Towards All Electric Aircraft: Focus on environmental control and ice protection
Aircraft systems architectures consist of complex technologies which make up the equipment used to power and fly a modern civil aircraft. In a conventional architecture, fuel is converted into power by the engines. Most of this power is expended as thrust to propel the aircraft. The remainder is transmitted via, and converted into, four main forms of non-propulsive power:
- Air is bled from the engine high-pressure compressor(s). This pneumatic power is conventionally used to power the Environmental Control System (ECS) and supply hot air for Wing Ice Protection System (WIPS).
- A mechanical accessories gearbox transfers mechanical power from the engines to central hydraulic pumps and other mechanically driven subsystems, and to the main electrical generator.
- The hydraulic pumps transfer hydraulic power to the actuation systems for primary and secondary flight control, to landing gear and to numerous ancillary systems.
- The main generator provides electrical power to the avionics, to cabin and aircraft lighting, to the galleys, and to other commercial loads (entertainment systems, for example).
But each system has become more and more complex over decades of developments, resulting in an architecture that is far from being optimal. Therefore, an optimised architecture (e.g. no gearbox, reduced engine bleed, local hydraulic source and more electrical power) could substantially reduce the consumption of non-propulsive power.
Questions & answers
The main focus of demonstration in Clean Sky will be the validation and maturation of the technologies and sub-architectures, not just in a More Electrical Aircraft (MEA), but moving to an 'All Electric Aircraft' (AEA).
Thus, Clean Sky intends to demonstrate:
- Proven large-scale ground-based architectural integration of electrical generation, distribution and loads, and of thermal management
- Proven large-scale ground-based architectural integration of thermal management technologies. Where maturity is shown, these will be integrated with the electrical equipment systems
- Flight proven electrical equipment systems, including environmental conditioning and protection
- Flight proven technologies and sub-systems for thermal exchange and management, including liquid loops and heat exchangers
- Flight proven technologies, architectures and concepts for power generation and distribution.
Although in Clean Sky many technologies are developed, ranging from power generation-,distribution-, and-conversion systems to "electrical nacelle"-systems and (skin-) heat exchangers, only two technologies will be explained in some detail, the Electrical - Environmental Control System (E-ECS) and the electrical Wing Ice Protection System (WIPS)
On board of an all-electric aircraft the electrical environmental control system is one of the largest consumers of electrical energy, since there is no pneumatic energy available.
In SGO, the objective will be to demonstrate the maturity of the electrical driven air conditioning system for large, business and regional aircraft applications. The studies will also focus on process air contamination and the associated impact on the ECS.
E-ECS demonstrators for large and regional aircraft applications will be developed and tested in flight campaigns. The demonstrators will enable us to validate performances issues, integration, control strategies and system reconfiguration capabilities.
Demonstration activities will also include the development and delivery of ground demonstrators to validate electrical aspects on dedicated test rigs:
- an integrated electrical systems test rig called 'PROVEN' for large aircraft applications
- an electrical test bench (ETB) for regional/business applications
- A vapour cycle system complementary to the E-ECS will also be developed and tested in on a thermal test bench.
Depending on the aircraft category and engine type, changing existing aircraft ice protection solutions has either an energy saving objective (large aircraft) or de-icing performance increase (regional turboprop aircraft).
In 2012, three ice protection technologies will be integrated in a full-scale large aircraft slat and will be tested for function in a large icing wind tunnel:
- an electro-thermal ice protection solution for large aircraft using heating elements integrated in the slat leading edge structure.
- an adapted electromechanical ice protection technology using solenoid actuators integrated in the slat leading edge.
- a hybrid ice protection system for three platforms (Large aircrafts, business jets and regional turboprop aircraft). The hybrid system comprises a combination of electro-thermal mats and electromechanical actuation mats integrated in the leading edge.
Two flight test campaigns will be conducted in 2014-2015 to validate the electromechanical and electro-thermal technologies in a large aircraft, and the hybrid solution on a regional aircraft
Depending on the kind of aircraft system, the validation means to achieve Clean Sky SGO objectives, are either a ground test architecture test rig and/or a flight test aircraft:
- Electrical Ground Integration Test Bench
- Icing Wind Tunnel Integration Test
- Electrical Air and Thermal Ground Integration Test Rig
- Flight Test Campaign
Environmental control intake