Heat/mass transfer in a linear turbine cascade with a modified blade leading edge

Experimental heat/mass transfer measurements are performed in a linear gas turbine cascade. The blades are models of a first-stage rotor blade of a gas turbine aero-engine having fillets around the airfoil leading edges at the junction with the hub-endwall. The main objective of the fillets is that of altering the structure of the secondary flows within the blade passages to reduce the aerodynamic losses. The present study investigates the effect of fillets on mass/heat transfer within the cascade comparing the results to those obtained with a standard right-angled blade-endwall junction. Measurements are performed simultaneously on the hub endwall and airfoil surfaces using naphthalene sublimation. Mass transfer data can be converted to heat transfer data using a heat/mass transfer analogy. Tests are conducted at a Reynolds number of 600,000 based on true chord and cascade exit velocity and for values of freestream turbulence of 0.2% and 4.0% measured at the cascade inlet. The fillet reduces or eliminates the effects of the horseshoe vortex in the vicinity of the blade leading edge, but no significant changes are measured further downstream in the passage.