This thesis investigates the turbulent jet aeroacoustic phenomena and explores the potential of active flow control using synthetic jet actuators to mitigate noise emissions. The study initially focuses on the development and validation of a comprehensive noise-source prediction model that combines already existing theoretical jet aeroacoustics formulas into an iterative solver that utilises existing jet farfield noise data. The thesis then continues with the goal of designing a synthetic jet actuator to be used as active flow control in the jet that aims to contribute to the emitted noise mitigation. The research begins by analysing the literature revolving around aeroacoustics of jets in general and the efforts to locate and characterise the noise sources in the wake of the jet in specific. The aeroacoustic analogies created for jet noise emissions are reviewed and later on form the basis of the predictive model. The core of this first part of the work involves the integration of the aforementioned analogies in the form of analytical formulas for farfield noise calculation into the modelling framework that incorporates the already existing farfield noise data for the various jets. These noise data are used as the target within a loss function that aims for the convergence of the predicted farfield noise to the experimental one. The characterisation of the noise sources within the jet are then a product of this iterative solving and take the form of energy/frequency requirements. This framework is applied to various jet configurations resulting in a global guide of velocity/frequency requirements for effective actuation of subsonic jets. The major output of the model is regarding a Mach 0.5 jet for which the requirement for effective actuation was to introduce disturbances with an amplitude of 15m/s at the frequency range from 600 to 800Hz. Focus is then given on potential active flow control methods that take the outputs of the noise-source prediction model and are able to provide the specific energy requirement at the required frequency range. Given the Mach 0.5 jet, synthetic jet actuators are chosen as the type of actuation and the research henceforth continuous with the modelling of actuators as a coupled resonator system. Once more, the outcomes of this modelling point at a specific actuator geometry which sparks the design, manufacturing and testing of said actuator. The designed piezoelectric-driven synthetic jet actuator was found to provide the 15m/s requirement at the frequency range of 700 to 900Hz which is deemed sufficient. The report finally discusses the practical implications of these findings in an effort to construct and evaluate an active flow control demonstration using the aforementioned actuators on an actual jet while also putting everything into context for future aeroacoustic modelling and aerospace applications. This work contributes to the ongoing efforts in reducing noise pollution in aerospace environments and provides a foundation for future research in active flow control technologies. The methodologies developed and the results obtained are expected to have broader applications in the design and optimization of quieter, more efficient aircraft.

”To provide a novel remotely controlled aircraft for in-situ and remote sensing atmospheric
measurements at high altitudes designed for researching and monitoring climate change.”
“To design a costeffective unmanned subsonic aircraft for atmospheric measurements
at altitudes exceeding 25 km using sustainable fuels”.