Research Of Blade Vibration Suppression Method

Blade is a key component for power-to-energy conversion in blade wheel mechanical. Its operation in safety and reliability directly influence the security of the blade wheel mechanical. The bad vibration performance is the main factor in blade accident. The blade will vibrate, when it upon periodic exciting force. When the frequency of exciting force and the natural frequency of blade are equal or their frequencies are integral rate, the blade occurs sympathetic vibration. The blade may be subjected to the following exciting force: foundation frequency excitation,wake flow excitation,random excitation,self-excitation and external excitation.When use passive control, honeycomb seal can inhibit about 20 percent of vibration. Increase the length of the honeycomb seal, the blade vibration can be effectively suppression. When the depth of honeycomb seal is 5.4 mm, the blade vibration can be best suppression. When blade tips shroud is 3 mm, it can inhibit about 40 percent of vibration. When use active control, increase the flow rate of nozzle can not incessantly inhibit the blade vibration, inverse it may enlarge the blade vibration. Use spin jet only, the blade vibration can be effectively inhibit while the flow rate of nozzle is 20m/s-24m/s. When the seal gap is small, the little distance between nozzle and blade is good for blade vibration suppression. With the increase of the seal gap the large distance between nozzle and blade is good for blade vibration suppression. When use synthetic control, the blade vibration can be effectively inhibit when the flow rate of nozzle is 14m/s-18m/s. When the seal gap is 0.3 mm, use synthesis control can inhibit 30.6 percent of vibration, better about 11 percent than use passive control which can inhibit 19.3 percent of vibration, better about 20 percent than use passive control which can inhibit 10.1 percent of vibration.Use micromechanical analysis to study blade vibration, we can see the reason why honeycomb has the prominence to reduce the vibration is that honeycomb seal can dissipate the energy of air which flow from it, and form the vortex which can dissipate the energy in tip seal flow field. The augment of vortex and the large capacity of liquid correspond the reduced of vibration. When use the honeycomb seal, the speed of the liquid in capacity is lower. It quantitative confirmed that the vortex when the liquid pass the honeycomb seal can dissipate the energy of air which flow from it.