Rolls-royce Corporation

Ian W R Harrogate

Ian Tibbott

Roderick M Townes

Andrew Hewitt

A method of manufacturing a coated turbine vane () comprises manufacturing a turbine vane () having a platform () and an aerofoil () extending from the platform (), a curved transition () connects the platform () to the aerofoil () and a recess () is provided in the curved transition () from the platform () to the aerofoil (). A bond coating () is deposited on the platform (), the aerofoil (), the curved transition () and the recess (). A ceramic thermal barrier coating () is deposited on the platform (), the recess () and the curved transition () by plasma spraying. The recess () reduces the size of the step due to the ceramic thermal barrier coating () and hence improves the aerodynamics of the turbine vane ().

Method of manufacturing a coated turbine blade and a coated turbine vane

Within components such as high pressure turbine blades and aerofoils in a gas turbine engine it is important to provide cooling such that these components remain within acceptable operational parameters. Typically, film cooling as well as convective cooling is utilized. Film cooling requires holes from a feed passage from which the coolant is presented upon an external surface to develop the film. The holes themselves can create cooling through convective cooling effects. In order to maximize the convective cooling effect holes are created which have an indirect path about a direct line between an inlet and an outlet for the hole. By creating an indirect path in the form of a helix or spiral which in turn may have a variable cross sectional area from the inlet to the outlet control of coolant flow can be achieved. The inlet may have a bell mouth shape while the hole may have a slot or elliptical cross section to achieve greater diffusion of the coolant flow in order to create an improved exit blow rate for instant film development.

Cooling arrangement

Within aerofoils, and in particular nozzle guide vane aerofoils in gas turbine engines problems can occur with regard to coolant flows from respective inlets at opposite ends of a cavity within the aerofoil. The cavity generally defines a hollow core and unless care is taken coolant flow can pass directly across the internal cavity. Previously baffle plates were inserted within the cavity to prevent such direct jetting across the cavity. Such baffle plates are subject to additional costs as well as potential unreliability problems. Baffles formed integrally with a wall within the aerofoil allow more reliability with regard to positioning as well as consistency of performance. The baffles can be perpendicular, upward or downwardly orientated or have a compound angle.

Aerofoil and method for making an aerofoil

A cooling arrangementfor use within a gas turbine engine comprises a first shroud or platformincorporating coolant passagesand a second shroud or platform. Generally, each platform or shroudwill incorporate a pressure portion and a suction portion, with the pressure portion incorporating the coolant passagesthrough which the coolant flowbecomes incident on a surfaceof the suction portion of the second shroud. The surfaceis inclined or tapered towards the passage, such that there is limited direct impingement upon a front edgeof the surface. The coolant flowthereby remains adjacent to the surfacefor a longer period and so enhances cooling efficiency.

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Uttoxeter, United Kingdom

Ian W R Harrogate