Airfoil and corresponding guide vane, blade, gas turbine and turbomachine

Abstract

An airfoil suitable for being arranged in a compressor section of the gas turbine includes a platform, a pressure surface and a suction surface, and a tip region. The tip region is located between the pressure and the suction surface opposite to the platform in respect of the pressure and the suction surfaces, being a distant end of the airfoil in direction along the first direction perpendicular to the platform. The tip region includes a first surface with a first distance to the platform along the first direction, and a second surface with a second distance to the platform along the first direction. The first distance is greater than the second distance and the first surface and the second surface together build a profiled surface. The profiled surface is a ribbed surface. The material of the first surface is deformable to bend away from the rotation direction of the airfoil.

Description

FIELD OF THE INVENTION[0001]The invention relates to an airfoil, a guide vane, and a blade, particularly of a compressor or a turbine section of a turbomachine. Furthermore the invention relates to a turbomachine, especially a gas turbine, comprising at least one airfoil.BACKGROUND OF THE INVENTION[0002]A conventional gas turbine engine comprises a compressor which is used for pressurising ambient air. The compressed air is mixed with fuel and burned in a combustor. Energy is extracted from the hot combustion gas by passing it through a turbine section of the gas turbine engine. The rotatable sections of an engine typically comprise annular arrays of compressor or turbine rotor blades, the blades normally being intersected with annular arrays of static aerodynamic guide vanes, also called stator vanes. Each disc of guide vanes and each disc of rotor blades are arranged axially alternately. One disc of rotor blades and one disc of guide vanes are referred to as a stage. The guide van...

AI Technical Summary

Benefits of technology

[0012]The present invention seeks to mitigate drawbacks of the prior art. Specifically it is an object of the invention to provide an airfoil or a component comprising such an airfoil that leakage over the tip of the airfoil is reduced, by also considering material costs and / or durability of the airfoil.

[0019]The inventive airfoil may be advantageous—especially when also considering the subject matter of the dependent claims—, because this form of the airfoil provides only a small contact surface—the first surface—to an opposing surface, once assembled. This may lead to the possibility to have a deformable tip section. Thus a reduced operating clearance between the tip region and the opposing surface may be provided which leads to reduced leakage and eventually to an improved compressor efficiency.

[0028]The invention is particularly advantageous, as the tip region is composed of a deformable material. Therefore the cold clearance of the airfoil to its opposing mating part can be smaller. If contact is made with the adjoining part during operation, the tip region of the airfoil is allowed to deform. Thus no precise manufacturing or configuration of blades is required. Tolerances are allowed so that manufacturing or installation costs can be reduced. Also no expensive abradable or abrasive coating is required. If no contact of the tip region with the opposing part is present during operation due to tolerances and operating conditions, the operating gap and the leakage will be reduced. With reduced clearance and reduced leakage the overall compressor efficiency will be improved.

[0029]In yet another embodiment the tip region—particularly the first surface and possibly only the first surface—may either be coated with an abrasive coating for abrading an opposing surface or may be coated with an abradable coating, so that the tip region gets abraded. Such a coating may be used as an alternative to the deformable tip or may even be combined with the deformable tip. This is possible by using only less abradable or abrasive coatings on the tip region, because only the raised first surface may be coated. This again may reduce costs.

Problems solved by technology

Hardly any air should be able to leave the path of the air because this would lead to an unwanted drop of air pressure.

On the other hand the use of special coatings may be costly.

Images