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Rotating Disk (rotating + disk)

Distribution by Scientific Domains
Engineering50%

Selected Abstracts

An unsteady flow structure on a heated rotating disk under mixed convection

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2005
Noriyuki Furuichi
Abstract A flow field under mixed convection on a heated rotating disk has been measured using an ultrasonic velocity profiler (UVP). The measured velocity field is a spatio-temporal one as a function of radial coordinates and time. The objective of this paper is to clarify the vortex structure caused by the instability between buoyancy and centrifugal force. The vortex appears under typical conditions of Reynolds numbers and Grashof numbers and it moves toward the outside of the disk. This behavior can be classified into two patterns. The size of the vortex structure decreases with an increasing Reynolds number and increases with the Grashof number. The traveling velocity of the vortex increases with the Grashof number. Moreover, it decreases with an increasing Reynolds number in spite of increasing centrifugal force. According to these results, the region dominated by natural, forced, and mixed convection is classified in the relationship between Reynolds and Grashof numbers. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(6): 407,418, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20074 [source]

Numerical simulation of turbulent impinging jet on a rotating disk

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2007
A. Abdel-Fattah, Article first published online: 25 OCT 200
Abstract The calculations of quasi-three-dimensional momentum equations were carried out to study the influence of wall rotation on the characteristics of an impinging jet. The pressure coefficient, the mean velocity distributions and the components of Reynolds stress are calculated. The flow is assumed to be steady, incompressible and turbulent. The finite volume scheme is used to solve the continuity equation, momentum equations and k,, model equations. The flow characteristics were studied by varying rotation speed , for 0,,,167.6 rad/s, the distance from nozzle to disk (H/d) was (3, 5, 8 and 10) and the Reynolds number Re base on VJ and d was 1.45 × 104. The results showed that, the radial velocity and turbulence intensity increase by increasing the rotation speed and decrease in the impingement zone as nozzle to disk spacing increases. When the centrifugal force increases, the radial normal stresses and shear stresses increase. The location of maximum radial velocity decreases as the local velocity ratio (,) increases. The pressure coefficient depends on the centrifugal force and it decreases as the distance from nozzle to plate increases. In impingement zone and radial wall jet, the spread of flow increases as the angular velocity decreases The numerical results give good agreement with the experiment data of Minagawa and Obi (Int. J. of Heat and Fluid Flow 2004; 25:759,766). Copyright © 2006 John Wiley & Sons, Ltd. [source]

SPLITTING AND BREAKING OF PISTACHIO NUTS WITH STRIKING AND HEATING

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2008
H.I. CEM BILIM
ABSTRACT The objective of this study was to investigate the effects of heating process and striking on splitting and breaking of pistachio nuts and obtaining their kernels without damage. For this purpose, heating process (350C) was applied to pistachio nuts. Heated nuts were dropped onto the rotating disk and then thrown to strike the wall of the container by centrifuge effect . Striking velocity was adjusted with a rotating disk that was driven by an electrical engine. Three different disk rotations (400, 500 and 600/min) with three different moisture contents of pistachios (6.5, 22.0 and 42.5%) were evaluated in the experiments. Results indicated that the highest splitting rate was obtained as 29.33% at 22.0% moisture content with 400 1/min disk velocity. The most healthy kernel percentage obtained from unsplit pistachio nuts was 25.76% at 6.5% moisture content with 500 1/min disk velocity. Additionally, the study results showed that only the heating process had no affect while heating and crushing combinations increased splitting and obtaining the kernels. PRACTICAL APPLICATIONS Consumption of healthy foods is very important for human health. Kirmizi variety of pistachio nuts contains a high ratio of unsplit pistachio nuts after harvest. These pistachio nuts are either consumed as appetizers or used in the sweets sector after extracting the inner part (kernel). The economical value of unsplit pistachio nuts is very low. For this reason, pistachio nut processing plants try to split them or extract the inner part without causing any damage. Unsplit pistachio nuts are split by hand or by primitive hand tools, such as hammer or pliers, and then extracted. This method is not healthy. This study is one of the limited studies concerning automatic, quick and economic splitting and extraction of pistachio nuts. After handling problems like splitting and extracting the kernel of pistachio nuts, pistachio nut processing plants will achieve a healthy pistachio nut production. This study offers a new system for healthy pistachio nut production, with low initial cost, lower wages and in less time. [source]

Non-perturbative solution of three-dimensional Navier,Stokes equations for the flow near an infinite rotating disk

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 11 2010
Ahmet Y
Abstract In this paper, we present Homotopy perturbation method (HPM) and Padé technique, for finding non-perturbative solution of three-dimensional viscous flow near an infinite rotating disk. We compared our solution with the numerical solution (fourth-order Runge,Kutta). The results show that the HPM,Padé technique is an appropriate method in solving the systems of nonlinear equations. The mathematical technique employed in this paper is significant in studying some other problems of engineering. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Serroydyne modulator based on circularly polarized wave reflection

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2005
V. F. Fusco
Abstract In this paper, a technique is described whereby we can directly Serrodyne a signal reflected from a rotating metal disk. This is achieved by placing a spinning circular-patch antenna (which has two short-circuiting pins at its periphery) in the path of an incident circularly polarized (CP) field. When excited by a circularly polarized signal, the rotating disk produces a re-reflected signal with a modulo 0° to 360° phase shift encoded onto it. The sense of the re-radiated signal is the same as that of the incident signal. The developed technique can be used as a mechanical Serrodyne modulator providing a small frequency offset in the return signal that is directly related to direction and rate of rotation. A mathematical rationale for the principal of operation of the device is given and experimental validation of the method is provided. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 469,472, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20855 [source]

Formation of large-scale magnetic-towers in quasars

ASTRONOMISCHE NACHRICHTEN, Issue 5-6 2006
Y. Kato
Abstract The evolution of accretion disks and the formation of jets around super-massive black holes are studied by 3-D magnetohydrodynamic simulations. The previous studies of astrophysical jets have been concentrated on the effects of large-scale magnetic fields permeating accretion disks. However, the existence of such global magnetic fields is not evident in astrophysical objects, and their origin is not well understood. Instead, we concentrate on the effect of the magnetic fields amplified as a result of the magneto-rotational instability in the differentially rotating disk. In our simulations, we found the emergence of accumulated toroidal magnetic fields from the inner region of the disk (a so-called magnetic-tower) and also the formation of jets accelerated by the magnetic pressure of the magnetic-tower. The magnetic energy, ejected by the magnetic-tower jet during a lifetime of an active galactic nuclei (AGNs), is about 1046 erg. Our results indicate that the magnetic-tower jet can be one of the most powerful process for the formation and the evolution of the large-scale structured magnetic .elds in the cluster of galaxies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]