Optimization And Flow Field Analysis Of A New Ultra Low Specific Speed Diagonal Turbine

As a special turbine for recycling residual energy of circulating water system,industrial cooling tower turbine has the typical characteristics of ultra-low specific speed.At present,Francis turbine is used for cooling tower.Although it meets the application requirements of cooling tower in ultra-low specific speed characteristics,there are some problems such as too large plane size affecting the ventilation effect of wind tunnel,too flat runner and difficult to weld.Taking ultra-low specific speed Francis Turbine as a template and adopting equivalent theory,this paper establishes the corresponding relationship between the parameters of inclined-flow turbine and ultra-low specific speed Francis Turbine.Based on the design rules of conventional inclined-flow turbine and reversible inclined-flow turbine,an ultra-low specific speed inclined-flow turbine which meets the application requirements of industrial cooling tower turbine is designed and solved theoretically.The design obstacles and difficulties of ultra-low specific speed diagonal turbine are discussed.Based on CFD flow field analysis,aiming at the problem that the original model head of ultra-low specific speed diagonal turbine cannot meet the requirements,this paper firstly chooses the number of guide vanes and blades of the turbine,and then determines five schemes of different volute sections by changing the section area of the volute.The hydraulic performance and flow field characteristics of each scheme are analyzed.The results show that the inlet circulation of the optimized final scheme increases and the head increases significantly,which meets the application requirements and the efficiency basically meets the original design requirements.The specific speed of the oblique-flow turbine designed in this paper is lower than 80 m.k W.For the conventional oblique-flow turbine,it belongs to the range of ultra-low specific speed.Its performance meets the working requirements of the industrial cooling tower turbine.It also proves the correctness of the equivalent theory of the turbine and the feasibility of realizing the ultra-low specific speed oblique-flow turbine.It has reference and practical significance.At the same time,the designed inclined-flow turbine is used in the numerical simulation of power generation turbine.The calculation results show that the hydraulic performance of the turbine designed in this paper is better in cooling tower and power generation turbine,and has certain application value.At the same time,it provides a new idea for the follow-up research.