Non-axisymmetric Flanges for Radial Compressor Diffusion
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Solution Overview
Problem
Existing diffusion stages in radial and mixed gas turbine compressors lack control over tangential fluid flow heterogeneity, leading to inefficiencies in kinetic energy transformation into static pressure, increased pressure drops, and reduced surge margins due to flat flanges that only allow one-dimensional control of passage section variations.
Innovation Solution
The implementation of non-axisymmetric flanges with alternating hollow and bump zones along the leading and trailing edges of blades, covering up to 80% of the blade chord, to redistribute and homogenize fluid flow, reducing secondary pressure drops and aerodynamic blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat flanges are used in diffusion stages, then the structure is simple and easy to manufacture, but the flow is not homogenized leading to increased secondary pressure drops and reduced compressor stability
Solution Approach 1:
The patent applies asymmetry by replacing traditional flat, axisymmetric flanges with non-axisymmetric flanges that have alternating convex and concave zones. This asymmetric geometry is specifically designed to homogenize the flow in the tangential direction, reducing secondary flows and pressure drops while maintaining manufacturing feasibility through defined geometric parameters.
Solution Approach 2:
The invention transitions from one-dimensional control (variation of flow cross-section only) to two-dimensional control by introducing tangential variations in flange geometry. The alternating convex and concave zones add a second dimension of flow control, enabling homogenization of tangential flow heterogeneity and improving diffusion efficiency.
2Device complexity
If flat flanges are used in diffusion stages, then the device complexity is low, but the flow homogeneity is poor leading to reduced compressor stability and surge margin
Solution Approach 1:
The patent applies asymmetry by replacing traditional flat, axisymmetric flanges with non-axisymmetric flanges that have alternating convex and concave zones. This asymmetric geometry is specifically designed to homogenize the flow in the tangential direction, reducing secondary flows and pressure drops while maintaining manufacturing feasibility through defined geometric parameters.
Solution Approach 2:
The invention applies local quality by creating zones with different geometric properties (convex and concave zones) at specific locations on the flange. Each zone serves a local flow control function, with convex zones preventing flow detachment and concave zones promoting flow homogenization, thereby improving overall compressor stability through localized flow management.
3Use of energy by moving object
If traditional diffusion stages are used, then the kinetic energy transformation is incomplete, but increasing the diffusion area increases device complexity
Solution Approach 1:
The invention transitions from one-dimensional control (variation of flow cross-section only) to two-dimensional control by introducing tangential variations in flange geometry. The alternating convex and concave zones add a second dimension of flow control, enabling homogenization of tangential flow heterogeneity and improving diffusion efficiency.
Solution Approach 2:
The patent applies parameter changes by modifying the flange geometry parameters (alternating convex and concave zones with specific angular positions and dimensions) to optimize flow homogenization. These parameter changes improve kinetic energy transformation efficiency without requiring a significant increase in the overall diffusion area or device complexity.
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
The aim of the invention is to produce an airflow by positioning flanges, the shapes of which are optimized. Non-axisymmetrical shapes in the direction of flow and in the tangential direction are thus provided. According to one embodiment, a radial or mixed gas turbine compressor diffusion stage comprises a wheel consisting of two flanges (9) between which the fluid centrifugally or inclinedly flows from the center towards the periphery. Vanes (60) of a grating are distributed among the flanges (9) in order to channel the flow of the fluid between the leading edges (6a) of said vanes (60) on the central side, and the trailing edges on the peripheral side. At least one of the flanges (9) has an inner surface (9i) comprising at least one area (Z1, Z2) having alternating concave (91) and convex (92) curvatures between two adjacent vanes (60), in at least one of two substantially perpendicular directions, namely in the direction of flow (F) along the vanes (60) and in an inter-vane tangential direction.