Rotating Diffuser Wall Reduces Friction in Centrifugal Compressors
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Solution Overview
Problem
Centrifugal compressors and pumps experience significant friction losses due to the high tangential velocity of fluids at the diffuser, leading to inefficiencies in energy conversion from kinetic to pressure energy.
Innovation Solution
Incorporating a crown extending radially beyond the blade envelope cylinder to form a rotating wall of the diffuser, which reduces the velocity difference with the fluid and minimizes friction losses, while also adjusting pressure forces and maintaining high mechanical resistance with minimal manufacturing modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a stationary diffuser wall is used in a centrifugal compressor, then the structure is simple and easy to manufacture, but friction losses are significant due to the high velocity difference between the fluid and the stationary wall
Solution Approach 1:
The patent applies the dynamics principle by transforming the stationary diffuser wall into a rotating wall that moves with the impeller. The diffuser wall is now part of the rotating assembly, rotating at the same speed as the impeller, which reduces the relative velocity between the fluid and the wall, thereby significantly reducing friction losses and improving energy efficiency.
Solution Approach 2:
The patent merges the diffuser wall with the impeller assembly, making them rotate together as a single unit. This combination ensures that the diffuser wall rotates at the same speed as the impeller, eliminating the velocity difference that causes friction losses, while maintaining structural integrity through proper mechanical coupling.
2Productivity
If the diffuser wall rotates at the same speed as the impeller, then friction losses are reduced, but the device complexity increases due to the need for additional rotating components
Solution Approach 1:
The diffuser wall is merged with the impeller assembly into a single rotating unit, ensuring they rotate together at the same speed. This integration reduces friction losses by eliminating velocity differences while avoiding the need for separate drive mechanisms, thus improving energy efficiency without proportionally increasing device complexity.
Solution Approach 2:
The rotating diffuser wall serves multiple functions: it acts as both a diffuser for converting kinetic energy to pressure energy and as a rotating surface that moves with the impeller to reduce friction losses. This multi-functionality improves energy conversion efficiency while minimizing the need for additional separate components.
3Loss of energy
If the diffuser wall moves with the impeller, then friction losses are minimized, but manufacturing complexity increases due to the need for precise rotational alignment
Solution Approach 1:
The diffuser wall is merged with the impeller assembly into a single integrated component or tightly coupled rotating unit. This integration ensures automatic rotational alignment without requiring complex separate mounting mechanisms, reducing friction losses while keeping manufacturing complexity manageable through standardized assembly procedures.
Solution Approach 2:
The diffuser wall is positioned and coupled to rotate with the impeller at the same rotational potential, ensuring consistent velocity matching throughout operation. This equipotential rotational relationship minimizes friction losses while allowing for straightforward manufacturing through precise but achievable alignment tolerances.
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
Substantially reduces friction losses and optimizes energy conversion efficiency by ensuring the fluid flows through walls moving at the same speed, balancing pressure forces, and enhancing mechanical resistance with few manufacturing changes.
Implementation Method 1
The fluid velocity at the diffuser is significant, resulting in substantial friction losses along the diffuser wall due to fluid viscosity
Implementation Method 2
The blades 1121 have a first edge 11211, called the leading edge, facing the axial opening 1110, and a second edge 11212, called the trailing edge, facing the diffuser 1111, so that the gases flow from the axial opening 1110 to the diffuser 1111, driven by the compressor wheel 112. The geometry of the blades 1121 is designed so that the gases receive mechanical energy from the compressor wheel 112, primarily by being accelerated; the kinetic energy thus obtained is then converted into pressure in the volute.
Data Source
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Figure 3
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AI summary
A centrifugal gas compressor or pump comprising a body (211), a wheel (212) rotatably mounted within the body (211) around a wheel axis (A), the wheel (212) comprising a hub (2120), a set of blades (2121) fastened to the hub (2120), the body (211) comprising a diffuser (2111) placed on the periphery of the wheel (212) and a fluid intake (2110) placed facing the hub (2120), the blades (2121) comprising a first edge (21211) facing the intake (2110) and a second edge (21212) facing the diffuser (2111) so that a fluid travels from the intake to the diffuser, the second edges (21212) being located inside a blade-enveloping cylinder (C) centred on the wheel axis (A). The wheel (212) comprises a toothed ring (21201) fastened to the wheel, which extends radially past the enveloping cylinder (C) to form a diffuser wall (2111).