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Cavitation in Engineering
Published in Dmitry A. Biryukov, Denis N. Gerasimov, Eugeny I. Yutin, Cavitation and Associated Phenomena, 2021
Dmitry A. Biryukov, Denis N. Gerasimov, Eugeny I. Yutin
The main principle of a hydrofoil (underwater wing) is the same as of an airfoil (air wing). A wing is a body of a special shape that allows it to interact with an incident flow in such a manner that the lifting force arises. Due to the structure of the flow past such an object, the pressure above the wing is lower, and below the wing it is higher than the ‘normal’ pressure in an undisturbed medium. Thus, moving forward, the wing also tries to lift up. Note, of course, that in a common case the ‘lifting force’ can be directed somewhat arbitrarily, not necessarily opposite to the acceleration of gravity: for instance, for a helicopter tail rotor, or for an underwater device which moves in its special direction.
Drag force and drag coefficient
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
Flow velocities higher than Mach 0.3 are associated with considerable pressure changes, accompanied by correspondingly noticeable changes in density. The aircraft drag at high subsonic speed (e.g., M = 0.9) is about twice that at low subsonic speed (e.g., Mach 0.2). Consider a wing with a free stream. The lift is created by the occurrence of pressures higher than free stream on the lower surface of the wing and lower than free stream on the upper surface. This usually coincides with the occurrence of velocities higher than free stream on the upper surface of the wing [15] and lower than free stream on much of the lower surface.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
All wings have a finite span, b, with two wing tips. The flow near the tips can greatly influence the flow characteristics over the entire wing. Hence, a wing has different lift and drag coefficients than those for the corresponding airfoil. That is, the lift and drag coefficients for a wing are a function of the aspect ratio, AR=b2/S. For a wing of rectangular planform (i.e., constant chord), the aspect ratio is simply b/c.
Developing an Interactive Digital Reality Module for Simulating Physical Laboratories in Fluid Mechanics
Published in Australasian Journal of Engineering Education, 2022
Fatemeh Salehi, Javad Mohammadpour, Rouzbeh Abbassi, Shaokoon Cheng, Sammy Diasinos, Ray Eaton
The focus of the VR module is on external flows around wings and aerofoils. This helps students to learn about flow behaviour around objects such as vehicles, aircraft, trains, and tall-rise buildings. Aerofoils are designed to increase the speed with which air flows over the low-pressure side of an aerofoil in comparison to that of the high-pressure side. The difference in pressure above and below the wing generates an upward force which is the lift. The lift generated by an aerofoil or wing can be altered by changing the angle of attack. Understanding the angle of attack at which flow separates from a wing is vital information for aircraft designers. The flow separation increases the drag while reducing the lift, resulting in a condition known as a stall when an aircraft no longer generates adequate lift to support its weight.
Fluid-structure interaction simulation for performance prediction and design optimization of parafoils
Published in Engineering Applications of Computational Fluid Mechanics, 2023
Hong Zhu, Qinglin Sun, Jin Tao, Hao Sun, Zengqiang Chen, Xianyi Zeng, Damien Soulat
During actual flight, the installation angle can be adjusted by the length of suspension ropes so that the parafoil system can be steady in a gliding state. Figure 19 shows the predicted velocities of Model A parafoil system with different suspended weights. Wing loading is the ratio of suspended weight to wing area. Horizontal and descent velocities increased with wing loading–the higher the attack angle, the smaller the velocities. The horizontal velocity can reach 8 m/s to 10 m/s with a payload in the range of 10 kg to 20 kg. With a 13 kg payload, horizontal and descent velocities at a steady angle of attack were about 9.9 m/s and 4.7 m/s, respectively.
Development of the flapping wing for ornithopters: a numerical modelling
Published in International Journal of Ambient Energy, 2022
S. Mahendran, R. Asokan, Ashutosh Kumar, Vitika Ria, S. Jayadeep
Figures 9–14 show the pressure change at the initial velocity of 3 m/s at different flapping angles. These graphs prove the law of ideal equation, i.e. pressure is inversely proportional to velocity. So, we know the velocity increases as the angle increases with higher flow separation, so the pressure over the wing decreases. The decrease in the pressure is on the top surface of the wing and due to higher flow separation, the pressure under the wing is high enough to produce the required lift.