Abstract: Catalytic combustion of hydrogen and oxygen mixture inside a sub-millimeter micro combustor is numerically investigated by using the commercial computational fluid dynamics (CFD) code which based detailed gas phase and surface catalytic chemical reaction mechanisms. Combustion characteristics for different reaction models and the influence of wall materials and inlet velocity on catalytic combustion reaction are discussed on the basis of experimental verification. The computational results show that the surface catalytic combustion restrains the gas phase combustion by reducing the mass fraction of OH at adjacent position. Combustion efficiency can reach maximum value when coupling the surface catalytic combustion and the gas phase combustion. Inlet velocity will take more influence onto the temperature of ouelet exhaust than the temperature of outerwall, and the too higher velocity will lead to the reducing of combustion efficiency. Wall materials also have important influence on catalytic combustion of hydrogen and oxygen, there are large temperature gradient and temperature value in the outer wall of combustor when materials with small heat conductivity are used. The high temperature combustion zone moves to the entrance side because of the increase of the heat exchange form the combustor wall to the mixed gas near the entrance when materials with large heat conductivity are used

Key words: Catalytic combustion, Micro scale, Numerical simulation, Sub-millimeter