Method for preventing backflow and forming a cooling layer in an airfoil

Abstract

The present invention relates to a method for preventing backflow and forming a cooling layer in an airfoil by creating separation regions at a cooling slot inlet and flowing cooling fluid through the cooling slot.

1 . A method for preventing backflow and forming a cooling layer in an airfoil, said airfoil comprising a leading edge, a trailing edge, a blade tip at a first blade end and a blade root at a second blade end, the tip and root being separated by a radial distance, a cooling passage extending between the leading and trailing edges, and at least one cooling slot having an inlet end in fluid receiving communication with the cooling passage and an outlet end proximate the trailing edge, and wherein for the at least one slot the inlet and outlet are located at different radial locations within the airfoil, the method comprising flowing a cooling fluid in a first direction through said cooling passage toward a cooling slot, flowing the cooling medium in a second direction through said cooling passage toward the cooling slot, forming a separation region proximate the cooling slot inlet and flowing the cooling medium through said cooling slot and out the slot to form a layer at the trailing edge of the airfoil 
   
   
       2 . The method of  claim 1  wherein the cooling fluid is flowed through the cooling slot at a pressure, the pressure at the cooling slot being different than the pressure of the fluid along the airfoil trailing edge, the pressure ratio between the pressure in the slot and at the trailing edge being between 1.05 and 2.0. 
   
   
       3 . The method of  claim 1  wherein the method comprises flowing the cooling fluid from the airfoil at a velocity of between 0.03 Mach number to about 1.0 Mach number. 
   
   
       4 . The airfoil of  claim 1  wherein the cooling fluid is flowed through the cooling slot having an angle of orientation between about 1 degree to about 88 degrees relative to a line of reference that is substantially parallel to an axially extending axis.