Compressor Recirculation Passage for Surge Stability
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Solution Overview
Problem
Conventional compressors face instability due to irregular air flow caused by recirculation close to the compressor wheel, leading to surge conditions, especially when air flow rates are reduced, which limits their operating region and efficiency.
Innovation Solution
The compressor design includes an additional air passage for recirculating air to a position significantly farther from the compressor wheel, allowing sufficient time for air flow to become uniform before entering, and optionally using a throttle valve to control air flow, thereby increasing the stable operating region and reducing surge risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air is recirculated from the compressor wheel to an upstream position close to the compressor wheel, then the stable operating region of the compressor is increased, but the air flow uniformity is disturbed and surge risk increases
Solution Approach 1:
A return conduit is introduced as an intermediary element to transport recirculated air from the compressor outlet back to the air conduit. This intermediary structure enables controlled recirculation while maintaining spatial separation between the recirculation path and the main air flow path, thereby stabilizing the operating region without compromising air flow uniformity at the compressor inlet
2Productivity
If recirculated air is returned to a position close to the compressor wheel, then recirculation is achieved, but the heated air reduces compressor efficiency
Solution Approach 1:
The invention extends the recirculation path in the longitudinal dimension by positioning the return point at least 1.5 times the inlet diameter upstream from the compressor wheel. This dimensional extension allows the recirculated air to cool down and reduces the temperature increase, thereby maintaining compressor efficiency while still achieving effective recirculation
3Reliability
If the additional air passage is made long to improve air flow uniformity, then stability increases, but the device complexity increases
Solution Approach 1:
The return conduit is merged with the existing air conduit structure, utilizing the available space within the compressor housing. The return conduit connects to the air conduit at a strategically chosen position, combining the recirculation function with the existing air delivery path without requiring completely separate parallel structures, thus reducing overall device complexity
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 enhances compressor stability and efficiency by ensuring a uniform air flow and reducing surge occurrences, allowing operation in a larger stable region with lower heating of air entering the compressor wheel, thus improving power delivery to the combustion engine.
Implementation Method 1
A compressor of a turbo charger increases the power of a combustion engine by supplying charge to the combustion engine
Implementation Method 2
a part of the air flow in the air intake passage recirculates, via the additional air passage, to an upstream position of the air intake passage
Data Source
Figure 1
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AI summary
The present invention relates to a compressor arrangement in an air line (9) supplying charged air to a combustion engine (2). The compressor arrangement comprises a compressor unit (14) comprising a housing (15) including an air intake passage (17), a compressor wheel (7) arranged in said air intake passage (17), and an additional air passage (24, 26, 28, 29, 30) allowing recirculation of air from the air intake passage (17) in a position radially outwardly of a part of the compressor wheel (7). The additional air passage (24, 26, 28, 29, 30) is configured to allow recirculation of air to an air conduit (9a) delivering an air flow to the air intake passage (17) of the compressor unit (14).