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.

The evolution of the pressure loss coef cient and the exit ow angle has been investigated for a conventional low pressure turbine rotor blade of Snecma-Moteurs mounted in a stationary cascade arrangement at the von Karman Institute. As the boundary layers along those airfoils could exhibit laminar characteristics over a non-negligible distance, the pro le losses are directly linked to the occurrence of transition and separation. The main parameters affecting the boundary layer status are taken into account. The exit Reynolds and Mach numbers respectively range between 190 000 and 680 000 and between 0.6 and 0.9, the inlet free stream turbulence is 0.8 per cent. The pitch-chord ratio has also been varied from its nominal value. Although general tendencies for the loss coef cient variation with respect to each parameter have been found, it has been demonstrated that a better loss estimation needs to consider the conjunction of all these parameters. The present work also points out the weakness of the traditional correlation methods when the aerodynamic load of the blades is increased.

The accurate heat transfer prediction of film‐cooled blades is a key issue for the aerothermal turbine design. For this purpose, advanced numerical methods have been developed at Snecma Moteurs. The goal of this paper is the assessment of a three‐dimensional Navier‐Stokes solver, based on the ONERA CANARI‐COMET code, devoted to the steady aerothermal computations of film‐cooled blades. The code uses a multidomain approach to discretize the blade to blade channel with overlapping structured meshes for the injection holes. The turbulence closure is done by means of either Michel mixing length model or Spalart‐Allmaras one transport equation model. Computations of thin 3D slices of three film‐cooled nozzle guide vane blades with multiple injections are performed. Aerothermal predictions are compared to experiments carried out by the von Karman Institute. The behavior of the turbulence models is discussed, and velocity and temperature injection profiles are investigated.

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, 190,000, 350,000, and 650,000. 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.

In the first part of the present article (Coton et al. [1]), experimental data on a very high lift blade subject to bars generated incoming wakes are presented in terms of losses at mid span, secondary losses and unsteady heat transfer coefficient. In the present part, time-accurate 3D Reynolds averaged Navier-Stokes (RANS) computations have been performed including the simulation of the transition process for attached and detached boundary layers. First, the capability of the method to take into account the Reynolds number effect is presented in the case of steady inlet condition, and comparisons are shown for all the available experimental data. Particular attention has been taken to the influence of the numerical spatial scheme. 3D unsteady computations have been performed for two different rotational speeds. The wake effects are presented in terms of turbulence intensity and static pressure fluctuation, which are both important to describe the unsteady transitional phenomenae.