Commercial aircraft original equipment manufacturers (OEMs) have been building more-electric aircraft – or MEA – for over a decade. MEA are aircraft that rely on electric power to operate non-propulsion systems such as those for lubrication, flight control, fuel, thermal management, and more.
Today’s aircraft makers are collaborating with their suppliers to design new systems and implement new electrical-intensive architectures that are key to unlocking such efficiency improvements as lower aircraft weight, better fuel consumption, reduced total life-cycle costs, and enhanced maintainability and reliability.
One such supplier collaboration supporting the move to MEA has been launched by Parker Aerospace Gas Turbine Fuel Systems Division (GTFSD).
GTFSD expertise: electric motor-driven smart pumps
Long recognized for its motor-driven pump technology and pedigree in major platforms for both military and commercial applications – particularly for fuel and thermal management pumps – GTFSD is breaking new ground through its development of electric motor-driven smart pumps that can accommodate a wide range of voltage to the digital controller. The motor speed can be controlled by sensors or sensorless, depending on the application.
Electronic controllers interpret system signals, enabling a pump to respond with a specific flow to meet a specific system demand. Whether for more fuel, enhanced cooling, or greater pressure, this demand flow results in a highly efficient use of the aircraft’s finite energy resources, creating less fuel burn and fewer engine emissions.
In the field: Boeing 787 APU fuel metering unit
Parker Aerospace’s auxiliary power unit (APU) fuel metering unit for the Boeing 787 Dreamliner is one such electric motor-driven smart pump already in service. The APU pump unit builds on GTFSD’s experience with electric motor-driven pumps, which includes those for missiles and military UAV applications, as well as for large transport turbine engines.
“The innovative APU fuel metering unit replaces conventional engine fuel control for the Boeing 787. Featuring an impeller boost pump and a high-pressure gear element, the two-staged pump assembly integrates 13 components into one and uses an AC- or DC-powered dual-processor digital controller with CAN bus interface to provide precise fuel flow in response to engine demand.”
– Rick Mossey, engine systems business development manager, Parker Aerospace, Gas Turbine Fuel Systems Division
Enhanced reliability is a key benefit of the APU pump unit. With 500-plus units fielded to date, the product is performing well.
In development: high-voltage motor-driven main engine feed pump (MEFP)
GTFSD has developed a 270-volt, 27-horsepower brushless DC (BLDC) motor-driven, high-pressure main engine feed smart pump that is currently in testing. With a simplified system design and lower system procurement cost, the new pump unit improves both pump efficiency and system reliability. It includes an electric motor, BLDC motor controller, impeller, and high-pressure piston-based pumping element, offering:
- Volumetric efficiency better than 97 percent
- Overall efficiency of 60 to 70 percent (typical efficiency is in the 35-45 percent range)
- Less than one second to stable output, with no overshoot, and full speed step input
- System flow and pressure hysteresis: less than plus or minus two percent
- System dynamic response: less than 20o lag with sinusoidal input of five percent of full speed at frequency between 0-6 Hz
Next generation: smart pumps for hybrid-electric propulsion
Alternative propulsion systems are being looked at as a means of achieving fuel savings, lowered emissions, and reduced noise. One such alternative approach uses hybrid gas turbines. A highly efficient gas turbine engine and electric motor are paired to provide thrust via combinations of both sources.
The electric power can be used for the duration of a flight or when added power is required. Since Parker Aerospace’s electric motor-driven smart pumps are able to vary their routines almost infinitely based on the requirements of the systems they serve, they are readily adaptable for such next-generation applications.
This post was contributed by Rick Mossey, engine systems business development manager, Parker Aerospace, Gas Turbine Fuel Systems Division.