1998 Volume 41 Issue 4 Pages 945-950
The hot surface ignition of methane-air mixtures in microgravity has been studied experimentally and numerically. Experiments on the ignition of the mixtures with electrically heated nickel wires and platinum wires in microgravity have been performed. Numerical calculations, including the catalytic reaction rate for platinum, have been performed to understand the experimental results obtained in microgravity. The ignition delays and ignition temperatures for a wide range of equivalence ratios were investigated. experimental results show that the ignition temperatures with platinum wires have a maximum near the stoichiometric mixture ratio, while those with nickel wires increase as the equivalence ratio increases. Ignition temperatures with platinum wires are higher than those with nickel wires. Numerical results show that reactants next to platinum wires are consumed by the catalytic reaction. Therefore, a higher temperature is required to ignite mixtures with platinum wires. The catalytic inhibition of hot surface ignition is simulated successfully by the numerical model.