Rheometric Tests and Extrusion

1951 ◽  
Vol 24 (3) ◽  
pp. 520-540
Author(s):  
Silvio Eccher
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Laminar Flow ◽  
Experimental Determination ◽  
Power Law ◽  
Reasonable Agreement ◽  
Straight Line ◽  
Flow Through ◽  
The Relationship

Abstract A cylindrical rheometer of the Couette type, suitable for the experimental determination of the rheological properties of extruded materials, was designed to provide data which could not be obtained with existing plastometers. The purpose of this study was strictly practical, as the work was performed in connection with a study of extruders. The results obtained on twenty-five different materials—natural and synthetic rubbers and compounds of both with various fillers—are reported; measurements fall within shear rate limits from 1 to 100 seconds−1. In this interval the relationship between logD (rate of shear) and logτ (shear stress) is nearly a straight line. It may, therefore, be analytically interpreted by the power law : D=−(τ/c)n, where n and c are parameters characteristic of the material. As the power law is known to be of limited validity, attempts were made to ascertain the limits of its application in laminar flow through a cylindrical hole. The results of measurements carried out on a 2-inch extruder and employing the same materials as were tested by the rheometer are reported. Measurements of pressure and flow were made, using discharge holes of various diameters and operating the screw at various speeds. Reasonable agreement was found between values of flow and pressure determined with an extruder and those calculated from parameters n and c determined with the cylindrical rheometer.

Laminar Flow of Non-Newtonian Fluids in Concentric Annuli

1963 ◽  
Vol 3 (04) ◽  
pp. 274-276 ◽  
Author(s):  
Robert D. Vaughn
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Laminar Flow ◽  
Power Law ◽  
Experimental Work ◽  
Newtonian Fluids ◽  
Horizontal Line ◽  
Parallel Plates ◽  
Bingham Plastic ◽  
Fluid Behavior

The limiting cases of non-Newtonian fluids flowing inside a concentric annular duct are developed without using a model of the fluid behavior. The solutions provide limits with which to test the various models of fluid behavior such as the power law and Bingham plastic models. The results of previous theoretical work are discussed in terms of limiting cases. This limiting case study also shows that experimental work on flow of non-Newtonian fluids in annular ducts should be confined to ducts for which the ratio of the radius of the inner wall to that of the outer wall is less than 0.3 and preferably less than 0.2. Introduction During the last 10 years the problem of laminar flow of non-Newtonian fluids in concentric annuli has received much attention largely because of its application to the hydrodynamics of the wellbore. Recently solutions utilizing the power law and Bingham plastic models have been published.In this paper the method of limiting cases, which has been successfully applied to laminar-flow heat transfer will be applied to the problem of flow of non-time dependent, non-Newtonian fluids through annuli. This method permits solutions for the limiting cases to be made without using a model of unknown validity. The solutions, therefore, provide limits with which to test the various models which have been or will be proposed. A pertinent conclusion concerning the region of experimental work is also provided. DEVELOPMENT OF LIMITING CASES The limiting cases for the axial flow of fluids in concentric annuli may be defined with reference to Fig. L It is possible to define two limiting cases which pertain to the physical dimensions of the annulus. First, the annulus must degenerate to a circular pipe as the radius of the inner wall decreases or, as K = (KR/R) - 0. Second, the annulus must approach the limit of parallel plates of infinite extent as the spacing between the inner and outer tubes becomes small in comparison with the radius R of the annulus, or as K - 1. It is also possible to ascertain three limbing cases which pertain to fluid behavior. With reference to Fig. 2, as a fluid becomes progressively more pseudoplastic, the shear stress- shear rate relationship progressively approaches the indicated horizontal line more closely. At this limit the shear stress becomes independent of the shear rate. At the other extreme of increasingly dilatant behavior, the vertical asymptote is approached. Intermediate between these two limiting cases lies the case of the Newtonian fluid. Fluids which exhibit a yield shear stress also approach the limbing case of "infinite" pseudoplastic behavior. SPEJ P. 274^

scholarly journals Experimental determination of noble gases and SF6, as tracers of CO2 flow through porous sandstone

2018 ◽  
Vol 480 ◽  
pp. 93-104 ◽  
Author(s):  
R. Kilgallon ◽  
S.M.V. Gilfillan ◽  
K. Edlmann ◽  
C.I. McDermott ◽  
M. Naylor ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Noble Gases ◽  
Porous Sandstone ◽  
Flow Through ◽  
Co2 Flow

scholarly journals The perforation of the frustules of planktonic diatoms Pseudosolenia calcar-avis and Proboscia alata (Bacillariophyceae)

2019 ◽  
Vol 2 ◽  
pp. 19-26
Author(s):  
Lyakh A.M.
Keyword(s):  
Surface Area ◽  
Geometric Modeling ◽  
Direct Determination ◽  
Entire Surface ◽  
Planktonic Diatoms ◽  
Centric Diatoms ◽  
Flow Through ◽  
Material Energy ◽  
The Relationship

Physiological and biophysical characteristics of microalgae should strongly depend on the surface area of the cover of organisms, as all the material-energy streams flow through the surface. However, to determine the relationship between the intensity of the flow of substances with the physiology of unicellular, it is necessary to take into account only the area of perforations, since the rest of the shell is impermeable for substances. The direct determination of the area of perforations on the entire surface of the microalgae is very difficult. Therefore, the indirect method of estimating the perforation area using geometric modeling of the perforation distribution (texture) on the surface was used in this study. The object of the research is two types of marine plankton diatoms with large cylindrical frustules. It was assumed that the frustules are covered with a regular triangular texture of the areola. This texture can be divided into regular hexagons, which allows us to estimate the number of areolas as the ratio of the surface area of the frustules to the area of one hexagon. The model takes into account that each areola is covered with a silicon plate perforated by a smaller pore. The multiplication of the number of areolas on the area of a given pore gives the value of the total area of perforations. Calculations showed that the perforation of the frustules of Proboscia alata was 4%, and Pseudosolenia calcar-avis – 6%. These are the first estimates of the perforation of the entire surface of the diatom frustules. The acquired data confirms the hypothesis that frustules of the most centric diatoms are covered by pores by about 5%, and the other surface is impervious to material flows.

An Experimental Determination of the Relationship between Lift and Aerodynamic Power in Calliphora Erythrocephala and Phormia Regina

1972 ◽  
Vol 56 (1) ◽  
pp. 31-36
Author(s):  
JAMES WOOD
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Insect Flight ◽  
Phormia Regina ◽  
Calliphora Erythrocephala ◽  
The Relationship

Lift and aerodynamic power were calculated for Calliphora and Phormia using assumptions which maximized and minimized the ratio of aerodynamic power to lift. The ratios of aerodynamic power to lift calculated by these methods, which do not rely on the assumption that steady-state aerodynamics applies to insect flight, are in agreement with results calculated by others using steady-state aerodynamics.

Rheology and structure of blood suspensions

1964 ◽  
Vol 19 (1) ◽  
pp. 127-133 ◽  
Author(s):  
S. E. Charm ◽  
W. McComis ◽  
G. Kurland
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Structural Model ◽  
Cell Suspensions ◽  
Rate Curve ◽  
Red Cell ◽  
Shear Rates ◽  
Straight Line ◽  
Rate Plot

A structural model developed for kaolin suspensions was applied to blood in order to determine the structure and strength of the red cell suspensions. The yield stress of red cell suspensions determined in settling experiments agreed with the yield stress determined from shear stress-shear rate information employing Casson's equation. Theoretical considerations indicate that the shear stress-shear rate curve for blood should approach a straight line. This was found to be true at shear rates above 40 sec-1. The slope of this line was predicted from calculations based on sedimentation experiments and a modified Einstein's equation. The data suggest that the curvature of the shear stress-shear rate plot at low shear rates is due to aggregates of cells which break down under increasing shear rate, resulting finally in individual flocs. It is suggested that a floc consists of one to four cells with adhering plasma. The aggregate was calculated to have twice as much plasma associated with it as does a floc. However, the size of the aggregate could not be determined since the number of flocs associated with an aggregate could not be determined. shear stress-shear rate curve; red cell floc; red cell aggregate; sedimentation rate; blood viscosity and flow Submitted on February 28, 1963

Determination of an effect of 3-chlorophenol on hydroxyl radical generation during ozonation through kinetic study in the power law type

2004 ◽  
Vol 4 (5-6) ◽  
pp. 305-311
Author(s):  
Y.-H. Han ◽  
I. Koshiishi ◽  
H. Utsumi
Keyword(s):  
Power Law ◽  
Ozone Decomposition ◽  
Oh Radical ◽  
Catalytic Intermediates ◽  
Stable Adduct ◽  
Solution Proceeds ◽  
Radical Generation ◽  
Power Law Equation ◽  
The Relationship

Ozone decomposition in aqueous solution proceeds through a radical type chain mechanism. These reactions involve the very reactive and catalytic intermediates hydroxyl (OH) radical, O2− radical, HO2 radical, OH−, H2O2, etc. OH radical is proposed as an important factor in the ozonation of water. In the previous study, generation of OH radical in the ozonation of water containing 3-chlorophenol was mathematically evaluated. In this study, we estimated the kinetic equation for the effect of 3-chlorophenol on OH radical generation during ozonation using the power law equation, in order to analyze it more correctly. The OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO-OH. The relationship between the ozone concentration, 3-chlorophenol content, and the initial velocity (ν0) of DMPO-OH generation was analyzed mathematically, and the following equation was obtained: ν0 (10−6 M/s)=(1.58×10−5)×[3-chlorophenol (10−6 M)]×[ozone (10−6 M)]2.40+(3.09×10−5)×[ozone (10−6 M)]1.72. The equation fitted very well with the experimental results, and square of the correlation coefficient was larger than 0.9.

The theory of ionisation measurements in gases at high pressures

1934 ◽  
Vol 30 (1) ◽  
pp. 80-101 ◽  
Author(s):  
D. E. Lea
Keyword(s):  
High Pressure ◽  
Experimental Determination ◽  
Experimental Technique ◽  
Alpha Particle ◽  
Reasonable Agreement ◽  
High Pressures ◽  
Industrial Research ◽  
Heavy Nuclei ◽  
Nuclear Tracks

The columnar theory developed by Jaffé to account for the recombination of ions in alpha particle tracks is extended to beta rays by taking account of the clusters of secondary ionisation. Reasonable agreement is obtained with experiment. Recombination in proton tracks produced in hydrogen by neutrons is shown to be in agreement with the columnar theory, but in the case of nitrogen nuclear tracks in nitrogen the recombination is only a hundredth of that predicted by the theory. An explanation of this effect is advanced, and it is suggested that recombination is likely to be abnormally small for all heavy nuclei of velocities not exceeding 5 × 108 cm. per sec.An experimental determination of the coefficient of recombination of ions in nitrogen and hydrogen at pressures of 20, 40 and 90 atmospheres is reported.My thanks are due to Dr Chadwick for interest in this work, and to Dr Gray and Dr Tarrant for advice on the experimental technique of high pressure ionisation measurements. I am indebted also to the Department of Scientific and Industrial Research for a maintenance grant.

scholarly journals Selected physical properties of liquid biofuels

2013 ◽  
Vol 59 (No. 4) ◽  
pp. 121-127
Author(s):  
P. Trávníček ◽  
M. Valach ◽  
Z. Hlaváčová ◽  
J. Mareček ◽  
T. Vítěz ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Methyl Ester ◽  
Physical Properties ◽  
Methyl Esters ◽  
Calorific Value ◽  
Diesel Oil ◽  
Rapeseed Methyl Ester ◽  
Control Samples

The goal of this study was the determination of basic physical properties such as density, calorific value and rheological properties of liquid biofuels. Biofuels on the base of bioethanol and rapeseed methyl ester were chosen. Following control samples were selected: diesel oil without admixture of methyl esters and commercially available diesel oils with small amount of methyl ester admixture (6.2 and 6.5%). Dynamic viscosities of individual samples were measured in the range from –10°C to 50°C. Then dependence of shear rate on shear stress was measured at temperatures –10, 0, 20 and 40°C. The most of samples showed the Newtonian behaviour. However, samples with high content of methyl esters or pure methyl esters showed thixotropy behaviour at the low temperature.

Sign in / Sign up

Export Citation Format

Share Document