Centrifugal Compressor Impeller Blade Curvature and Clearance
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Solution Overview
Problem
Centrifugal compressor impellers with traditional aerodynamic surfaces face inefficiencies in fluid acceleration and flow rate management, leading to suboptimal compression efficiency and leakage issues due to non-uniform flow passage geometry and clearance gaps.
Innovation Solution
The impeller design features a back plate with radially extending blades having non-linear leading edges, concave suction sides, and convex pressure sides, along with a non-uniform clearance gap between the blade tips and intake housing, which reduces leakage and enhances fluid acceleration and pressure rise by optimizing blade geometry and clearance distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional aerodynamic surfaces are used in centrifugal compressor impellers, then the structure is simple and easy to manufacture, but the fluid acceleration efficiency is suboptimal and leakage issues occur due to non-uniform flow passage geometry
Solution Approach 1:
The patent applies curvature to the blade leading edges, making them rounded rather than sharp or linear. This curved geometry optimizes fluid acceleration by creating more uniform flow passages, reducing turbulence and improving the efficiency of fluid compression while maintaining manufacturability through standard forming processes.
Solution Approach 2:
The patent implements non-uniform clearance gaps between blade tips and the intake housing, varying the gap size along the blade span. This local variation optimizes flow distribution and reduces leakage at critical locations, improving overall fluid acceleration efficiency without requiring complete redesign of the entire impeller structure.
2Productivity
If non-uniform clearance gap is used between blade tips and intake housing, then leakage is reduced and fluid acceleration is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent deliberately changes the clearance gap parameter from uniform to non-uniform distribution. By varying the gap size strategically along the blade span, the design optimizes fluid acceleration and reduces leakage paths while the non-uniform nature actually relaxes manufacturing precision requirements compared to attempting to maintain perfectly uniform tight clearances throughout.
3Productivity
If blades with non-linear leading edges are used, then flow passage geometry is optimized and secondary flows are reduced, but the device complexity increases
Solution Approach 1:
The patent applies curved, non-linear leading edges to the blades to optimize flow passage geometry. This curvature reduces secondary flows and improves compression efficiency by creating more favorable fluid acceleration paths, while the curvature can be achieved through standard manufacturing processes without requiring excessively complex blade designs.
4Productivity
If concave suction sides and convex pressure sides are implemented, then pressure rise uniformity is improved and energy losses are reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent implements different surface geometries on different sides of the blades - concave suction sides and convex pressure sides. This local differentiation optimizes pressure distribution and improves pressure rise uniformity across the flow passage, while each surface geometry can be manufactured using standard forming and machining processes.
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 improves the efficiency of fluid compression by reducing secondary flows, leakage, and enhancing uniform pressure rise, resulting in improved flow capacity and reduced energy losses.
Implementation Method 1
The impeller draws in the fluid to be compressed, accelerates the fluid to a high velocity and discharges the fluid
Implementation Method 2
The fluid velocity is then reduced in a diffuser, volute, and/or other associated components. As the fluid velocity is reduced, the pressure increases.
Data Source
AI summary
An impeller rotatable in a direction of rotation in a centrifugal compressor including an intake ring. The impeller includes a back plate having a shaft portion and a plurality of blades. Each blade extends from the back plate and includes an inducer portion adapted to draw fluid into the impeller and including a leading edge and an exducer portion adapted to discharge the fluid from the impeller and including a trailing edge. A blade pressure side is defined between the leading edge, the trailing edge, the back plate, and a blade tip. The pressure side is convex from the back plate to the blade tip. A blade suction side opposite the pressure side is defined between the leading edge, the trailing edge, the back plate, and the blade tip. The suction side being concave from the back plate to the blade tip.