Optimization of Lift Generation for a Spinning Surface through its Design and Speed

2015 ◽  
Vol 793 ◽  
pp. 630-634
Author(s):  
Azharrudin Asrokin ◽  
Mohammad Rizal Ramly

The rotational motion of a ball, be it a tennis ball, a golf ball or even a soccer ball, will yield a curving trajectory during airborne. We would best describe this phenomenon by its popular handle, the curve ball. The vortex generated by the ball is the one responsible for such behavior. Basically, the stronger the vortex, the more enhanced the arched flight we will get. Simply put, the ball is producing lift, thus the inclination to deviate to one side from otherwise a straight path. The same principle was employed to harness lift force in rotating cylinder. The question is, how strong the vortex should be and how much is too much. In this paper, we found that certain shape and speed (to make the surface rougher and yield stronger vortex) of the cylindrical surface will determine whether or not it generates better lift when the surface is rotating.

1969 ◽  
Vol 73 (702) ◽  
pp. 524-528 ◽  
Author(s):  
R. T. Griffiths ◽  
C. Y. Ma

When a rotating body is placed in a stream of fluid the viscous drag of the rotating surface moving forward on one side and backwards on the other causes the flow velocity to be lower and hence the pressure on the forward-moving side higher than on the backward-moving side, thus giving a lateral (lift) force L in the direction shown in Fig. 1. This force, known as the Magnus force, is well known to engineers and also to sportsmen. In tennis, for example, top spin is used to swerve a fast ball downwards so that it falls within the required area of play, while in golf the Magnus force causes the all too familiar sliced shot when the club is drawn across the ball at impact.


Author(s):  
A. B. Goltsov ◽  
K. I. Logachev ◽  
O. A. Averkova ◽  
V. A. Tkachenko

A dust-air flow near a vertically located rotating cylinder with a suction unit located on the lateral surface was investigated. A computer model of this suction unit was developed, the effect of disks mounted on a cylindrical surface on the intake air flow and on the capture of dust particles in the suction unit, as well as the design and operating parameters of the proposed disk cylindrical suction (DCC), which reduce the dust loss. The influence of the size and number of discs, aspiration air flow on dust removal has been established. This design of a rotating disk cylinder suction unit can be used in aspiration shelters with the function of a dust-collecting chamber. Ill. 6. Ref. 15.


1992 ◽  
Vol 114 (1) ◽  
pp. 2-11 ◽  
Author(s):  
Joseph A. C. Humphrey ◽  
Hiroyuki Murata

Little is known about the rotational motion of spheres falling through viscous fluids in inclined tubes. Most studies have investigated translational and rotational motions in vertical tubes. These works show that in creeping flow a sphere’s translational and rotational velocities are independent. Rotation is predicted and observed for eccentric spheres while concentric spheres fall without rotation. Experiments were performed by us with steel spheres of radius r falling through glycerine in a tube of variable inclination angle and of radius R such that r/R = 0.882, 0.757, 0.442. For the cases involving two or three spheres falling together various modes of motion were observed. Especially interesting was the finding that the rotation direction of a sphere gradually changes from positive (opposite to downhill rolling) to negative (in the sense of downhill rolling) as the tube inclination angle is increased. This is allowed by the inertia-induced lift force which maintains a sphere at a very small but finite distance from the inclined tube wall. However, by further increasing the inclination angle the lift force eventually becomes smaller than the apparent weight of the sphere which, upon finally contacting the tube wall, descends by rolling along it. Examination of our findings in the light of earlier results for vertical and inclined tubes suggests that, through its effect on sphere eccentricity, inertia indirectly affects the rotational motion of a falling sphere when Rep10−3 but it does not significantly affect the translational motion when Rep<1. None of the inclined tube studies performed to date has been completely devoid of inertia-induced lift effects.


2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Nan Shao ◽  
Guofeng Yao ◽  
Chang Zhang ◽  
Min Wang

The wake flow of a vehicle significantly influences its aerodynamic performance and the stability during high-speed drive. Therefore, optimization of the vehicle wake flow is an effective way to improve its aerodynamic performance and further improve the handling stability and fuel economy. In this paper, a new method, the leading edge rotating cylinder, is used to optimize the wake flow of a vehicle. According to the results of simulations, this method can reduce the pressure drag, increase the negative lift force, and strengthen the stability of the vehicle under crosswind. Furthermore, this method optimizes not only the wake flow of the vehicle with rotating cylinders but also the interactive vehicles in the driving route in overtaking maneuvers or platoon driving. In conclusion, this method effectively optimizes the flow fields around the vehicles, and it significantly helps to improve the handling stability and fuel economy of the vehicle.


2020 ◽  
Vol 44 (3) ◽  
pp. 80-86
Author(s):  

Предпринят анализ возможности создания устройства по удалению жидких фракций (воды и топлива) из отработанного моторного масла для восстановления его эксплуатационных свойств с целью повторного использования в судовых дизелях. Показано, что необходимость повторного использования отработанных моторных масел обусловлена требованиями защиты окружающей среды. Проанализированы особенности вихревого движения жидкости как твёрдого тела или как «потенциального вихря» (вихри Ренкина). Однако эти особенности не объясняют эффект Ранка–Хилша. Теоретическое объяснение эффекта Ранка–Хилша: в вихревых трубах происходит энергетическое разделение газа за счёт центробежного эффекта турбулентных элементов по величине тангенциальной скорости. В результате разделения заторможенных элементов под действием центробежной силы и их адиабатного расширения происходит снижение температуры центрального потока. На основе использования эффекта Ранка–Хилша, мы полагаем, можно создать установку по отделению от масла топлива и воды. Идея заключается в том, что вращательным движением тонкой плёнки масла, содержащей водотопливные фракции, как и любым другим вращательным движением, создаётся центробежная сила. Дисперсная фаза воды, как обладающая большей плотностью, отжимается к периферии, а дизельное топливо с меньшей плотностью находится ближе к центру вращения. Моторное масло, имеющее промежуточное значение плотности, будет находиться между этими слоям воды и топлива. Согласно эффекту Ранка–Хилша, температура на периферии будет выше, она постепенно понизится от слоя воды к слою топлива. Основная задача при разработке устройства удаления жидких загрязнителей – создать такие давление и температуру, чтобы на наружном слое происходило выпаривание влаги, а с внутреннего слоя испарялось топливо, при этом защищённое этими двумя слоями масло, имеющее температуру кипения выше, чем у дизельного топлива и ниже, чем у воды, не испарялось. Ключевые слова: регенерация, моторное масло, эффект Ранка–Хилша, удаление воды, удаление топлива, устройство для удаления воды и топлива из масла. An analysis is made for the possibility of creating a device for removing liquid fractions (water and fuel) from used engine oil to restore its operational properties for subsequent reuse in marine diesels. It is shown that the need for reuse of used motor oils is based on environmental protection requirements. The features of the vortex motion of liquid as a solid body or as a “potential vortex” (Rankine vortex) are analyzed. However, these features do not explain the Ranque–Hilsch effect. A theoretical explanation of the Ranque–Hilsch effect is that in the vortex tubes energy separation of the gas occurs due to the centrifugal effect of the turbulent elements in terms of the tangential velocity. As a result of the separation of inhibited elements under the action of centrifugal force and their adiabatic expansion, the temperature of the central stream decreases. Based on the use of the Ranque–Hilsch effect, we believe it is possible to create a facility for separating fuel and water from oil. The idea is that the rotational motion of a thin film of oil containing water-fuel fractions, like any other rotational motion, creates a centrifugal force. The dispersed phase of water, as the one of higher density, is squeezed to the periphery, and diesel fuel as the one of lower density gets closer to the center of rotation. Engine oil of intermediate density will then be positioned between these layers of water and fuel. According to the Ranque–Hilsch effect, the temperature at the periphery will be higher; it will gradually decrease from the water layer to the fuel layer. The main task in developing a device for removing liquid pollutants is to create such pressure and temperature that moisture evaporates on the outer layer, and fuel evaporates from the inner layer. At the same time, engine oil protected by these two layers, the boiling point of which is higher than that of diesel fuel and lower than that of water, would not evaporate. Keywords: regeneration, motor oil, Ranque–Hilsch effect, water removal, fuel removal, device for removing water and fuel from oil.


2017 ◽  
Vol 5 (3) ◽  
pp. 21-35 ◽  
Author(s):  
Владимир Вышнепольский ◽  
Vladimir Vyshnyepolskiy ◽  
Николай Сальков ◽  
Nikolay Sal'kov ◽  
Е. Заварихина ◽  
...  

Loci of points (LOP) equally spaced from two given geometrical figures are considered. Has been proposed a method, giving the possibility to systematize the loci, and the key to their study. The following options have been considered. A locus equidistant from N point and l straight line. N belongs to l. We have a plane that is perpendicular to l and passing through N. N does not belong to l – parabolic cylinder. A locus equidistant from F point and a plane. In the general case, we have a paraboloid of revolution. The F point belongs to the given plane. We get a straight line perpendicular to the plane and passing through the F point. A locus equidistant from a point and a sphere. The point coincides with the sphere center. We get the sphere with a radius of 0.5 R. The point lies on the sphere. We get the straight line passing through the sphere center and the point. The point does not coincide with the sphere center, but is inside the sphere. We get the ellipsoid. The point is outside the sphere. We have parted hyperboloid of rotation. A locus equidistant from a point and a cylindrical surface. The point lies on the cylindrical surface’s axis. We get the surface of revolution which generatix is a parabola. The point lies on the generatrix of the cylindrical surface of rotation. We get a straight line, perpendicular to that generatrix and passing through the cylinder axis. The point does not lie on the axis, but is located inside the cylindrical surface. We get the surface with a horizontal sketch line – the ellipse, and a front sketch lines – two different parabolas. The point is outside the cylindrical surface. A locus consists of two surfaces. The one with the positive Gaussian curvature, and the other – with the negative one.


1998 ◽  
Vol 53 (9) ◽  
pp. 751-754 ◽  
Author(s):  
F. Winterberg

Abstract In the dynamic Lorentz-Poincare interpretation of Lorentz invariance, clocks in absolute motion through a preferred reference system (resp. aether) suffer a true contraction and clocks, as a result of this contraction, go slower by the same amount. With the one-way velocity of light unobservable, there is no way this older pre-Einstein interpretation of special relativity can be tested, except in cases involving rotational motion, where in the Lorentz-Poincare interpretation the interaction symmetry with the aether is broken. In this communication it is shown that Ehrenfest’s paradox, the Lorentz contraction of a rotating disk, has a simple resolution in the dynamic Lorentz-Poincare interpretation of Lorentz invariance and can perhaps be tested against the prediction of special relativity.


Author(s):  
M.Sundararaj, Et. al.

In this research work we investigate the performance of golf ball with 256 circular arc dimples on golf ball. The turbulence characteristics and flow pattern over golf with various velocities investigated by computational fluid dynamics in suitable turbulence model, in addition that the distance covered by a ball and rotational motion characteristics also investigated with same turbulence model


2020 ◽  
Vol 23 (1) ◽  
Author(s):  
Bin Lyu ◽  
Jeffery Kensrud ◽  
Lloyd Smith

AbstractThe following considers the lift and drag response of three commercially available golf balls. The balls were projected with spin through still air in a laboratory setting to investigate a reverse Magnus effect, where balls move in the opposite direction of the expected lift force. The drag and lift coefficients were found by measuring ball position and speed at three points along its trajectory. Three ball types, with different dimple patterns, exhibited reverse Magnus behavior between 5 × 104 < Re < 7 × 104 and 750 < ω < 2250 rpm. The golf ball with circular dimples had the least severe reverse Magnus effect, CL = − 0.1, while the ball with hexagonal dimples had the greatest, CL = − 0.15. The magnitude of the reverse Magnus effect was related to the drag crisis of each ball model. As the slope of the drag crisis became steeper, the magnitude of the reverse Magnus effect increased.


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