Experimental Study Of Temperature Distribution And Combustion Wave Propagation During Ceramic Foam Combustion

Combustion of premixed gases in porous media, providing advantages such as high thermal efficiency, extended flammability limit and low pollutant emission, has important scientific and industrial application value. The thesis presents an intensive investigation on combustion characteristic of methane/air in ceramic foams experimentally. The experimental setup is designed and built. Infrared thermal imaging camera is used to measure the temperature of porous media combustor and the temperature distribution characteristic is studied. The combustion wave propagation velocity is calculated from the temperature distribution of the quartz glass window and the combustion wave propagation characteristic is studied.Firstly, the characteristic of temperature is studied experimentally. The effects of equivalence ratio, inlet velocity, ceramic foams material and pore density on temperature distribution and temperature change are investigated in detail. Experimental results show that the direction of combustion wave progapation is influenced by equivalence ratio. Downstream, upstream, and stabilized waves are obtained in ceramic foams combustor. The combustion temperature increases with the inlet velocity. Temperature of20PPI is higher than that of10PPI and30PPI. Temperature of Al2O3is higher than that of ZrO2and SiC. The shape of temperature distribution has continuous changes, from triangle-shaped to ladder-shaped, saddle-shaped.Secondly, the characteristic of combustion wave propagation is studied experimentally. The effects of equivalence ratio, inlet velocity, ceramic foams material and pore density on combustion wave propagation velocity are investigated in detail. Standing wave equivalence ratio and equivalence ratio range of stable flame are determined. Experimental results show that the combustion wave propagation velocity is of the order of10-4m/s under all test conditions, ranging from-0.35mm/s to0.32mm/s. The combustion wave propagation velocity decreases with the equivalence ratio and changes little as inlet velocity increases. The velocity of30PPI is higher than that of10PPI and20PPI. The velocity of SiC is higher than that of Al2O3and ZrO2. The equivalence ratio range of stable flame of Al2O3and20PPI is wider than that of ZrO2, SiC and20PPI,10PPI. It is more suitable to choose SiC ceramic foams as porous media or ceramic foams of20PPI when the equivalence ratio is low. Conversely, the choice should be Al2O3or 30PPI.Finally, wall temperature of combustor is analyzed on the base of temperature distribution and combustion wave propagation charateristics, and compared to the experimental results. The effects of thermal resistance of quartz glass and air on heat transmission are investigated. An instability phenomenon of split wave is observed as the combustion wave moved upstream or downstream.