Rotor Winding Ventilation Holes with Asymmetric Bulges
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Solution Overview
Problem
Existing rotary electric machine rotors face insulation failures due to inadequate cooling performance, particularly because ventilation resistance and heat transfer characteristics are not optimized for the secondary flow generated during rotor rotation, leading to increased temperature and reduced heat transfer efficiency.
Innovation Solution
The rotor design incorporates channels for axial cooling gas flow and ventilation holes with a smooth inner surface on the positive pressure side and linear bulges on the negative pressure side, which suppress secondary flow and enhance the velocity of the main radial flow, thereby reducing the temperature boundary layer and improving heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ventilation holes with rib-shaped projections are provided to increase cooling efficiency, then heat radiation performance is improved, but ventilation resistance increases due to turbulent flow
Solution Approach 1:
The invention applies different surface characteristics to different regions of the ventilation hole: the positive pressure side has a smooth surface to reduce resistance, while the negative pressure side has bulges to enhance heat transfer. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The ventilation hole is designed with asymmetric surface features: smooth surface on the positive pressure side and bulges on the negative pressure side. This asymmetry allows the structure to exploit the pressure difference and flow direction to achieve both low resistance and high heat transfer efficiency simultaneously.
2Power
If the output of the rotary electric machine is increased, then power generation capacity is improved, but heat generation and temperature increase occur
Solution Approach 1:
The invention changes the geometric parameters of the ventilation hole by introducing bulges on the negative pressure side, which modifies the flow characteristics and heat transfer coefficients. This parameter change enables effective cooling even at higher power outputs where heat generation is increased.
3Temperature
If cooling gas flow velocity is increased to improve heat transfer, then cooling performance is enhanced, but secondary flow effects become more significant
Solution Approach 1:
The invention converts the harmful secondary flow effect into a beneficial one by strategically placing bulges on the negative pressure side. These bulges utilize the secondary flow to enhance the main flow velocity and reduce boundary layer thickness, turning the previously detrimental effect into a heat transfer enhancement mechanism.
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 effectively suppresses secondary flow, increases the velocity of the main cooling gas flow, and enhances heat transfer, preventing insulation failures and maintaining low temperatures in the rotor winding, even at increased output levels.
Implementation Method 1
allowing the cooling gas flowing in a radial direction to be a turbulent flow state from a laminar flow state near the wall surface
Implementation Method 2
improving heat radiation performance in an inner wall of the ventilation hole for cooling
Implementation Method 3
an inner wall surface on a positive pressure side generated at the rotation
Implementation Method 4
a cooling gas such as air or hydrogen is allowed to flow in the ventilation hole directly for cooling the rotor winding
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
In order to improve cooling performance of a rotor (10) of a rotary electric machine, attention is paid to the relation between the secondary flow of a cooling gas generated inside ventilation holes (20) for the cooling gas provided in a rotor winding (2) formed by stacking a conductor (4) and an interlayer insulating layer (5) and the main flow of the cooling gas during the rotary motion of the rotor (10), and the secondary flow of the cooling gas is suppressed by changing the shape of bulges (21) appearing in a linear shape in the stacked direction on an inner wall surface of each rotor winding ventilation hole (20) on a negative pressure side.