RMC-defined tip blowing slots for turbine blades

Abstract

A process for forming an airfoil portion of a turbine engine component, such as a turbine blade, is described. The process comprises the steps of placing a ceramic core having a configuration of a passageway to be formed in the airfoil portion within a mold, attaching a refractory metal core element to the ceramic core to stabilize a tip region of the ceramic core, and casting the airfoil portion.

Description

BACKGROUND[0001](1) Field of the Invention[0002]The present invention relates to a process for forming a turbine engine component, such as a turbine blade, having a plurality of as-cast blowing slots in a tip region using a refractory core element.[0003](2) Prior Art[0004]One of the typical failure modes for high pressure turbine (HPT) rotor airfoils (blades) is tip distress via oxidation and erosion. It is particularly challenging to design a cooling configuration for a tip region for a variety of reasons. First, it is very difficult to determine the external thermal boundary conditions near the tip due to the highly-three dimensional nature of the gaspath flow. Also, the tip region of a turbine blade is typically the thinnest portion of the airfoil, which makes it more difficult to package the desired cooling features. Furthermore, the tip region of a turbine blade is typically difficult to accurately produce with investment casting processes because the internal ceramic core is t...

AI Technical Summary

Benefits of technology

[0007]In accordance with the present invention, there is provided a new tip cooling design that utilizes refractory metal core (RMC) technology in order to create a tip cooling scheme for a turbine engine component that is capable of more efficient use of cooling air and a more reliable casting process.

Problems solved by technology

One of the typical failure modes for high pressure turbine (HPT) rotor airfoils (blades) is tip distress via oxidation and erosion.

It is particularly challenging to design a cooling configuration for a tip region for a variety of reasons.

First, it is very difficult to determine the external thermal boundary conditions near the tip due to the highly-three dimensional nature of the gaspath flow.

Also, the tip region of a turbine blade is typically the thinnest portion of the airfoil, which makes it more difficult to package the desired cooling features.

Furthermore, the tip region of a turbine blade is typically difficult to accurately produce with investment casting processes because the internal ceramic core is thin and weak near the tip.

However, it is desirable to have the tip print-out holes be smaller so that they do not flow an excessive amount of cooling air in the finished part, which results in inefficiency in the cooling design and, therefore, the turbine performance.

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