Centrifugal Compressor Circulation Path for Anti-Surge Flow Stability

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Solution Overview

Problem

Centrifugal compressors fail to curb surging when connected to an engine, despite successful standalone testing.

Innovation Solution

The centrifugal compressor design includes a circulation flow path with a downstream slit, an upstream slit, and an intermediate flow path that expands radially and axially, featuring an inner peripheral surface inclined more than an outer peripheral surface, with a spread angle greater than 20°, to stabilize air flow and reduce fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a circulation flow path is added to curb surging, then anti-surge performance is improved, but device complexity increases

Engineering Contradiction:

Improveanti-surge performanceVSAvoidflow path structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The circulation flow path is segmented into distinct functional sections: a downstream slit positioned at the diffuser outlet, an intermediate flow path with expanding cross-section, and an upstream slit at the diffuser inlet. This segmentation allows each section to perform its specific function optimally while maintaining overall system simplicity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The circulation flow path is positioned in the radial dimension outside the main flow path, utilizing the annular space between the diffuser and compressor housing. This dimensional arrangement allows the circulation path to be integrated without interfering with the axial main flow path, reducing overall device complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If the intermediate flow path is expanded with specific inclination angles, then air flow stability is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveair flow stabilityVSAvoidsurface inclination angle

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The intermediate flow path cross-sectional area is systematically changed along its length, expanding from the downstream slit toward the upstream slit. The outer peripheral surface is inclined at angle α and the inner peripheral surface at angle β (where β > α), creating a controlled geometric progression that stabilizes flow while providing manufacturable dimensions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Different sections of the intermediate flow path have different geometric properties: the outer peripheral surface has inclination angle α, the inner peripheral surface has inclination angle β > α, and the cross-sectional area varies along the length. These localized quality variations optimize flow stability at each position while maintaining overall manufacturing feasibility

Inventive Principle:

Principle #3Local quality

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 design effectively curbs surging by minimizing air flow fluctuations in the circulation flow path, even when connected to an engine.

Implementation Method 1

the intermediate flow path is expanded as the intermediate flow path moves from the downstream slit toward the upstream slit

Methodology Applied

Scientific EffectFluid flow expansion:

Implementation Method 2

an outer peripheral surface of the intermediate flow path is inclined radially outward as the outer peripheral surface moves from the downstream slit toward the upstream slit

Methodology Applied

Scientific EffectFlow stabilization through geometric configuration:

Data Source

PatentUS20260043414A1Centrifugal compressor

Publication Date: 2026.02.12 IHI CORP

AI summary

A circulation flow path of a centrifugal compressor includes a downstream slit, an upstream slit, and an intermediate flow path connecting the downstream slit to the upstream slit. An outer peripheral surface of the intermediate flow path is inclined radially outward as it moves from the downstream slit toward the upstream slit at least in a part continuous with the downstream slit. An inner peripheral surface of the intermediate flow path is inclined radially inward as it moves from the downstream slit toward the upstream slit at least in a part continuous with the downstream slit. An angle of the inner circumferential surface with respect to a straight line passing through the intermediate flow path and parallel to a central axis is greater than an angle of the outer circumferential surface with respect to the straight line.