Composite Flywheel Energy Storage Density Analysis

Flywheel energy storage is a new type of pollution-free green energytechnology, in order to increase the flywheel energy storage density, using highspecific modulus, high specific strength of fiber reinforced composite materialto prepare the flywheel rotor. The fiber winding composite flywheel rotor isanisotropic, and usually the high strength composite material is actually refers tofiber direction (hoop) high strength, but perpendicular to the direction of thefiber transverse strength (radial) is low, in order to solve the problem ofinadequate radial strength of flywheel rotor, there are a number of studies usinga plurality of thin annular interference suit or pre-stressed winding technology. Ifcomposite material with multi-ring adopt assembly technology, although theinterference assembly process can improve the rotational speed of the flywheel,thin ring of large processing is difficulty, and manufacturing processrequirements are very strict, which causes the exorbitant cost of flywheel andlimits its popularization and application; Pre-stressed winding in the tight underthe action of compressive stress, will face a stiffness buckling problem.Composite can be designed in this paper, so we attempts to calculate thecomposite flywheel energy storage density from the modulus ratio λ, thus wehope to maximize the energy storage density from the material utilization.First, put aside the composite winding technology, based on FEA software ofANSYS, using the hoop and radial ratio of the material as a parameter, a givensize of flywheel rotor in different composite materials for single-ring andmulti-ring isomorphism and multi-ring isomerism are simulated in numerical,thereupon a stress distribution rule about circumferential and radial of flywheelrotor in high-speed rotating is proposed, by which the right materials is foundand better distribution of stress field is achieved. Second, based on the iterativealgorithm on stress analysis of FEA, the maximum rotation speed is got, andthen the energy storage density of the flywheel rotor in various cases can be received.The following conclusions can be achieved by the analysis in this paper: Theenergy storage density of metal flywheel rotor is far less than λ>2compositeflywheel rotor. The energy storage density of multi-ring flywheel rotor is fargreater than the single-ring flywheel rotor. With the same material, the energystorage density is increasing as the number of rings increase. So it's necessary toincrease the number of rings with the extent of technology permitted; Energydensity increases with the value of λ increase for the multi-ring isomorphismflywheel, that is to say it's a good choice to make flywheel rotor with thematerial of larger λ. For multi-ring heterogeneous composite flywheel rotor, λfrom inside diameter to the outer diameter gradually increasing is comparativelygood.