Exhaust Diffuser Strut Stepped Trailing Edge Flow Separation

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Solution Overview

Problem

Flow separation at the trailing edge of exhaust diffuser struts in gas turbines leads to pressure loss, reducing efficiency and affecting the overall performance of the power generation system.

Innovation Solution

An exhaust diffuser strut with a cut portion and ribs along its trailing edge, forming a stepped portion, which delays boundary layer formation and accelerates the extinction of flow separation, reducing pressure loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a conventional strut with airfoil-shaped cross-section is used, then the flow interruption is minimized, but flow separation occurs at the trailing edge causing pressure loss

Engineering Contradiction:

Improvepressure lossVSAvoidstrut structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The trailing edge of the strut is segmented into multiple steps rather than being a single continuous surface. This segmentation creates a multi-level stepped structure that progressively guides the flow, preventing sudden separation and reducing pressure loss while maintaining structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution transitions from a two-dimensional trailing edge surface to a three-dimensional stepped structure. By adding the vertical dimension with multiple levels, the flow is guided through a progressive descent rather than a sudden drop, eliminating flow separation and reducing pressure loss.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the strut structure is modified to reduce flow separation, then exhaust efficiency improves, but manufacturing complexity increases

Engineering Contradiction:

Improveexhaust efficiencyVSAvoidstrut fabrication

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The strut trailing edge is divided into discrete stepped levels that can be manufactured as separate features and then assembled or formed in sequence. This segmentation allows for standardized manufacturing processes while achieving the complex flow control geometry needed for high exhaust efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design optimizes specific parameters such as the number of steps, step height, and step positioning to balance manufacturing ease with performance. By carefully selecting these parameters, the strut achieves reduced flow separation and improved exhaust efficiency while remaining manufacturable using conventional techniques.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces pressure loss and improves exhaust efficiency by minimizing flow separation, enhancing the performance of the gas turbine and connected power generation systems.

Implementation Method 1

delay the formation of a boundary layer in the combustion gas disturbed by an abrupt change in the flow

Methodology Applied

Scientific EffectBoundary layer: Boundary Layer

Implementation Method 2

accelerates the extinction of flow separation

Methodology Applied

Scientific EffectFlow separation: Flow Separation

Data Source

PatentUS11873726B2Exhaust diffuser strut for reducing flow separation

Publication Date: 2024.01.16 DOOSAN ENERBILITY CO LTD

AI summary

A strut provided in an exhaust diffuser and having an airfoil-shaped cross-section is provided. The strut may include a cut portion configured to be formed in a trailing edge in a span direction. The cut portion is configured to provide a stepped portion in at least a portion of the trailing edge.