Our Motivation
The focus of this project lies on the fan of future aircraft engines. As the fan will be required in new engine architectures, independent of the energy supply, its efficiency has a crucial impact on the sustainability of future air traffic. While the fan efficiency is already high for its design flow conditions, an improvement of its off-design operation becomes increasingly important.
Numerical and design investigations
To achieve this goal shape-adaptive fan blading is researched within this project. To introduce a shape-adaption capability, piezoceramic Macro-Fiber-Composite actuators are integrated into the fan rotor. Energizing the actuators leads to a contraction or expansion along their fibers. Through the adhesive connection between blade and actuators, the actuators’ morphing is transferred into the rotor blading, leading to a span-wise variation of the blade staggering and turning. With the goal to ideally morph the blade’s shape according to the prevalent off-design flow conditions, the actuator configuration needs to be optimized. For this optimization and for the determination of aerodynamic morphing targets an aero-structural design methodology has been developed. This method is now being extended to include UHBR fan designs, 3D-shapes, such as lean and sweep, as well as alternative blade materials. For a stronger tailoring of the deformation behavior Carbon-Fiber-Reinforced-Polymers (CFRP) are investigated as potential blade materials. Those materials additionally allow to weave the actuators into the blade’s structure, which is expected to increases structural integrity and operational safety under aerodynamic loading.
Experimental investigations
While all morphing investigations so far have been conducted numerically a prototype is now available for a preliminary validation of the design methodology. In this project further blade prototypes are planned. Based on the first results of the project, the prototypes will be made of CFRP materials, while having the main dimensions of a scaled UHBR fan blade. Here, also the impact of the blade reference shape on its deformability will be considered. Experimental investigations for all prototypes are planned with a major focus on the blade’s morphing behavior under realistic load conditions. In a first step, all investigations are conducted with stationary blades and load equivalents that include centrifugal and aerodynamic strains. Uncertainties are also covered to estimate the impact of the manufacturing process on the expected morphing behavior.
Outlook and future application
The main goal of the three-year project is to assess the impact shape-adaptive fan blading can have on the off-design efficiency of future aircraft engines with a special focus on the experimental validation of the results. The results gained in this project are expected to pave the way towards an application of the shape-adaption technology in a rotating test-rig environment.