Numerical Analysis Of The Flow Through The Middle Pressure Section Of Steam Turbine Under Variable Operating Conditions

Power plant efficiency is closely related to steam turbine.Under the background of energy saving and emission reduction,the improvement of turbine unit efficiency is very meaningful to the improvement of power plant efficiency.The flow part of steam turbine has a great influence on the efficiency of steam turbine,so the research on the flow part has a certain positive effect on improving the efficiency of steam turbine unit and promoting energy saving and emission reduction.Its main research contents and conclusions are as follows:This paper mainly uses the ANSYS Workbench to carry on the numerical analysis and the blade part optimization improvement to the flow part involved in the paper.The content of the article includes: the research background and significance of the subject;The research content and research method are determined according to the information queried.In this paper,the physical model,governing equation and turbulence model,grid division,working fluid properties and boundary conditions of flow flow are introduced.Then grid quality inspection,runner interface scheme inspection and inlet and outlet boundary condition type inspection are carried out.Numerical simulation The part is to carry on the numerical analysis under the standard working condition first,then changes the operating condition to carry on the analysis to the flow part numerical simulation situation.It mainly includes the internal flow field,the pressure distribution,the trace map corresponding to the temperature distribution,the vector map and the distribution cloud map.The optimization improvement part includes modifying the blade shape of the existing blade and changing the number of blades throughout the week to improve the flow of fluid in the flow channel to achieve the purpose of optimizing the flow part.The main conclusions are:(1)A leakage flow will occur at the suction surface and the pressure surface,which will cause the pressure at the top of the blade and the pressure loss coefficient on the surface of the blade to fluctuate greatly and increase the loss(2)The loss at the outlet section of the moving blade is mainly the loss of leakage flow from the middle to the top part of the moving blade.The leakage flow also leads to an increase in the loss of fluid flow in the channel.(3)When the pressure ratio of the moving blade increases,the corresponding flow rate decreases,which will cause the pressure difference between the front and back of the blade to become smaller,the corresponding leakage rheology is weak and the influence range becomes smaller.(4)In the process of improving and optimizing the flow section,adjusting the data of the blade,it is concluded that the influence of adjusting the front trailing edge data of the blade on the numerical analysis of the flow section is relatively large.(5)In the Prs/Sct Mode mode,the profile of the pressure surface and suction surface of the curve is adjusted many times and the numerical simulation is carried out repeatedly,which will reduce the leakage flow and the loss of the adjusted blade.(6)Since changing the number of blades for the whole cycle has little effect on the flow rate and isentropic efficiency,the appropriate number of blades for the whole cycle is adjusted according to the magnitude of the shaft power increment.