Application of pulse excitation for forced vibration of selected eigenmode of blade wheel under rotation

Application of pulse excitation for forced vibration of selected eigenmode of blade wheel under rotation. The paper deals with a solution of multipoint electromagnetic pulse excitation of turbine blade wheel under rotation for analysis of its dynamic behaviour. Since a width of electromagnetic pulses should decrease with revolution speed, magnetomotoric forces acting to the blades decrease, too. So, the application of more “high-speed” electromagnets distributed along a circumference of the wheel that multiply the excitation potential seems to be inevitable for such a stiff structure. It, however, requires accurate synchronization of the electromagnets with wheel revolutions and with a dynamic response of the selected blade. Furthermore impulse excitation causes, in general, transient oscillations of many superposed eigenmodes of the wheel. Therefore an attention, herein, was paid to develop an appropriate control algorithm for the pulse excitation of electromagnets and to find a proper strategy of electromagnet interconnections to gain a multiplepoint excitation for excitation of selected eigenmodes