Computational modelling of inflow turbulence effects on transitional flow in a highly transonic linear turbine

Abstract

PurposeThe purpose of this paper is to numerically study inflow turbulence effects on the transitional flow in a high pressure linear transonic turbine at the design incidence.Design/methodology/approachThe three‐dimensional (3‐D) compressible turbulent flow in a turbine inlet guide vane is simulated using a finite volume based fluid solver coupled with dynamic large eddy simulation (LES) computations to investigate the effects of varying inflow turbulence length scale and the turbulence intensity on the aero‐thermal flow characteristics and the laminar‐turbulent transition phenomena. The computational analyses are extended to very high exit Reynolds number flow conditions to further study the effect of high exit Reynolds numbers on the transitional behavior of the present flow around the inlet guide vane cascades of the turbine. The calculations are performed with varying degree of inflow turbulence intensity values ranging from 0.8 to 6 percent and the inflow turbulence length scales ranging from one to five percent of pitch for different exit isentropic Mach and Reynolds numbers.FindingsThe numerical predictions in comparison with the experimental data demonstrate that the level of inflow turbulence closure provided by the present LES computations offers a reliable framework to predict complex turbulent flow and transition phenomena in high free‐stream turbulence environments of high pressure linear turbines.Originality/valueThis is the first instance in which both artificially modified random flow generation method in association with the dynamic procedure of LES application is employed to represent the realistic inflow turbulence conditions in the high pressure turbine and to resolve the transitional flow in a dynamic approach.

Numerical investigations of unsteady passing wake effects on turbine blade tip aerothermal performance with different tip clearances

“…Some researchers have conducted steady simulations under non-uniform inlet boundary conditions. Tutar and Sönmez (2012) numerically studied the effects of inflow turbulence on the transitional flow, and the adverse pressure gradients and heat transfer on the blade surfaces are highly related inflow turbulence intensity. Nikparto and Schobeiri (2018) numerically studied turbine blade heat transfer under periodical inlet flow conditions, in combination with experiment, and concluded that the accurate prediction of heat transfer strongly relies on the accuracy of aerodynamic calculations.…”