Two aircraft engine concepts to reduce fuel consumption by 15 pc

Two aircraft engine concepts, geared turbofan and open rotor, can enable a significant reduction to aircraft fuel consumption.

With open rotor, the potential reduction is 15 percent. These are the findings of Linda Larsson, who has analysed and evaluated the two concepts.

The average annual increase in passenger kilometres travelled by air has been 5.8 percent over the last 40 years, and fuel sales have increased by 2.2 percent annually during the same period. New technological solutions are needed if aviation is to reduce its impact on the climate.

Larsson recently defended her doctoral thesis at Chalmers, where she has been studying two promising aircraft engine concepts.

She said that the two concepts have a propulsive efficiency; in other words, the energy generated by the core engine can be efficiently converted into thrust.

What differentiates a geared turbofan from a regular turbofan is that the large fan at the front of the engine operates at a lower speed than the turbine that drives it. There is a gearbox between the turbine and fan that reduces the number of revolutions, which enables a lighter turbine and a higher turbine efficiency.

An open rotor engine generates most of the thrust from two counter-rotating propellers instead of a ducted fan. This enables a larger engine diameter and thus a higher propulsive efficiency, without resulting in excessively large and heavy engine nacelle.

Larsson said that both of the concepts demonstrated very good potential in terms of reducing fuel consumption: geared turbofan by up to 4 per cent and open rotor by up to 15 percent.