The Fluctuation Characteristics Of The Transfer Process Strengthed By Liquid-continuous Impinging Streams

Liquid-continuous Imping Stream Reactor(LISR) is a new type reactor of many new chemical reactors.The excellent mixing characteristics come from the ability of enhancing the mixing dispersion process.It has a special fluid flowing structure,samll changes of structure and operating characteristics will influence the mixing efficiency, the dispersion range and strength and so on in the flow field. From the reaction efficiency of the reactor itself, the process of heat and mass transfer and reaction are related to reactor. The mechanical phenomenon and the reaction process are exhibited complicated in the flowing field, thus problems can be solved by studying the fluctuation characteristics. So research of the fluctuation characteristics under different modes and operating Parameters for describing mechanism and optimization of the structure is necessary and informative.The different LISR physical models are established by Gambit software and simulated by the fluid dynamics software CFD-Fluent to discuss the fluctuations rules of distribution of speed velocity field and pressure field on the sPatial and temporal under the conditons of different structures, such as: different blade types, different tube diameter ratio, different distances and operating Parameters, such as: material component content, blade speed, the law of pressure and velocity field in the axial and radial direction under the various working conditions of the imPacting and circulation areas are obtained, the correlations between working conditions and pressure fluctuation distribution is also obtained by numerical simulation, which provide certain mathematical models for the basic theory of impinging stream technology and its application in practical production.Main contents include: when the operating Parameters is certain, the ways of changing the structure have no influence on the overall trends for the fluctuation of pressure and velocity over time in the imPact area, stabilization time for the pressure and velocity of flow field required 3s under the speed of 1000r/min; when the structure is certain, changing the operating Parameters will affect the flow field stabilization time, the time is 3s when air volume ratio of material content is 0,the air volume ratio increases to 0.3,time increases to 4.5s, the air volume ratio increases to 0.6,time increases to 6.0s. At the same time when the blade speed from 1000r/min down to 500r/min, the flow field stabilization time from 3s to 4.5s, the low speed increases stability of the flow field time.The ways of changing the structure and operating Parameters have no influence on the overall trends for rules of the sPace distribution of velocity, pressure and pressure fluctuation intensity in the imPact area. The speed distribution and pressure distribution on each imPac surface are symmetrical structure on the axial centerline, the distribution of pressure fluctuation intensity is symmetrical structure on the radial centerline.The velocity increases at first and then decreases in radial direction. Position of maximum velocity and pressure values is near the axial centerline with distance from the center imPact surface increases, and larger the pressure fluctuation intensity with distance from the center imPact surface is farther.Increasing the blade areas is favor of conversion of axial pressure and velocity to radial pressure and velocity, largest pressure on each imPact surface and the dimensionless blade areas are linear relationship, with the distance from the center imPact surface are multiple relationship, the larger areas and distance, the greater pressure fluctuation value.Increasing the ratio of length and diameter will makes axial pressure and velocity increase in the draft-tube entrance area, the length of the draft tube is increased moderately, the pressure of center of the imPact surface decreases and the pressure of central axial increases, while it presents opposite trend if it excessively increases, as for the velocity field, when the ratio of length and diameter increases, the axial velocity in the draft-tube entrance area increases, radial velocity reduces after imPacting.The maximum pressure on each imPac surface and the ratio of length and diameter are quadratic curve relationship, showing a decreasing trend after the first increasing.Pressure fluctuation value and velocity increase with blade opposite distance adding in the draft-tube entrance area, and also weaken the pressure fluctuation and speed value in the imPact area, the corresponding pressure and speed values will decrease doubled with blade opposite distance has doubled.When the distance increases 100 mm to 140 mm, the pressure fluctuation intensity value is certain which is is kept within a certain range, the maximum pressure value on each imPact surface and dimensionless distance are decreasing power function relationship.Increasing air component content of materical will weaken the pressure fluctuation and velocity. On the flow instability stage, the velocity fluctuation range and severity increase with air volume fraction adding. And the circulation area, water velocity and flow range reduce in the draft-tube entrance area. Rasing the air content is not conducive to the water flow properties of the entire flow field. Air component is mainly concentrated on both sides of the imPact surface in reactor, the water component is mainly concentrated at the bottom of the reactor. Volume fraction distribution of the entire flow field is symmetrical structure on the axial centerline, the maximum pressure value on each imPact surface and air component volume ratio are exponential function.Pressure and velocity fluctuation value increase with speed of blade adding.When the speed is 1500r/min, the largest amplification value of pressure fluctuation intensity of two adjacent imPact surface is 123.92 Pa, while the speed is 1000r/min and 500r/min respectively, the value decreases to 47.01 Pa 13.17 Pa.The distance from center of the imPact surface increase under the same speed, velocity is larger and more uniform on overall imPact surface, and velocity of cycle area increases out of the draft tube and velocity gradient increases significantly. The maximum pressure value on each imPact surface and blade speed along with diameter are decreasing power function relationship.