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Aerodynamic Forces – Subsonic Flight
Published in Rose G. Davies, Aerodynamics Principles for Air Transport Pilots, 2020
The aspect ratio can affect the lift coefficient as well. The lift coefficient of a wing with a high aspect ratio is higher than that of a wing with a low aspect ratio, if they have the same relative thickness and same camber. The wing with a low aspect ratio should produce stronger downwash, which draws the relative airspeed closer to the wing, and induce the lift vector tilting rearward more, then the actual magnitude of lift is reduced. The effective angle of attack of this wing will be decreased as well. Therefore, the lift coefficient of the wing with a low aspect ratio should produce lower lift coefficient than the wing with a high aspect ratio, but the stall AoA of the wing with a low AR is higher than that of the wing with a high AR as shown in Figure 4.22.
The flow characteristics around a hydrofoil and the stall mechanism influenced by the electromagnetic force
Published in Guojun Hong, Gongxun Liu, Liquan Xie, Hydraulic Engineering V, 2018
Jinfu Yin, Guojun Hong, Ke Chen, Yunxiang You, Tianqun Hu
Fig. 4 shows the comparisons of the time-averaged value of lift/drag coefficients with the experimental values (Jacobs, 1937) when ReL = 1.63 × 105 and t = 50 s. It can be seen from Fig. 4 that the coefficient of lift and drag agree with the experimental results. The stall angle of the NACA0018 hydrofoil is about α = 14° at the Reynolds number ReL = 1.63 × 105 in the subcritical region. When the angle of attack is greater than the stall angle, the lift coefficient decreases sharply and the drag coefficient increases.
L
Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[fluid dynamics, general] Number used to account for the impact on lift of all of the complex dependencies of curvature, shape, as well as particular flow conditions. This number follows from rearranging the lift equation. Coefficient in an equation that describes the threshold limit for airborne lift force (FL) of an object outfitted with wings, as described in the following equation: FL=(1/2)ρv2ACL, where ρ is the fluid density (e.g., accounting for altitude), A the surface area of the airfoil (i.e., wing), v the air velocity (net velocity with respect to the wing, including for instance air flow and wing speed). This lift force describes the conditions for an airfoil to remain afloat during flight. The lift coefficient is defined as a function of the angle of incidence, or the wing angle with respect to the airflow in addition as a function of Mach number and Reynolds number, describing the local fluid conditions (e.g., humidity and fluid mixture: rain). At a specific altitude, the velocity needs to exceed the orbital velocity to remain in lift, the point at which the flight velocity equals the orbital velocity is called the Kármán line. The lift coefficient is defined as cℓ=2FL/ρv2A, where FL is the lift for the wing with surface area A, under relative flow velocity v (see Figure L.94).
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:
Heat transfer and temperature effects on a dimpled NACA0012 airfoil with various angles of attack
Published in International Journal of Ambient Energy, 2018
P. Booma Devi, V. Paulson, V. Madhanraj, Dilip A. Shah
This graph represents the relation between angle of attack to the lift coefficient. The lift coefficient is linearly increasing with increasing angle of attack. At an angle of attack of 15° to 16°, the flow on the upper surface of the airfoil began to separate, and this condition is known as stall condition. At an angle of attack of −10° to 10°, the result of three models is more accurate to the experimental data, and its behaviour remained the same until reaching stall condition. But in the Spalart-Allmaras turbulence model had the accurate data to the experimental and also same behaviour after stall angle. Near stall angle, the difference between the data was shown (Figure 3).
Synthetic jet application in the wind turbine concentrator design
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Teoman Oktay Kutluca, Emre Koç, Tahir Yavuz
As the angle of attack increases, the ability of the flow to adhere to the upper surface of the airfoil decreases and the separation occurs after an angle of attack. For this reason, the increase in the angle of attack in the flow on the airfoil linearly increases the lift coefficient up to a certain value, and then the lift coefficient starts to decrease after the critical value at the stall angle. The reason for this situation is that the flow on the upper surface of the airfoil breaks off in the areas very close to the leading edge from the standpoint of the stall and reverse flow is observed in a large part of the upper surface.