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Le, Tuyen Quang,Truong, Tien Van,Park, Soo Hyung,Quang Truong, Tri,Ko, Jin Hwan,Park, Hoon Cheol,Byun, Doyoung Royal Society 2013 Journal of the Royal Society, Interface Vol.10 No.85
<P>In this work, the aerodynamic performance of beetle wing in free-forward flight was explored by a three-dimensional computational fluid dynamics (CFDs) simulation with measured wing kinematics. It is shown from the CFD results that twist and camber variation, which represent the wing flexibility, are most important when determining the aerodynamic performance. Twisting wing significantly increased the mean lift and camber variation enhanced the mean thrust while the required power was lower than the case when neither was considered. Thus, in a comparison of the power economy among rigid, twisting and flexible models, the flexible model showed the best performance. When the positive effect of wing interaction was added to that of wing flexibility, we found that the elytron created enough lift to support its weight, and the total lift (48.4 mN) generated from the simulation exceeded the gravity force of the beetle (47.5 mN) during forward flight.</P>
Le, Tuyen Quang,Lee, Kwang-Soo,Park, Jin-Soon,Ko, Jin Hwan The Society of Naval Architects of Korea 2014 International Journal of Naval Architecture and Oc Vol.6 No.2
In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simulations with a given tip speed ratio (TSR). First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D) turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flow-driven rotor simulations with an optimal geometry then show that a helical-bladed turbine has the following prominent advantages over a straight-bladed turbine of the same size: an improvement of its self-starting capabilities and reduced fluctuations in its torque and RPM curves as well as an increase in its power coefficient from 33% to 42%. Therefore, it is clear that a flow-driven rotor simulation provides more information for the design of a Darrieus turbine than a simulation with a given TSR before experiments.
Le, Tuyen Quang,Ko, Jin Hwan Elsevier 2015 RENEWABLE ENERGY Vol.80 No.-
<P><B>Abstract</B></P> <P>In this study, we investigate the effect of hydrofoil flexibility on the power extraction of a flapping tidal stream generator with hydrofoils down-scaled for a water channel in an experiment with a typical Strouhal number and frequency. The described deformations in the chord and spanwise directions are imposed onto the surfaces of the hydrofoil to analyze the flexibility effect. In a two-dimensional (2D) simulation, parameter studies of the chordwise flexure are conducted and a 30% improvement in the rate of the power-extraction efficiency is then achieved when the chordwise flexure is 20% of the chord length. In a three-dimensional (3D) simulation, the chordwise flexure of 20% achieves a 15% improvement in the rate of the power-extraction efficiency for the hydrofoil with an aspect ratio (AR) of 5, which is less than that in the 2D simulation due to 3D effects such as tip loss and a spanwise vortex. Meanwhile, the effect of the spanwise flexure on the power extraction is minor as compared to that of the chordwise flexure. It was also found throughout the parametric study of the AR variation that the 3D effect of the chordwise flexible hydrofoil is slightly stronger than that of the rigid hydrofoil.</P>
Parametric study of chordwise flexibility of airfoil in plunge motion
Tuyen Quang Le,Jin Hwan Ko(고진환),Soo Hyung Park(박수형),Hoon Cheol Park(박훈철),Doyoung Byun(변도영) 한국항공우주학회 2009 한국항공우주학회 학술발표회 논문집 Vol.2009 No.11
The unsteady, incompressible, and viscous flow over airfoil NACA0012 in plunge motion was analyzed by using the Navier-Stokes equation. We explored the optimal phase angle for thrust force and propulsive efficiency while the chord flexure amplitude is varied from 0.05 to 0.7 in the condition that reduced frequency and non-dimensional plunge amplitude were fixed. Throughout the parametric study on the phase angle and chord flexure amplitude, maximum thrust force is able to be achieved near at 0 degree in all given conditions, meanwhile, it is found that the optimal phase angle has dependency of chord flexure amplitude, which achieves higher performance compared to previous studies.
Experimental and numerical study of corrugated beetle wing
Tuyen Quang Le(르광투엔),Doyoung Byun(변도영),Hoon Cheol Park(박훈철) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Unlike the bird wing, most of the insect wings have been constituted from the veins and membrane forming corrugated cross section. The effects of this corrugation shape on the aerodynamic performance are investigated by experimentally observing the corrugation cross section and flight mechanism and numerically simulating the flapping flight. Main vein thickness is measured to be around 500 ㎛, and meanwhile, the thickness of membrane is around 5㎛. The corrugation shape of cross section of the wing varies along the spanwise directions. The numerical simulations show that the corrugation cross section increases the vertical force allowing higher aerodynamic performance than elliptic wing in a case of forward.
Tuyen Quang Le,이광수,박진순,고진환 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.2
In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simula-tions with a given tip speed ratio (TSR). First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D) turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flow-driven rotor simulations with an optimal geometry then show that a helical-bladed turbine has the following prominent advantages over a straight-bladed turbine of the same size: an improvement of its self-starting capabilities and reduced fluctuations in its torque and RPM curves as well as an increase in its power coefficient from 33% to 42%. Therefore, it is clear that a flow-driven rotor simulation provides more information for the design of a Darrieus turbine than a simula-tion with a given TSR before experiments.