Evaluating Inflight Ice Protection Methods for Applications on Next Generation Aircraft

Abstract

This paper reviews the current aircraft ice protection methods with a view to gaining insight into their capabilities and limitations for applications on next generation aircraft. The next generation airframe systems are likely to be powered electrically through an intelligent electronic control and management system. There is therefore the need to take advantage of the current advancement in digital control and use of electricity as a means of powering essential systems in future aircraft to reduce their power demand. At present, there are three basic methods of coping with in-flight icing. These are the thermal, mechanical and chemical methods. This of course includes some more novel state-of-the-art methods that are currently under development such as the heater mat, microwave, laser, icephobic coatings and smart de-icing systems. This paper critically reviews the difference of these methods in terms of performance, economy and green credentials. They were compared in terms of installed weight, efficiency of operation, fuel burn and complexity. The thermal method is very efficient in operation, however, it is characterized by high power demand. The mechanical method is a low power user but is sometimes associated with structural fatigue. The chemical method is constrained by the finite volume of the de-icing fluids that can be carried on board. Presently, hot air thermal method is the leading ice protection technology on most of the medium and large transport aircraft. Hot air anti-icing system taps power from the engine which results in high fuel burn, CO2 and NOx emissions and engine performance degradation. Put together these consequences cause negative effects on the environment and air transport economics. Meanwhile electro-thermal power can be provided by the on-board generators, however, generators provide less power in comparison to pneumatics systems. A typical electro-thermal de-icer requires 12 kW/m2 and about 20kW/m2 for continuous heating of parting strips. This is still high in the context of next generation aircraft. Previous studies have shown contradicting results for sizing electro-thermal de-icers. With the growing demand for new technologies and flight procedures that will enable aircraft operators to burn less fuel and reduce the adverse effect of aviation to the environment, maximizing the anti/de-icing efficiency of the electro-thermal system in order to minimize their power demand has become crucial for an all-electric next generation aircraft.