Influence of Mainstream Turbulence Intensity on Heat Transfer Characteristics of a High Pressure Turbine Stage With Inlet Hot Streak

Abstract

An unsteady computational study was carried out on GE-E3 high pressure (HP) turbine at inflow turbulence intensities of 5%, 10%, and 20% accompanying with inlet hot streak (HS) at two circumferential positions (impinging and nonimpinging relative to vane leading edge) to analyze the interacted turbulence and HS influences. Turbulence decay mechanisms in turbine passage were presented, and the airfoil heat transfer behaviors were explored by means of adiabatic wall temperature, heat transfer coefficient (HTC), and wall heat flux. The results indicate that the elevated turbulence leads to favorable turbine airfoil temperature distributions, and turbulence induced HS attenuation mainly occurs in vane passage. In addition, the HS dispersion is related directly to the temperature gradients. Although the endwall temperature increases by more than 20 K (2.8% inlet mass-averaged temperature) and midregion temperature decreases by 16 K at blade leading edge, the hot region on blade pressure surface (PS) is only weakened by about 7 K, when turbulence intensity is increased from 5% to 20%. Higher turbulence significantly affects the airfoil HTC, excepting the regions secondary and leakage flow effects are dominating. Therefore, the tip and blade suction surface (SS) trailing edge heat flux is decreased for the temperature decline at higher turbulence, which is beneficial to tip cooling. HS position not only affects the airfoil surface temperature variations but also slightly affects the vane and blade midspan HTC for the variation of heat transfer driving temperature.