Noise reduction analysis of supersonic unheated jets with fluidic injection using large eddy simulations

Abstract

A set of large eddy simulations is used to perform a numerical analysis of fluidic injection as a tool for noise reduction. This technique, developed at the Pennsylvania State University, allows one to turn on and off the air injectors in order to reduce the noise during takeoff and landing without penalizing performance in other flight regimes. Numerical simulations are performed on a military-style nozzle based on the GE F400-series engines, with a design Mach number of 1.65, for overexpanded jet conditions. The numerical results are compared and validated with the outcome of experiments performed at the Pennsylvania State University. For the case chosen, the fluidic injection shows the potential of breaking down shock cells into smaller structures with different orientation and strength. This directly reduces the intensity of broadband shock associated noise, with a positive effect of reducing the overall sound pressure level by more than 1:5 dB along the direction of maximum sound propagation of the baseline case. The maximum noise reduction was found to be almost 3 dB at 55 on the azimuthal plane in between two lines of injectors.

Research Progress on Active Secondary Jet Technology in Supersonic Flow Field of Aerospace Propulsion Systems

“…[127] Flow field analysis of noise reduction using a fluid insert nozzle. [136] Research on noise reduction mechanisms based on LES method. [137] In summary, since the 1940s, active secondary jet technology has developed many promising applications in the aerospace field, and in recent years, it has been receiving increasing attention.…”

“…Figure 28. Schematic drawing comparison of the nozzle with six corrugations[127].In 2018, Coderoni et al[136] conducted a noise reduction study on GE F400-series engines and investigated the fluid insert method proposed by McLaughlin's team using LES. As shown in Figure29, they found that the injection of the secondary fluid breaks down the shock cell into smaller structures with different directions and intensities, which directly reduces the intensity of noise related with broadband shock.…”