Research On Internal Flow And Energy Conversion Mechanism Of Screw Entirfugal Pump

Screw centrifugal pump is a solid-liquid two-phase flow pump that with uniquestructure and more efficient than centrifugal trash pump and cyclone trash pump,Screw centrifugal pump combines the advantages of screw pump and centrifugalpump, and the special structure can bring into play their advantages sufficiently.Comparing with the traditional impurity pump, screw centrifugal pump has a series ofstrong points, such as: without clogging, suction performance, adjust the performanceand cavitation resistance, and with no load, high efficiency and high efficiency zonewidth.A long time, the pump industry workers has been being plagued how to improvethe energy efficiency of pump products and they are most concerned how to obtain ahigher efficiency at the same working conditions. Generally, screw centrifugal pumphas low efficiency, that is, the efficiency of the screw centrifugal pump is still vastimprovement room. Impeller is a very important components of Screw centrifugalpump, One could even say that it is the heart of Screw centrifugal pump, and the vaneshape have a decisive impact to the impeller hydrodynamic characteristics. For screwcentrifugal pump which transport liquid-solid two-phase flow media, because it’simpeller flow state complexity, the one dimension flow theory and empirical designmethod are difficult to meet the need for well-designed hydraulic performanceimpeller. From the solid-liquid two-phase media in the screw centrifugal pumpimpeller state of the sport，it’s impeller make fluid from axial to radial completion ofthe transition, fluid velocity of axial from large to small, and radial velocity on thecontrary. Which require the pitch of blade do descending smooth change from inlet tooutlet. Therefore, to explore the impeller energy conversion mechanism and thevarious parts of the impeller flow acting to provide more effective improve programsfor the rational design of the impeller.For the topic of this paper, the main research contents are as follows:On the one hand, the fluid mechanical internal fluid flow is analyzed ontheoretically, Bernoulli equation is adopted, the conversion of the fluid in the impellerwas divided into the dynamic pressure and static pressure head to study,whichprovide a theoretical foundation for the application of numerical simulation theimpeller various paragraphs the acting ability. The other hand, throughout thenumerical simulation, analyzing the pressure distribution, the velocity distribution,solid concentration distribution on the impeller, obtained the screw centrifugalimpeller mechanism of energy conversion and intimate contact which produced itssuperior anti-clogging and non-destructive features.The innovation points of this paper are as follows: 1) Bernoulli equation of fluid mechanical was adopted and energy of impellerconversion was divided into dynamic pressure and static pressure head to studyenergy transfer and transformation of the law of the screw centrifugal pump,2) Study the law of along the impeller distribution Of pressure field and velocityfield, and the rim of the lines and wheel lines of screw centrifugal pump were dividedsegments, the pressure head change from the movement of energy along the screwcentrifugal pump impeller corners conversion capabilities, it is valuable guide forimproving performance and design theory of screw centrifugal pump.Through theoretical analysis and numerical calculation, from the overallconversion performance of the screw centrifugal pump energy, and specificallyexplored the design conditions, the media were the speed of the flow field in the waterand the solid-liquid two-phase flow of sand water, pressure, flow lines, hydrauliclosses, it’s full of flow numerical simulation results of qualitative analysis withquantitative contrast, access to the main conclusions of the following:1) The relative velocity along the corners of small to large (from the pump inletto outlet) is the overall situation is gradually increased, decreased slightly in a smallsection, which in a certain extent, reduce the spiral centrifuge pump efficiency;2) In the screw centrifugal pump impeller acting project, the spiral section of thestatic head and dynamic head overall increase is developing, not necessarily in thecentrifugal section. The maximum radius of the hydrostatic head of the largest, thepressure of the screw centrifugal pump is mainly generated in spiral helical segmentof the front of the impeller played a multi-level role, which also verified the helicalsegment in the impeller acting plays a major role;3) In the case of the turbulent motion of the two-phase flow, due to the differentof force field, screw centrifugal pump impeller propeller and centrifugal role makethe solid-liquid two-phase movement at different speeds. Energy conversion insimulated operating conditions of screw Centrifugal pump main is the energy changeof the liquid, and solid phase in liquid wrapped association movement. Solid energy iscarried out indirectly through the liquid.