Distribution Of Velocity And Pressure Within Balance Disk Of Multi-stage-section Pump

Multi-stage pump is a kind of hydraulic machines which play an irreplaceable role in metallurgy and heat energy power generation. Magnitude of axial force is the main causation which influences stability and service life under the working conditions. Large magnitude of axial force is the main working characteristic for multi-stage pump. Balancing disk is the main balancing mechanism to counteract impeller axial force at present, which depends on pressure difference being produced by radial clearance and axial gaps. The size of balancing disk is calculated currently according to empirical formula and semi-empirical formula. There is limited theoretical analysis about flowing law in two clearances. And it is hard to analyze the reason of grinding within multi-stage-section pump.For this top point, the equation N-S is applied to derive the mathematical expression about the flowing law in two clearances, which is used to describe the flowing characteristic. And the mathematical expression is as the basis for designing of balance disk.The task makes use of computational fluid dynamics(CFD) method, selecting calculation model, laminar and turbulence, and the body-fitted coordinate systems and the tetrahedron grid systems are applied to establish grids for calculation. At last, the software Fluent, numerical value simulation, is applied to get distribution of velocity and pressure.This paper will describe the research of flow law in the two clearances, in order to discover the flowing characteristic. The paper will also show the distribution of velocity and pressure in axial gap and radial clearance, applying mainly the theory, Equation N-S, and simulation. Firstly, make the assumption of laminar flow and turbulence flow respectively in axial gap and radial clearance of balancing disk, apply the N-S equation to derive the mathematical expression for distribution of the two clearances, under two kinds of conditions, pump shaft actionless and existing pressure difference, pump shaft circumvolving and no pressure difference. Secondly, make the model of two clearances under the help of three-dimensional software, calculate the distribution, assumption of laminar flow and turbulence flow respectively in axial gap and radial clearance of balance disk. Lastly, analyze the result of simulation, discover the flow law, and verify the mathematical expression.Analyzing the result of simulation, discover those conclusions:Under the condition of laminar flow and turbulence flow, weather axial gap or radial clearance, pump shaft circumvolving and existing pressure difference, the flow is superposition on two kinds of flows, axial flow being caused by pressure difference with pump shaft actionless, circular flow being caused by circumrotation of pump shaft without pressure difference.