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Canard Airplanes and Biplanes
Published in James DeLaurier, Aircraft Design Concepts, 2022
Further, because these have sharp leading edges, ηle=0. Therefore, the drag equation becomes Cd≈(Cd)fric+2παZLL2+2αZLLCl+Cl2/(2π)
Auxiliary Hydraulic Variables
Published in Jochen Aberle, Colin D. Rennie, David M. Admiraal, Marian Muste, Experimental Hydraulics: Methods, Instrumentation, Data Processing and Management, 2017
Jochen Aberle, Colin D. Rennie, David M. Admiraal, Marian Muste
A body exposed to flow is subject to a drag force F, which is generally parameterized by the classical form drag equation F = 0.5ρCDACUc2, where ρ is the fluid density, CD is the drag coefficient, AC is the characteristic area (usually the projected frontal area) and Uc is the approach velocity. The drag coefficient CD includes both components arising due to viscous and pressure drag, and depends on the flow conditions which are usually characterized by the object Reynolds-number (e.g., Nakayama, 1999). However, theoretical computation of the viscous and pressure drag components is generally impractical, except for bodies of simple shape (e.g., cylinders, spheres) for which functional relationships between the drag coefficient and object Reynolds number can be found in textbooks. For more complex and/or flexible bodies, one must rely on measurements in order to determine drag forces and hence to parameterize CD. Reporting such measurements, it is important that both Ac and Uc are clearly defined so that the results can be generalized and/or used by other researchers (e.g., Statzner et al., 2006).
Straight-level flight
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
By using Equations 6.5 and 6.6, we can determine the required power for a steady-level flight at any speed. In physics (mechanics/dynamics), for a body in motion, the power is basically defined as “applied force” times “body speed”. The required power (PR) is a function of the required force (i.e., thrust [TR]). In a steady-level flight, the required thrust/force is equal to the aircraft drag (Equation 6.6). So, the required power for an aircraft to fly at a specific speed in a straight-level flight is defined as follows: () PR=FV=TRV=DV
Erosion time scale in pipes below dikes for turbulent and laminar flow
Published in Journal of Hydraulic Research, 2023
In the Moody diagram (e.g. Chanson, 1999), the relative wall roughness varies from 10−6 to 0.05. As the relative wall roughness in the pipes is larger than 0.05 we use in this study, the drag force to express the friction force near the walls. To quantify the wall shear stress, we use the drag equation: with the drag coefficient as shown in Fig. 3. For Re,part > 100, the relation between r0 and CD is: Hence, the flow in narrow pipes can be highly turbulent if CD ≈ 1.5 and Re,part > 100, yielding r0 ≈ 1. However, k0 is extremely low with respect to the energy in rivers, as the characteristic mixing length in rivers is 103–104 times larger. So far, we have engineering tools to classify different types of flow as functions of particle size.
Closure to “Influence of erosion on piping in terms of field conditions” by GIJS HOFFMANS, J. Hydraulic Res. 59(3), 512–522. 2020. https://doi.org/10.1080/00221686.2020.1786741
Published in Journal of Hydraulic Research, 2023
The following river dike pipe properties as computed by DgFlow (also see Fig. 3 from Pol) are considered: flow velocity is 8 cm s−1, pipe height is 2 mm, and the Reynolds number is about 50. The relative roughness is approximately 0.1, which is extremely high; thus, we cannot use the Moody diagram. To compute the wall friction, we have to apply the drag equation (Auld & Srinivas, 2006; Tansley & Marshall, 2001). As the particle Reynolds number approximately equals the Reynolds number, the flow is transitional; thus, both viscous and turbulent stresses are active. Hence, we have a paradox in DgFlow as the pipe flow is calculated with the laminar equation of Hagen–Poiseuille.
Modeling and performance evaluation of sustainable arresting gear energy recovery system for commercial aircraft
Published in International Journal of Green Energy, 2023
Jakub Deja, Iman Dayyani, Martin Skote
where is the mass of the aircraft, is the resultant ground speed of an aircraft, is the moment of inertia and is the angular velocity of landing gear rotary components. During a landing roll, the aircraft is continuously subjected to drag which can be divided into parasitic and induced drag. Induced drag is assumed to be negligible whereas parasitic drag equation formula is given as: