Experimental investigation of mesoscale boundary layer flows over catalytic surfaces

The recent emergence of the fields of micro-power generation and micro-combustion revealed a particularly challenging realm of reactive fluid mechanics comprising intermediate Reynolds and Peclet number flows over catalytic surfaces. In this paper, we present preliminary results of our work in this field. Our focus is on the study of flat-plate boundary layers for the range of Reynolds (Peclet) numbers relevant for small-scale power generation. Catalytic platinum plates of dimensions on the order of 2 x 2 cm were placed in an appropriately designed burner where mixture composition, inlet speed, and inlet temperature were controlled and methane catalytic combustion was established. Temperature distribution on the catalytic coupons was measured as a function of mixture flow rate and composition using infrared thermography. The infrared measurement was calibrated by performing selected measurements on the surface using embedded thermocouples. The temperature measurements were complemented by spontaneous Raman scattering measurements of major combustion species and revealed that, under certain conditions, intense combustion due to enhanced transport to the surface occurs at the leading edge of the flat plate, which is then followed by a region of approximately constant surface temperature.