Experimental and Numerical Study of Thermal Effect of Catalysis on the Surfaces of Metals and Quartz in Underexpanded Jets of Dissociated Air
The heat transfer from supersonic under-expanded jets of dissociated air to the surface of a 30mm diameter cylindrical water-cooled model with a rounded edge was experimentally studied by the RF-plasmatron IPG-4 at the RF-generator power of 64 kW and air mass flow rate of 3.6 g/s. Stagnation point heat fluxes were measured by flat calorimetric probes embedded in the nose part of the model. Data were obtained using probes made of different materials: gold (Au), silver (Ag), copper (Cu), molybdenum (Mo), beryllium (Be), tantalum (Ta), niobium (Nb) and quartz. For the same mode of the RF-plasmatron operation, numerical simulation of the underexpanded jet of chemically nonequilibrium air plasma around the cylindrical model in the framework of the Navier - Stokes and simplified Maxwell equations is performed. Stagnation point heat fluxes at the model are calculated depending on the effective recombination coefficient of atomic components у in the range 0 < y< 1. From the comparison of experimental and calculated heat fluxes, the values of у for the above materials are determined and the quantitative scale of the catalytic properties of the metals and quartz considered is established. Data on the catalytic properties of metals and quartz are compared with the results obtained earlier in subsonic jets of dissociated air.