A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The resul...A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities in both upward inner flows and downward outer flows in the hydrocyclone, and the cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelope of zero vertical velocity. It is also found that the tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone. The increase of feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity in hydrocyclone, but the magnitude and gradient of tangential velocity are increased obviously to make the motion velocity of high density particles to the wall increased and to make the cyclonic separation effect improved.展开更多
The gas flow field in a cyclone separator,operated within a temperature range of 293 K-1373 K and a pressure range of 0.1-6.5 MPa,has been simulated using a modified Reynolds-stress model(RSM)on commercial software pl...The gas flow field in a cyclone separator,operated within a temperature range of 293 K-1373 K and a pressure range of 0.1-6.5 MPa,has been simulated using a modified Reynolds-stress model(RSM)on commercial software platform FLUENT 6.1.The computational results show that the temperature and pressure significantly influence the gas velocity vectors,especially on their tangential component,in the cyclone.The tangential velocity decreases with an increase in temperature and increases with an increase in pressure.This tendency of the decrease or increase,however,reduces gradually when the temperature is above 1000 K or the pressure goes beyond 1.0 MPa.The temperature and pressure have a relatively weak influence on the axial velocity profiles.The outer downward flow rate increases with a temperature increase,whereas it decreases with a pressure increase.The centripetal radial velocity is strong in the region of 0-0.25D below the vortex finder entrance,which is named as a short-cut flow zone in this study.Based on the simulation results,a set of correlations was developed to calculate the combined effects of temperature and pressure on the tangential velocity,the downward flow rate in the cyclone and the centripetal radial velocity in the short-cut flow region underneath the vortex finder.展开更多
A new computing technique is described for the solution'of dilute gas-particle fluid flow problems.The com- mon SIMPLE method is used for the calculation of the gas phase,but for the calculation of the particle ph...A new computing technique is described for the solution'of dilute gas-particle fluid flow problems.The com- mon SIMPLE method is used for the calculation of the gas phase,but for the calculation of the particle phase the MacCormack method(80 style)is used.Using the technique for gas-particle flows in a rotating cylindrical con- tainer,the field distributions of both phases are obtained.An important parameter Sk(Stokes number)is taken re- spectively as 0.01,0.1 and 1.The results show the influence of Sk on the flows.The collisions between particles and the side wall of the container are predicted when Sk=1.展开更多
基金Project (50974033) supported by the National Natural Science Foundation of ChinaProject (N100301002) supported by the Fundamental Research Funds for the Universities, China
文摘A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities in both upward inner flows and downward outer flows in the hydrocyclone, and the cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelope of zero vertical velocity. It is also found that the tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone. The increase of feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity in hydrocyclone, but the magnitude and gradient of tangential velocity are increased obviously to make the motion velocity of high density particles to the wall increased and to make the cyclonic separation effect improved.
基金the financial assistance from the National Key Project of Basic Research of the Ministry for Science and Technology of China(No.2005CB22120103).
文摘The gas flow field in a cyclone separator,operated within a temperature range of 293 K-1373 K and a pressure range of 0.1-6.5 MPa,has been simulated using a modified Reynolds-stress model(RSM)on commercial software platform FLUENT 6.1.The computational results show that the temperature and pressure significantly influence the gas velocity vectors,especially on their tangential component,in the cyclone.The tangential velocity decreases with an increase in temperature and increases with an increase in pressure.This tendency of the decrease or increase,however,reduces gradually when the temperature is above 1000 K or the pressure goes beyond 1.0 MPa.The temperature and pressure have a relatively weak influence on the axial velocity profiles.The outer downward flow rate increases with a temperature increase,whereas it decreases with a pressure increase.The centripetal radial velocity is strong in the region of 0-0.25D below the vortex finder entrance,which is named as a short-cut flow zone in this study.Based on the simulation results,a set of correlations was developed to calculate the combined effects of temperature and pressure on the tangential velocity,the downward flow rate in the cyclone and the centripetal radial velocity in the short-cut flow region underneath the vortex finder.
文摘A new computing technique is described for the solution'of dilute gas-particle fluid flow problems.The com- mon SIMPLE method is used for the calculation of the gas phase,but for the calculation of the particle phase the MacCormack method(80 style)is used.Using the technique for gas-particle flows in a rotating cylindrical con- tainer,the field distributions of both phases are obtained.An important parameter Sk(Stokes number)is taken re- spectively as 0.01,0.1 and 1.The results show the influence of Sk on the flows.The collisions between particles and the side wall of the container are predicted when Sk=1.
