Turbine Shroud Dimpled Forward Zone for Leakage Control

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Solution Overview

Problem

Turbine engines face challenges in reducing blade tip wear and leakage due to manufacturing and operational tolerances, thermal distortion, and the need for efficient airflow, leading to compromises that affect engine efficiency and performance.

Innovation Solution

The implementation of a turbine abradable layer with distinct axially varying zones, including composite multi-orientation groove and ridge patterns, non-directional dimples, or varying porosity profiles, which direct and block airflow to minimize leakage and wear, while maintaining structural integrity and thermal resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single abradable surface design is used, then manufacturing and installation are simplified, but it cannot optimize performance for both standard and fast start modes

Engineering Contradiction:

Improveoperational mode adaptabilityVSAvoidabradable surface design complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The abradable surface is segmented into multiple functional zones (forward zone with dimples, intermediate zone with ridges and grooves, aft zone with crosshatch pattern) that work together to provide different functions. This segmentation allows the surface to adapt to varying operational conditions while maintaining a unified structure, resolving the contradiction between versatility and complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the abradable surface are given different local qualities through distinct surface patterns optimized for specific functions: the forward zone uses dimples for erosion resistance, the intermediate zone uses ridges and grooves for leakage control, and the aft zone uses crosshatch for wear distribution. This local differentiation enables the surface to handle multiple operational modes effectively.

Inventive Principle:

Principle #3Local quality

2Use of energy by moving object

If blade tip clearance is reduced to improve efficiency, then engine efficiency increases, but blade tip wear and leakage increase

Engineering Contradiction:

Improveengine efficiencyVSAvoidblade tip wear and leakage

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The abradable surface incorporates porous structures including dimples, grooves, and crosshatch patterns that create a controlled porosity. These porous features trap leakage flows and reduce their impact on blade tip performance, allowing smaller clearances to be used without proportionally increasing leakage losses.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The design converts the potentially harmful blade tip contact and leakage into a beneficial abradion process. The abradable surface is intentionally designed to wear away controllably, transforming harmful contact into a mechanism that maintains optimal clearance and reduces leakage over time, thereby improving efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If abradable surface features are added to reduce leakage and wear, then blade tip performance improves, but manufacturing complexity increases

Engineering Contradiction:

Improveblade tip wear resistanceVSAvoidabradable surface fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The abradable surface features are arranged in periodic patterns (repeating dimple arrays, regular ridge and groove sequences, systematic crosshatch patterns) that can be manufactured using repetitive processes. This periodic arrangement simplifies manufacturing by enabling the use of standardized tooling and repeatable fabrication cycles, reducing the complexity burden despite the detailed surface features.

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution effectively reduces blade tip leakage and wear, enhances engine efficiency, and allows for a single design to operate in both standard and fast start modes, preserving performance and longevity.

Implementation Method 1

The zone A profile comprises an array pattern of depression dimples, or upwardly projecting dimples, or both in the abradable surface. The forward zone dimples are aerodynamically compatible with different blade camber profiles and resist hot working gas erosion of the forward zone.

Methodology Applied

Scientific EffectTurbulence: Turbulence

Implementation Method 2

Methodology Applied

Scientific EffectAerodynamic flow direction:

Data Source

PatentUS10189082B2Turbine shroud with abradable layer having dimpled forward zone

Publication Date: 2019.01.29 SIEMENS ENERGY GLOBAL GMBH & CO KG

AI summary

Turbine and compressor casing abradable components for turbine engines include abradable surfaces with a zonal system of forward (zone A) and rear or aft sections (zone B) surface features. The zone A surface profile comprises an array pattern of non-directional depression dimples, or upwardly projecting dimples, or both, in the abradable surface. The dimpled forward zone A surface features reduce surface solidity in a controlled manner, to help increase abradability during blade tip rubbing incidents, yet they provide sufficient material to resist incoming hot working fluid erosion of the abradable surface. In addition, the dimples provide generic forward section aerodynamic profiling to the abradable surface, compatible with different blade airfoil-camber profiles. The aft zone B surface features comprise an array pattern of ridges and grooves.