Improvement Of Gas-Solid Mixing Structure Of Tracer Particle Seeder And Analysis Of Internal Flow Characteristics

With the rapid development of industry and science and technology,higher and higher requirements are put forward for the display technology of flow field.As an important part of particle image velocimetry(PIV),tracer particle generator is one of the important factors affecting the accuracy of flow field measurement.In order to obtain detailed flow field information and master the movement law of fluid,particles output by particle generator should be evenly distributed under the condition of satisfying velocity and concentration.Therefore,it is of great significance to study the structure and flow characteristics of tracer particle generator and improve its structure so as to improve its performance.Based on the Venturi effect,the structure of the tracer particle generator is designed,and the simulation model of the tracer particle generator is established.The Fluent-DPM method is used to simulate the tracer particle generator with different structures.The effects of different structures on streamlines,velocity and pressure in tracer particle generator and the distribution of tracer particles at the exit are studied.The influence of different structural parameters on the tracer particle trajectory and the tracer particle distribution at the exit is studied.On this basis,the reasonable structural parameters of the tracer particle generator are given.The results show that :(1)when the intake nozzles of the tracer particle generator are changed from two to three,the time for the tracer particle concentration to reach the stable state is reduced by 0.21 s,and the uniformity of the tracer particle is increased by 30%.When the intake nozzles were changed from three to four,the time for tracer particle concentration to reach the stable state was reduced by 0.2s,and the uniformity of tracer particle was increased by 10%.(2)The tracer particle generator with four inlet nozzles has more uniform streamline distribution,larger pressure difference,stronger adsorption capacity for tracer particles,better mixing effect,and better uniformity of tracer particles at the exit.(3)The effect of contraction angle on reflux and particle distribution uniformity is more significant.When the contraction angle changes to,the time for the concentration of tracer particles to reach stability decreases by 0.17 s.The uniformity of tracer particles was also improved,and the coefficient of variation decreased by 0.02.(4)When the throat length-diameter ratio of the tracer particle generator is2.5,the radial displacement fluctuation of the tracer particle in the contraction segment is the smallest.(5)As the expansion Angle changes from 15° to 25°,with the increase of the expansion angle,the time for the export tracer particle concentration to reach the stable state is shorter,the time to reach the stable state is increased by 0.244 s,and the coefficient of variation is decreased by 0.281.(6)Reasonable structural parameters of tracer particle seeder are as follows: intake nozzle is 4,contraction Angle,throat length-diameter ratio is 2.5,expansion angle is 25°.