http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Chaoying Zhou (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
-
Chao Wang,Chaoying Zhou,Xiaorui Zhu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.4
A numerical investigation into the effects of flapping modes on the aerodynamic performance of insect hovering flight is carried out through the solution of the two-dimensional unsteady Navier-Stokes equations. Four types of idealized flapping modes with the identical quasi-steady lift force are compared, and the influences of the Reynolds number (Re), the translational duration and the rotational duration on the aerodynamic characteristics of the hovering are systematically analyzed flight. It is found that the instantaneous aerodynamic forces of the wing differ significantly in each flapping mode. The mode with harmonic translation and harmonic rotation leading the highest lifting efficiency is suitable for long-time flight while the mode with harmonic translation and trapezoid rotation giving the largest instantaneous forces is suitable for maneuvering flight. When Re increases from 100 to 1000, the lift force and lifting efficiency of the wing are increased significantly with the increasing Re first, and then slow down with the further increase in Re. In addition, the fast-translational mode with short translational duration will reduce the time-averaged lift force and the efficiency, whereas the fastrotational mode with short rotational duration can enhance the time-averaged lift force with the sustained efficiency.
-
Chao Wang,Chaoying Zhou,Peng Xie 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1
A numerical study on the effects of the asymmetry in flapping motions on the aerodynamic performance of a 2-D inclined hoveringwing is carried out through the solution of the two-dimensional unsteady Navier-Stokes equations. Asymmetric flapping motions withdifferent flapping durations as well as different angles of attack during downstroke and upstroke are considered, correspondingly theaerodynamic forces, the energy consumption and the flow structures of the wing are examined for the purpose. The results show that theasymmetry either in flapping duration or in angle of attack can effectively alter the aerodynamic characteristics of the wing. It is foundthat much larger vertical force is generated in the downstroke with smaller duration. As for the angle of attack, an increase in the angleduring the downstroke gives rise to a larger vertical force and lifting efficiency while for the upstroke the increase in the angle results in alarger thrust force. Furthermore, a combined model with asymmetry in both flapping duration and angles of attack is also studied and theresults show that a combined flapping motion with a faster downstroke and a higher downstroke angle of attack can produce much largervertical force than a motion with asymmetry simply in stroke duration or angle of attack. The present results provide physical insight intoa better understanding of the asymmetric stroke mechanisms in the flapping motion of insects.
-
Chao Wang,Chaoying Zhou,Peng Xie 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4
Various stroke trajectories may be observed in insect hovering flight in nature; however their influences on the flight performance of insect are not well estimated. In this study, a numerical investigation into the effects of stroke trajectories on the aerodynamic performance of insect hovering flight is carried out through the solution of the two-dimensional unsteady incompressible Navier-Stokes equations. An insect wing model with ellipse cross section in hovering flight is considered for the purpose and four types of idealized trajectories (Named linear, oval, figure-eight and double-eight) which possess different deviation characteristics from the stroke plane are examined. The influences of the deviation amplitude of trajectory, the attack angle of wing and the inclined angle of stroke plane on the aerodynamic characteristics of hovering wing are systematically analyzed. The results show that in the case of the wing in a normal hovering flight where the stroke plane is horizontal, the trajectory deviation from the stroke plane weakens the aerodynamic performance for each trajectory case considered, and this deteriorative effect becomes more serious as the amplitude of deviation increases. With regard to the influence of the angle of attack, the results show that the time-averaged drag force and power consumption increase monotonically with the angle, whereas the time-averaged lift force and the lifting efficiency increase first and then decrease as the angle increases further. In the case of a hovering flight with an inclined stroke plane, distinctly different trends from a normal hovering flight are obtained.
-
The aerodynamic performance of flexible wing in plunge
Jianyang Zhu,Chaoying Zhou 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.7
Inspired by the fact that flexible wing in nature possesses advance aerodynamic performance, a numerical experiment is applied to investigatethe aerodynamic performance of flexible wing in plunge motion, where the incompressible Navier-Stokes (N-S) equations coupledwith the structural dynamic equation for the motion of the wing is solved. A two-dimensional, elastic and inextensible beam modelwing is considered at Re = 1256. The harmonic plunge motion is specified at the leading edge of wing, and the other part of wing is respondedpassively deforming by the aerodynamic force. By analyzing the flow field, aerodynamic force and energy efficiency of differentflexibility wings, it is found that the flexibility influences the aerodynamic characteristics of the plunge wing greatly and when theplunge frequency is less than the structural frequency the flexibility can increase the thrust force and the energy efficiency of the wing,and the maximum energy efficiency is obtained when the wing plunge near the resonance. Moreover, a lighter wing possesses largerenergy efficiency than a heavier wing, but it may not be functioning for too light wing. The results obtained in this study will providephysical insight into the understanding of fluid and structure interaction problem.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
