Wyniki wyszukiwania - BazTech

1

CFD simulation on wind turbine blades with leading edge erosion

Wang Yan, Wang Liang, Duan Chenglin, Zheng Jian, Liu Zhe, Ma Gaosheng

Journal of Theoretical and Applied Mechanics

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2021

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Vol. 59 nr 4

579--593

EN

Deep understanding on the impacts of leading edge erosion on the performance and flow characteristics of wind turbines is significant for the blade design and wind farms manage- ment. Pitting erosion and three levels of delamination are considered in the present study. The results show that the degrees of leading edge erosion have great influence on the flow separation, tangential force coefficient, normal force coefficient as well as the power output of the wind turbine. Leading edge erosion has the greatest impact on aerodynamics of the wind turbine at 15m/s, where the maximum loss in the power output can reach up to 73.26%.

2

Aerodynamic performance of a new double-flap wing sail

Li Dongqin, Zhang Yili, Li Peng, Dai Jingjing, Li Guohuan

Polish Maritime Research

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2019

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nr 4

61--68

EN

As a type of natural energy resource, wind power is used in the modern implementation of wind-assisted technologies as a method for reducing the fuel consumption and environmental pollution of ocean-going ships. In order to promote the full usage of ocean wind energy for cargo ships, an innovative type of ship propulsion-assisted wing sail is proposed in this paper. The propulsion efficiency of this new wing sail can be increased by enlarging its area in both the transverse and vertical directions in good weather conditions, and it can be folded up automatically in poor weather conditions, improving the sailing safety of the ship. The sail parameters relating to the gaps and rotation angles between different parts of the wing sail are compared, and the values giving the best aerodynamic performance are identified using CFD simulation technology. The results for the lift and drag coefficients for the new wing sail at different attack angles are also compared with those of traditional aerofoil sails, including an arc-shaped rigid sail and a variable-camber sail proposed in 2015. From the viewpoint of the sailing performance of the vessel, our results demonstrate that this new type of wing sail has good aerodynamic performance and can reduce fuel costs for commercial vessels.

3

Performance comparison of different aerodynamic shapes for autonomous underwater vehicles

Khalin Anatoliy, Kizilova Nataliya

Archive of Mechanical Engineering

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2019

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Vol. LXVI, nr 2

171--189

EN

A brief review of the existing autonomous underwater vehicles, their types, design, movement abilities and missions is presented. It is shown, the shape optimization design and enhancement of their efficiency is the main problem for further development of multipurpose glider technologies. A comparative study of aerodynamic performance of three different shape designs (the airfoil NACA0022 based (I), flattened ellipsoidal (II) and cigar-type (III) bodies of the same volumes) has been carried out. Geometrical modelling, meshing and computational fluid dynamics (CFD) simulations have been carried out with AnSys15.0. The pathlines and wall shear stress distributions have been computed to understand the advantages and disadvantages of each shape. The lift and drag coefficients, aerodynamic quality, power index and pitching moment have been computed. The higher efficiency of the shape I/shape II at higher/lower angles of attack (greater than 20o and less than 20o) has been found. The shape III develops high speeds at the same angles of attack and has higher manoeuvrability at relatively low aerodynamic quality. The comparative analysis of the flow capabilities of studied autonomous undersea vehicles proposes some design improvement for increasing their energy efficiency and flow stability.

4

Experimental analysis of aerodynamic performance of flapping wings nano aerial vehicles

Czekałowski P., Drewniak T., Sibilski K., Żyluk A.

Journal of KONES

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2014

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Vol. 21, No. 3

47--57

EN

The aerodynamics of flapping wings is ultimately concerned with the relation between motion kinematics and the time-history of aerodynamic forces and moments. However, an important intermediate quantity is the evolution of the flow field – and in particular of flow separation. Nature’s solution to large time-varying pressure gradients, for example those due to aggressive motions, is to form and eventually to shed vortices. We are interested in understanding and exploiting these vortices – for example, in delaying vortex shedding to promote lift in situations where flow separation is in any case inevitable. From the engineering viewpoint, the question is to what extent closedform models and conventional numerical/analytical tools can estimate the aerodynamic force history, with an eye to eventually running large parameter studies and optimizations. Our paper contains results of water tunnel experiments on flapping wings aeromechanics. The idea of investigation is to optimize the wing trajectories, and to find methods providing stability and control. In the paper, we present, also, conception and methodology of tests. The investigation is dividing into two parts: preliminary and principal tests. The aim of initial part is to extract quasi – state characteristic for wings of different platforms shapes. This characteristic will be used to generate initial kinematics of movement of wing. It will be initial point of further tests. The purpose of the main experiment is to find the best way of movement for wing taking account all of unsteady phenomena (interaction between vortices, wing – wing interference, etc.). Finally, we want to identify efficient way of controlling nano-microelectromechanical flying insect (entomopter).