Numerical Flow Field Under The Laws Of Local Ventilation CO Diffusion

The proportion of more serious consequence accidents of poisoning and suffocation caused by fire and smoke at metal and nonmetal underground mines is more than40%, of which number of accidents and deaths is the most in underground mines. In this type of accidents, a considerable part is caused by poor auxiliary ventilation.The main reason of poor auxiliary ventilation is due to shorter " effective extraction length " of exhaust ventilation. The distance between inlet of ventilation duct and working face has to be longer than the " effective extraction length " for the protection of inlet of ventilation duct, so methods to improve the auxiliary ventilation effect of distance shorter than " effective extraction length " need to be further studied.Combined with the actual situation and the results of previous studies, the thesis uses a research method combination of field monitoring test and simulation one. Numerical simulation model of auxiliary ventilation is established by the CFD software and the results of field measurement verify the simulation ones. And then more repeated tests of multiple schemes are done for rich test data to provide basis of projects for better auxiliary ventilation effect.In the view of this, carbon monoxide monitoring system based on STC12C5608AD MCU is designed and made, and microcontroller and PC software programs are developed in the study of the topic. An auxiliary ventilation field experimental project is proposed and implemented. Carbon monoxide mass fractions are monitored after blasting in a new excavation tunnel for transport equipment returning at Yunxi Laochang Mine. Based on field measuring parameters of the tunnel, it is modeled and meshed in CFD pre-processing software CFD pre-processing software. And meshes are imported into the CFD software CFD software for setting parameters and boundary conditions, so a three-dimensional turbulence model of CO diffusion under auxiliary ventilation is established. After comparison of CFD simulation and field monitoring results, it is confirmed scientificity and reliability of the model.Based on the model and by changing different simulation parameters of tunnel cross-sectional area, distance between inlet of ventilation duct and working face, wind velocity, diameter of ventilation duct,ventilation time and other ventilation mode, and testing more times of different schemes, the influence of different model parameters on the effect of auxiliary ventilation and " effective exhausting length " comes to light. The research results show that the " circular eddy zone "," effective jetting length " and " effective extraction length " by theoretical studies exist in reality; The empirical formulae to calculate " effective jetting length " and " effective extraction length " are verified validity and the use and modification of the empirical formulae under similar conditions are proposed; When the distance between inlet of ventilation duct and working face is too short to reach" effective jetting length " or " effective extraction length ", the speed of eliminating toxic gases and smoke in " circular eddy zone " can be accelerated by increasing wind velocity, diameter of ventilation duct and ventilating for a longer time.The carbon monoxide monitoring system based on MCU made in the thesis, through replacement of other types of sensors, can be used for monitoring other parameters of underground mine ventilation, which has practical significance for underground mine ventilation monitoring realization of intelligence. The results and suggestions obtained in thesis through the field and simulation test, which has certain guiding significance for improving auxiliary ventilation effect and reducing underground accidents caused by poor ventilation.