Inner Diameter Of Cylinder Research Articles

Natural-convection of Newtonian fluids between two concentric cylinders of a special cross-sectional form

In this paper, we performed a numerical simulation of natural-convection of Newtonian fluids between two cylinders of different cross-sectional form. The inner cylinder is supposed to be hot and the outer cylinder is assumed to be cold. The diameter of inner cylinder to the diameter of outer cylinder defines the radii ratio (RR = 2.5). The governing equations describing the physical behavior of fluid-flow and heat transfer are solved using finite volume method. The effects of Prandtl number (Pr = 0.71-100), Rayleigh number (Ra = 103-105), and inclination angle of inner cylinder (? = 0-80?) on streamlines, isotherms, and dimensionless velocity are presented and discussed. Also, the mean average Nusselt number of inner cylinder is plotted vs. the governing parameters. All present simulations are considered in 2-D for steady laminar flow regime. The obtained results showed that the flow between cylinders is more stable for the inclination angle ? = 0?. Increase in Rayleigh number increases the heat transfer rate for all values of inclination angle. Furthermore, the effect of Prandtl number on the mean average Nusselt number becomes negligible when Prandtl number is over the value 7.01. For example at Pr = 0.71 and Ra =105, increase in inclination from 0? to 40? decreases the average Nusselt number by 5.4%. A new correlation is also provided to describe the average Nusselt number as function of Prandtl number and Rayleigh number at ? = 0?.

On site calibration of inner defect detection based on structured light

A special calibration cylinder is intended to meet the actual requirement of calibration in defect detection system, and a calibration method is proposed based on this calibration the cylinder. The relative measurement method is adopted in the measurement of inner diameter of cylinder. Through processing the structured light image of inner surface of calibrated cylinder, the relationship between the depth of groove in calibrated cylinder and the distance between the displaced pixels of structured light stripes is obtained, which is used in the calculation of groove depth, and the wear of inner diameter of cylinder is obtained. Experiments show that this method can effectively adapt to the detection environment with a small field of view and weak light, and have higher calibration accuracy, and can meet the actual needs of the detection system calibration.

SU‐F‐T‐461: Dosimetric Evaluation of Indigenous Farmer Type Chamber FAR65‐ GB for Reference Dosimetry of FFF MV Photon Beam

Purpose:Indigenous Farmer type chamber FAR 65 GB is a reference class 0.6 cc ion chamber. It can be used for dosimetric evaluation of photon and high energy electron beams. We studied dosimetric characteristics of the chamber for 6MV and 10MV Flattening filter free FFF photon beams available on trueBEAM STx Linac.Methods:The study was carried out on trueBEAM STx Linac having 6 and 10 MV FFF photon beam with maximum dose rate 1400 and 2400 MU per min respectively. The dosimetric device to be evaluated is Rosalina Instruments FAR 65‐GB Ion Chamber with active volume 0.65 cc, total active length 23.1cm, inner diameter of cylinder 6.2mm, wall thickness 0.4mm, inner electrode diameter 1mm. Inner and outer electrodes are made from Aluminium 2.7 gm per cc and graphite 1.82 gm per cc respectively. The ion chamber was placed along central axis of beam at 10cm depth and irradiated for 10cm × 10cm field size at SAD of 100 cm in plastic phantom. We studied Precision, Dose Linearity, Dose Rate dependence, directional dependence, Recombination effect. Recombination effect was determined using standard two‐voltage method.Results:1. Measurements were reproducible std deviation of 0.0105 and type A uncertainty 0.003265 under same set of reference conditions 2. Chamber exhibit dose linearity over a wider dose range. 3. Chamber shows dose rate independence for all available dose rate range. 4. Response of chamber with the angle of incidence of radiation is constant. 5. Recombination correction factors were 1.01848 and 1.02537 for dose rate 1400 and 2400 MU per min resp.Conclusion:Our study reveals that the chamber is prone to saturation effect at dose rate of 2400 MU per min. FAR 65‐GB can be used for reference dosimetry of FFF MV photon beam with proper calculation of recombination effect.

Flow control downstream of a circular cylinder by a permeable cylinder in deep water

The flow characteristics of a circular cylinder surrounded by an outer permeable cylinder were experimentally investigated using Particle Image Velocimetry Technique in deep water flow. In order to consider the effects of diameter and porosity of the outer cylinder on flow structures of the inner cylinder, five different outer cylinder diameters (D=37.5, 52.5, 60, 75 and 90 mm) and eight different porosities (<TEX>${\beta}$</TEX>=0.4, 0.5, 0.6, 0.65, 0.7, 0.75, 0.8 and 0.85) were selected. During the experiments, the diameter of inner cylinder was kept constant as d=30 mm. The depth-averaged free-stream velocity was adjusted as U=0.156 m/s, which corresponds to the Reynolds number of Re=5000 based on the inner cylinder diameter. It has been concluded that both the outer permeable cylinder diameter and the porosity have important influences on the attenuation of vortex shedding in the wake region. The presence of outer permeable cylinder decreases the magnitude of Reynolds shear stress and turbulent kinetic energy compared to the bare cylinder case. Moreover, the spectral analysis of vortex shedding frequency has revealed that the dominant frequency of vortex shedding downstream of the cylinder arrangement also reduces substantially due to the weakened Karman shear layer instability.

Fluid flow due to combined convection in lid-driven enclosure having a circular body

The present work is aimed to study mixed convection heat transfer characteristics for a lid-driven air flow within a square enclosure having a circular body. Flows are driven by the left lid, which slides in its own plane constant velocity. This wall is isothermal and it moves up or down in y direction while the other walls remain stationary. The horizontal walls are adiabatic. The cavity is differentially heated and the left wall is maintained at a higher temperature than the right wall. Three different temperature boundary conditions were applied for the inner cylinder as adiabatic, isothermal or conductive. The computation is carried out for wide ranges of Richardson numbers, diameter of inner cylinder and center and location of the inner cylinder. It was found that the most effective parameter on flow field and temperature distribution is the orientation of the moving lid. The circular body can be a control parameter for heat and fluid flow. An interesting obtained result that the thermal conductivity becomes insignificant for small values of diameter of the circular body.

Fundamental Investigation on an Oil Damper : 3rd Report Comparison of Analyses Based on Cylindrical Coordinates and Cartesian Coordinates

This paper deals with a theoretical research of an oil damper, whose piston is vibrating in a viscous fluid filling a fixed circular cylinder. In the previous report, transforming the annular clearance between the cylinder and the piston into a straight channel, the authors induced a drag force acting on the piston from an equation of motion of the fluid expressed in Cartesian coordinates. Therefore the result of this analysis contained an error due to the transformation. So in this report, the authors try to derive a more exact value using an equation represented in cylindrical coordinates. Comparing this solution with the former one, they proved that these are very close to each other, if there is not so much difference between the diameter of piston and the inner diameter of cylinder.