Effect of spherical internal surface irregularities (SISIs) on thermohydraulic features of modified SSWH riser tube flow

2021 ◽  
Author(s):  
Satish Kumar Dewangan
Keyword(s):  
Internal Surface ◽  
Tube Flow ◽  
Surface Irregularities

Die drool theory

2013 ◽  
Vol 33 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Andrew M. Schmalzer ◽  
A. Jeffrey Giacomin
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Analytical Solution ◽  
Production Rate ◽  
Exact Analytical Solution ◽  
Internal Surface ◽  
Tube Flow ◽  
Cohesive Failure ◽  
Open Face ◽  
Slip Layer

Abstract When molten plastic is extruded from a die, it sometimes collects on the open face of the die. Known as die drool, this phenomenon costs plastics manufacturers by requiring die cleaning. This has been attributed to many causes, but none of these has led to an equation for the drool rate. In this work, we provide an exact analytical solution for the drool rate, and we base this solution on a postulate of a cohesive slip layer near the die walls. We thus attribute die drool to cohesive failure within the fluid at an internal surface where the fluid slips on itself. We adimensionalize the drool rate with the production rate, and call this the buildup ratio, BR. We provide an exact analytical solution for BR when the cohesive slip layer either slips at the die wall, or when it does not. We examine two important extrusion geometries: slit (which we then extend to pipe) and tube flow. We identify two new experiments: one to measure BR as a function of pressure drop, and another as a function of the die aspect ratio, and we then use our new theory to design droolometers.

scholarly journals Internal surface roughness of plastic pipes for irrigation

2017 ◽  
Vol 21 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Hermes S. da Rocha ◽  
Patricia A. A. Marques ◽  
Antonio P. de Camargo ◽  
José A. Frizzone ◽  
Ezequiel Saretta
Keyword(s):  
Surface Roughness ◽  
Roughness Parameter ◽  
Internal Surface ◽  
Low Density Polyethylene ◽  
Pipe Diameter ◽  
Roughness Parameters ◽  
Pressure Losses ◽  
Plastic Pipes ◽  
Irrigation Pipes ◽  
Surface Irregularities

ABSTRACT Assuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC) and low-density polyethylene (LDPE) pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry) and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 μm for PVC and LDPE pipes, respectively.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

The distribution and density of ciliary tufts on the siphons of Anodonta cygnea (Mollusca: Bivalvia)

1990 ◽  
Vol 48 (3) ◽  
pp. 518-519
Author(s):  
Wen-lung Wu
Keyword(s):  
Osmium Tetroxide ◽  
Internal Surface ◽  
Mechanical Stimuli ◽  
Type Ii ◽  
Sensory Receptors ◽  
Anodonta Cygnea ◽  
Type Iv ◽  
Sem Study ◽  
Inhalant Siphon ◽  
Type V

The mantle of bivalves has come entirely to enclose the laterally compressed body and the mantle margin has assumed a variety of functions, one of the pricipal ones being sensory. Ciliary tufts, which are probably sensory, have been reported from the mantle and siphons of several bivalves1∽4. Certain regions of the mantle margin are likely to be more or less, sensitive to certain stimuli than others. The inhalant siphon is likely to be particularly sensitive to both chemical and mechanical stimuli, whereas the exhalant siphon will be less sensitive to both. The distribution and density of putative sensory receptors on the in-and ex-halant siphon is compared in this paper.The excised siphons were fixed in glutaraldehyde and osmium tetroxide, the whole procedure of SEM study is recorded in Wu's thesis.Type II cilia cover the tips of tentacles, 6.13um. Type IV and type V cilia are found on the surface of tentacles. Type IV cilia are occasionally present at the tips of tentacles, 8 um long. They are the commonest type on the surface of tentacles. Type VI cilia occor in the internal surface of the inhalant siphon, but are not found on the surface of tentacles, 6.7-10um long.

Internal surface finishing

2018 ◽  
Author(s):  
JIANG GUO
Keyword(s):  
Internal Surface ◽  
Surface Finishing

This entry introduces five kinds of established internal surface finishing technologies.

Physical and Optical Properties of The Films Ð’i2Te3-Bi2Se3

2015 ◽  
Vol 11 (2) ◽  
pp. 3017-3022
Author(s):  
Gurban Akhmedov
Keyword(s):  
Thin Film ◽  
Optical Properties ◽  
Surface Temperature ◽  
Thermal Evaporation ◽  
Low Voltage ◽  
Internal Surface ◽  
Differential Resistance ◽  
Work Cycle

Results of researches show, that film p-n the structures received by a method of discrete thermal evaporation in a uniform work cycle, are suitable for use in low-voltage devices.  As a result of work are received p-n heterojunctions in thin-film execution, described by high values of differential resistance. Show that, thermo endurance - T0 maybe using as characteristic of thermo endurance of optic materials. If heating flow, destruction temperature and internal surface temperature is measured during test, it is possible to determine value T0 and other necessity characteristics. As a result of the taking test was lead to comparison evaluation of considered materials. Working range of heating flow and up level heating embark have been determined.

SURFACE IRREGULARITIES AS A COMPLEX SIGNAL OF TOOL REPRESENTATION TOGETHER WITH UNEVEN DISPLACEMENT IN RESPECT TO THE WORKPIECE

2014 ◽  
Vol 21 (1) ◽  
pp. 133-144 ◽  
Author(s):  
Adam Boryczko ◽  
Wojciech Rytlewski
Keyword(s):  
Machining Process ◽  
Surface Irregularity ◽  
Complex Signal ◽  
Complex Phenomenon ◽  
Tool Profile ◽  
Surface Irregularities ◽  
The Individual ◽  
Frequency Functions

Abstract In a dynamic machining process, distortion in surface irregularity is a very complex phenomenon. Surface irregularities form a periodic representation of the tool profile with various kinds of disturbance in a broad range of changes in the height and length of the profile. To discern these irregularity disturbances, interactions of the tool in the form of changes perpendicular and parallel relative to the workpiece were analyzed and simulated. The individual kinds of displacement of the tool relative to the workpiece introduce distortions in the changes of height and length. These changes are weakly represented in standard height and length irregularity parameters and their discernment has been found through amplitude-frequency functions.

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