Asymmetric Self-Recirculating Casing Treatment for Centrifugal Compressors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Centrifugal compressors with symmetric casing treatments face limitations in extending their stable operating range due to flow distortion and asymmetric flow parameters, particularly at low flow rates, leading to instability and reduced efficiency.

Innovation Solution

An asymmetric self-recirculating casing treatment with an optimized distribution of the axial distance and width of the suction ring groove in an arc shape, which includes a suction ring groove, a ring guide channel, and a back-flow ring groove, is used to enhance the stable operating range while maintaining efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a symmetric casing treatment is used, then the structure is simple and easy to manufacture, but the stable operating range cannot be extended due to flow distortion and asymmetric flow parameters

Engineering Contradiction:

Improvecasing treatment structureVSAvoidstable operating range

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by configuring the casing treatment asymmetrically with respect to the rotation axis of the impeller. The suction ring groove is positioned at a specific circumferential location rather than being symmetrically distributed, which compensates for the asymmetric flow distortion caused by the scroll channel and extends the stable operating range to low-flow-rate conditions.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by optimizing the position and width of the suction ring groove at specific locations within the casing. The groove dimensions and positioning are tailored to local flow conditions, particularly addressing the asymmetric flow parameters in different circumferential directions to improve overall compressor stability.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a symmetric casing treatment is used, then the manufacturing is easier, but the flow uniformity is poor leading to shock waves and reduced efficiency

Engineering Contradiction:

Improvecasing treatment symmetryVSAvoidflow uniformity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The asymmetric configuration of the suction ring groove in the casing treatment compensates for the asymmetric flow distortion generated by the scroll channel. This asymmetry restores flow uniformity by counteracting the circumferential variations in flow parameters, reducing shock waves and improving efficiency at low flow rates.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The suction ring groove is positioned and dimensioned to preemptively counteract the asymmetric flow distortion before it propagates through the compressor. By placing the groove at a specific circumferential location upstream of the impeller, the treatment prevents the development of severe flow asymmetry and associated shock waves.

Inventive Principle:

Principle #9Preliminary anti-action

3Ease of manufacture

If the axial distance and width of the suction ring groove are not optimized, then the manufacturing is simpler, but the stable operating range extension is insufficient

Engineering Contradiction:

Improvegroove configurationVSAvoidstable operating range

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by optimizing specific geometric parameters of the suction ring groove, including its axial distance from the impeller leading edge and its width in the circumferential direction. These parameter optimizations enable the asymmetric casing treatment to effectively extend the stable operating range while maintaining manufacturability.

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 asymmetric self-recirculating casing treatment effectively extends the stable operating range of centrifugal compressors to low-flow-rate conditions while maintaining efficiency, compared to symmetric treatments and untreated compressors, by improving flow uniformity and reducing shock waves and pressure gradients.

Implementation Method 1

Centrifugal compressor using an asymmetric self-recirculating casing treatment

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2535595B1Centrifugal compressor using an asymmetric self-recirculating casing treatment

Publication Date: 2019.04.17 IHI CORP

Figure 1A~1B
Figure 2A~2B
Figure 3

AI summary

A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. A position or a width of the suction ring groove 1 is distributed in an arc shape in a circumferential direction, and the arc has a center angle α in a range of 0<α≤30°.