Effects of porosity, pumping power, and L/ D ratio on the thermal characteristics of an N 2O catalytic igniter with packed bed geometry

Abstract

In this study thermal characteristics of an N 2O catalytic igniter with packed bed geometry which is recently introduced as a hybrid ignition system for small satellites are theoretically considered. For the purpose a so-called porous medium approach has been opted for modeling the N 2O catalytic igniter with packed bed geometry. Using the Brinkman-extended Darcy equation with Ergun term for fluid flow and the one-equation model for heat transfer, both velocity and temperature distributions are presented. To ensure the validity of the approach, the calculated wall temperature solutions have been compared with previous experimental data. Based on the results, parameters of engineering importance such as the porosity, the pumping power and the ratio of length to diameter of the catalytic igniter are identified. Their effects on thermal performance of the catalytic igniter are systematically presented. Finally an effective volume flow rate has been defined to determine the optimum values of the parameters capable of delivering maximum catalyst performance.