EXPLORING EFFECTIVE MEASURES TO INCREASE STABILITY OF HYDROTURBINES

摘要

Francis turbine vibration and crack on runner blade already seriously affected units, stable operation and the economic benefits won, t be realized. With unit capacity and dimension increasing, the problem will be sharper and worse. This article discusses the countermeasures for insresing turbine stability from five aspects. Firstly choosing appropriate head variation range is the precondition to achieve turbine stability, the ratio between maximum head and, design head is controlled under 1.2. Secondly choose excellent hydraulic design, the specific speed shouldn,t be too high, select lower guide vane relative height bo, reduce unit flow, reduce the pressure fluctuation in draft tube, try the best to exclude the channel vortex from operation ranges, avoid the frequency vibration of the vortex under the low load, optimize blade shape. Thirdly optimize structure design, raise the runner,s rigidity and strength, reduce local maximum stress on runner. Fourthly develop manufacturing quality, VOD vacuum deoxygenation refining and numerical control machining should be adopted for stainless steel blade, try the best possible to build integral runner, improve welding technique of runner, reduce residual stress. Fifthly scientific management and operating according to rules and regulations, avoid operating in vibration zones and go through quickly.