The Temperature And Resistance And Throttling Effect Of Fire Research In Mine Tunnel Fire

Mine fire is one of the main factors and threats to mine safety. As the coal production of China develops toward the high yield, high efficiency and intensive situation gradually, efficient, the frequency and severity of fire also increases and upgrades. For the research of the fire of mine laneway, this paper researches the fire zones and temperature, resistance, the influence of throttle effects when smoke streams flows through the tunnel firstly. Those have important theoretical and practical significance to the reliability of the ventilation system by scientific analysis in fire condition, designing the mine ventilation well, mine fire rescue, controlling the direction of wind reasonably, mastering the temperature and blowing rate of the smoke plume at any time, realizing voltage-sharing ventilation, and so on.Based on the variation of temperature and the resultant in the fire, the fire process is divided into three phases:rapid growth phase, the stage of stable development and the decay stage. By studying the way of variation about the airflow and temperature in fire zone, this article get two maximum temperature formulas of wind current in the fire. And this paper first supposes the fire consumed oxygen of wind current so that oxygen concentration is zero.Because the tunnel fire zone is relatively short, we do not consider the volume of heat exchange between the smock plume and roof-floor of the tunnel, and think the smoke-flow process as a stabilize process. So this paper obtains a highest temperature formula. Then, this article regards the wind current as one-dimensional steady flow, without considering the changing of kinetic energy and quality in the process of flow. According to combustion, heat release rate and thermal energy equation, the paper builds maximum thermometer formula of wind current.Combination of the two above formulas, the paper derives a maximum temperature of formula in the steady environment assumptions of fire zone.Based the maximum temperature of wind current and heat transfer theory, this paper deduces the temperature distribution formula of downwind side of the fire zone.According to describing the fire resistance and its generated mechanism, this paper points out that the thermal resistance and drag resistance constitute fire resistance. The generating of thermal resistance is due to fire and heat, so that the wind current begins thermal expansion in roadway to produce resistance。The generating of drag force is due to flame itself occupying the space of the roadway, hindering wind flow and producing the local drag force. Based on the continuity equation and energy equation of mine air flow, this article derives out the resistance formula in the during of mine fire.According to theory of similarity of fluid, this paper builds a model of fire tunnel experiment to fire, proving the deduction about fire temperature and resistance of fire zones, obtains a result that resistance of fire zones relates to factors, such as wind speed and fire size, testifies maximum temperature changes with different speed and the relationship between the two. According to experiment, it proves the transformation situation of wind speed in tunnel under the fire, and the relationship between the temperature, resistance, pressure and throttling effects. At last, this article reaches the following conclusions:(1) Under the fire condition, with the wind speed increasing, the maximum of fire district temperature increases. When the wind speed reaches a certain value, the fire the maximum reaches the top, and with wind speed continuing to increase, the maximum drops.(2) Along with the increase of space of fire district, the temperature of airflow within the tunnel showed a decreasing trend. When it reaches a certain distance, the temperature becomes a essential constant.(3) Under the fire condition, because of the influence of the throttle effect, the wind speed in fire tunnel becomes smaller but the wind speed in parallel with the fire tunnel became bigger.(4) With the fire in tunnel increasing, the resistance of fire zone manifests stronger. Dynamic pressure and total pressure which are inside the tunnel that is in parallel with the fire tunnel also change strong. With the reduction of the fire, the resistance of fire zone weakens; dynamic pressure and total pressure weaken.(5) When the fire happens, the higher the temperature of the fire district rises, the stronger the resistance of fire zones manifests; and the opposite in the lower temperature.(6) With the resistance of the fire district increasing, the fire throttling effects manifest more obvious; and the opposite with decreasing.(7) When the fire happens, the higher the temperature of the fire district rises, the more obvious the throttling effect of tunnel fire manifests. With the temperature of the fire district decreasing, the fire throttling effect gradually weakens.