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Elementary Aerodynamics
Published in Rama B. Bhat, Principles of Aeroelasticity, 2018
Consider the forces acting on the airfoil shown in Figure 2.3. Vectors normal to the surface represent normal pressure. Velocity of the flow over the top of the airfoil is greater than free stream velocity and hence the pressure over the top is lower than the ambient/gauge pressure (resulting in a negative pressure coefficient). Velocity along the underside is less than the magnitude of free stream velocity and hence the pressure there is greater than free stream ambient/gauge pressure (resulting in a positive pressure coefficient). A negative pressure coefficient over the top and positive pressure coefficient along the bottom contribute to the lift. It should be noted that the absolute pressure over the surfaces can never be negative.
An aerodynamic optimization design study on the bio-inspired airfoil with leading-edge tubercles
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Yu Lu, Ziying Li, Xin Chang, Zhenju Chuang, Junhua Xing
Regarding to the four optimal airfoils, it can also be observed from Figures15(b–e)–17 (b–e) that under the condition of α=4°, though the CP on the upper surface declines beginning with the trailing edge to the leading edge but it increases near the leading edge. A negative pressure area arises at the trough of the leading-edge tubercles, along the lengthening direction. In addition, the pressure coefficient at the crest of the concave and convex nodules has diminished little by little along the spanwise. Inversely on the lower surface of the airfoils, the pressure coefficient reduces beginning with the trailing edge to the leading edge. As the angle of attack rising till the respective stall angle for each optimal airfoil, the variation tendency of pressure coefficient distribution on both wing surfaces keep accordance with the condition of α=4°, the difference fall in the values of CP.
Effect of probe geometry on fluid flow near laboratory-scale quench probes
Published in Canadian Metallurgical Quarterly, 2020
R. Cruces-Reséndez, B. Hernández-Morales
To analyze the evolution of the pressure distribution around the probes, pressure coefficient contours for a water free-stream velocity of 0.6 m/s were computed and are plotted in Figure 13. The pressure coefficient is a dimensionless quantity that describes the relative pressure through a flow field, and is defined by:The three geometries show regions where the pressure coefficient is negative; for the flat-end probe, they are located near the lower edge and correspond to suction zones, where the pressure gradient drives the fluid into a low-pressure area, causing it to recirculate. This result is consistent with the velocity field shown on the closer view to the right of each figure and confirms that the edge acts as a fluid separation point in this probe. Also, the contours show regions where the pressure coefficient values are close to unity; this indicates the presence of stagnation regions, which agrees with the computed velocity field in those regions, where values tend to zero.
Aerodynamic interaction between in-line runners: new insights on the drafting strategy in running
Published in Sports Biomechanics, 2021
Fabien Beaumont, Fabien Legrand, Fabien Bogard, Sébastien Murer, Victor Vernede, Guillaume Polidori
Our primary objective was to investigate the various aerodynamic effects that are closely linked to the interaction between each runner. Firstly, we focused on the static pressure that is known to be a fundamental parameter in competitive running. The pressure coefficient is often used in aerodynamics to predict fluid pressure at different locations. The pressure coefficient is defined as follows: