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Your search keyword '"Lift and drag"' showing total 5 results
Start Over Descriptor "Lift and drag" Topic aerodynamics
5 results on '"Lift and drag"'

1. AN EXAMINATION OF THE "LANIER WING" DESIGN.

Author

STOKES, Y. M., SWEATMAN, W. L., and HOCKING, G. C.

Subjects
*VACUUM chambers, *AEROFOILS, *INVESTIGATION reports
Abstract

Six patents were secured by E. H. Lanier from 1930 to 1933 for aeroplane designs that were intended to be exceptionally stable. A feature of five of these was a flow-induced "vacuum chamber" which was thought to provide superior stability and increased lift compared to typical wing designs. Initially, this chamber was in the fuselage, but later designs placed it in the wing by replacing a section of the upper skin of the wing with a series of angled slats. We report upon an investigation of the Lanier wing design using inviscid aerodynamic theory and viscous numerical simulations. This took place at the 2005 Australia–New Zealand Mathematics-in-Industry Study Group. The evidence from this investigation does not support the claims but, rather, suggests that any improvement in lift and/or stability seen in the few prototypes that were built was, most probably, due to thicker airfoils than were typical at the time. [ABSTRACT FROM AUTHOR]

Published
2023
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2. A numerical investigation on aerodynamic characteristics of an air-cushion vehicle.

Author

Kaya, K. and Özcan, O.

Subjects
*GROUND-effect machines, *AERODYNAMICS, *NUMERICAL analysis, *TRANSLATIONAL motion, *COMPUTATIONAL fluid dynamics software, *DRAG force, *LIFT (Aerodynamics), *DYNAMICS
Abstract

Abstract: This paper describes a numerical study of incompressible, steady, three-dimensional turbulent air flow inside and around a simplified air-cushion vehicle (ACV) model. Two distinct cases have been studied separately regarding type of motion of the ACV; the first case is sole hovering with no forward motion where only flow through the ACV was considered, the second case is both hovering and translational motions for which the external flow around the vehicle body becomes of interest. It is assumed that both motions take place on land (above a solid plane). A hybrid mesh was generated and solutions were obtained for various lift fan pressures and air-clearance heights. Computations have been carried out by means of the computational fluid dynamics (CFD) software ANSYS FLUENT. Mean flow aerodynamic characteristics of the ACV are presented and discussed in terms of lift and drag forces, factors contributing to the drag, flow separations and singular points in the streamline patterns. The Q-criterion is employed to identify vortical structures. Differences in the aerodynamic characteristics of an ACV and a road vehicle are also discussed. [Copyright &y& Elsevier]

Published
2013
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3. Direct numerical simulation of different finite cylinders rolling on a horizontal surface: The thickness effects on the aerodynamics.

Author

Javadi, Ardalan

Subjects
*AERODYNAMICS, *REYNOLDS number, *COMPUTER simulation, *SURFACE pressure, *VORTEX shedding, *FRICTION, *DRAG coefficient, *COUETTE flow
Abstract

The flow around a cylinder rolling along a horizontal ground plane is investigated using direct numerical simulation for a Reynolds number based on the cylinder diameter, D , of R e D = 3 × 1 0 4 . Three cylinder thicknesses, T / D = 0. 040 , 0.126, and 0.400, are considered. The time-averaged drag coefficients are found to be 0.87, 0.69, and 0.97 for the three cylinders, respectively. The non-monotonic variation in drag coefficient with thickness suggests a transition in the proportion of contributions of friction and pressure drag to the total drag which changes about 30% with thickness increase. Indeed, the ratio of friction drag to pressure drag varies from 0.333 to 0.085 and finally to 0.013 for the three cylinders. The pressure coefficient become more negative in the aft of the thicker cylinders, because the cylinder become more bluff body which suggests more pronounced pressure drag. Temporal fluctuations in the drag coefficient associated with vortex shedding events increase monotonically with thickness, though the root-mean-square of the drag coefficient follows the same trend as the mean drag coefficient. The lift coefficients are − 0. 057 , 0.066, and 0.64 for the three respective cylinders. The negative value for the thinnest cylinder indicates down force. The transition from negative lift on the thin cylinder to positive lift on the thick cylinder is associated with elevated surface pressure just upstream of the ground contact point as thickness increases. As the flow is more detached from the cylinder sides, the friction lift is less significant with thickness increase. Furthermore, the pressure coefficient is negative spatially larger in the top of the thicker cylinders which the expansion offers a more significant upward pressure lift. • Three cylinder thicknesses, T/D = 0.04, 0.126, and 0.4, are studied in Re D = 3 × 104. • The time-averaged C D is 0.87, 0.69, and 0.97 for the three cylinders, respectively. • The ratio of friction to pressure drag varies from 0.3 to 0.08 and to 0.01. • The time-averaged C l is downward for the thinnest cylinder. • The time-averaged C l is upward for other two cylinders. [ABSTRACT FROM AUTHOR]

Published
2022
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4. Aerodynamics of Golf Balls in Still Air

Author

Jeff Kensrud, Taylor Tosaya, Bin Lyu, and Lloyd V. Smith

Subjects
Physics, Lift-to-drag ratio, Lift coefficient, Drag coefficient, golf aerodynamics, lift and drag, Ranging, lcsh:A, Mechanics, Aerodynamics, drag crisis, light gate, Drag, Drag crisis, Ball (bearing), speed sensor, lcsh:General Works
Abstract

The following considers lift and drag measurements of 13 production golf ball models propelled through still air in a laboratory setting. The balls travelled at speeds ranging from 18 m/s to 91 m/s and spin ranging from 1500 rpm to 4500 rpm. Speed sensors measured the speed and location of the balls at three locations from which the coefficient of lift and drag were found. The sensors were sufficiently close (3.81 m to 5.08 m) so that the lift and drag effects were nearly constant. Lift and drag were observed to depend on speed, spin rate, and ball model. The difference in the drag coefficient between the ball models were relatively large (>0.1) at low speed (Re < 105), and smaller ( 105). The lift coefficient had a non-linear dependence on spin (fit with a 2nd order polynomial). A trajectory of each ball model was found from the measured lift and drag response. Carry distance varied by 18 m over the models considered here and was not strongly correlated with ball cost.

Published
2018

5. CFD Simulations for the Selection of an Appropriate Blade Profile for Improving Energy Efficiency in Axial Flow Mine Ventilation Fans

Author

Durga Charan Panigrahi and Devi Prasad Mishra

Subjects
Lift-to-drag ratio, Airfoil, lcsh:TN1-997, Engineering, Environmental Engineering, business.industry, Angle of attack, Renewable Energy, Sustainability and the Environment, lift and drag, mine ventilation, Stall (fluid mechanics), Geology, Structural engineering, Aerodynamics, Geotechnical Engineering and Engineering Geology, Pollution, Lift (force), Axial compressor, Drag, axial flow fan, aerofoil, business, CFD, energy efficiency, lcsh:Mining engineering. Metallurgy
Abstract

Purpose This study focuses on one of the key design aspects of mine ventilation fans, i.e. the selection of an appropriate aerofoil blade profile for the fan blades in order to enhance the energy efficiency of axial flow mine ventilation fans, using CFD simulations. Methods Computational simulations were performed on six selected typical aerofoil sections using CFD code ANSYS Fluent 6.3.26 at angles of attack varying from 0° to 21° at an interval of 3° and at Reynolds number Re = 3 × 106 , and various aerodynamic parameters, viz. coefficients of lift (Cl) and drag (Cd) as a function of angle of attack (α) were determined to assess the efficiency of the aerofoils. Results The study revealed that the angle of attack has a significant effect on the lift and drag coefficients and stall condition occurred at α values of 12° and 15° in most of the aerofoils. Based on the criterion of higher lift to drag ratio (Cl/Cd), a blade profile was chosen as the most efficient one for mine ventilation fans. Practical implications This study forms a basis for selecting appropriate blade profiles for the axial flow fans used for ventilation in mining industry. Originality/value The application of an appropriate aerofoil blade profile will impart energy efficiency to the mine ventilation fans and thereby result in energy saving in mine ventilation.

Published
2014
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