Blade and vane leading edge fillet on endwall cooling in linear turbine cascades. (original) (raw)

Endwall-temperature and flow measurements are obtained in two linear turbine cascades-one employs blade profile and the other employs vane profile. The measurements provide the effects of blade/vane leading edge contouring on cascade endwall cooling. Fillets are employed at the junction of endwall and blade/vane leading edge in the cascades. The blade cascade operates at low speed atmospheric conditions while the vane cascade operates at high speed conditions with the exit Mach number near to 1.0. The blades/vanes are scaled two-dimensional profiles of the hub-side airfoils of the first stage section of the GE-E 3 turbine. Measured temperatures with constant heat flux in the blade passage provide Nusselt numbers along the endwall. In the vane passage, the temperatures are measured with the film cooling to obtain the adiabatic film cooling effectiveness. The coolant flow is ejected from cylindrical holes located upstream of the vane passage. Static pressure and velocity vectors near the exit of blade cascade provide the size and strength of the passage vortex responsible for the endwall heating and thermal stresses in the turbine passages. The results indicate smaller size and strength of the passage vortex in the blade passage when the fillets are present. The Nusselt numbers are then smaller for the filleted blades than for the non-filleted blades. The film cooling effectiveness increases with the coolant blowing ratio in the vane passage. However, the film cooling effectiveness is lower for the filleted vanes as the fillets mask some of the coolant holes blocking partially the coolant flow coverage.