Wall elements for gas turbine engines

Abstract

A double-wall structure for use in components in gas turbine engines that are exposed to high temperatures has a first wall spaced apart from a second wall. The first wall has a protrusion extending therefrom towards the second wall. The second wall has a cooling fluid orifice, or hole, through which cooling fluid is directed in use towards the protrusion. The protrusion extends across a significant percentage of the gap between the first and second walls. The cooling fluid removes heat from protrusion as it flows over it through convection, thereby cooling the first wall. The cooling fluid is also redirected so as to become more aligned with the first wall as it flows over the protrusion. In some cases, a trench is provided at the base of the protrusion. The cooling fluid causes a vortex to form in the trench, thereby further assisting cooling.

1 - 17 . (canceled) 
     
     
         18 . A gas turbine engine component comprising a double-wall structure, the double-wall structure comprising:
 a first wall having a first surface and a second surface;   a second wall spaced apart from the first wall such that the second surface of the first wall faces the second wall, the second wall comprising at least one cooling fluid orifice configured to direct cooling fluid in the direction of the first wall; and   a protrusion extending from a base on the second surface of the first wall to a tip, wherein:   the protrusion is located such that, in use, cooling fluid from a respective cooling fluid orifice is directed towards the tip thereof; and   the height of the protrusion above the second surface is at least 25% of the distance between the first wall and the second wall.   
     
     
         19 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein the protrusion has a generally tapered shape from the base to the tip such that, in use, the cooling fluid is caused to diverge over the protrusion as it passes from the tip to the base. 
     
     
         20 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , the double-wall structure comprising a plurality of protrusions, each protrusion corresponding to a respective cooling fluid orifice such that, in use, substantially all cooling fluid that is directed towards the tip of any given protrusion is from its corresponding respective cooling fluid orifice. 
     
     
         21 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , the double-wall structure comprising a plurality of cooling fluid orifices, each cooling fluid orifice corresponding to a single respective protrusion such that, in use, substantially all cooling fluid from any given cooling fluid orifice is directed towards its corresponding single respective protrusion. 
     
     
         22 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , further comprising a trough extending around at least a part of the perimeter of the base of each protrusion, the trough being formed in the second surface of the first wall. 
     
     
         23 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein each protrusion has a major axis that is aligned with a major axis of a corresponding cooling fluid orifice. 
     
     
         24 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein each protrusion has a major axis that is parallel to and offset from a major axis of a corresponding cooling fluid orifice. 
     
     
         25 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein the or each protrusion is axisymmetric about a major axis that is substantially normal to the second surface of the first wall, from which the protrusion extends. 
     
     
         26 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein each protrusion is skewed from base to tip in a direction that is parallel to a principal rotational axis of the gas turbine engine when assembled, and in the upstream direction of the fluid flow through the gas turbine engine when in use. 
     
     
         27 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein cross sections taken through the or each protrusion in any plane perpendicular to the major axis are circular. 
     
     
         28 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein each protrusion has a major axis that is parallel to the second surface of the first wall. 
     
     
         29 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein the or each cooling fluid orifice is a feed hole in the second wall. 
     
     
         30 . A gas turbine engine component comprising a double-wall structure according to  claim 29 , wherein the tip of the or each protrusion extends at least partially into a respective feed hole in the second wall. 
     
     
         31 . A gas turbine engine component comprising a double-wall structure according to  claim 18 , wherein each protrusion has a major longitudinal axis, the spacing between neighbouring longitudinal axes being at least 50% of the spacing between the first wall and the second wall. 
     
     
         32 . A combustor, an aerofoil, or a nozzle comprising a double-wall structure, the double-wall structure comprising:
 a first wall having a first surface and a second surface;   a second wall spaced apart from the first wall such that the second surface of the first wall faces the second wall, the second wall comprising at least one cooling fluid orifice configured to direct cooling fluid in the direction of the first wall; and   a protrusion extending from a base on the second surface of the first wall to a tip, wherein:   the protrusion is located such that, in use, cooling fluid from a respective cooling fluid orifice is directed towards the tip thereof; and   the height of the protrusion above the second surface is at least 25% of the distance between the first wall and the second wall.   
     
     
         33 . A method of cooling a double-wall structure the double-wall structure having a first wall and a second wall, the second wall being spaced apart from the first wall, the method comprising:
 supplying a cooling fluid flow to a protrusion from a respective cooling fluid orifice, the protrusion being provided on a second surface of the first wall, the protrusion extending from a base in the direction of the second wall to a tip, the cooling fluid flow being directed towards the tip of the protrusion, wherein:   the cooling fluid flows over the surface of the protrusion from the tip to the base, thereby removing heat from the protrusion.   
     
     
         34 . A method according to  claim 33  wherein the cooling fluid orifice is a hole in the second wall, and the method comprises supplying cooling fluid flow through the hole.