Measuring device and method for drag coefficient of non-spherical particles considering wall effect

Abstract

The invention relates to the field of physical experimental equipment, and in particular to a measuring device and a measuring method for the drag coefficient of non-spherical particles considering wall effects. The measuring device includes a cylindrical cylinder, a cylindrical expansion body and a conical base. The cylindrical cylinder is placed on a conical base. Inside the base, there are multiple grooves with different diameters on the inner wall of the conical base, and the cylindrical cylinder is embedded in the grooves. The measuring device also includes an air distribution plate equipped with multiple equal-diameter circular holes. The air distribution plate also It is embedded in the groove on the inner wall of the conical base and placed parallel to the lower end surface of the cylindrical barrel; in the measurement method, the flow meter is adjusted to control the gas velocity in the cylindrical barrel to obtain the fluid velocity u f And the average value of the particle inclination angle θ of the particles to be measured during the falling process, and finally the drag coefficient is calculated. The measuring device can measure the drag coefficient of various types of particles under different wall conditions, and can measure various types of loose particles that are widely used in energy, chemical industry, metallurgy, construction and other fields.

Description

technical field [0001] The invention relates to the field of physical experiment equipment, in particular to a measuring device and a measuring method for the drag coefficient of non-spherical particles considering the wall surface effect. Background technique [0002] Dense gas-solid systems are widely used in physical and chemical processes in the fields of energy, environmental protection, metallurgy, chemical industry, materials, and pharmaceuticals. In the physical and chemical processes of many dense gas-solid flow systems, in most cases, particles The shapes are non-spherical, such as strips, columns, blocks, ellipsoids, cones, etc. Considering the flow structure, the unique geometry of non-spherical particles introduces more uncertainties in the particle-particle and particle-fluid interactions. Compared with spherical particles, the drag force experienced by non-spherical particles in the airflow field is significantly different. Usually, it is difficult to express...

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Problems solved by technology

Compared with spherical particles, the drag force experienced by non-spherical particles in the airflow field is significantly different. Usually, it is difficult to express the drag force with a unified expression. The calculation of the drag force also comes down to the calculation of the drag coefficient , when calculating the drag coefficient, the commonly used test method is to use the free-settling method of particles in a static liquid. This method is based on Newton’s law of motion. When the gravity, buoyancy and drag force are balanced, the drag force can be calculated, and then the drag coefficient can be deduced; another method for calculating the drag coefficient is the test method based on fluidization, in which When the particles are kept stable in the flow field by the upward moving fluid, the gravity, buoyancy and drag force on the particles can achieve the balance of the three forces, and then the drag force can be calculated, and then the drag coefficient can be calculated. When measuring the drag coefficient of spherical particles, the experimental devices used ignore the wall effect, resulting in inaccurate measurement results. How to use a unified mathematical model to describe a series of problems such as the force and motion of non-spherical particles has not yet been solved. completely resolved

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