Turbine Blade Tip Pocket Rib Design

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Solution Overview

Problem

Turbine blade tips in gas turbine engines face thermo-mechanical fatigue due to high temperatures and mechanical forces, leading to costly engine downtime and reduced efficiency, as existing designs struggle to maintain a minimal gap between the blade tip and shroud while ensuring adequate cooling and structural integrity.

Innovation Solution

A turbine blade design featuring a radially recessed tip pocket with a rib extending between the pressure and suction side walls, where the rib height is less than the wall height, providing structural reinforcement without impeding cooling air flow and reducing stress concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a full height rib is used to divide the tip pocket, then structural reinforcement is improved, but cooling air flow is impeded and stress concentration increases

Engineering Contradiction:

Improvestructural reinforcementVSAvoidcooling air flow

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The rib is designed with varying height along its length, being tallest at the trailing edge where structural reinforcement is most needed and progressively shorter toward the leading edge where cooling air flow is prioritized. This local variation in rib height optimizes both structural strength and cooling efficiency by placing reinforcement only where thermally and mechanically critical.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of using a full height rib that would provide maximum structural reinforcement, the invention uses a partial height rib that provides sufficient reinforcement for the critical trailing edge region while allowing adequate cooling air flow through the tip pocket. The rib height is carefully controlled to be less than the full tip pocket depth.

Inventive Principle:

Principle #16Partial or excessive action

2Use of energy by moving object

If cooling air flow is maximized, then cooling efficiency is improved, but structural reinforcement is reduced

Engineering Contradiction:

Improvecooling efficiencyVSAvoidstructural reinforcement

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The rib height varies locally along its length, providing maximum height at the trailing edge for structural reinforcement and minimum height at the leading edge for optimal cooling air flow. This creates different local characteristics that simultaneously satisfy both cooling efficiency and structural reinforcement requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The tip pocket is segmented into a leading portion and a trailing portion by the rib, with each portion optimized for different functions. The trailing portion receives structural reinforcement from the rib while the leading portion maintains open geometry for cooling air flow.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11118462B2Blade tip pocket rib

Publication Date: 2021.09.14 PRATT & WHITNEY CANADA CORP

AI summary

A turbine blade for a gas turbine engine, the turbine blade having a peripheral blade tip wall surrounding a radially recessed tip pocket, the peripheral blade tip wall having: a wall height; a leading edge; a trailing edge; a pressure side wall; and a suction side wall; and a rib extending between the pressure side wall and the suction side wall defining a leading portion and a trailing portion of the radially recessed tip pocket, the rib having a rib height less than the wall height.