Patent ID: 7001141

Claim:
A nozzle guide vane or turbine rotor blade for a gas turbine engine; the vane or blade comprising an aerofoil having a pressure wall and a suction wall and at least one aerofoil internal cavity between the pressure and suction walls for conveying cooling air through the aerofoil, and at least one aerofoil platform adjacent and generally perpendicular to the aerofoil, the at least one aerofoil platform having at least one internal platform cavity with a platform pressure wall on a pressure wall side of the aerofoil and on an aerofoil side of the platform cavity, and a platform suction wall on a suction wall side of the aerofoil and on the aerofoil side of the platform cavity, the platform cavity being divided into at least two chambers with no direct flow path therebetween, including a first chamber for receiving cooling air for cooling the platform pressure wall and a second chamber for receiving cooling air for cooling the platform suction wall, wherein the first chamber is in flow communication with the aerofoil cavity for discharging at least part of the cooling air entering the first chamber to the aerofoil cavity, and a plurality of impingement cooling holes are provided in a wall on an opposite side of the platform cavity to the platform pressure wall and the platform suction wall for cooling the platform pressure wall and the platform suction wall by the impingement of cooling air admitted, in use, into the platform cavity through the impingement cooling holes from a common source, including a first set of impingement cooling holes for conveying cooling air into the first chamber and a second set of impingement cooling holes for conveying cooling air into the second chamber.