Study Of The Numerical Simulation Platform And Experiment Of Welding Fume Control And Displacement Ventilation In Large Integral Industrial Workshop

Welding is an indispensable technique in machinery industry. With the development of modern industry, welding and related process are changing fast. However, the amount of toxic and harmful substance-welding fumes is more than ever before. Welding fume often accumulates and suspends in the upper space of the workshop, resulting in poor work condition.Recent years, scholars and engineers pay their attention to displacement ventilation for its advantages of thermal comfort, indoor air quality and energy saving. Experiments and CFD are used to investigate this type of ventilation. With the development of computer technology, CFD method has occupied the main position in studying displacement ventilation. However, in practical welding halls, the complexity of air inlet configuration, the difficulty in determining weld heat dissipation ways and pollutant diffusion ways and the diversity of obstacles in plants have become obstacles in successfully application of CFD technology.In this paper, simplified methods of engineering precision are put forward to meet challenges in CFD modeling of welding fume control and displacement ventilation. Firstly, a simplified method for orifice plates is proposed after studying flow field around orifice plates of different sizes, and then a method for simplifying cylindrical air supplier is put forward. Secondly, the characteristic of welding thermal plume is analyzed and a method for simplifying welding heat source is proposed. After then, the welding fume source is simplified as a line-pollution- source. Meanwhile, by studying the relationship between the number of welding fume particles, particle mass cumulative percentage and particle size, a method for defining particle size in simulating pollutants is proposed: particle size can be represented by a specific size in 0.1~0.2μm, 0.5~1μm and 1~4μm. Finally, welding fume control and displacement ventilation of an aluminum alloy welding hall are simulated based on the foregoing simplified models. The author finds that the existing ventilation system has good ability in welding fume removal, temperature control and air velocity control. Meanwhile, the paper studies the effect of the intensity of welding heat on welding fume distribution, temperature distribution and air velocity distribution in the hall and finds no influence on welding fume removal, temperature control and air velocity control for a existing displacement ventilation system. However, high intensity heat source will impair the ability in welding fume removal for a existing displacement ventilation system.Furthermore, the PIV technique is used to verify the simplification method for cylindrical air supplier. The result indicates that the proposed simplification method is practical and feasible.