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Shanying ZHANG
Supervisor Dr John T. Turner and Dr S. Zhong
Phone 0161 275 44 26
e-mail s.zhang@stud.man.ac.uk
Title of Project Experimental investigation of axis-symmetric jet flow with aerodynamic excitation induced by thin co-axis secondary jet
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Research objective : Through systematically experiments, fully understand of the jet flow control by fluid dynamical excitation will be made. We hope to enhance the mixing of jet flow through choosing right secondary co-axis jet (radius), right pulse waveform, suitable flow rate (mean velocity) and excitation frequency.

Application : The fundamental work associated with this research project will look at the interaction of synthetic jets with cross-flow boundary layers. The aim is to assess the effectiveness of synthetic jets in revitalising reduced momentum within boundary layers, and hence delay separation.

Methods
Control methods: Many researches controlled flow development using sound excitation and also found that sound excitation seemed to modify the flow significantly at high-speed situation. Unfortunately, low-amplitude forcing (sound forcing) is ineffective because the applied perturbations are overwhelmed by turbulence. In my experiment, special thin co-axial secondary jet was used for excitation. The pulse flow of secondary jet can be fully controlled in amplitude and frequency.

Experiment methods: LDA, PIV and other flow visualisation methods. LDA has unique advantages such as non-contact measurement, no calibration, well-defined directional, and high spatial and temporal resolution response. It is suitable for investigation of turbulence flow in the free shear layer of jet flow.

Key results expected/ achieved: All kind of data presentation methods has been used in processing the data of the natural jet. The results include traditional velocity profile, central line velocity and intensity, thickness of the free shear layer, half jet radius, vector representation of the velocity and shear stress, contour field of the velocity and intensity.

Optimal rule of control jet flow hope to be achieve at the end of the systematically experiments. The factor should include flow rate, excitation and waveform of secondary pulsing jet.