Compressor Intake Duct Asymmetric Strut Spacing
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Solution Overview
Problem
The conventional single suction structure intake ducts in compressors experience un-uniform air inflow, leading to rotating stall, increased profile loss, and restricted blade design freedom due to unequal strut spacings and harmonic components, resulting in reduced compressor efficiency.
Innovation Solution
The intake duct is designed with struts arranged in a radial pattern with unequal spacings, a curved portion that projects inwardly, and connection positions adjusted to reduce harmonic components and promote uniform flow, allowing for increased blade design freedom and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If struts are arranged at equal spacings in the circumferential direction, then the structure is simple and easy to manufacture, but un-uniform air inflow occurs leading to rotating stall and increased profile loss
Solution Approach 1:
The patent applies asymmetry by arranging struts at unequal circumferential spacings instead of equal spacings. Specifically, the spacing between adjacent struts varies around the circumference, with some gaps being larger and others smaller. This asymmetric arrangement disrupts the formation of harmonic components and rotating stall patterns, thereby improving compressor stability while preventing the un-uniform air inflow that occurs with symmetric equal-spacing arrangements.
2Device complexity
If a single suction structure is used, then the intake duct structure is simplified, but un-uniform air distribution occurs in the circumferential direction
Solution Approach 1:
The patent applies local quality by varying the circumferential spacing of struts at different locations around the intake duct. Instead of using a uniform spacing pattern throughout, the spacing is locally adjusted - some regions have larger gaps between struts while others have smaller gaps. This local variation compensates for the inherent un-uniformity of single suction structures, promoting more uniform air distribution across the compressor inlet while maintaining the simplified single suction configuration.
3Strength
If struts are provided to support inner and outer casings, then structural support is achieved, but harmonic components increase and blade design freedom is restricted
Solution Approach 1:
The patent applies asymmetry in strut arrangement to simultaneously achieve structural support and maintain blade design freedom. By positioning struts at unequal circumferential intervals rather than symmetric equal intervals, the structure provides adequate support for the inner and outer casings while avoiding the generation of strong harmonic components. This asymmetric configuration reduces interference with blade design options, allowing for greater adaptability and versatility in compressor blade geometry optimization.
Data Source
AI summary
A compressor which includes: an inner casing arranged so as to cover a rotor shaft; an outer casing arranged so as to cover the inner casing and forming a fluid flow path around the rotor shaft; and a plurality of struts mounted in the entrance of the fluid flow path and between the inner casing and the outer casing; in which the plurality of struts are arranged in a radial pattern centered on the rotor shaft, and the spacings between the adjacent struts in the circumferential direction of the rotor shaft are unequal.