Effects of Reynolds and Mach numbers on the profile losses of a conventional low-pressure turbine rotor cascade with an increasing pitch-chord ratio

Abstract

The evolution of the pressure loss coefficient and the exit flow 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 profile 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 190000 and 680000 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 coefficient 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.