Unsteady and Calming Effects Investigation on a Very High Lift LP Turbine Blade: Part I — Experimental Analysis

Abstract

An experimental and numerical study was performed about the influence of incoming wakes and the calming effect on a very high lift low pressure turbine rotor blade. The first part of the paper describes the experimental determination of the pressure loss coefficient and the heat transfer around the blade mounted in a high speed linear cascade. The cascade is exposed to incoming wakes generated by high speed rotating bars. Their aim is to act upon the transition/separation phenomena. The measurements were conducted at a constant exit Mach number equal to 0.8 and at three Reynolds number values, namely 190000, 350000 and 650000. The inlet turbulence level was fixed at 0.8%. An additional feature of this work is to identify the boundary layer status through heat transfer measurements. Compared to the traditionally used hot films, thin film heat flux gages provide fully quantitative data required for code validation. Numerical computations are presented in the second part of the paper.

Profile Loss Coefficient Definitions Revisited

“…Also kinetic energy loss coefficients, KSI, (e.g. Coton et al [3] for low speed and Vera et al [19] for high speed) and total pressure loss coefficient nondimensionalised by exit incompressible dynamic pressure, P 0 =0:5 U 2 , (e.g. Curtis et al [5] for low speed or Jouini et al [13] for transonic speeds) are commonly used.…”

Transition Models for Turbomachinery Boundary Layer Flows: A Review

“…As with natural transition, mean-flow turbulence accelerates and controls the growth of the Kelvin-Helmholtz vortices and makes the process less sensitive to other disturbances. The mechanisms of separation-induced transition were studied by experiments, by LES and by DNS by many researchers [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Generally, the free shear layer, once sufficiently turbulent, reattaches forming a separation bubble.…”