Gas Turbine Mateface Gap Configuration for Flow Control

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Solution Overview

Problem

Aerodynamic losses in gas turbine engines persist due to stagnation and recirculation of working gas in mateface gaps between airfoil structures, which counteract the benefits of endwall contouring and lead to increased pressure losses.

Innovation Solution

A non-linear mateface gap configuration with transverse and aligned portions, including inflection points and a backward facing step design, along with cooling fluid passages to redirect and energize the flow, minimizes stagnation and secondary vortices, and facilitates attached flow over the endwalls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If endwall contouring is incorporated on blade and vane shrouds, then aerodynamic losses are reduced and thermal efficiency is improved, but mateface gaps between airfoil structures cause stagnation and recirculation of working gas that counteracts these benefits

Engineering Contradiction:

Improveaerodynamic lossesVSAvoidstagnation and recirculation in mateface gaps

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The mateface gap is segmented into multiple zones with different orientations: a first zone aligned with streamlines, a second zone transverse to streamlines, and a third zone aligned with streamlines. This segmentation allows each zone to perform a specific function in controlling flow behavior, preventing stagnation while maintaining the benefits of endwall contouring.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mateface gap configuration extends in the axial direction with varying orientations, adding a dimensional aspect to flow control. The gap transitions from aligned to transverse and back to aligned orientations, creating a three-dimensional flow path that manages working gas movement and prevents recirculation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If a traditional linear mateface gap configuration is used, then manufacturing is simpler, but aerodynamic performance deteriorates due to increased pressure losses and secondary vortices

Engineering Contradiction:

Improvemateface gap fabricationVSAvoidpressure losses

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The mateface gap employs curved and transitional sections instead of straight linear segments. The gap includes curved transitions between aligned and transverse zones, which smoothly guide flow and reduce turbulence, thereby decreasing pressure losses while maintaining manufacturability through standard forming processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If the mateface gap is oriented transverse to streamlines, then flow attachment is improved, but manufacturing complexity increases due to non-linear configuration requirements

Engineering Contradiction:

Improveflow attachmentVSAvoidmateface gap geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The complex non-linear mateface gap is divided into manageable segments: aligned zones for flow attachment, transverse zones for flow direction control, and transition zones for smooth connections. This segmentation simplifies the manufacturing process while maintaining the aerodynamic benefits of the overall complex geometry.

Inventive Principle:

Principle #1Segmentation

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

The proposed design reduces pressure losses and secondary vortices, enhancing the aerodynamic efficiency and thermal performance of the turbine section by maintaining a continuous attached flow and reducing recirculation within the mateface gaps.

Implementation Method 1

cooling fluid passages to redirect and energize the flow, minimizes stagnation and secondary vortices

Methodology Applied

Scientific EffectFluid flow redirection:

Implementation Method 2

The mateface gap comprises a transverse portion that traverses a direction of the streamlines at the location of the transverse portion

Methodology Applied

Scientific EffectFlow separation: Flow Separation

Implementation Method 3

The mateface gap further comprises an aligned portion that is aligned with the direction of the streamlines at the location of the aligned portion

Methodology Applied

Scientific EffectAttached flow:

Data Source

PatentUS8961135B2Mateface gap configuration for gas turbine engine

Publication Date: 2015.02.24 SIEMENS ENERGY INC

AI summary

In a gas turbine engine, adjoining pairs of airfoil structures include airfoils mounted to respective platforms. The platforms have side edges defining matefaces that form a mateface gap extending from an upstream edge of the platforms to a downstream edge of the platforms. A flow field of working gas adjacent to endwalls of the platform comprises streamlines extending generally transverse to the axial direction from a first airfoil toward an adjacent second airfoil. To achieve improved aerodynamic performance, the mateface gap has portions oriented transverse to the streamlines and oriented aligned with the streamlines. A step in elevation of the side edges at the transverse portion can include injected cooling flow in a direction that enhances attachment of the flow at a downstream side.