Natural Convection Heat Transfer From a Vertical Hollow Cylinder With Surface Holes

Three-dimensional continuity, momentum, and energy equations have been solved around a perforated vertical hollow cylinder to predict the buoyancy-induced flow field and the temperature distribution around it. Finite volume method (FVM) has been implemented for the discretization of the underlying governing equations. Second-order upwind scheme has been adopted to discretize the convective terms in the momentum and energy equation. Results have been obtained by varying the input parameters like hole diameter to cylinder length ratio (d/L), pitch to length ratio (P/L), angular pitch (θ), cylinder length to diameter ratio (L/D), and Rayleigh number (Ra) spanning from 0.005 to 0.08, 0.1 to 0.3333, 30 deg to 180 deg, 2 to 20, and 104 to 108, respectively. It has been found that the average surface Nusselt number (Nu) for the outer surface increases with the diameter of the hole for Ra of 106, however for Ra of 108, it marginally decreases up to d/L of 0.01 and then increases. Nu for the inner surface increases when d/L is more than 0.04 for all Ra. The cylinder with the staggered holes shows a slightly higher Nu compared to the inline holes. Nu for the inner and outer surface at a lower pitch is less than that of the higher pitch when d/L is less than 0.02 for all Ra. The heat transfer rate of the perforated cylinder is more than the nonperforated cylinder for all the cases when L/D is less than 10 and Ra less than 106. However, for Ra more than 106, the perforated cylinder always loses more heat compared to the nonperforated one for all L/D. Finally, the correlation for Nu has been proposed as a function of the pertinent input parameters for future reference in the academic as well as industrial practices.

KINEMATICS FEATURES OF HAMMER PERFORATED TILLAGE ROLL

The task of improving the quality of agricultural tools by improving the technological processes of their functioning, taking into account the kinematic features of the combined impact of working elements of tools on the soil environment is important from a scientific and technical point of view. To form the required structure and density of the soil layer at the depth of sowing, a hammer perforated tillage roller (HPTR) has been developed. The study aim is to improve the quality of post-sowing compaction and structuring of the soil layer in the seed location zone based on the development of an innovative design of HPTR that combines different effects on the treated environment. The object of research is the kinematic mode of operation of the HPTR, equipped with cylindrical hammers installed at the ends of the rod, which, in turn, are radially and pivotally installed on the axis of the gunFeature of offered HPTR is the excitation of hammer vibrations, which changes the kinematic parameters of the tillage tool as a whole. Lagrange equations of the second kind are used to describe the process of HPTR operation, which is represented as a system of material objects with several degrees of freedom. The conducted studies revealed the periodic nature of changes in the strength of the impact of HPTR on the soil. The obtained equations allow us to determine the features of the HPTR movement at different masses of a hollow perforated cylinder and cylindrical hammers. This is of great importance for increasing the efficiency of soil bolster destruction and creating the soil structure recommended for winter crops sown in the Middle Volga region.

Controlling The Flow Structure of Circular Cylinder by Using Concentrically Installed Perforated Cylinder and Splitter Plate

The purpose of this work was to control undesired structure and vibrations caused from vortex shedding by controlling the flow downstream of the cylinder. The porosities of the outer cylinder and the splitter plate used for this purpose are available. The other parameter was plate angle based on the flow direction as a reference. The parameter expressed as porosities, ß was chosen to have a %70 openness for the outer cylinder (ß = 0.7) and was kept constant throughout all experiments. On the other hand, two different porosities were used for the splitter plate. For the first plate, there was no hole on the plate which we call ß = 0 or solid plate. For the second plate, it has ß = 0.7 porosity. ß = 0.7 porosity was also the value chosen for the outer cylinder. The range of the splitter plate angle was selected within 60o? ? ?180o with an increment of 30o. The results were extracted using two different methods. The first was the dye visualization experiment and the second is the PIV (Particle Image Velocimetry) measurement. As a result, it was observed that independently from the outer cylinder effect, the plate porosity and plate angle are effective on the level of turbulence and the flow structure in the annular region.

TECHNOLOGY OF RABBIT’S FUR PROCESSING

Analyzed shadowy the method of keeping rabbits, the design of cells. Developed two technologies of processing of skins of rabbits with use of energy of electromagnetic radiation. The first technology involves the drying skins of rabbits on pravicah in the electromagnetic field of ultrahigh frequency (MPSVC). Designed installation can provide periodic or continuous mode of operation. The second technology involves separating the fur from the leather hides of rabbits with the simultaneous rychle-tion, beating and separating fibres from bunches. Discusses the design of facilities that implement these technologies of processing of skins of rabbits. The sequence of development of technological process of heat treatment of fur raw materials: a study of the shapes and sizes surround the cavity of the microwave generator; the development of modes of processing of raw materials; selection of equipment and controls. Taking into account the structural features of the device, intended for primary processing of wool, developed by the working chamber of the microwave unit that provides the melting of the skin, breaking and separation of the fibers from the fur of fried dross. The working chamber is made in the form of a rotating perforated cylinder containing the inner side surface of the special pins. On the vertical axis of the cylinder, the shaft. On the shaft wearing the stationary pipe, the outer surface of which also has pins. The cylinder is coaxially installed in the cylindrical shielding housing containing an inlet for pneumatic transport fur squares. On the upper base of the body has a generator and the drum dispenser of raw materials. Proposed operational-technological scheme of processing of fur raw materials using electromagnetic fields of ultrahigh frequency. Analyzed electrical parameters of the components of raw materials. One of the proposed variants of the working chamber of the microwave installation, ensuring continuous operation. The working chamber is made as a coaxial screen-roumega housing, the perforated cylinder with pegs and hollow pipe with pegs, inside of which a shaft for rotation of the cylinder.

Natural Convection Heat Transfer From Perforated Hollow Cylinder With Inline and Staggered Holes

The continuity, momentum, and the energy conservation equation for air around a hollow cylinder with inline or staggered holes have been solved in three dimensions to assess the buoyancy driven flow and temperature field around the cylinder. From the thermal field, the average surface Nu could be computed for hollow cylinders with inline or staggered holes and the heat loss from the cylinder could be compared with that of a hollow cylinder without holes. Interesting flow and thermal plume around the hollow cylinder with holes could be seen, which could help to explain why there is more heat loss from a cylinder with staggered holes compared to a cylinder with inline holes at lower Ra of 105, whereas for higher Ra of 106 or more, there exists an optimum d/D where the heat loss from the perforated cylinder has a maximum value and thereafter it reduces. There are interesting comparisons on Nu for the hollow cylinder with inline or staggered holes and new correlations for Nu versus many different pertinent input parameters have been developed for many cases, which can be used practically in industry for designing perforated cylinder with heat loss.

Variations of Hydrodynamic Characteristics With the Perforated Cylinder

Presence of the perforated outer cover on the existing column members of offshore platforms reduces the direct wave impact on these members. Such applications are common in the coastal structures where perforated covers are provided on the seaside to dissipate the wave energy and to reduce the pressure on the members. Detailed studies on the variations of the hydrodynamic characteristics on the inner cylinder, encompassed by a perforated outer cover are scarce in the literature. Present study is focused the development of numerical model to investigate the variations in the water particle kinematics on the inner cylinder encompassed by perforated outer cover. Hydrodynamic characteristics are examined along the water depth through computation fluid dynamics (CFD) for perforation ratios (p%) varying in the range of 10 to 15%. Velocity profiles for different wave steepness are developed along with the design charts for the chosen perforation ratios. These design charts can be readily used for estimating the water particle kinematics for perforated members along the water depth.