Turbomachine Compressor Reaction Control
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Solution Overview
Problem
Conventional axial compressors in turbomachines face efficiency issues due to a significant drop in radially averaged degree of reaction from the inlet to the outlet, leading to increased load on rear stages and reduced efficiency, as well as residual swirl that affects load distribution and stability.
Innovation Solution
Maintaining a constant or almost constant radially averaged degree of reaction in the middle to rear compressor area, with a residual twist of at least 47°, and reducing the degree of reaction to be closer to the minimum, achieved through non-circumferentially symmetrical sidewall contouring and/or tandem design of the outlet guide vane cascade, which stabilizes boundary layers and reduces side wall losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the degree of reaction increases from front to rear compressor area to reduce residual swirl, then the residual swirl is reduced, but the load on rear stages increases leading to reduced efficiency
Solution Approach 1:
The patent applies parameter changes by setting the radially averaged degree of reaction to be constant or almost constant (closer to minimum than maximum) throughout the middle and rear compressor areas, rather than allowing it to increase toward the outlet. This parameter optimization reduces the load on rear compressor stages while maintaining acceptable residual swirl levels, thereby improving overall compressor efficiency
Solution Approach 2:
The patent employs asymmetry through non-circumferentially symmetrical sidewall contouring in the outlet guide vane cascade. This asymmetric design stabilizes boundary layers and reduces side wall losses, contributing to improved compressor efficiency without significantly increasing the load on rear stages
2Power
If the number of stator blades in rear compressor area is increased to handle high load, then the load capacity is improved, but the compressor efficiency decreases
Solution Approach 1:
The patent optimizes the parameter of degree of reaction by maintaining it at constant or almost constant values (closer to minimum) in the rear compressor area. This allows the rear stages to operate with lower load while maintaining effective power transmission, reducing the need for excessive stator blade numbers and improving efficiency
Solution Approach 2:
The patent applies local quality by implementing specific sidewall contouring in the outlet guide vane cascade that stabilizes boundary layers in critical areas. This localized optimization reduces side wall losses without requiring increased blade numbers throughout the entire rear compressor section
Data Source
Figure 1
Figure 2~3
AI summary
A method for operating a compressor of a turbomachine is disclosed, wherein, viewed in the direction of a main flow, a degree of reaction, in particular radially averaged, which has fallen from a maximum to a minimum in a front compressor section (12), is kept constant or nearly constant via a middle compressor section (14) to a rear compressor section (16), wherein in the rear compressor section a degree of reaction, in particular radially averaged, is set which is closer to the minimum than to the maximum, and a residual swirl of at least 47° is present in the middle section, a compressor and a turbomachine.