Aerodynamic and Acoustic Characterization of Rectangular and Beveled Installed Nozzles

With the size increase of turbofan engines, jet-wing interaction noise has become a significant component of aircraft noise, during landing in particular. Jet noise reduction techniques have been largely investigated in literature but their efficiency remains unclear when the jet is grazing the wing and its trailing edge. In this experimental study, a rectangular and a beveled nozzle have been sub-selected from a previous noise study and further aerodynamically and acoustically investigated and compared to a round nozzle. All nozzles have been considered in free and installed configurations. The results show that beveled nozzles offer the highest noise reduction in all directions, especially perpendicularly to the plate. The rectangular nozzles reduce the noise along their minor axis, perpendicularly to the plate, while regenerating noise along their major axis. Particle Image Velocimetry measurements suggest that the jet shear layer modification plays a significant role in noise production, reducing the immersed part of the plate for beveled nozzles and moving shear layers away from the plate for rectangular nozzles. This has been confirmed by wall pressure Kulite measurements, showing similarities with the flow measurements close to the plate.