Cooled airfoil with reduced internal turn losses

Abstract

A cooled airfoil 10 has an internal fluid passage 34 that includes upstream and downstream legs, such as a co-centrifugal leg 40 and a counter-centrifugal leg 42 . The legs are separated from each other by a rib 44 but are connected in series with each other. The airfoil also includes a vent passage 56 for venting fluid from the internal passage. The intake 60 to the vent passage resides in the counter-centrifugal leg. The vent at least partially counteracts the separation potential of a separation susceptible region 54 by allowing some of the coolant to vent from the passage leg 42.

1 . An airfoil having an internal fluid passage, the passage including a co-centrifugal leg and a counter-centrifugal leg in series with the co-centrifugal leg and separated therefrom by a rib, the airfoil also including a vent passage with an intake for venting fluid from the internal passage, the intake residing in the counter-centrifugal leg.  
   
   
       2 . The airfoil of  claim 1  wherein the intake resides in a region susceptible to fluid separation.  
   
   
       3 . The airfoil of  claim 1  wherein the counter-centrifugal leg has a width and the intake resides in a region susceptible to fluid separation extending chordwisely up to about 50% of the width of the counter-centrifugal leg as measured from the rib to an opposing sidewall of the counter-centrifugal leg.  
   
   
       4 . The airfoil of  claim 1  wherein the counter-centrifugal leg has a width and the intake is spaced from the rib by about 25% of the width as measured from the rib to an opposing sidewall of the counter-centrifugal leg.  
   
   
       5 . The airfoil of  claim 1  wherein the intake resides immediately adjacent to the rib.  
   
   
       6 . The airfoil of  claim 1  wherein the intake resides in a region susceptible to fluid separation, the region extending about three and one half hydraulic diameters lengthwise along the counter-centrifugal leg.  
   
   
       7 . The airfoil of  claim 1  wherein the counter-centrifugal leg has an inlet and the intake resides within a region extending about three and one half hydraulic diameters lengthwise from the inlet.  
   
   
       8 . The airfoil of  claim 1  wherein the intake resides lengthwisely at a location where a separation susceptible region has a maximum chordwise dimension.  
   
   
       9 . The airfoil of  claim 1  wherein the intake is an array of intakes centered at a location where a separation susceptible region has a maximum chordwise dimension.  
   
   
       10 . The airfoil of  claim 1  wherein the vent passage is a film cooling hole.  
   
   
       11 . The airfoil of  claim 1  wherein the vent exhausts to a suction side of the blade.