Papers by Keyword: Rotating Cylinder

Abstract: 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.

Abstract: In the fields of materials science and engineering, measuring temperature has become one of the most fundamental and important issues. In particular, there are growing demands for monitoring temperature gradient and its transient variation of materials being processed at higher temperatures because the temperature state during processing crucially influences the quality of final products. Such temperature monitoring is also required for rotating machining processes such as tuning, milling and friction stir welding (FSW). In this work, a new noncontact method for monitoring temperature distribution of a heated rotating cylindrical object is presented. A laser-ultrasonic technique is employed in the method. Surface temperature measurements for the cylindrical object using the laser-ultrasonic technique and heat conduction analyses are combined together for making quantitative evaluation of temperature distribution in the radial direction of the cylindrical object. To demonstrate the feasibility of this method, an experiment with a steel cylinder of 100 mm in diameter rotating at 300 min^-1 and heated up to 100 °C on the surface is carried out. A pulsed laser generator and a laser Doppler vibrometer are used for generating and detecting surface acoustic waves (SAWs) on the steel cylinder, respectively. Measured SAWs are used for determining both surface and internal temperatures of the cylinder. As a result, the estimated temperature distributions during heating almost agree with those measured by an infrared radiation camera.

Abstract: To solve the problem of low lift to drag ratio of Magnus cylinder airfoil, the Computational Fluid Dynamics software Fluent was used to study the principle of a drop of the drag force of cylinder when rotating. And the principle was used to further reduce the drag of rotating cylinder. A traditional airfoil head and a triangle tail was used to study the effect of the aerodynamic performance change of the combined airfoil. A conclusion was made that with a suitable profile of the tail would reduce the drag force of the combined airfoil thus increase the lift to drag ratio of the airfoil. At last an orthogonal test was made to determine the size of the tail airfoil. The result show that the optimized airfoil reduce the drag force to 50% of the original cylinder and improve the lift to drag ratio to 50%.

Abstract: Particle trajectory within rotating cylinders has been investigated in terms of radial positions by using the discrete element method (DEM). The dynamic information of particle groups has been obtained under a wide range of rotation speed by a method of particle marking and tracking. The results show a periodic way of inwards trend for particle motion within material bed. The period of particle motion is directly related to the rotation speed of the cylinder. However, the residence time of particles in the active layer shortens with periods, while that in the static zone prolongs. Moreover, the peak value of radial positions periodically decays, whereas the valley value periodically increases. This research laid a good foundation for further research on particle mixing and heat transport within the material bed in rotating cylinders.

Abstract: A study on the effect of allocating a square blockage in front of a rotating cylinder is presented. The aim of the study is to determine the optimum design of the blockage to enhance the lift generating performance of the rotating cylinder. A numerical simulation is carried out to investigate the effect of different sizes of blockage towards the lift generating performance of the rotating cylinder. The simulation adopted a fully turbulent flow, having Reynolds number of 600. The cylinder is spinning at 5000 RPM. The validation of the simulation RANS code FLUENT is done through comparison with the published results from past studies. In general, the results suggest that the lift generating performance of the rotating cylinder will be improved by placing a blockage in front of it.

Abstract: In this paper, a new solution is presented for one-dimensional steady-state mechanical and thermal stresses in a FG rotating hollow disk and cylinder. The material properties for FG are expressed as nonlinear exponential functions through the radius and Poisson’s ratio is taken to be constant. The temperature distribution is derived from first law of thermodynamics by solving energy equation, with a general thermal and mechanical boundary conditions on the inside and outside surfaces. Heat conduction and Navier equations are solved analytically by choosing elliptic cylinder coordinates system and the results are shown for displacement and stress components along the radial direction.