Abstract
Flow control is a wide and varied research field with a myriad of practical applications in engineering and science. The study of boundary layer separation control is of particular interest in the area of aircraft and wing section design. Active flow control has the potential to revolutionise this industry through increasing the rational efficiency of aeroplanes and thus reducing their impact on the environment. Synthetic jet actuators are promising devices that have the advantage of being small and provide a net momentum flux across the system boundary for zero net mass flux. These attractive properties have led them to be widely researched for flow control applications. The purpose of this study is primarily focused on two pects of active separation control using synthetic jet actuators. Firstly, to verify and help extend the current research into low order models of synthetic jets issuing into a quiescent medium, such models are useful for designing optimal actuators for engineering applications. Secondly, to develop such an actuator and use it in a realistic flow control application. In summary, a lumped element (LE) model of an axisymmetric synthetic jet actuator was developed and validated. The model was able to reproduce the frequency response of a wide range of geometries both from the current study and those in the existing literature. The model was presented in a decoupled way to allow individual validation of each section. The results suggested that the model, despite accurately predicting the jet velocity was not as accurate when predicting the individual components of the cavity pressure and displacement. The application of a synthetic jet to the control of separated flow at the trailing edge of a NACA 0015 symmetric aerofoil was presented. The aim of the investigation was to demonstrate that the jets could provide control authority, this was successful over a range of dimensionless frequencies and showed a strong dependence on the momentum coefficient. Proper Orthogonal Decomposition of the flow field data taken using Particle Imaging Velocimetry was used to demonstrate the presence of coherent structures in the controlled and uncontrolled flow. The jets were shown to have an effect on these structures altering the distribution of energy in the flow.