摘要: The primary objective of this work is to develop a high-fidelity simulation model for active jet noise control predictions, and to quantify the sound reduction when an external-source frequency mode excitation is imposed on the je... 展开 The primary objective of this work is to develop a high-fidelity simulation model for active jet noise control predictions, and to quantify the sound reduction when an external-source frequency mode excitation is imposed on the jet flow. Whereas passive approaches using mixing devices, such as chevrons, have been shown to reduce low-frequency noise in jet engines, such approaches often incur an engine performance penalty. The current work investigates an open-loop active noise control (ANC) approach that utilizes an unsteady micro-jet actuator installed in the nozzle lip and injecting air in the streamwise direction to impact the dynamics of the jet coherent structures and thereby directly affect the jet sound sources. In contrast to the passive approaches, the investigated open-loop control design utilizes a localized jet flow excitation that can be adjusted according to the desired control signal specific to the jet mean velocity. The current analysis considers a 3D unheated round jet at Mach 1.8. The high-fidelity approach employs the Detached-Eddy Simulations (DES) developed on the basis of the open-source OpenFOAM software. The results of the current study are compared against the preceding 2D axisymmetric round jet simulations [1], and the previous low-order simulations conducted using Linearized Euler Equations (LEE) solutions coupled with the previously developed reduced-order model (ROM) for jet acoustic source [2]. In contrast to the previous 2D axisymmetric DES study, the obtained results indicate that the selected excitation modes are unable to provide any notable reduction in the far-field response. Further refined studies are needed to clarify if there is an optimal single-frequency excitation that could produce the desired effect. 收起