Abstract
This paper presents an investigation of the aerodynamic and aeroacoustic interaction of propellers for distributed electric propulsion applications. The rationale underlying the research is related to the key role that aeroacoustics plays in the establishment of the future commercial aviation scenario. The sustainable development of airborne transportation system is currently constrained by community noise, which limits the operations of existing airports and prevents the building of new ones. In addition, the substantial saturation of the existing noise abatement technologies inhibits the further development of the existing fleet, and imposes the adoption of disruptive configurations in terms of airframe layout and propulsion technology. Simulation-based data may help in clarifying many aspects related to the acoustic impact of such innovative concepts. Blended-wing-body equipped with distributed electric propulsion is one of the most promising, due to the beneficial effect of the substantial shielding induced by its geometry. Nevertheless, the novelty of the layout requires a thorough investigation of specific aspect for which no previous experience is available. Herein, the interaction between propellers is analysed for a fixed propeller geometry, as a function of their mutual distance and compared to the acoustic pattern of the isolated one. The aerodynamic results have been obtained using a boundary integral formulation for unsteady, incompressible, potential flows which accounts for the interaction between free wakes and propellers. For the aeroacoustic analyses, the Farassat 1A boundary integral formulation for the solution of the Ffowcs Williams and Hawkings equation has been used. These results provide an insight into the minimum distance between propellers to avoid aerodynamic/aeroacoustic interaction effects, which is an important starting point for the development of distributed propulsion systems.
Highlights
In the last few decades, the efficiency of air transportation has become a primary aspect for aeronautical designers, due to the constant growth of the aviation industry throughout the last century and its expected further increase in the near future [1]
The aeroacoustic response of the selected case studies is evaluated through the Farassat 1A boundary integral formulation [31]
It should be emphasized that both the aerodynamic and the aeroacoustic code used for the present numerical analysis have been widely validated in the past by comparison with numerical and experimental data available in the literature [38,39]
Summary
In the last few decades, the efficiency of air transportation has become a primary aspect for aeronautical designers, due to the constant growth of the aviation industry throughout the last century and its expected further increase in the near future [1]. The CO2 emissions due to the aviation industry are foreseen to grow in the future—a 75% increment was recorded between 1990 and 2012 and it is projected to grow 300% by 2050 [2]. At this purpose, the international institutions have set quantitative goals for limiting chemical pollution and perceived noise to be fulfilled by the future aviation.
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