The Vibration Suppression Study Of Water Pumping And Automatic Controllable Air Pumping In Sealing Cavity

The turbine machinery has been used extensively in a great many fields of the national product presently. Its security and stability become the important puzzles. The fluid flow-induced vibration is one of factors on the rotor vibration and blade failure. In accordance with long-term study on the mechanism of fluid flow-induced vibration and all kind of methods to solve sealing flow-induced vibration successfully, the recent air pumping damping technology has been improved in this paper. The details are as follows:1. According to the methods about air pumping to control the sealing flow-induced vibration in the steam turbine, it has been proposed that this ways are used in the labyrinth seal in the seal ring of water turbine in order to reduce the sealing flow-induced vibration. Wherefore, firstly, the main cause of sealing flow-induced vibration is due to the unbalanced sealing clearance in the labyrinth; secondly, in the light of specificity and complexity of the water turbine, the sealing construction was simplified and the experiment rig was set up based on it; thirdly, in accordance with the air pumping mechanism and experiment rig, the vibration behaviors are contrasted by installing water pumping device in upstream and downstream of minimal seal clearance. The results prove that the water pumping device in upstream of minimal seal clearance can reduce rotor vibration effectively.2. In the anti-swirl theory, appropriate flow of anti-swirl can suppress the flow-induced vibration effectively, but the control of flow is difficulty. If the jet flow is too little, the vibration can't be suppressed effectively; if it's too much, the vibration will raise instead. Therefore, according to this mechanism, the new closed-loop automatic control system of air pumping has been proposed in the self-built blade vibration experiment rig. The improved system is based on the advanced the Labview programmatic software and it can achieve that experiment apparatus is automatic controlled. By measuring the blade vibration regulate the valve opening automatically in order to control air capacity. The control procedures are divided into three steps corresponding to three valve opening. When the vibration exceed to each step, the valve arrive at the specified opening and adjust to the air pumping flow to attain the best damping effect. The experiment data manifests under the regulation of appropriate pumping flow, the different step can reduce the blade vibration by about 30%. If the honey comb seal is used together, the amplitude of damping can reach about 40%. Besides this, the results show that the air pumping technology is much more stable than the anti-swirl technology.