Study On The Time-Dependent Law Of Thermophysics Parameters Of Combustion In Fullscale Tunnel Fire And Simulation Of It

The fullscale tunnel fire experiments were completed for 14 times in the maximum testing tunnel in Asia, and the variations changing with time at different position were acquired continually, such as temperature of smoke flow, temperature of wall and rock, pressure, concentration of oxygen and carbon dioxide and air-flow velocity etc. The time-dependent law of the main thermophysics parameters wree studied, of which are thermal resistance, fan pressure, thermal potential pressure, coefficient of throttled flow, dimensionless viscous drag force, expansion thermal resistance, flame velocity spreading on the surface of fuels, dimensionless rate of mass loss, and synthetic coefficient of heat transfer in the process of burning and in the airtight space abruptly cut off fresh air-flowing. The characteristics of the determinacy and chaos in the process of motion of smoke was described by use of Lyapunov characteristic exponent. The dimensionless rate of mass loss of fuels as a significant nature parameter was defined for studing the unsteady flow during fire, and a series of models were set up for the simulation of fire. Based on the thermochemistry and chemical kinetics, the combustion mechanism and flowing direction of combustion heat for the three main species of solid fuels was studied. Based on the principle of heat and mass transfer, the main forms and quantity of heat transfer between the smoke-flow and the surround rock were studied. The new formula for calculating thermal potential pressure was drawn out. The mechanism and time limit of throttled flow taking place was brought to light.