國立陽明交通大學 機械工程學系Time: 3:30pm – 5:00pm
Venue: 工程五館B1國際會議廳 Engineering Building 5 B1 International Conference Hall
Speaker：
1. Dr. Khoo Boo Cheong, Prefessor, Mechanical Engineering, National University of Singapore
2. Dr. Nhan Phan Thien, Head of Department and Professor, Mechanical Engineering, National University of Singapore
Topic：
1. Study of sub- and supersonic flow control with dielectric barrier discharge plasma actuator
Abstract:
The nanosecond (ns) dielectric barrier discharge (DBD) plasma actuator is driven by pulse voltage with pulse duration ranging from tens of to hundreds of nanoseconds. The relatively quick plasma discharge causes the conversion of part of electrical energy into near surface gas heating within the discharge volume in a short time period of less than 1 µs. As a result, the temperature and pressure in the actuator region increase appreciably, which in turn causes the generation of a micro shock wave. The ns DBD plasma actuator has proved to be an effective actuation technique in many aerodynamic systems, and actually functions via the Joule heating effect1. By contrast, the alternating current (ac) plasma actuator achieved the control authority through the discharge induced flow jet. In the current study, a combined numerical and experimental study of flow separation control over a NACA 0015 airfoil with ns and ac plasma actuators is conducted for a comparison of performance between two types of devices. It is found that for the airfoil leading edge separation control in the subsonic regime, the nanosecond discharge induced residual heat causes the generation of spanwise vortices and finally makes the separated flow being reattached, whereas the shock wave contributes little to control authority. The advection of residual temperature with external flow offers a nanosecond plasma actuator a lot of flexibility to extend its influence region. Therefore, under certain situations, the ns DBD is superior to its ac counterpart, whose influence region is limited to the discharge region. In addition, a concept study of the supersonic flow control with the nanosecond DBD is performed by means of numerical simulation.
2. Sediment disturbance and sediment dispersion from technical activities on seafloor
Abstract :
Polymetallic nodules, which contain high economic-value metals, such as manganese (~30wt%), Nickel (1.5wt%), Copper (1.4wt%), Cobalt (0.25wt%), Iron (6wt%), Aluminium (3wt%), are found naturally and in abundance on the seabed in some areas in the Pacific ocean and the Indian ocean. They are considered as an important resource of rare metals for future. However, nodule collection activities are likely to disturb the ocean floor and possibly re-suspend a large amount of sediment into the ambient water region. Environmental impacts from the activities are unavoidable and thus taken seriously by the International Seabed Authority (ISA). Many studies on chemical compositions and physical and rheological properties of the bottom-ocean sediment, sediment disturbance and subsequent sediment spreading, and possible responses of benthic communities to rise of sediment concentration in the ambient water have been extensively conducted. In the scope of this presentation, we would like to share some experimental and computational works on the sediment rheology, sediment disturbance, and sediment spreading that have been carrying out in the Keppel-NUS Corporation Laboratories, National University of Singapore.
About the speakers:
Dr. Khoo Boo Cheong：
Director, Teamsek Laboratories, National University of Singapore (NUS);
Professor, Department of Mechanical Engineering, Faculty of Engineering, NUS
BC Khoo graduated from the University of Cambridge with a BA (Honours, 1st Class with Distinction). In 1984, he obtained his MEng from the NUS and followed by PhD from MIT in 1989. He joined NUS in 1989.
From 1998 to 1999, he was seconded to the Institute of High Performance Computing (IHPC, Singapore) and served as the deputy Director and Director of Research.
In 1999, BC returned to NUS and spent time at the SMA-I (Singapore MIT Alliance I) as the co-Chair of High Performance Computation for Engineered Systems Program till 2004. In the period 2005-2013, under the SMA-II, he was appointed as the co-Chair of Computational Engineering Program.
In 2011-2012, BC was appointed the Director of Research, Temasek Laboratories, NUS. Since 2012, he has been the Director, Temasek Laboratories.
BC Khoo serves on numerous organizing and advisory committees for International Conferences/Symposiums held in USA, China, India, Singapore, Taiwan, Malaysia, Indonesia and others. He is a member of the Steering Committee, HPC (High Performance Computing) Asia. He has received a Defence Technology Team Prize (1998, Singapore) and the prestigious Royal Aeronautical Prize (1980, UK). Among other numerous and academic and professional duties, he is the Associate Editor of Communications in Computational Physics (CiCP) and Advances in Applied Mathematics and Mechanics (AAMM), and is on the Editorial Board of American Journal of Heat and Mass Transfer, Ocean Systems Engineering (IJOSE), International Journal of Intelligent Unmanned Systems (IJIUS), The Open Mechanical Engineering Journal (OME) and The Open Ocean Engineering Journal.
In research, BC ‘s interest are in:
- Fluid-structure interaction
- Underwater shock and bubble dynamics
- Compressible/Incompressible multi-medium flow
BC has published over 360 international journal papers, and over 360 papers at international conferences/symposiums. He has presented at over 115 plenary/keynote/invited talks at international conferences/symposiums/meetings.
Dr. Nhan Phan Thien
Dr. Nhan Phan-Thien started his academic career in 1978 as a Lecturer at the University of Newcastle, Australia. In 1991 he was appointed to a Personal Chair in Mechanical Engineering at the University of Sydney. He was the founding Head of BioEngineering Division at NUS, 2001-2004. Currently he is a Professor in Mechanical Engineering at NUS.
He was elected a Fellow of the Australian Academy of Science in 1999, the European Academy of Science in 2002, and the Asean Academy of Engineering and Technology in 2016. He published more than 350 technical papers and five books. He was awarded the 2003 Centenary Medal by the Australian Governor General, for service to Australian society and science in Mechanical Engineering, the 1997 Gordon Bell Prize, for Parallel Algorithm in the Price-Performance category, by the Computer Division IEEE, the 1997 Australian Society of Rheology Medal, the 1982 Edgeworth David Medal by the Royal Society of New South Wales.
