| Oily medium in industrial sewage is difficult to degrade in nature.Cyclone separator has absolute advantages in oily sewage treatment because of its simple internal structure,low separation cost and high separation efficiency.The size of dispersed oil droplets in oily sewage ranges from 10 to 100 microns,the oil droplets suspende in the sewage.A cyclone separator works to the separation of oil droplets with this size separation.More than 95%separation efficiency can be achieved after treatment by oil-water cyclone separator,which can meet the requirements of treatment standards.The internal fluid of oil-water cyclone separator belongs to turbulent flow state,the main factors affecting separation performance are capacity,split ratio and pressurization mode.The research on the main factors affecting separation performance mostly focuse on the assumption that the cyclone separator is in static condition,and no research results have been found about the separation efficiency of the cyclone separator under vibration condition.If the cyclone separator works under vibration,the dynamic response of the cyclone separator is formed.The internal flow field is a very complex three-dimensional turbulent flow.When the excitation vibration is taken into consideration,the flow field structure will change and the separation efficiency will also change accordingly.Therefore,the study of flow field characteristics of cyclone separator under vibration conditions and the establishment of reliable fluid-solid coupling numerical model can not only predict the flow field structure and separation efficiency under different vibration frequencies and amplitudes,but also provide theoretical basis for the selection of equipment causing the vibration.At the same time,it can provide theoretical guidance for the study of the internal swirl generation mechanism and the optimization design of the overall structure of the cyclone separator,which has important theoretical value and engineering significance.The flow field characteristics of the oil-water two-phase cyclone separator under the simple harmonic vibration condition are studied in this paper,the factors affecting the vibration of the cyclone separator are analyzed,and the transmission mode of vibration between the equipment is simplified.The main vibration source of the cyclone separator is the simple harmonic vibration force generated by the periodic operation of the connecting equipment.The finite element model and the mechanical model of the cyclone separator and part of the connecting pipe string are established through theoretical analysis.The vibration frequency and amplitude of the cyclone separator,which are used as displacement excitation conditions to provide technical parameters for the subsequent study of flow field characteristics under vibration mode,are determined using modal analysis and transient dynamic analysis.This article chose the spiral channel-inner cone cyclone separator as the research object.Compared with the traditional structure,the new structure not only improves the separation efficiency,but also shortens the length of the cyclone separator and reduces the requirement of installation space.A numerical model of fluid-structure interaction of a cyclone separator under harmonic vibration is developed.A numerical model of fluid-structure interaction of a cyclone separator under harmonic vibration is established.The finite volume method is used to solve the fluid field.Based on anisotropy,the Reynolds stress model in the Reynolds averaging method is used to establish the turbulence model.The calculation method of the fluid domain is determined after discretizing the governing equation.The finite element method is used to simulate and establish the numerical model and the calculation method of the structure domain for the structure domain of the cyclone separator.The Lagrange-Euler description is used to analyze the mesh matching of the coupling interface,the transfer of physical quantities and the solution method of the coupling interface for the fluid-structure coupling problem in fluid and structural domains.The coupled transient dynamic model of the structure and fluid of the cyclone separator under harmonic vibration is established,and the corresponding axial velocity is obtained by numerical simulation under different excitation conditions.Axial velocity,radial velocity,zero velocity envelope,turbulent kinetic energy and tangential velocity are obtained.The coupled flow field characteristics of the cyclone separator under simple harmonic vibration are described comprehensively.A PIV flow field test platform suitable for the study of periodic variation is established in order to verify the validity of the fluid-structure coupling model of the internal flow field of the cyclone separator under the condition of simple harmonic vibration.The flow field inside the cyclone separator under non-excitation and harmonic vibration is measured and studied.The structure of flow field in different regions of the cyclone separator at different frequencies and amplitudes is revealed by measuring and studying the flow field inside the cyclone separator under non-excitation and harmonic vibration.Velocity vector field,axial velocity,radial velocity,zero-speed envelope,turbulent kinetic energy and vorticity on the central axis are obtained.The PIV results are compared with the simulation results of the fluid-solid coupling numerical model to verify the accuracy of the simulation results.The experimental study on the separation efficiency of a cyclone separator is used to further verify the correctness of the fluid-solid coupling model of the flow field in the cyclone separator under the condition of simple harmonic vibration.The separation efficiency of the cyclone separator under different excitation is tested,and the comparison between the test results and the simulation results shows that the two models are in good agreement.The vibration response law of the spiral channel-cone cyclone separator under harmonic vibration is expounded based on the simulation results and experimental results of the fluid-solid coupling mathematical model,that is,the Vibration frequency and amplitude have influence on the separation efficiency of spiral channel-cone cyclone separator.The separation efficiency decreases with the increase of the amplitude;and the separation efficiencydecreases linearly with the increase of the frequency while the amplitude remains unchanged.The separation efficiency of the cyclone separator is higher than that of the static state in laboratory tests at low frequencies(2-6 Hz)and low amplitude(1 mm).It shows that vibration can promote oil-water separation of the conical cyclone separator in the helical channel under certain frequency excitation. |
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