New low-carbon, low-noise aircraft design
Open rotor engines refers to operating the aircraft propeller blades without a surrounding nacelle. These offer significant reductions in fuel consumption and carbon dioxide (CO2) emissions. However, when it comes to noise, they struggle to match the reductions that have been achieved by turbofan engine technology. The EU-funded project WENEMOR (Wind tunnel tests for the evaluation of the installation effects of noise emissions of an open rotor advanced regional aircraft) was a collaborative effort to reduce noise pollution in a new open rotor aircraft design being developed in Europe. The WENEMOR project run under Clean Sky is a public-private partnership between the European Commission and the aeronautical industry. Clean Sky associated projects seek to significantly change how aeroplane manufacturers design new equipment to minimise the damaging environmental impact resulting from aviation. WENEMOR designed and built a 1:7.5 scale aircraft with installed counter-rotating open rotor engines. They put the combined model through its paces in a 8 m wide and 4.2 m high wind tunnel in Italy, one of the largest in Europe. The wind tunnel was acoustically treated to reduce background noise. It can produce a very uniform velocity flow over the test section area. In addition, the turbulence intensity can be controlled between 0.26 - 8 % as the wind tunnel is equipped with an advanced turbulence generation system. Testing such a design at this scale has never been done before in Europe and the European aviation industry was eagerly awaiting the results. Measurements were performed for different aircraft configurations, air flow speeds and angles of attack to understand the influence of each parameter on the noise emitted. Specifically, the aircraft model was tested with different tail pieces, the open rotor in tractor or pusher configuration and placed at various distances with respect to the model fuselage. The test campaign that was completed in 2014 provided a comprehensive database on noise effects for new regional aircraft designs. The parametric study successfully identified the optimum low-noise aircraft configurations. The results of the WENEMOR project are expected to pave the way for flight testing of the demonstrated noise reduction technologies.
Keywords
Aircraft design, open rotor engine, CO2 emissions, noise emissions, wind tunnel
