Print
Pilot concepts for commercial applications: Geared turbofan and other concepts
MTU develops pilot concepts for all applications forming part of its strategic product portfolio. In the commercial domain, these are engine concepts for business and regional jets, short-, medium and long-haul aircraft. An important pilot concept of MTU is the geared turbofan.
Advanced turbofan versus geared turbofan
Today, the turbofan engine has found a home on practically all jet-propelled aircraft. However, the ambitious emission goals of ACARE 2020 cannot be fully met with the turbofan concept. Further developments of the turbofan are aimed at raising its bypass ratio to a little above ten and optimizing individual components for better aerodynamic efficiency and lower weight. A high bypass ratio is key to effectively reducing consumption and noise.
Geared turbofan: A concept that offers great potential
The geared turbofan is the engine concept of the future. MTU is partnering with Pratt & Whitney on demonstrator and development programs for this new engine generation.
Unlike conventional turbofans, where fan and low-pressure turbine rotate on a common shaft and at the same speed, the two components are decoupled by a gearbox arranged between them. Accordingly, the large fan operates at a slower and the low-pressure turbine at a faster speed, which improves their respective efficiencies, lowers the noise level and about halves the number of stages in the turbine. Bypass ratios of 12 and beyond become a possibility.
Orders from Mitsubishi, Bombardier and Irkut, who are going to use the geared turbofan engine on their emerging regional jets and short-and medium-haul aircraft, have paved the way for the successful placement of the product on the market.
Crisp: Geared turbofan of the second generation
Any further increase in the propulsion efficiency of an engine requires a higher bypass ratio. The next step towards achieving this objective is the further development of the geared turbofan of the second generation.
In parallel, alternatives are being investigated, such as the counter-rotating integrated shrouded prop-fan, or Crisp for short. In this derivative of the geared turbofan, two counter-rotating fan rotors are arranged one behind the other. This arrangement boosts the propulsive efficiency of the engine, with the fan diameter remaining unchanged, and permits bypass ratios as high as 20 to 25 to be achieved.
Recuperated engine based on the geared turbofan
The recuperated propfan engine is MTU's long-term pilot concept and constitutes stage three of the Claire program. It is designed to take the last hurdle on the route to 30 percent carbon dioxide reduction. The concept bases on the geared turbofan with a high-speed low-pressure turbine.
In addition, it features an intercooler between the compressors and a recuperator in the exhaust gas stream. Intercooling and recuperating energy from the exhaust gas stream markedly increase the engine's thermal efficiency.