Extended Wheel Tip and Back-Disk Cavity for Low-Loss Diffuser Transition
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Solution Overview
Problem
Existing centrifugal compressors experience significant turbulence and energy dissipation during the transition of the fluid stream between rotating impeller passageways and static diffuser walls, leading to inefficient energy transfer.
Innovation Solution
The compressor wheel design features a hub with a flow surface that transitions smoothly from concave to convex curvature, combined with a back-disk surface and a conical inner-diffuser wall, creating a minimized clearance gap to reduce turbulence and maintain tangential velocity, thereby improving the transition of the fluid stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional compressor wheel design with standard hub and diffuser configuration is used, then the structure is simple and easy to manufacture, but significant turbulence and energy dissipation occur during fluid stream transition between impeller passageways and diffuser walls
Solution Approach 1:
The hub flow surface is designed with a smooth curvature transition from concave to convex, eliminating abrupt geometric changes. This curved surface configuration guides the fluid stream smoothly from the impeller passageways into the diffuser, reducing turbulence and energy dissipation during the transition phase.
Solution Approach 2:
The invention extends the hub tip radially beyond the diffuser inlet plane, creating a three-dimensional extended tip geometry. This additional spatial dimension allows the fluid stream to transition more smoothly by providing an extended path along the hub surface, reducing turbulent mixing and energy loss at the impeller-diffuser interface.
2Productivity
If the hub extends beyond the diffuser inlet plane with extended wheel tip, then turbulence is reduced and energy efficiency is improved, but the manufacturing complexity and precision requirements increase
Solution Approach 1:
The smooth concave-to-convex curvature transition on the hub flow surface is designed to be continuous and differentiable, avoiding sharp edges or discontinuities. This geometric continuity simplifies manufacturing by allowing the use of standard CNC machining or casting processes while achieving the desired aerodynamic performance.
Solution Approach 2:
The invention optimizes specific geometric parameters such as the curvature radius, transition length, and extended tip distance to achieve the best balance between turbulence reduction and manufacturability. By carefully selecting these parameters, the design achieves high compressor efficiency while remaining feasible for conventional manufacturing 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 reduces turbulence and maintains static pressure at the diffuser exit, minimizing energy dissipation and enhancing the efficiency of the compressor.
Implementation Method 1
Existing centrifugal compressors experience significant turbulence and energy dissipation during the transition of the fluid stream between rotating impeller passageways and static diffuser walls
Implementation Method 2
The compressor wheel, being driven in rotation by the exhaust-gas driven turbine wheel 111, is configured to compress an axially received input of the fluid stream (e.g., ambient air 131, or already-pressurized air from a previous-stage in a multi-stage compressor) into a pressurized fluid stream (e.g., pressurized air stream 133) that is ejected circumferentially from the compressor
Data Source
AI summary
A compressor having a housing along with a wheel including a hub and a plurality of impellers defining flow channels is disclosed. The hub forms a flow surface that defines a concave surface-curve from an inducer end to an inflection point, and a convex surface from the inflection point to an exducer end of the flow surface. The hub forms a back-disk surface including a circumferential edge-channel inset from and surrounding a central portion. The housing includes a conical inner-diffuser wall surrounding a circular inset wall. The central portion of the back-disk surface is received by the conical inner-diffuser wall, while the exducer end of the flow surface extends radially outward to be axially over an inner portion of the inner-diffuser wall.