Pratt & Whitney’s new Geared Turbofan engine could reduce jet fuel use by up to 15% and emissions by as much as 20%.  (see the Matter Network piece and the more detailed Machine Design write up) The technology is covered at least in part by U.S. Patent Nos. 7,021,042 and 6,964,155.
In a turbofan engine, a fan powered by a turbine directs incoming air into and around the combustion chamber. Generally, a big, powerful fan is required because a large volume of air needs to be directed into the combustion chamber. The power comes from rotating turbine blades, which turns a shaft that drives the fan.Â
The problem is that turbines are most efficient at high speeds, but spinning the large fan quickly generates more noise and increases the torque requirements. So the goals of reducing noise (by lowering fan speed) and increasing efficiency (by increasing turbine speed) are in direct conflict.
To achieve the desired low fan speed and turbine efficiency, Pratt & Whitney’s Geared Turbofan integrates a gear box between the fan and the turbine. This arrangement keeps the turbine and fan on the same driveshaft while allowing both to operate closer to their optimal speeds.
The Geared Turbofan comes just as airlines are looking for ways to combat the astronomical costs of jet fuel, and Pratt & Whitney’s new engine will be a part of the solution. According to the company’s web site, aircraft manufacturer Bombardier will use the Geared Turbofan for its CSeries jets, and Mitsubishi will be using the new engine for its regional jets.Â
(Thanks to Franco Serafini – a blog reader, colleague and IP attorney with aerospace industry experience – who provided invaluable editorial assistance for this post).
