Improving prediction methods to reduce engine noise Research has been carried out to develop innovative concepts and enabling technologies that reduce aero-engine noise at source. Industrial Technologies © Shutterstock Fan broadband noise is currently a major aircraft noise challenge. New, low-noise engine designs, such as ultra-high bypass-ratio engines and lower speed fans, can go towards improving jet noise and fan-tone noise. However, a reduction in fan broadband noise is unlikely to be achieved without an improved understanding of the source mechanisms. Numerical methods have advanced considerably and although these have improved tone noise prediction, they have yet to offer the same benefits to broadband noise prediction. The 'Improvement of Fan Broadband Noise Prediction: Experimental investigation and computational modelling' (Proband) project validated broadband noise-prediction methods on non-rotating airfoils, and then applied the methods to a fan configuration. Results from analytical and computational fluid dynamics (CFD) models were then compared. A parametric study was carried out on broadband noise sources in a laboratory-scale fan rig; advanced measurement and analysis techniques to achieve this were developed. Detailed broadband noise and turbulence measurements were acquired on an industrial Fan-outlet guide vane (OGV) stage rig at representative flow conditions, and broadband noise models and CFD methods were demonstrated and validated against this data. The EU-funded Proband project provided the industry with an improved understanding of broadband noise-source mechanisms, with validated broadband noise-prediction methods, and with low fan broadband noise concepts. It exploited the noise technology and methodology acquired in previous EU-funded projects and national programmes. It then developed methods to allow the design of a fan system that will generate sufficiently low broadband noise to meet the EU's noise-level targets. These results will provide the European engine industry with an improved prediction capability for broadband noise that can be used to develop low fan broadband-noise concepts.
