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Aerodynamics of Wind Turbine
Published in Anirbid Sircar, Gautami Tripathi, Namrata Bist, Kashish Ara Shakil, Mithileysh Sathiyanarayanan, Emerging Technologies for Sustainable and Smart Energy, 2022
Here A is the platform area (B*C), as depicted in Figure 6.9. CL and CD are coefficient of lift and drag. When angle of attack increases lift force increases until it reaches maximum value and then it rapidly start decreasing with that drag force increase. This is because once the aerofoil reaches its maximum angle of attack, the boundary layer gets separated known as stall. Hence it is important to have aerofoil at optimum angle of attack to extract more energy. Another factor on which coefficient of lift or drag depends is Reynolds number as shown in Equation 6.11 (based on the chord length): Re=ρVCμ where ρ is the density of fluid, V is the velocity, C is the chord length and μ is the dynamic viscosity.
Aircraft
Published in Milica Kalić, Slavica Dožić, Danica Babić, Introduction to the Air Transport System, 2022
Milica Kalić, Slavica Dožić, Danica Babić
The four forces acting on an aircraft in straight-and-level flight are thrust, drag, lift, and weight (Figure 2.1). Thrust is the force that moves an aircraft in the flight direction, provided by a piston, turboprop, or jet engine. Thrust itself is a force than that can best be described by Newton’s second law. This forward force opposes the force of drag. Drag is the aerodynamic force component parallel to the direction of relative motion. This is a retarding force caused by the disturbance of airflow by the aircraft and its parts. In other words, drag tends to slow the motion of aircraft, and acts opposite to the direction of motion. Lift is a force that is produced by the dynamic effect of the air flow acting on the aerofoil. This force opposes the downward force of weight. Lift represents a component of the aerodynamic force, perpendicular to the direction of aircraft movement through the air, which is equal to or exceeds the weight. Weight is the force that pulls the aircraft downward owing to gravity. When the four forces of flight are balanced, a plane flies in a level direction. The plane climbs if the forces of lift and thrust are greater than gravity and drag. To descend, thrust must be reduced below the level of drag and lift below the level of weight.
Communication
Published in Mark W. Wiggins, Introduction to Human Factors for Organisational Psychologists, 2022
According to the National Transportation Safety Board (1988), the most significant factor involved in the crash was the failure of the flight crew to extend the flaps and leading-edge slats prior to take-off. The flaps and leading-edge slats extend the surface area of the wing, increasing the capacity of the aircraft to produce lift at a lower airspeed. It comprised an item on the pre-take-off checklist that, if not completed, would result in a significantly lower angle of climb than would normally be the case (see Figure 15.2). In the case of Flight 255, the inability to climb at the normal angle resulted in the collision with the building, following which the aircraft rotated through 90o before a second collision occurred.
Role of shape on the forces on an intruder moving through a dense granular medium
Published in Particulate Science and Technology, 2022
Bitang Kwrung Tripura, Sonu Kumar, K. Anki Reddy, Julian Talbot
We have presented extensive numerical simulation results of an intruder dragged horizontally through a granular medium to understand the drag and lift forces it experiences as a function of its velocity (v), immersion depth (h/d), and shape. The drag force gradually increases with v in frictionless systems (), while we observe a constant drag regime at low velocities when friction is present. For a fixed cross-section, the drag force depends weakly on the intruder shape. In contrast, the lift force has a strong shape dependence. It may increase in a certain velocity range, but we observe a decrease in the lift force at higher velocities. The intruder shape has a major effect on the distribution of contacts around its surface, which explains the strong lift experienced by certain shapes. The force profiles around the intruder surface, resulting from granular contacts, exhibit a strong angular dependence.
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.
Influence of suction flow control on energy extraction characteristics of flapping foil
Published in International Journal of Green Energy, 2022
Jiayue Wang, Shengxian Huang, Longfeng Hou, Ying Wang
where Cy(t) and CM(t) are lift force coefficient and torque coefficient respectively. Lift coefficient is a dimensionless quantity, which refers to the ratio of the lift of an object to the product of aerodynamic pressure and reference area. The torque coefficient refers to the pitching moment around the Y-axis of the body generated by the external force acting on the FF. The lift force coefficient and torque coefficient are calculated by and , where is the density of the fluid and is the swept area of the FF. The correspondence between them can be expressed as: