analysis = DataModel.AnalysisByName('Static Structural')
rotor_speed = analysis.AddRotationalVelocity()
rotor_speed.Magnitude.Output.SetDiscreteValue(0,Quantity(30000,'rev min^-1'))
ns = DataModel.GetObjectsByName('axis')[0]
cs = ExtAPI.SelectionManager.AddSelection(ns)
rotor_speed.Axis = ns