Experimental closure of the heat and mass transfer theory of spheroidal hailstones

Abstract

Hailstone growth experiments were performed in a vertical icing wind tunnel using 2 cm oblate ice spheroids (axis ratio of 0.67) mounted on a gyrator system. The liquid water content ranged from 1 to 5 g m- 3, air temperature from -21° to -3°C, air speed from 9 to 24 m s-1, and air pressure from 40 to 100 kPa. Icing time, ice and water mass of the hailstone deposit, and final major and minor axis diameters were measured to determine the accretion of supercooled droplets from the air flow. An infrared imaging system was used to measure local and mean hailstone surface temperatures. These experiments allowed calculation of the last two unknowns in the heat and mass transfer equations for spheroidal hailstones: the net collection efficiency, and the Nusselt number. -from Authors