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| 1 | EXPERIMENTAL STUDY OF FLOW STRUCTURE BEHIND A CIRCULAR CYLINDER WITH WAVY SURFACE BY PIV显示文摘The wake behind a circular cylinder with wavy surface was investigated using single-frame PIV technique at Re=5200. The mean flow field and spatial distribution of turbulence statistics in the nodal, saddle and middle planes were presented and compared with those of a smooth cylinder. The near wake behind the wavy cylinder shows pronounced spanwise periodicity of flow structures. Compared with a smooth cylinder, the vortex formation region considerably expands in the streamwise direction, particularly reaching maximum in the saddle plane of the wavy cylinder. However, the longitudinal vortices in the nodal plane were noticeably suppressed in the transverse direction. In addition, the wake in the nodal plane contains the peak value of turbulent kinetic energy and the Reynolds shearing stress due to the intensive entrainment of free flow and the momentum exchange in the spanwise direction. | ZHANG Wei Daichin | 2006 | Journal of Hydrodynamics2006，18，1： | 8 |
| 2 | PIV MEASUREMENTS OF THE NEAR-WAKE FLOW OF AN AIRFOIL ABOVE A FREE SURFACE显示文摘The near-wake flow of a NACA0012 airfoils mounted above a water surface were experimentally studied in a wind/wave tunnel. The main objective of this study is to investigate the influence of the free surface on the structure of the airfoil trailing wake. The flow structure was measured with different ride heights between the airfoil and free surface using a Particle Image Velocimetry (PIV) system. The Reynolds number based on the chord length of the airfoil was about 3.5×103. For each experimental condition, large amount of instantaneous velocity fields were captured and ensemble-averaged to get the spatial distributions of mean velocity and mean vorticity, as well as turbulence statistics. The results show that the flow structures of the airfoil wake varies remarkably with the change in the ride height. | Daichin KANG Wen ZHAO Li-li | 2007 | Journal of Hydrodynamics2007，19，4： | 6 |
| 3 | Experimental investigation on tip vortices and aerodynamics of a wing with ground effect显示文摘The tip vortices and aerodynamics of a NACA0012 wing in the vicinity of the ground were studied in a wind tunnel.The wing tip vortex structures and lift/drag forces were measured by a seven-hole probe and a force balance,respectively.The evolution of the flow structures and aerodynamics with a ground height were analyzed.The vorticity of tip vortices was found to reduce with the decreasing of the ground height,and the position of vortex-core moved gradually to the outboard of the wing tip.Therefore,the d... | Ruimin Sun Daichin | 2011 | Theoretical & Applied Mechanics Letters2011，1，3： | 2 |
| 4 | Drag reduction and flow structures of wing tip sails in ground effect显示文摘The hydrodynamics and flow structures of a base wing slotted with tip sails in proximity to the ground were studied experimentally in order to investigate the flow control efficiency of wing tip sails in ground effect.The experiment was conducted in a towing tank at a Reynolds number 1.5×10^5.The lift and drag forces were measured by a transducer,the velocity fields of the wing tip vortices were measured using a time-resolved particle image velocimetry system(TR-PIV).The tip-sails and ground clearance were both effective in reducing the total drag,the lift coefficients of the tip-sails wings were increased as compared with that of a base wing.The lift-drag ratios of the tip-sails wings were improved obviously in a range of angles of attack from 2°to stalling angle.The tip-sails played more important role in unwinding the concentrated wing tip vortices at higher angle of attack,the intensity of the tip vortices were much weaker than that of the base wing.The development of the wing tip vortices was suppressed as well due to the inhibition of the ground,the downwash speed was reduced and the induced drag was decreased. | Jian-xun Zhou Cheng-hong Sun Daichin | 2020 | Journal of Hydrodynamics2020，32，1： | 2 |
| 5 | Flow past a circular cylinder over a free surface:Interaction between the near wake and the free surface deformation 显示文摘 | LEE S J DAICHIN | 2004 | Journal of Fluids and Structure2004，19，： | 1 |
| 6 | PIV measurements of the near-wake behind a sinusoidal cylinder显示文摘 | Wei Zhang Daichin Sang Joon Lee | 2005 | Experiments in Fluids2005，，6： | 1 |
| 7 | Flow past a circular cylinder over a free surface:In-teraction between the near wake and the free surfacedeformation显示文摘 | Daichin L J | 2004 | Journal of Fluids and Structure2004，19，： | 1 |
| 8 | An Introduction to 2-CCD Digital Particle Image Velocimetry System and Its Application in Ocean Engineering显示文摘The basic principle of particle image velocinmetry(PIV)is described.When a PIV image is an-alyzed by the method of auto-correlation,there is a direction ambiguity of 180~0 in velocity measurement.The problem can be solved by using'Image Shifting Technique',but this makes devices much complicat-ed and difficult to control.A new arrangement of 2-CCD(Charge Coupled Device)fully digitized PIV sys-tem,which can also solve the problem successfully,is introduced in the paper.As an example of applica-tion of the system,an experimental result of flow field around a horizontal cylinder in wave is presented. | Daichin Timothy P.Dewhirst | 1997 | China Ocean Engineering1997，12，3： | 1 |
| 9 | Flow past a circular cylinder over a free surface: Interaction between the near wake and the free surface deformation显示文摘 | S.J. Lee Daichin | 2004 | Journal of Fluids and Structures2004，，8： | 1 |
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