Piccolo Tube(Anti-Icing System)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

The hot air from the turbo engine is introduced to the leading edge through pipes and valves. The control module regulates the wing anti-icing valve (WAIV) to control the heat flux into the Piccolo tubes in the leading edge anti-icing bays. It in turn adjusts the skin temperature of the wing leading edge. The control system works in a closed loop with the temperature sensors located at several points of the wing leading edge surface.

2. Model Description

1)There are a number of small hoses on the front side of the Piccolo tube from where the hot jets impinge the inner surface of the leading edge. The small holes are located staggered in two rows of angles 15 upper and lower from the wing chord plane.

2) The aluminium skin is heated by the hot air in the anti-icing operation.

3) Two exhaust holes on the lower side of the bay allow the hot air to exit to the external flow.

4) Two ribs separate the bays in the span direction with the hoses on the ribs neglected.

5) The heat shield serves as the back wall of the bay.