Rotor Winding Head Blocking Element for Serpentine Cooling Flow
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Solution Overview
Problem
Turbogenerators with radial bores in rotor caps face inefficiencies in cooling due to increased volume flow, which reduces cooling of the stator active part and creates a gas barrier at the air gap inlet, limiting machine utilizability and efficiency.
Innovation Solution
A blocking element with a small radius inlet and large radius outlet, featuring a channel guide that directs cooling gas in a serpentine or meandering manner through glass or plastic gas guide channels, placed between conductors in the rotor winding head to optimize gas flow and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If radial ventilation bores are provided in the rotor cap to cool the rotor winding head, then the cooling capacity of the rotor winding head is significantly improved, but the volume flow through the groove base channels is reduced, worsening the cooling of the rotor active part
Solution Approach 1:
The blocking element introduces local quality differentiation by creating distinct flow resistance characteristics in different regions. The element has different cross-sectional areas at its inlet and outlet, and incorporates flow guidance structures that selectively direct cooling gas flow. This allows the rotor cap region to receive sufficient cooling flow while the groove base channels maintain adequate flow volume, resolving the contradiction between localized cooling effectiveness and overall flow distribution.
2Temperature
If large volume flow is directed radially through the rotor cap, then convective cooling of the rotor winding head is enhanced, but a gas barrier is created at the air gap inlet, worsening the cooling of the stator active part
Solution Approach 1:
The blocking element inverts the conventional approach by positioning the larger cross-sectional area at the inlet side and the smaller area at the outlet side. This inverted geometry, combined with flow guidance structures, creates a flow resistance that reduces the volume flow exiting the rotor cap radially. By inverting the typical flow amplifier design, the element acts as a flow restrictor that prevents the formation of a harmful gas barrier at the air gap inlet while still providing adequate cooling to the rotor winding head.
3Object-generated harmful factors
If the radial bores are made smaller to reduce volume flow and eliminate the gas barrier, then the cooling of the stator active part is improved, but the cooling conditions of the rotor winding head are significantly worsened
Solution Approach 1:
The blocking element serves as an intermediary device between the radial ventilation bores and the groove base channels. It mediates the cooling gas flow by selectively directing and regulating the distribution of cooling fluid. The element's specific geometry with flow guidance structures allows it to maintain adequate flow volume for rotor winding head cooling while simultaneously restricting the radial outflow that creates the gas barrier, thus resolving the contradiction without requiring reduction of the radial bore size.
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
Significantly improves convective cooling capacity by reducing volume flow and eliminating the gas barrier, enhancing heat dissipation by a factor of 2.5 compared to conventional methods, while maintaining reduced volume flow requirements.
Implementation Method 1
guides the cooling gas selectively along the components (winding) to be cooled
Implementation Method 2
the rotor winding head to be cooled convectively by a direct, radially directed flow
Implementation Method 3
Such an element increases the flow resistance, resulting in a reduction in the volume flow
Implementation Method 4
The element is provided for arrangement between the conductors in the rotor winding head... The outlet opening connects to the bore through the rotor cap
Data Source
AI summary
A blocking element for a rotor head winding of a turbogenerator has a form which is adapted to the contour of the adjacent conductor of the rotor head winding. A depression extending in the axial direction is made in the side of the blocking element facing the conductor, which depression forms a serpentine channel for a cooling fluid from an inlet port on the small radius to a discharge port on the highest radius, with the discharge port communicating with a ventilation bore of the rotor cap enclosing the rotor winding head. An improved cooling effect with a reduced flow of cooling fluid and an increase in the efficiency of the turbogenerator as a whole results.