nstx oh coil optimization ali zolfaghari amir salehzadeh
TRANSCRIPT
NSTX OH Coil Optimization
Ali Zolfaghari
Amir Salehzadeh
Optimization Parameters:
• Coolant channel diameter – Large coolant diameter leads to:
• Higher resistance and ohmic heating.• Higher coil voltage and turn-to-turn voltage gradients.• More efficient cooling
– Smaller coolant diameter leads to:• Lower resistance and ohmic heating.• Higher coil voltage and turn-to-turn voltage gradients.• Longer cooling time
Possible Approaches:
• 0D analysis with closed form formulas for turbulent flow and heat transfer. Crude method, but useful for trade-off study. Got the Mathcad files from Mike Kalish.
• Finite section (node) transient simulation of flow parameters and cooling along the conductor length. Fcool program from Fred Dahlgren.
• Coupled 3D CFD/Heat transfer simulation of coolant flow and conjugate heat transfer. We started with this approach.
Coupled CFD/Heat Transfer
• Ansys multiphysics/CFD is used to model the turbulent flow and heat transfer as well as heat conduction in solid.
• Initial conditions for the solid to be cooled are simulated first using the pulse current profile as energy source. Copper will be heated and will reach a temperature profile. This serves as the initial condition for the transient CFD/Heat transfer simulation of cooling.
NSTX OH Coil Optimization
• Coil geometry was brought into Ansys from Pro/E using STEP format.
• It was determined that for meshing simplicity and with negligible loss of accuracy the coil can be modeled
as a straight conductor.