Unsteady Low Reynolds Number Aerodynamics

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Situations involving unsteady aerodynamics are common for marine, land andaerospace vehicles of all sizes. Gusts are frequently experienced by aircraft andautomobiles due to atmospheric turbulence and the flow structures shed by nearbybuildings at low altitudes. Further illustrations of unsteady aerodynamics includebodies undergoing large accelerations and flapping wings. The unsteadyphenomena can have a significant detrimental impact on the performance and safeoperation of these vehicles. This is particularly important for smaller flying vehiclestravelling at low speeds where the relative flow unsteadiness is higher, leading tolarger changes in incidences and relative loading.Despite the clear importance and numerous applications, understanding of unsteadyaerodynamics is greatly limited in comparison to that of steady aerodynamics. Thisis partly due to the increased complexity of unsteady flow as well as the fact thatsteady and quasi-steady state assumptions are routinely used in design processes.It is becoming increasingly necessary, however, to improve our understanding ofunsteady flows, as the use of smaller unmanned air vehicles becomes moreprevalent.Existing models for unsteady flow include those developed by Kussner and Wagner.These models divide the unsteady aerodynamic loading into circulatory and noncirculatory components; vorticity and added-mass. Unfortunately, the application ofthese models is severely restricted by the associated assumptions which includesmall angles of incidence and enforcement of the Kutta condition.This project will utilise experimental facilities to investigate the nature of unsteady,low Reynolds number fluid flows. The research will look to improve understanding ofconditions with significant added mass and vortex dynamics effects. This researchfalls within the EPSRC research area "Fluid dynamics and aerodynamics".