Modeling of Piezoelectric Actuators for Active Control of Jet noise

Many investigators have successfully used acoustic or mechanical actuators to promote increased mixing in the initial shear layers of jets. Actuator designs for active noise control must be further refined to control the production of large scale turbulence and its contribution to the low frequency jet noise spectrum. Although many concepts reduce energy associated with large turbulence scales, a commensurate energy increase at smaller scales is often observed. Actuators better tuned to the flow and acoustic environment are needed if active flow control is to successfully negotiate this difficulty. This work focuses on the development of a numerical performance model to better understand the coupling between the actuators and the turbulent flow field. Los Alamos National Laboratory’s CFDLib provides the framework for our modeling effort. We have incorporated a “realizable” turbulence model, spatial filtering to better resolve the turbulent structures, and numerical sampling to generate time-averaged turbulence parameters. Performance predictions are presented for a cold, M=0.9 jet issuing from a nozzle fitted with 13 piezoelectric tab-type actuators. Comparisons of predictions with and without actuators demonstrate the potential benefit of this approach.