UNSTEADY NUMERICAL SIMULATIONS OF RADIAL TEMPERATURE PROFILE REDISTRIBUTION IN A SINGLE-STAGE TURBINE

Experimental data taken front gas turbine combustors indicate that the flow exiting the combustor can contain both circumferential and radia l temperature gradients. A significant amount of research recently has been devoted to studying turbine flows with inlet temperature gradien ts, but no total pressure gradients. Less attention has been given to flows containing both temperature and total pressure gradients at the inlet. The significance of the total pressure gradients is that the se condary flows and the temperature redistribution process in the vane b lade row can be significantly altered Experimental data previously obt ained in a single-stage turbine with inlet total temperature and total pressure gradients indicated a redistribution of the warmer fluid to the pressure surface of the airfoils, and a severe underturning of the flow at the exit of the stage. In a concurrent numerical simulation, a steady, inviscid three-dimensional flow analysis was able to capture the redistribution process, but not the exit flow angle distribution. In the current research program, a series of unsteady two- and three- dimensional Navier-Stokes simulations have been performed to study the redistribution of the radial temperature profile in the turbine stage . The three-dimensional analysis predicts both the temperature redistr ibution and the flow underturning observed in the experiments.