Secondary Flow For More Research On The Effects Of Six Nozzles Pelton Turbine

With the rapid development of C hina’s economy and the continuous improvement of people’s living standards, people’s demand for electricity is growing. In the same time, electricity is becoming the fastest growing energy. Hydropower development in C hina gradually changes from the low head and large discharge to the high water head, Pelton turbine is adapt well to the characteristics of high head operation,and the impulse pelton output will be improved with the nummber of nozzle improved. Therefore, the impulse turbine is gradually developed from single nozzle to multi nozzles. Compared with the mature technology of the hydraulic turbine, the research of the impulse turbine has just started in our country. The internal flow of the impulse turbine is much more complex than that of the internal flow of the teaction turbine, because its internal flow is a three-dimensional unsteady gas- liquid two-phase flow. In Pelton turbine guided water pipeline belongs to the typical bends and bifurcations of pipe flow, the secondary flow generated upstream will affect the flow pattern of the nozzle inlet, and will develop towards the downstream, which w ill eventually affec t the flow pattern of the jet. However, the impact of efficiency of turbine is composed of a water supply unit efficiency and runner efficiency. In particular, efficiency of the runner is influenced by the quality of the jet. So it is very important to study the development of the secondary flow in the water supply unit. In this paper, a numerical simulation of a certain type of six nozzles impact turbine is carried out:1.Through the analysis of the energy loss of water supply mechanism of the six nozzles impulse turbine, find out the reasons of the energy loss of the water supply mechanis m;2.Through the analysis of the secondary flow in the water supply mechanis m. Explore the the development process of secondary flow in downstream. Through the analysis of the development process of the jet flow, find out the influence of upstream flow on the flow and shape of the jet;3.Do the whole basin numerical simulation of the six nozzles impulse turbine. Through the analysis of the jet work process on the bucket, to find out the working characteristic of Pelton turbine and internal adverse flow phenomenon.The results show that energy loss of water supply mechanis m mainly involve energy loss of water distribution ring and energy loss of nozzle, where energy loss of nozzle is the main loss. With the same opening, the energy loss of the nozzle increases with the increasing of the head. But the ratio of the total head is basically unchanged; Due to the water distribution pipe belongs to the typical internal pipe flow, the interior will produce a typical Dean vortex, this symmetry of the Dean vortex will shift to the inner side and lead to bifurcation of jet. There are serious adverse flow phenomena inside the bucket for the model in this paper, the water bucket adverse flow phenomenon is more serious, and Creates a low-pressure zone remains in the bucket back, and low pressure area can be a phenomenon of cavitation.