An experimental and theoretical investigation of an air injection type anti-icing system for aircraft

An anti-icing system was investigated in connection with the ice accretion on an aircraft engine inlet and wing leading edge. Air injection at the leading edge was used to prevent supercooled water droplets in the atmosphere from striking the surface. Through the consideration of the droplet dynamics in a two-phase flow, i.e. air-water droplets, the effectiveness and feasibility of the air injection as a means of anti-icing technique was studied. An experimental investigation was also undertaken to complement the analytical study. An experimental model of a circular cylinder w.th injection slots was tested in a two-phase flow environment in a wind tunnel. A circular cylinder was used as an approximation of the leading edge of an engine inlet and a wing. It was shown that air injection at the leading edge reduces the ice collection rate and that the ice reduction rate is dependent on the air injection rate and location of the injection as well as the number of slots. The ice reduction due to the surface injection was determined by weighing the ice collected on the model. The predicted reduction in the ice collection due to the injection at a rate of 100 ft³/hr from each slot (slots were located at 0 and ±50 degrees from the front stagnation point) was 42 percent. The difference between predicted and measured ice weights ranged from 1 .9 to 35.4 percent. A specially designed profilometer was used to obtain ice profiles for a qualitative assessment of the system performance.