Analysis of wall partial pressure-dependence on oxygen surface catalytic recombination with shock-heated flow

Abstract

Wall partial pressure dependence analysis of oxygen surface catalytic recombination efficiency on copper-coated surface is experimentally performed in a shock tube at room temperature. Three flow conditions with different flow enthalpy in a gas mixture that contains 21% oxygen and 79% argon are considered. The recombination efficiency is determined based on the stagnation heat transfer measurement at the end-wall of the shock tube. A copper-coated platinum thin-film gauge is used to determine the total stagnation heat transfer. An additional silicon dioxide-coated platinum thin film gauge is applied to measure the conductive heat transfer. Catalytic heat transfer theories based on binary and tertiary gas mixtures are applied to obtain the oxygen catalytic recombination efficiency and the corresponding atomic wall fraction. The oxygen atomic wall partial pressure is computed based on the oxygen atomic wall mass fraction which varies according to the surface catalysis. By combining theoretical and stagnation heat transfer measurement, the oxygen recombination efficiency on copper material is found to be between 0.0022 and 0.0213 as the oxygen atomic wall partial pressure decreases from 25.62 kPa to 13.41 kPa. The results observed in the present work confirm that the wall partial pressure influences the oxygen recombination efficiency.

Keywords

• Catalytic recombination
• Atomic oxygen
• Pressure dependence
• Copper surface
• Shock tube