Multistage Compressor Bypass Flow for Interstage Swirl Suppression
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Solution Overview
Problem
In multistage compressors, the swirling flow generated by the first impeller can negatively affect the compression performance of subsequent impellers, leading to issues such as surge and decreased pressure ratio.
Innovation Solution
A compressor design that includes an interstage passage and a bypass passage, where gas from the downstream of the second impeller is recirculated to the interstage passage, with the downstream end of the bypass passage oriented to counteract the swirling flow direction in the interstage passage, thereby mitigating the influence of swirling on the second impeller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If gas is compressed by a first impeller in a multistage compressor, then the gas pressure is increased, but a swirling flow is generated that negatively affects the compression performance of the second impeller
Solution Approach 1:
The bypass passage is configured to utilize the swirling flow generated by the first impeller beneficially. By directing this swirling flow through the bypass passage to mix with the main gas stream before entering the second impeller, the harmful swirling effect is converted into a beneficial mixing action that improves compression performance and reduces surge likelihood.
Solution Approach 2:
The bypass passage acts as an intermediary element between the first and second impellers. It introduces a portion of the compressed gas through a specific orientation (downstream end facing the swirling direction) to mediate and counteract the harmful swirling flow, thereby protecting the second impeller's performance.
2Object-generated harmful factors
If a bypass passage is added to recirculate gas, then the swirling flow influence is suppressed, but the device complexity increases
Solution Approach 1:
The bypass passage is designed to serve multiple functions simultaneously: it recirculates gas to control swirling flow, mixes gas streams to improve flow uniformity, and potentially regulates pressure distribution. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving multiple performance benefits.
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 design effectively suppresses the impact of swirling flow on the second impeller, reducing the likelihood of surge and maintaining compressor performance by canceling out the swirling flow before it reaches the second impeller.
Implementation Method 1
a swirling flow generated in the gas when the gas is compressed by the first impeller may affect the compression performance of the second impeller
Implementation Method 2
a bypass passage that recirculates the gas from downstream of the second impeller to the interstage passage
Data Source
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AI summary
A compressor in which gas compressed by a first impeller is further compressed by a second impeller includes an interstage passage that introduces the gas from the first impeller to the second impeller; and a bypass passage that recirculates the gas from downstream of the second impeller to the interstage passage. A downstream end of the bypass passage opens to the interstage passage so as to face a direction in which the gas in the interstage passage swirls in a passage cross-section of the interstage passage.