The influence of inlet swirl intensity and hot-streak on aerodynamics and thermal characteristics of a high pressure turbine vane

Abstract

In modern gas turbines, the High Pressure Turbine (HPT) is exposed to an extreme thermal environment due to the burned gases leaving the combustor. The burned gases are characterized by flow and temperature distortions that effect the aerodynamics and heat transfer of the turbine. The purpose of this paper is to investigate numerically the effect of the intensity of the swirling flow combined with the temperature non-uniformity “Hot-Streak” (H-S) on the aerothermal performances of a HPT Nozzle Guide Vane (NGV). The investigations are conducted on the solid untwisted NGV annular cascade developed in NASA Lewis Research Center. Four swirl intensities (|Sn| = 0, 0.1, 0.25 and 0.5), two swirl orientations (positive and negative) and two hot-streaks (rounded and radial) at the NGV inlet are considered. The simulations are done by solving the Reynolds Averaged Navier-Stokes (RANS) equations using ANSYS-CFX software. The results show that the H-S with swirl undergoes twisting following the orientation of the swirl. The H-S twist is aggressive under positive swirl compared to the negative swirl case. The inlet swirl generates a new secondary flow structure, so called Swirl Vortex (SV), which induces more aerodynamic losses. The aerodynamic efficiency under negative swirl found to be higher than that under positive swirl. The maximum temperature on the vane surface is controlled by the radial transport of the SV towards the endwalls.