Shape optimization of energy storage flywheel rotor

A flywheel plays an important role in storing energy in modern machine systems. Flywheels can store rotational energy at a high rotating speed and have the ability to deliver a high output power if the system needs a stored energy to overcome a sudden loading or keep rotating for an expected long time. The energy density (stored energy per unit mass) and the amount of rotational energy are the two essential parameters to evaluate the performance of energy storage flywheels. In order to improve the energy storage capability of flywheels, parametric geometry modeling and shape optimization method for optimizing the flywheel rotor geometry is proposed in the present paper. We first build the shape optimization model of flywheel by parametric geometry modeling method with the objective to maximize the energy density of a flywheel rotor. Then the downhill simplex method is adopted to solve the nonlinear optimization problem in multidimensional space. Finally, we obtain the optimized shapes of flywheel rotor which could significantly improve the energy storage capability and working safety performance compared with the traditional design flywheel of constant thickness rotor. It is found that the maximum structural stress constraint applied in the designed region has a remarkable effect on the shape optimization.