Research on Flow Field in Nozzle of Fluidized Bed-Type Jet Mill
|Course||Mechanical and Electronic Engineering|
|Keywords||Fluidized bed jet mill Laval nozzle Stagnation pressure Backpressure Jet Intracavity FLUENT|
The jet mill is one of the main technologies and methods of preparation of ultra-fine powder material, jet mill capable of producing higher purity ultrafine powder materials. Fluidized bed jet mill is the most advanced equipment in the jet mill. Fluidized bed jet mill through the Laval nozzle compressed air is accelerated into a supersonic air stream is injected into the crushing chamber. The material particles are accelerated in the high-speed gas stream under the action of the interchanges occur at the nozzle jet mutual impact collision, friction, to achieve pulverization purposes. Laval nozzle is a key component of a supersonic airflow. In order to make the compressed air through the Laval nozzle to accelerate to the large supersonic flow speed and Mach number, the Laval nozzle must have a reasonable shape of the inner cavity, the the airflow pressure difference between the nozzle inlet section and the outlet section must have appropriate value. Laval nozzle inner cavity shape design of the merits of the decision in the case of a certain the Laval nozzle inlet section and the outlet section of the air pressure is the overall performance of a fluidized bed jet mill. The purpose of this thesis is reasonably designed Laval nozzle the intracavity shape, the compressed air through a Laval nozzle fully crushed material particles accelerated for greater speed and Mach number supersonic flow, improve production efficiency, reduce production costs. In this thesis, Laboratory of Materials and Metallurgy, Northeastern University School of QLM-Ⅱ type fluidized bed jet mill nozzle for the study. The use of the basic theory of fluid mechanics and gas dynamics to determine the flow parameters of the Laval nozzle inlet section; entropy theory given the often one-dimensional gas the Laval nozzle gas flow field research to study the state of the airflow movement within the nozzle and state factors of air movement, determined to produce supersonic flow conditions, to establish the relationship between the type of nozzle gas flow field; Laval nozzle gas flow field simulation using FLUENT software; determine a reasonable value and nozzle stagnation pressure gas The basic theory of the back pressure, the design of the the Laval nozzle inner cavity shape the Laval nozzle outlet section of the air speed and Mach number larger supersonic flow; study on nozzle jet, the use of the gas jet nozzle jet calculated ensure compressed air through the Laval nozzle to accelerate to supersonic jet nozzle jet simulation using FLUENT software; verified through the nozzle jet, compressed air through the Laval nozzle supersonic jet accelerated Laval nozzle intracavity shape design to meet the production requirements of the fluidized bed jet mill.