Ice Protection System Design for the Next Generation Civil Tiltrotor Engine Intake

This paper focuses on the design of the thermoelectric ice protection system (IPS) for the engine air intake of the Next Generation Civil Tiltrotor (NGCTR), a demonstrator under development in Leonardo Helicopters. A specific IPS design strategy for the novel intake configuration is proposed. The main constraint which driven the design strategy is a maximum power of 10.6 kW available for the full intake IPS system. The IPS was designed for safe aircraft operations within the Appendix-C icing envelope. The numerical approach adopted to perform the design and the resulting IPS concept are presented. Calculations of the required IPS heat fluxes revealed that maintaining running wet conditions on the entire intake surface is not feasible due to the limitation to the maximum IPS power demand. Therefore, a de-icing IPS design strategy is proposed. The anti-icing mode is adopted only on the lip region to avoid formation of ice caps whereas de-icing zones are defined within the intake duct. The de-icing zones cover the main impingement areas, and their splitting and power densities were designed to keep the instantaneous IPS power below the specified limit. The performances of the proposed IPS design were evaluated by means of ice accretion simulations. The effects of runback water were considered, and the de-icing effects were modelled by assuming that ice is perfectly shed by the de-icing zones. Computations of the residual ice accreted on the unprotected intake area demonstrated that the IPS drastically reduce the ice accretion and effectively protect the NGCTR engine air intake.