Return Vane End Cutting to Expand Centrifugal Compressor Range
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Solution Overview
Problem
Centrifugal compressors with return vanes having an exit angle of 0° suffer from a reduced operation range, necessitating a method to easily and retroactively enlarge this range without requiring new vane manufacturing.
Innovation Solution
The method involves cutting the inner radial end portion of the return vane to increase its exit angle, forming the cut surface in a linear or arc shape, and adjusting the separation distance between vanes to enhance fluid flow guidance, thereby allowing for a larger operation range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the exit angle of the return vane is set to 0° to improve the head of the compressor, then the head is raised, but the operation range of the compressor decreases
Solution Approach 1:
The invention changes the exit angle parameter of the return vane from 0° to a larger angle (10° or more) to resolve the contradiction. This parameter modification allows the compressor to maintain improved head performance while expanding the operation range, as the larger exit angle enables better adaptation to varying operating conditions without sacrificing the head improvement achieved by the return vane configuration
2Adaptability or versatility
If the exit angle of the return vane is increased to enlarge the operation range, then the operation range is enlarged, but a swirling flow component remains in the flow which may cause vortex or separation
Solution Approach 1:
The invention applies curvature to the cut surface of the return vane, forming an arc-shaped surface that is recessed forward in the rotation direction. This curved geometry smoothly guides the fluid flow along the cut surface, effectively reducing the harmful swirling flow components, vortex formation, and flow separation while maintaining the beneficial larger operation range achieved by the increased exit angle
3Ease of manufacture
If the cut surface is formed in a linear shape to simplify machining, then the exit angle can be changed with simple machining, but the flow guidance may be less smooth compared to arc shape
Solution Approach 1:
The invention selects the arc-shaped cut surface that recesses forward in the rotation direction to optimize fluid flow guidance. While this curved geometry is more complex to manufacture than a linear cut, it significantly reduces flow separation and vortex formation by smoothly guiding the fluid along the curved surface, thereby prioritizing performance optimization over machining simplicity
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 approach effectively enlarges the operation range of the centrifugal compressor by maintaining a swirling flow component, reducing vortex and separation possibilities, and allowing for simple machining adjustments.
Implementation Method 1
When the exit angle increases, a swirling flow component remains in the flow of the fluid having passed through the return vane
Implementation Method 2
since the cut surface is formed in an arc shape, the flow of the fluid flowing along the cut surface is smoothly guided. Accordingly, it is possible to reduce the possibility of separation or vortex in the flow
Data Source
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AI summary
What is provided is a method of manufacturing a centrifugal rotary machine including: a fixing step S1 of fixing a return vane body having a virtual airfoil curved forward in a rotation direction of a rotation shaft as it goes inward in a radial direction and formed by a pressure surface recessed forward in the rotation direction and a negative pressure surface protruding forward in the rotation direction onto a guide flow path; and a cutting step S2 of forming a cut surface by cutting a portion including an inner radial end portion of the return vane body from the pressure surface to the negative pressure surface.