Study On Particle Deposition Characteristics And Modification Simulation Of Guide Vane Surface Of Geothermal Turbine Based On DPM

Geothermal steam turbine is one of the important equipment in geothermal power plant.The biggest difference between geothermal steam turbine and other fields is that the purity of working medium of steam turbine is different.The working medium composition of geothermal steam turbine is more complex.The working medium of traditional steam turbine is mostly high-temperature and high-pressure fluid,while the working medium of geothermal steam turbine is geothermal medium.The composition of geothermal medium is complex.In addition to a large number of acidic components such as hydrogen sulfide chloride,carbonate,ammonium,sodium hydrogen carbonate,carbonate gas,sulfate,etc.,there are also a large number of solid impurities in the steam water thermal medium For example,silicon dioxide,calcium carbonate,iron and other chemical substances,although filter devices are installed on the main steam valve tag to deal with these particles,because the particle volume is too small,there will still be solid particles below 10 microns entering into the turbine,particles will cause impact,wear,deposition erosion and other hazards to the blades.Therefore,in addition to the study of the guide vanes of the geothermal turbine In addition to the aerodynamic characteristics,the particle trajectory in the guide vane passage and the effect of particles on the guide vane should be studied.Therefore,the particle trajectory in the guide vane passage and the deposition characteristics of particles on the blade surface can play a good guiding role in the design of the blade and the protection of the blade.In this paper,a guide vane of a geothermal steam turbine is taken as a modified design prototype.According to the data measured in the field experiment,the flow field inside the guide vane is numerically reduced,and the flow field characteristics are analyzed.On this basis,discrete phase is added to the working fluid to simulate the gas-solid two-phase flow inside the guide vane,and the movement of particles and the vehicle and characteristics of particles on the blade surface are analyzed.The results show that:the flow efficiency of steam will be reduced by the addition of discrete phase particles,and the particles will deposit on the trailing edge of the pressure surface of the blade due to the double effects of turbulence diffusion and inertia.In the study of the modification of meridional contraction of the prototype guide stator cascade,the optimal contraction ratio is 0.35-0.4 through the study of contraction ratio and flow efficiency,and 0.4 is selected as the contraction ratio blade to carry out the modification of meridional contraction.The simulation analysis of the internal flow shows that the meridional contraction cascade can effectively improve the secondary flow disturbance at the tail of the blade,and at the same time,through the modification It can also improve the deposition of particles on the blade surface.