencies. The presented semi-unsteady coupling method is finally applied to a turbine geometry and compared to steady and fully-unsteady coupled approaches. The results of both time-resolved simulations show the expected significant influence of the unsteady flow on the time-averaged wall temperatures and highlights their relevance for the thermal design process of turbines.