GE engineers working on a revolutionary new jet engine have achieved the highest combination of temperatures ever recorded in aviation history inside the compressor and the turbine, the engine’s core. This feat is not just for the record books. Heat inside a jet engine works the same way it does in your kitchen, more heat equals more power.
“It’s pure thermodynamics,” says Rick Albrecht, manager for advanced military systems at GE Aviation.
The higher the temperature inside the engine core, the more efficiently the engine runs. GE engineers figure that the new core in combination with other design changes could improve fuel efficiency by as much 25 percent, extend flying ranges by 30 percent, and boost thrust up to 10 percent, compared to current engines.
Raising the heat inside a jet engine is a tricky business. Jet fuel burns at temperatures higher than the melting point of even the most advanced aviation alloys. As a result, jet engine designers had to come up with elaborate ways to prevent melting and cool off the hot section of the engine by “bleeding” in air through tiny ducts and pinholes inside the turbine blades. This makes the engine cooler, but also less efficient.
Looking for a better way, scientists at GE Global Research have developed new lightweight and heat-resistant materials called ceramic matrix composites (CMCs) that remain strong at temperatures as high as 2,400 F, well above any advanced alloy. Since the new jet engine core has CMC parts inside, it can get hotter and extract more power from the intense heat.
The core will feed that power to a groundbreaking supersonic jet engine that combines the fuel economy of the latest engines for passenger aircraft, called high-bypass turbofans, with the raw power of military jets. GE and the U.S. Air Force Research Laboratory call this engine design ADVENT, short for ADaptive Versatile ENgine Technology.
The idea for the concept dates back to the 1970s, when jet engine pioneer Gerhard Neumann realized that he could manage engine performance by controlling the amount of air that flows through the engine core. More flow through the core results in more thrust and speed (good for fighter jets); less flow in the core saves fuel (airlines like this design). The ADVENT design can automatically switch between the two modes and give fighter pilots the speed they need during combat, and save fuel while cruising home at a slower pace.
Applications for the new core go far beyond the military. “The latest GE jet engines like the LEAP, the GE9X, and even the GEnx are looking at an extensive use of CMCs,” says Dave Jeffcoat, ADVENT project manager at GE Aviation. “The tests show that we’ve picked the right technology. We are building on a solid foundation.”