旋风分离器

A 3D Computation of Fluid-structure Interaction in a Cyclone SeparatorPan ZHANG 1a , Bei WANG 1a, ZhiPeng GUO 1a and YaNan SHEN 1a1 College of Electromechanical Engineering, Qingdao University of Science and Technology,Qingdao 266061, Chinaa pan_zh@Keywords: Cyclone, CFD, FEM, fluid-structure interaction.Abstract. This work presents a 3D computation of fluid-structure interaction in a cyclone separator. The finite volume method was used to simulate the flow field in the cyclone separator. The fluid-structure interaction was conducted by transferring the computational pressure distribution to the corresponding surface of the cyclone shell. The stress and deformation distribution in the cyclone shell was computed by the finite element method. Results obtained show that the maximum equivalent stress and deformation is linearly increases with the increases of the inlet gas velocity. IntroductionCyclone is a kind of equipment that takes advantage of rotary motion of airflow to make the solid particle separated from the gas flow by centrifugal force. Because of its simple structure, easy to operate, low operating and maintenance costs, and adaptability to a wide range of operating conditions, it is widely used in many industries.The computational fluid dynamics (CFD) was widely utilized to simulate the gas-particle flow field in a cyclone separator [1]. However, the study is less on the influence of the internal complex swirling flow field to the cyclone shell [2]. This paper gave a 3D computation of fluid-structure interaction in a cyclone separator. The internal complex swirling flow field was firstly simulated. Then, the computed gas pressure distribution is exerted to the finite element model as the body load to calculate the static stress and the deformation of the cyclone shell.Geometry of the cyclone separatorIn this study, the typical Stairmand cyclone [3] (shown in Fig.1) was choose to conduct the 3D computation of fluid-structure interaction. The cyclone dimension used is shown in Table. 1.Fig. 1 Cyclone configurationTable 1 Geometrical dimensions of the cyclone separator(Unit: mm)a b De S h H D B100 40 100 100 300 800 200 75Simulation methodThere are several turbulence models available for gas turbulent flow: k-ε model, ARSM (Algebraic Reynolds stress turbulence) model, RSM (Reynolds stress turbulence) model and LES (Large Eddy Simulation) model. The RSM model can yield a more accurate prediction on swirling flow pattern on cyclone simulation than k-ε model, ARSM model [4]. The LES model need more computational source than RSM model. Thus, RSM model was choose to simulate the turbulent flow. QUICK model was adapted to discrete convection item [3]. The SIMPLEC algorithm was used to couple the pressure with the velocity [4]. After getting the flow field, the pressure distribution information will be transferred to the FEM model. The top ring is set as a fixed constraint condition. The details parameters are presented in Table 2.Table 2 Details parametersBoundary conditionInlet Velocity inletOutlet OutflowCyclone wall Standard wall functionViscousTurbulence Reynolds stress model (RSM)DiscretizationPressure PRESTO!Pressure-velocity coupling SIMPLECMomentum QUICKTurbulence kinetic energy QUICKTurbulence dissipation rate QUICKReynolds stresses QUICKResults and discussionsPressure distributionAs it can be seen in Fig. 2(a), the static pressure distribution along the radial firstly increases with the increase of the radius. Then, it decreases gradually. Near the axial center, it has an even negative value. There is a vacuum area near the central along the axial in the cyclone separator. It is should be resulted from which it is a high-velocity area. Meanwhile, there is a little pressure difference along the axial. It is also suggested the change of the radial velocity is much less than that of the tangential velocity.As it can be seen in Fig. 2(b), the total pressure is the largest at the interface between the forced vortex and the quasi free vortex. In the free vortex area, the total pressure decrease with the decrease of the radius. The total dynamic pressure distribution is not symmetrical, which is may be caused by the symmetrical gas inlet.( a) (b) Fig. 2 Contours of the static pressure and the total PressureStress and deformationThe material of the cyclone shell is structural steel. The thickness of the envelope is 5 mm. The environment temperature condition is 298K. The properties of the structural steel are presented in Table 3. After getting the internal pressure distribution, the computed gas pressure distribution is exerted to the finite element model as the body load to calculate the static stress and the deformation of the cyclone shell.A contour of the equivalent stress is shown in Fig. 3. As it can be seen, the stress level in the whole cyclone shell is low, which is far less than allowable value, but the stress distribution is not uniform. The stress value in the up part is bigger than that in lower part. The maximum equivalent stress value appears in the superstructure. The upper cylinder appears stress concentration.A contour of total deformation is shown in Fig. 4. The maximum equivalent stress value always appears at the inlet pipe and the upper part for various velocities. In addition, the investigations of the relationship between the maximum equivalent stress, the total deformation and the gas inlet velocity were carried out. The results are shown in Fig 5. It shows that the maximum equivalent stress and the total deformation almost linearly increase with the increases of the gas inlet velocity.Table 3 Properties of the structural steelDensity7850kg/m 3 Young's Modulus2E+11Pa Poisson's Ratio0.3 Bulk Modulus1.6667E+11Pa Shear Modulus7.6923E+10Pa Tensile Yield Strength2.5E+08Pa Compressive Yield Strength 2.5E+08PaFig. 3.Contours of equivalent stress Fig. 4 Contours of total deformationFig 5 Maximum equivalent stress and total deformation versus inlet gas velocityConclusionWe have presented presents a 3D computation of fluid-structure interaction to study the effect of the gas inlet velocity on the stress and deformation of the cyclone shell in a cyclone separator. Our numerical simulations show that the maximum equivalent stress and the total deformation almost linearly increases with the increases of the gas inlet velocity.Acknowledgments. This study has been supported by Natural Science Foundation of China (No. 21276132) and Science Projects of Qingdao City (No. 12-1-4-3-(19)-jch).References[1] H. J. P.Morand, R ,Ohayon. Fluid structure interaction. John Wiley (1995).[2] Hoekstra, A. J., Derksen, J. J., Van Den Akker, H. E. A. (1999). An experimental and numerical study of turbulent swirling flow in gas cyclones. Chemical Engineering Science, 54(13), 2055-2065.[3] C. J. Stairmand. The design and performance of cyclone separators. Trans. Inst. Chem. Eng(1951), 29, 356-383.[4] Kaya, F., Karagoz, I. Performance analysis of numerical schemes in highly swirling turbulent flows in cyclones. Current Science (00113891) (2008), 94(10).。