Compressor Stator Vane Leakage Path Design

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Solution Overview

Problem

Conventional compressors in gas turbines experience leakage of compressed air through cavities between the shroud and rotor, leading to secondary flow and pressure loss, which existing solutions attempt to address with increased structural complexity and manufacturing costs.

Innovation Solution

A compressor stator vane unit with an annular joint member that sets specific ratios for the distance between the leakage fluid flow path opening and the upstream edge of the stator vanes relative to the vane pitch and thickness, preventing interference between main and leakage fluid flows without increasing complexity or cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a seal member is provided between the shroud and rotor to prevent leakage, then the leakage of compressed air is reduced, but it is difficult to completely eliminate the leakage and the structural complexity increases

Engineering Contradiction:

Improvecompressed air leakageVSAvoidseal member structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent extracts the leakage prevention function from the traditional seal member and relocates it to the stator vane unit structure itself. By forming the leakage prevention function within the stator vane assembly (through the annular plate and support plate configuration), the patent eliminates the need for separate seal members between the shroud and rotor, thereby reducing structural complexity while maintaining effective leakage prevention.

Inventive Principle:

Principle #2Taking out (Extraction)

2Loss of energy

If conventional seal members are used to prevent compressed air leakage, then some leakage is reduced, but the structural complexity and manufacturing cost increase

Engineering Contradiction:

Improvecompressed air leakageVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent merges the leakage prevention function with the stator vane unit structure by integrating the annular plate and support plate into the existing stator vane assembly. This consolidation eliminates the need for separate seal members and reduces the number of manufacturing steps, thereby lowering manufacturing cost while maintaining effective leakage prevention.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If the distance D between the leakage fluid flow path opening and upstream edge of stator vanes is optimized, then pressure loss is reduced, but the positioning precision requirement increases

Engineering Contradiction:

Improvepressure lossVSAvoidpositioning precision of leakage fluid flow path

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent incorporates the leakage fluid flow path opening directly into the stator vane unit structure during manufacturing, establishing the optimal distance D between the opening and upstream edge of stator vanes as an inherent design feature. By pre-positioning the opening at the optimal location during stator vane fabrication, the patent achieves the desired pressure loss reduction while avoiding the need for additional post-assembly adjustments or higher precision requirements during final assembly.

Inventive Principle:

Principle #10Preliminary 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 configuration effectively prevents leakage fluid from flowing out and reduces pressure loss by optimizing the positioning of the leakage fluid flow path, ensuring efficient operation within the specified speed and pressure ranges.

Implementation Method 1

The pressure of the air increases as the air flows downstream in an air flow direction. The compressed air having a higher pressure at a downstream side of the compressor stator vanes tends to flow into the compressed air having a lower pressure at an upstream side of the compressor stator vanes through a cavity provided between the shroud and the rotor.

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

Setting a relation between the distance D which is in the axial direction between the opening of the leakage fluid flow path close to the low-pressure space and the upstream edge of the compressor stator vanes and the pitch P between the compressor stator vanes in the circumferential direction to an appropriate range can prevent interference between the main fluid flow and the leakage fluid and can prevent generation of a secondary flow

Methodology Applied

Scientific EffectFluid flow interference:

Data Source

PatentUS11499441B2Compressor stator vane unit, compressor, and gas turbine

Publication Date: 2022.11.15 MITSUBISHI HEAVY IND LTD

AI summary

A compressor stator vane unit includes multiple compressor stator vanes disposed at a certain interval in a circumferential direction; and an annular joint member connected with inner ends of the multiple compressor stator vanes; wherein the annular joint member constitutes an outer diameter side surface of a leakage fluid flow path provided in an inner diameter side of the joint member to communicate a high-pressure space with a low-pressure space respectively located downstream and upstream of the multiple compressor stator vanes in a fluid flow direction, and D/P is set to 0.05≤D/P≤0.2, wherein D is defined as a distance in an axial direction between an upstream end surface of the annular joint member and an upstream edge of the multiple compressor stator vanes in the fluid flow direction and P is defined as a pitch between the adjacent compressor stator vanes in the circumferential direction.