Quieter jet engines get ready to take off
Air traffic is predicted to grow by 5 % each year in the short to medium term. Technology advances are required to facilitate this growth without creating unacceptable levels of noise. As most of this is broadband noise generated by the fan blades, the reduction of such noise will have maximum effect on aeroengine noise in general. The 'Adaptive and passive flow control for fan broadband noise reduction' (FLOCON) project, funded by the EU, is addressing this requirement by developing innovative concepts. A major objective was to deliver the technology needed to reduce fan noise at source, based on flow control technologies. During the FLOCON project, a wide range of concepts were considered and developed to the technology-readiness level of laboratory-scale validation. Experiments were performed on two rotating test rigs, supported where possible by more detailed measurements. Project partners used numerical methods to optimise the concepts for experimental validation and to extrapolate the results from laboratory scale to real engine application. The potential benefit of each concept has been assessed, including any associated penalties, such as weight, complexity and aerodynamic performance. FLOCON successfully tested and assessed a large number of novel technologies for fan broadband noise reduction. It selected the best concepts by balancing noise benefit and overall impact. However, before being integrated into new engine designs, more tests are required on the noise reduction concepts proposed by the project team. The next steps in developing these new technologies for broadband noise reduction are to validate their performance on engine-representative test rigs or with full engine-scale testing.
