Optimization Design Of Hydraulic Cyclone Based On CFD Simulation And Multi-objective Coupling Preference Decision Optimization Method

Hydrocyclone is a commonly used liquid-solid separation device,widely applied in industrial separation processes such as petrochemical,coal,and mineral industries,as well as in emerging fields such as cell separation,soil purification,and bioengineering.In the separation process,relatively fine particles enter the overflow,while relatively coarse particles enter the underflow.However,due to the presence of multiphase flow phenomena such as highspeed rotational turbulence,short-circuit flow,and recirculation flow,as well as the mutual influence of particles of different sizes and densities,the internal flow state is extremely complex.This can cause particle misplacement,seriously affecting the separation performance of the hydrocyclone and increasing the separation cost of particles.Therefore,optimizing the design of high-efficiency and low-energy consumption hydrocyclones has significant practical significance.This paper builds a simulation model based on a 75 mm hydrocyclone and verifies its accuracy with error of less than 10% for key indicators.Based on the spiral and tangential inlet,the paper proposes optimized design methods for both types of inlets,and explores the effects of radius and spiral angle on their separation performance.Analyzing the separation curve,the internal flow field characteristics,and the flow stability,the results show that the optimized design can significantly increased the separation efficiency of large particles(the separation efficiency of particles with a diameter of 22.5 μm increases from 70% to 94%);a smaller spiral angle(90°)optimizes the distribution of the internal flow field and obtains a higher tangential velocity,reducing the influence of recirculation flow and short-circuit flow on particle separation.In addition,the symmetrical radial velocity distribution and stable air column achieve a pre-separation effect of particles.To improve the centrifugal force for separating the particles in the hydrocyclone,this paper proposes a gradually tapered inlet design based on the tangential inlet.Simulation results show that compared with traditional inlet designs,the optimal width of the cross-section for the tapered design is 8 mm.Under this width,the new hydrocyclone is in a stable separation state,achieving higher classification accuracy and smaller cut size.Compared with the basic hydrocyclone,the tapered design significantly increases the tangential velocity of the internal flow field(the peak velocity is nearly doubled),enlarges the radius of LZVV by nearly 25%,effectively reduces the influence of secondary flow and short-circuit flow,and forces particles to enter the separation channel smoothly,reducing the effect of particle misplacement on the separation of coarse particles.This design also helps to form a stable internal flow field(symmetrical radial velocity and smaller turbulent pulsation).To reduce the energy consumption of the separation process.This work proposes an optimization method that integrates data-driven,multi-objective optimization,and multicriteria decision-making to achieve this goal.The mapping relationship between various parameters(velocity,underflow pipe,overflow pipe,and cone angle)and performance indicators(split ratio,cut size,pressure drop,and separation sharpness)is established.Six commonly used multi-objective optimization algorithms are compared,and the best performing algorithm(SPEA2)is selected.The results show that the extreme learning machine neural network model can well predict the performance indicators of the hydrocyclone;when four objectives are simultaneously optimized,the mutual influence between the indicators is small;under the same inlet velocity condition(4.49 m/s),the pressure drop of the optimized hydrocyclone is only 56.9% of the original.