Supercooled liquid water droplets or ice particles may exist in atmospheric clouds when the local ambient temperature is below freezing. When an aircraft flies through a cloud, these droplets or ice particles are intercepted by the wings, engine inlets and other aircraft surfaces. The water impinging on these surfaces may freeze and result in the build-up of ice. This ice build-up adversely affects the stability and aerodynamic performance of the aircraft by adding weight and altering the wing profiles (which results in higher drag). Anti-icing mechanisms are employed to prevent or minimize ice build-up by either totally or partially evaporating the supercooled droplets that impinge on the wing surface. Most aircraft adopt anti-icing systems using thermal energy, either in the form of hot air (bled from an intermediate or high stage compressor) or electrical energy. Although being energy intensive, these options are highly reliable, which is critical for aircraft applications. CFD, in conjunction with analytical models (to simulate ice formation), can play a significant role in the analysis of such systems with the resultant benefit of requiring a reduced experimental program to test various designs.

FLUENT has been used to simulate the flow and temperature field generated by an anti-icing system mounted inside an airplane wing. The complex 3D nature of the flow suggests that CFD can play an important role in the design of these systems. Experimental programs are expensive, and probing the wing interior and exterior would give limited data on the performance of the system. CFD analysis, in conjunction with a test facility, would serve to provide far more insight than an experimental program alone.

Velocity contours near the inlet from the Piccolo tube