Design of cooling-air permeable coil support

Sammanfattning: Coil supports are integral load-bearing components employed in generators andmotors. They serve the purpose of preventing excessive deformation and maintaininga stable position of the coils responsible for generating power and magnetic fieldswhen rotating. However, a problem with these coil supports is that they block theairflow aimed to cool the coils. Thus, this master thesis aimed to conduct a topologyoptimization to develop a cooling-air permeable coil support and select a suitablematerial. The new design was required to withstand 30,000 operational cycles andan overspeed test running at 120% speed without plastic deformation or failure. The material selection process was initiated and based on mechanical and physicalproperties requirements. One of these was that the material should be non-magnetic.Utilizing Ansys Granta EduPack, two materials were suggested, the reference materialcurrently used for the coil support, and a titanium alloy, Ti-6Al-4V. The subsequentstep was to create a CAD model of the original design based on technical drawingsprovided by ABB. With the generated design, finite element analysis (FEA) simulationand the topology optimization could be performed. The generated topology optimizedmodel was modified and two new models were created, one with smaller central cutoutsand one with larger central cutouts and a top surface cutout. Furthermore, a thirdmodel was created based on the fundamentals of fluid mechanics, the Rounded originalmodel. Computational Fluid Dynamics (CFD) simulations of the four models wereexecuted. The findings indicate that the design with larger central cutouts exhibited the mostsubstantial increase in airflow through and in between the coil supports, achieving a122 % improvement compared to the original design. The model satisfied the fatiguerequirement and successfully passed the overspeed test. Both the current referencematerial and the Ti-6Al4V alloy are suitable to use for coil support. However, theutilization of a titanium alloy might be deemed excessive in terms of its mechanicalproperties and cost.