Centrifugal Compressor Flow Changing Groove for Backflow Deflection
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Solution Overview
Problem
Centrifugal compressors in turbochargers experience pressure loss due to backflow of suction gas, which leads to unstable behavior and inefficiency.
Innovation Solution
A centrifugal compressor design with a flow changing groove on the inner wall of the suction passage, where the upstream boundary is radially inward and the downstream boundary is radially outward, with specific angles between the groove walls and the passage walls to deflect backflowing gas effectively, reducing frictional drag and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a flow changing groove is formed on the inner wall of the suction passage to deflect backflowing gas, then the stability of the compressor is improved, but pressure loss increases due to gas flowing inside the groove
Solution Approach 1:
The patent optimizes geometric parameters of the flow changing groove including the angle between the groove wall and suction passage wall (5-15 degrees), the depth of the groove, and the position of boundaries. By carefully controlling these parameters, the groove effectively deflects backflow while minimizing the volume of gas that enters and flows inside the groove, thus reducing pressure loss while maintaining compressor stability.
Solution Approach 2:
The flow changing groove is positioned specifically at the leading edge region of the compressor wheel where backflow occurs. The groove is not formed throughout the entire suction passage but only in the critical local area where flow separation and backflow happen, minimizing unnecessary frictional drag on the main flow while addressing the stability issue locally.
2Stability of the object's composition
If the groove depth and position are increased to better capture backflow, then compressor stability improves, but frictional drag on the main flow increases
Solution Approach 1:
The patent specifies that the depth of the flow changing groove should be 0.05-0.2 times the radius of the compressor wheel, and the angle between the groove wall and suction passage wall should be 5-15 degrees. These optimized parameters ensure the groove is deep enough to intercept backflow but not so deep as to create excessive frictional drag on the main suction flow.
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 reduces pressure loss and stabilizes the flow by deflecting backflowing suction gas, enhancing the efficiency of the compressor and minimizing mixing losses.
Implementation Method 1
When the suction gas flown back to an area where the suction flow rate is low reaches the circular groove, the suction gas flows along the circular groove whereby the flow direction of the suction gas is changed from backflow to forward flow
Implementation Method 2
the turbocharger compresses the air by the rotation of the compressor wheel
Data Source
AI summary
A centrifugal compressor includes a flow changing groove that is formed on an inner wall of the suction passage and extends in a rotation direction of the compressor wheel. A boundary part of a groove wall of the flow changing groove and the inner wall of the suction passage includes an upstream boundary part positioned on an upstream side in the circulation direction of the gas, and a downstream boundary part positioned on a downstream side in the circulation direction. The upstream boundary part is positioned on the inner side in a radial direction of the compressor wheel than the downstream boundary part, and the flow changing groove is positioned on the upstream side of the wheel in the circulation direction.