Centrifugal Compressor Return Vane Angle Design
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Solution Overview
Problem
Reducing the size of a centrifugal compressor while maintaining performance is challenging due to the trade-off between diffuser outlet diameter and pressure recovery, where decreasing the diffuser outlet diameter leads to insufficient pressure recovery and increased pressure loss in the return flow channel.
Innovation Solution
The compressor features return vanes arranged at predetermined intervals with varying vane angles from the leading edge to a predetermined position and maintaining a constant angle from that point to the trailing edge, along with a larger fluid channel area at the trailing edge and a shorter second-stage inlet guide vane, which improves efficiency and reduces pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the outer diameter of the diffuser at the outlet portion is decreased to reduce compressor size, then the device size is reduced, but pressure recovery at the diffuser becomes insufficient and pressure loss at the return flow channel increases
Solution Approach 1:
The return vane is designed with a non-uniform vane angle distribution along its length. The vane angle is changed in the region from the leading edge to a predetermined position and maintained constant from the predetermined position to the trailing edge. This local variation in geometric properties optimizes flow control at different positions, enabling effective pressure recovery despite the reduced diffuser outlet diameter.
Solution Approach 2:
The invention changes the geometric parameters of the return vane, specifically the vane angle, to optimize performance. By varying the vane angle along the meridian plane distance and maintaining it constant in certain regions, the design achieves better pressure recovery and reduced pressure loss while keeping the diffuser outlet diameter small.
2Loss of energy
If the vane height of the return vane at the inlet portion is increased to reduce fluid inflow speed, then pressure loss at the return vane is reduced, but the efficiency of the entire compressor decreases
Solution Approach 1:
Instead of uniformly increasing the vane height throughout the return vane, the invention applies local quality by varying the vane angle specifically in certain regions while maintaining constant angles in others. This localized optimization reduces pressure loss without unnecessarily increasing the overall vane height, thereby preserving compressor efficiency.
Solution Approach 2:
The return vane design incorporates dynamic geometric variation through the non-uniform vane angle distribution. This dynamic approach allows the vane to adapt to different flow conditions along its length, optimizing both pressure loss reduction and efficiency without requiring a uniform increase in vane height.
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 configuration allows for a smaller compressor size with improved efficiency and reduced pressure loss, maintaining performance by optimizing the flow rate and vane angles in the centrifugal compressor.
Implementation Method 1
a return flow channel at which a fluid that flows from an inner side in a radial direction of the rotary shaft to an outer side in the radial direction after flowing through the diffuser is reversed to the inner side in the radial direction
Implementation Method 2
a centrifugal compressor that raises the pressure of a fluid to obtain a compressed fluid... a compressor that uses an impeller to compress a refrigerant gas
Implementation Method 3
pressure recovery at the diffuser... a diffuser that is disposed downstream of the first-stage impeller
Data Source
AI summary
A centrifugal compressor includes a rotary shaft; a hollow casing; a first-stage inlet guide vane; a first-stage impeller; a diffuser; a return flow channel; return vanes; a second-stage inlet guide vane; and a second-stage impeller. The return vanes are arranged at predetermined intervals in a circumferential direction of the rotary shaft and a vane angle of each return vane is changed in a region from a leading edge, at which the fluid is introduced, to a predetermined position and the vane angle is maintained constant in a region from the predetermined position to a trailing edge, at which the fluid is discharged, in terms of meridian plane distance in a direction from the leading edge to the trailing edge.