Centrifugal Compressor Impeller Web Geometry for Weight Reduction
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Solution Overview
Problem
Centrifugal compressors face challenges in maintaining aerodynamic efficiency and reducing weight due to centrifugal stresses, which lead to increased clearance and aerodynamic losses, and existing solutions either compromise on performance or are difficult to implement in existing compressor designs.
Innovation Solution
The impeller design features a web with a concave front face that moves the point of intersection between the trailing edge and blade root forward, inverting the bending moment and allowing for a lighter rim and disk fastening system, while maintaining aerodynamic efficiency by reducing axial movement and fluid overflow between blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the web is reinforced to withstand centrifugal bending moment, then the impeller can operate at high speeds, but the weight of the impeller increases significantly
Solution Approach 1:
The invention inverts the conventional web geometry by making the web advance forward in the axial direction at intermediate diameters rather than at the periphery. This geometric inversion changes the bending moment distribution, reducing the peak moment and allowing weight reduction while maintaining high-speed operation capability
Solution Approach 2:
The web is designed with non-uniform geometry where the forward advance is localized to intermediate diameters rather than being uniform throughout. This local modification optimizes the bending moment distribution specifically where needed, reducing overall weight while maintaining structural integrity at critical locations
2Weight of moving object
If a large portion of the impeller web is eliminated to reduce weight, then weight is reduced, but aerodynamic performance drops due to flow from pressure side to suction side
Solution Approach 1:
By inverting the web geometry to advance at intermediate diameters, the invention maintains sufficient web material in the aerodynamic zones to prevent flow leakage while still reducing overall weight. The inverted geometry strategically positions web material to balance aerodynamic requirements with weight reduction goals
3Stability of the object's composition
If the web advances at the periphery to reduce axial deformation, then deformation is reduced, but a reinforcing disk is required which complicates integration into existing compressors
Solution Approach 1:
Instead of advancing the web at the periphery as in conventional designs, the invention advances the web at intermediate diameters. This inversion achieves axial deformation control through the inverted geometry itself, eliminating the need for additional reinforcing disks and simplifying integration into existing compressor systems
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 design reduces axial deformations and weight, enabling smaller clearance and improved aerodynamic efficiency, while allowing for a conventional radial diffuser and easier integration into existing turbine engines, particularly beneficial in aviation applications.
Implementation Method 1
By virtue of the web and the blades having this shape, centrifugal acceleration generates a bending moment on the impeller tending to bend the periphery of the impeller forwards
Implementation Method 2
In operation, the impeller typically rotates at a high speed. It is therefore subjected to centrifugal stresses
Data Source
AI summary
An impeller of a centrifugal compressor, the impeller including a web and blades secured to the web on a front face of the web. A point of intersection between a trailing edge and a blade root is at least one half-thickness of the web further forward than the blade root at an intermediate diameter of the impeller, and a point of intersection between the trailing edge and the blade tip is also further forward than the blade tip at an intermediate diameter of the impeller.