2021 Volume 20 Issue 4 Pages 254-257
This paper considers the scaling laws of hot-surface ignition of combustible gases. Premixed stagnation flows impinging on hot surfaces were theoretically analyzed. Dimensional analysis was first conducted to identify a Damköhler number as the key parameter that controls ignition. Basic equations were then numerically solved to obtain the critical conditions for ignition. It was confirmed that ignition occurs when the heat flux from the hot surface to the gas phase exceeds a critical value. The obtained dependence of critical heat flux on the Damköhler number indicated the importance of thermal inertia in the gas phase. It was also found that the critical hot-surface temperature for ignition decreases with an increase in the Damköhler number. The dependence of critical temperature on the Damköhler number is nevertheless weak especially when the Damköhler number is large. This result suggests that the minimum ignition temperature (MIT) be used for safety-management purposes.
