Eventos Anais de eventos
COBEM 2019
25th International Congress of Mechanical Engineering
EXPERIMENTAL ANALYSIS OF A PASSIVE DEVICE TO REDUCE THE NOISE OF SUBSONIC JETS
Submission Author:
Felipe Câmara , SC , Brazil
Co-Authors:
Felipe Câmara, Victor H. P. Rosa, Cesar Deschamps
Presenter: Victor H. P. Rosa
doi://10.26678/ABCM.COBEM2019.COB2019-2461
Abstract
This paper presents an experimental analysis of a passive device to reduce the noise of subsonic jets which are typical of the engine exhaust of civil aircraft. The noise-reducing device consists of a thin tape glued to the inner nozzle surface near the nozzle exit. The tape covers the entire nozzle circumference, having a zigzag shape with thickness around 1% of the nozzle diameter. This device has also been studied elsewhere, so the objective of this work is to further explore its overall effect on the noise output and on the jet flow through measurements of velocity in the nozzle-exit boundary layer and in the jet plume with hot-wire anemometry. These flow measurements are used to quantify the thrust reduction caused by the device and to relate the noise reduction to changes in the flow turbulence levels. The results for a jet with acoustic Mach number of 0.5 showed that the reduction of the thrust output is small and that a net noise reduction remains even if the nozzle-exit velocity is increased to recover the thrust loss. It was also observed that the device reduces the turbulence kinetic energy in the jet plume, which can explain the observed broadband noise reduction.
Keywords
Jet mixing noise, noise-reduction device, hot wire anemometry
