Rotor Sleeve Riblet Coating for Windage Loss Reduction
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Solution Overview
Problem
Existing rotating electric machines experience windage loss due to turbulent air flow around the rotor, leading to increased friction resistance and reduced energy conversion efficiency, particularly at high rotational speeds, which is exacerbated by the use of carbon fiber reinforced polymer sleeves and metal armoring solutions that are difficult to process and heavy.
Innovation Solution
A resin coating layer with parallel ridges is applied to the outer circumferential wall of a carbon fiber reinforced polymer sleeve, forming riblets that reduce turbulent vortex generation and lower friction viscosity, using machining to create ridges in the resin coating layer rather than the sleeve itself, thereby maintaining rigidity and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a transfer film with convex pattern is used to form riblets on carbon fiber reinforced polymer sleeve, then riblet structure can be obtained, but fine irregularities cannot be transferred with high dimensional accuracy
Solution Approach 1:
A resin coating layer is applied as an intermediary between the sleeve and the riblet-forming tool. This resin layer can be easily molded into fine irregularities and then cured to form the riblet structure, avoiding the difficulty of directly forming fine structures on the carbon fiber reinforced polymer sleeve.
Solution Approach 2:
The invention changes the physical state and properties of the surface by applying a resin coating that can be easily shaped. The resin is applied in a moldable state, formed into the desired riblet pattern, and then cured to achieve the final structure, thereby achieving high dimensional accuracy that would be difficult to obtain directly on the sleeve material.
2Strength
If metal armoring is used to reduce windage loss, then structural integrity is improved, but weight increases
Solution Approach 1:
The invention uses a composite structure combining carbon fiber reinforced polymer sleeve with a resin coating layer. This composite material approach maintains the lightweight advantage of carbon fiber while adding the functional benefits of the resin layer for windage loss reduction, avoiding the need for heavy metal armoring.
3Loss of energy
If fine irregularities are formed on sleeve to reduce windage loss, then energy conversion efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The resin coating layer is applied and formed into the desired riblet pattern before the final curing step. This preliminary formation of the fine irregularities on the easily-moldable resin makes the manufacturing process simpler compared to attempting to directly form fine structures on the cured carbon fiber sleeve.
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
The riblets effectively suppress windage loss, preventing permanent magnet heating and maintaining magnetic force, thus enhancing energy conversion efficiency and reducing weight, while avoiding breakage and maintaining structural integrity at high speeds.
Implementation Method 1
the air flow becomes turbulent. Under this condition, frictional resistance of the sleeve with respect to the air layer increases
Implementation Method 2
frictional resistance of the sleeve with respect to the air layer increases. As a result, so-called windage loss occurs
Implementation Method 3
If the permanent magnet is heated due to the windage loss, the energy conversion efficiency of the rotating electric machine decreases
Data Source
AI summary
A rotor constituting a rotating electric machine includes a rotating shaft and a permanent magnet. A sleeve covering the outer surface of the permanent magnet is attached to the rotating shaft. A resin coating layer is formed on an outer circumferential wall of the sleeve. The resin coating layer includes a base portion and a plurality of ridges formed on the outer circumferential wall of the base portion. A riblet recessed relative to the plurality of ridges is formed between the plurality of ridges.