Direct aeroacoustic simulation using compressible flow solver

Böke, M. (2016) Direct aeroacoustic simulation using compressible flow solver.

Abstract:During this study the interactions between a cylinder and an airfoil are studied. The presence of a cylinder decreases the flow speed at the bottom of the airfoil, creating more lift and less drag. Under higher attack angles, however, the effect for the lift diminishes. The increase in lift is the biggest if the cylinder is placed near the trailing edge, however this effect is small in comparison to the effects of the attack angles. With respect to acoustics, the cylinder acts as an acoustic source. The flow of the airfoil alters the flow speed at the cylinder and thereby altering the shedding frequency. The airfoil acts as an acoustic mirror for higher frequencies. This reflects the sounds coming from the cylinder back downward. This effect is less present when the cylinder is placed near either edge of the airfoil. The effects at the bottom of the airfoil is relatively small while on the upper side of the airfoil, the effects are influenced more. The biggest reduction in downward sound radiation was depending on the angle of attack. The optimum angle of attack was around 7 degrees. A goal for the research group, with this program, was to create an easy to use software package which can be used by people with minor experience with respect to flow simulations. The software indeed did not need much work for the set-up of meshes and other tedious work that are often the case in flow simulations. However, a certain level of knowledge is still needed. The user can model physically impossible situations and use settings that create inaccurate measurements. The results will than be unusable while an inexperienced user might feel it does. A final mention is made of a near field effect. When the cylinder and airfoil are placed close to each other, an anomaly occurred for low angles of attack. The lift drastically increased and the drag was inaccurate as well. The effect could not be explained by physical means and might results from a faulty set-up or errors caused from the internal calculations. A source of this problem was not found.
Item Type:Internship Report (Master)
University of Tokyo, Japan
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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