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1.
L. A. Kovaleva N. M. Nasyrov V. I. Maksimochkin R. R. Suf'yanov 《Journal of Applied Mechanics and Technical Physics》2005,46(6):851-856
A mathematical model is developed to numerically predict the heating of heavy hydrocarbon systems. A comparative analysis
of numerical and experimental data is performed. It is found that the thermal conductivity of a hydrocarbon system under study
heated from an initial temperature of 24°C to 100°C increases by a factor of 40 and, with allowance for free convection, an
additional substantial (up to 16 times) increase in heat transfer due to enhanced effective thermal conductivity is observed.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 96–102, November–December, 2005. 相似文献
2.
The effect of temperature on the interfacial tension for PS/PMMA, PS/PE, and PMMA/PE was measured using the imbedded fiber
retraction method. Interfacial tensions for PS/PMMA, PS/PE, and PMMA/PE were measured over temperature ranges of 160–250 °C,
140–220 °C, and 140–220 °C, respectively. The interfacial tension was found to follow a dependence of 3.6–0.013 T dyn/cm, 7.6–0.051 T dyn/cm and 11.8–0.017 T dyn/cm for PS/PMMA, PS/PE, and PMMA/PE, respectively. Comparison of the data with the mean field theory of Helfand and Sapse
were made; however, a simple linear fit to the data described the temperature dependence in the experimental window as well
as the predictions of the mean field theory.
Received: 6 July 1999 Accepted: 23 March 2000 相似文献
3.
The purpose of this study is to investigate the effects of various bimodal pore size distributions of biporous wicks for a
loop heat pipe (LHP). The study was conducted following a statistical method using a two-level factorial plan involving three
variables (particle size of pore former:74–88 and 125–149 μm Na2CO3, pore former content:20% by volume and 25% by volume, sintering temperature:700 and 750°C). Finally, the heat transport capability
of the LHP between monoporous wicks and biporous wicks has been investigated. Experimental results show that, at the sink
temperature of 10°C and the allowable evaporator temperature of 80°C, the heat transfer capacity of the better biporous wick
achieved 200 W and the total thermal resistance was 0.31°C/W. The performance is enhanced about 60%, compared to a monoporous
wick for 125 W and 0.53°C/W. Therefore, LHPs with biporous wicks are very attractive for high heat flux applications in the
future. 相似文献
4.
V. I. Bukreev 《Journal of Applied Mechanics and Technical Physics》2006,47(2):169-174
This paper gives results of two experiments in which warmer water in the form of a vertical plane jet was let into colder
water. In one experiment, the temperature of inflowing and initially quiescent water exceeded 4°C and warm water propagated
only along the free surface. In the other experiment, the temperature of inflowing water was above 4°C and that of quiescent
water was below 4°C. In this case, two jets — surface and bottom — first formed, and then the inflowing liquid was entirely
concentrated in the bottom jet.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 2, pp. 23–29, March–April, 2006. 相似文献
5.
A. Yu. D’yachenko V. I. Terekhov N. I. Yarygina 《Journal of Applied Mechanics and Technical Physics》2007,48(4):486-491
Convective heat transfer in a transverse cavity with a small aspect ratio, angle of wall inclination ϕ = 30–90°, and heated
bottom, frontal, and rear walls of the cavity is studied experimentally. Temperature distributions are measured in longitudinal
and transverse sections on three walls; temperature fields are measured over the entire heated surface. Local and mean heat-transfer
coefficients are calculated. The highest intensification of heat transfer is found to occur on the rear wall for low values
of ϕ Reconstruction of the one-cell structure to the two-cell structure of the primary vortex in the cavity leads to a drastic
decrease in heat transfer over the cavity span from the end faces toward the center in the case with ϕ = 60 and 70°. A certain
increase in the mean heat-transfer coefficient averaged over the entire heated surface is noted for ϕ = 60°.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 4, pp. 23–29, July–August, 2007. 相似文献
6.
M. C. J. Coolen R. N. Kieft C. C. M. Rindt A. A. van Steenhoven 《Experiments in fluids》1999,27(5):420-426
The application of Laser Induced Fluorescence (LIF) for temperature measurements in water using a Nd : YAG laser is investigated.
A natural convection problem is used to test the applicability of LIF in the temperature range of 20–60°C. The measured temperature
field is compared with numerical results and the influences of shadowgraph effects on the measured temperature field are investigated.
An accuracy of 1.7°C is attained if shadowgraph effects can be neglected. This only holds if correction for photobleaching
and variation of laser power output is applied.
Received: 8 July 1998/Accepted: 3 February 1999 相似文献
7.
Andréas Redl Marie Hélène Morel Joëlle Bonicel Stéphane Guilbert Bruno Vergnes 《Rheologica Acta》1999,38(4):311-320
The rheological behaviour of a gluten plasticized with glycerol has been studied in oscillatory shear. The mixing operation
in a Haake batch mixer leads to a maximum torque for a level of specific energy (500–600 kJ/kg) and temperature (50–60 °C)
quite independent of mixing conditions (rotor speed, mixing time, filling ratio). The gluten/glycerol dough behaves as a classical
gluten/water dough, with a storage modulus higher than the loss modulus over the frequency range under study. A temperature
increase induces a decrease of moduli, but the material is not thermorheologically simple. Glycerol has a plasticizing effect,
which can be classically described by an exponential dependence. Mixing conditions influence the viscoelastic properties of
the material, mainly through the specific mechanical energy input (to 2000 kJ/kg) and temperature increase (to 80 °C). Above
50 °C, specific mechanical energy highly increases the complex modulus. The aggregation of proteins, as evidenced by size-exclusion
chromatography measurements, occurs later as the dough temperature reaches 70 °C. The nature of network interactions and the
respective influence of hydrophobic and disulphide contribution is discussed. A general expression is proposed for describing
the viscous behaviour of a gluten/glycerol mix, which could seem simplistic for such a complex rheological behaviour, but
would remain sufficient for modelling the flow behaviour in a twin screw extruder.
Received: 24 November 1997 Accepted: 28 April 1999 相似文献
8.
9.
H. J. Seuntiëns R. N. Kieft C. C. M. Rindt A. A. van Steenhoven 《Experiments in fluids》2001,31(5):588-595
A technique is described to measure the instantaneous 2D temperature distribution in the wake of a heated cylinder using
`laser-induced fluorescence'. Rhodamine B, a fluorescent dye, is used as a temperature indicator. The relation between fluorescence
intensity and temperature is determined by means of calibration experiments in the temperature range of 20–35 °C with an accuracy
of ±0.1 °C. The temperature distribution behind the heated cylinder is well visible and can be measured with a high spatial
resolution. Corrections for variation in laser energy and intensity distribution in the laser sheet have to be made to further
improve the accuracy of the measuring method.
Received: 3 January 2001/Accepted: 18 May 2001 相似文献
10.
Martin Sentmanat Omar Delgadillo-Velázquez Savvas G. Hatzikiriakos 《Rheologica Acta》2010,49(9):931-939
In this paper, the effect of uniaxial extension on the crystallization of an ethylene-based butane plastomer is examined by
using rheometry coupled with differential scanning calorimetry (DSC). Uniaxial extension experiments were performed at temperatures
below and above the peak melting point of the polyethylene in order to characterize its flow-induced crystallization behavior
at extensional rates relevant to processing. The degree of crystallinity of the stretched samples was quantified by DSC, i.e.,
by analyzing the thermal behavior of samples after stretching. Analysis of the tensile strain-hardening behavior very near
the peak melt temperature revealed that crystallization depends on temperature, strain, and strain rate. In addition, it was
revealed that a very small window of temperatures spanning just 1–2°C can have a dramatic effect on polymer crystallization.
Finally, flow-induced crystallization experiments at temperatures close to the peak melting point have shown the recrystallization
of multiple crystalline structures within a polymer matrix, witnessed by double peaks within a narrow window of 89–93°C in
the DSC thermographs, with the most demonstrable double peak behavior occurring at a temperature of 91°C, a temperature that
is just 1°C cooler than the peak melt temperature of the polymer. 相似文献
11.
Experimental investigation on the sensible effectiveness of LiCl wheel is reported. The measurements were made for balanced
flow (C* = 1) for a wide range of rotational speed 0–10 rpm, regeneration temperature of 50–70°C and airflow rate 150–550 kg/h.
The results revealed that the operation rotational speed for LiCl wheel is about 5 rpm which is significantly lower that for
Silica gel wheel. It is also found that the sensible effectiveness is independent of the regeneration temperature. The experimental
results are also fitted to the existing correlation of Simonson et al. (ASHRAE Trans 106(1):301–310, 2000). For the range
of the applicability of the correlation, most of the experimental data fit the correlation within an error band of ±5%. 相似文献
12.
O. V. Sosnin B. V. Gorev I. V. Lyubashevskaya 《Journal of Applied Mechanics and Technical Physics》1999,40(6):1133-1137
Experimental results for high-temperature deformation of an iron-based structural material in the temperature ranges including
the points of the Feα→Feβ→Feψ transition are given. It is shown that the strain-strength properties of the material change nonmonotonically on the interval
700°C<T<1000°C and that the internal phase-structural changes exert an effect on the thermal effects. Approximating dependences
that permit one to describe deformation processes in the indicated temperature ranges upon uniaxial loading are proposed.
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 6, pp. 152–156, November–December, 1999. 相似文献
13.
Asterios Pantokratoras 《Transport in Porous Media》2009,76(3):309-325
A steady laminar boundary layer flowing along a vertical plate immersed in a Darcy–Brinkman porous medium saturated with water
at 4°C is studied. The plate temperature varies sinusoidally along the plate between 0 and 8°C where the density of water
varies parabolically and is almost symmetrical at about 4°C. Except for the existence of the buoyancy force, it is assumed
that either the plate moves upwards or the ambient water moves upwards (moving stream). The results are obtained with the
direct numerical solution of the boundary layer equations taking into account the temperature dependence of water thermophysical
properties (ρ, μ and c
p). Results are presented for the wall temperature gradient and the wall shear stress along the plate for free convection and
mixed convection. Temperature and velocity profiles are also presented. 相似文献
14.
G. G. Savenkov 《Journal of Applied Mechanics and Technical Physics》2005,46(6):857-860
Results of dynamic rupture tests of a series of metals obtained using a composite Hopkinson bar and shock-wave loading of
plane specimens are described. It is shown that the actual rupture strength at a strain rate of 5 · 103 sec−1 is very close to the spall strength at higher strain rates. Results of testing the same metals using a composite Hopkinson
bar within a temperature range of 20–350°C are given.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 103–107, November–December, 2005. 相似文献
15.
İbrahim Doymaz 《Heat and Mass Transfer》2011,47(3):277-285
The effect of blanching and drying temperature (50, 60 and 70°C) on drying kinetics and rehydration ratio of sweet potatoes
was investigated. It was observed that both the drying temperature and blanching affected the drying time and rehydration
ratio. The logarithmic model showed the best fit to experimental drying data. The values of effective moisture diffusivity
and activation energy ranged from 9.32 × 10−11 to 1.75 × 10−10 m2/s, and 22.7–23.2 kJ/mol, respectively. 相似文献
16.
Andreja Zupančič Valant Lovro Žiberna Yannis Papaharilaou Andreas Anayiotos Georgios C. Georgiou 《Rheologica Acta》2011,50(4):389-402
During the complicated cardiac surgery on a non-beating heart with cardiopulmonary bypass, protection of the heart is accomplished
by injecting cold cardioplegic solutions. In most forms of circulatory shock, it is necessary to immediately restore the circulating
volume. Intravenous solutions of volume expanders, such as hydroxyethyl starch and dextrans, are used to increase the volume
of fluid in the circulating blood. In this work, blood samples of six donors were obtained and used to prepare mixtures with
different volume expanders in concentrations ranging from 10 to 50 vol./vol.%. The flow curves of all mixtures in the temperature
range from 4°C to 37°C were constructed and fitted to the Herschel–Bulkley model, in order to extract the shear thinning and
yield stress parameters. To assess the influence of the observed changes in the rheological properties of blood on the hemodynamics
in arterial vasculature, a realistic three-dimensional rigid-wall computational model was constructed from MRI images of the
right carotid bifurcation obtained in vivo from a healthy male volunteer. The time-varying flow field was numerically computed
using the Newtonian model as well as the Herschel–Bulkley model with the Papanastasiou regularization. The numerical simulations
indicate only moderate changes in the time-averaged flow field that become accentuated when the instantaneous flow field is
considered. We also found that although the influence of temperature, hematocrit, and volume expanders on hemodynamics is
significant, this can primarily be attributed to the changes in the nominal viscosity of the flow medium. 相似文献
17.
Fatigue of the Near-Alpha Ti-Alloy Ti6242 总被引:1,自引:0,他引:1
Ti6242 is the workhorse of high-temperature Ti-alloys in the high pressure compressor of aero engines. In this study the influence
on isothermal fatigue of different load controls, i.e. stress, total strain and plastic strain control at different temperatures
and environments was investigated. The alloy had a bi-modal microstructure (some 30 vol.% primary alpha), which yields a good
balance between fatigue and creep properties. In addition thermomechanical fatigue (TMF) tests were also performed. Modelling
lifetime on the basis of a Basquin–Coffin–Manson relationship revealed only marginal scattering in the temperature range between
350°C and 650°C. Increasing the temperature led to a decrease in lifetime. This can be attributed to increased oxidation and
creep. The latter one is clearly seen in isothermal tests under stress control. Tests in vacuum resulted in longer lifetimes.
In-phase TMF tests exhibited a longer lifetime than out-of-phase tests, with a factor of about 4. Lifetime and stress response
of in-phase tests are similar to the corresponding lifetime of an isothermal test at the maximum temperature. This similarity
can be considered as a starting point for modelling TMF behaviour on the basis of isothermal fatigue. 相似文献
18.
The modified imbedded disc retraction method for measurement of interfacial tension in polymer melts
The imbedded disc retraction method is used to estimate interfacial tension in LLDPE/PS system with PS as the imbedded disc.
Shape evolution of a disc of one material (PS) imbedded into the matrix of another material is observed (LLDPE). Three to
five repetitions at three different temperature levels are observed. The Newtonian model of Rundqvist et al. (1996) for the
imbedded disc retraction is modified to include elastic effects. The modified model is derived assuming uniaxial extension,
starting with the lower convected Maxwell model. Both the original model and modified imbedded disc retraction model are used
in data analysis. The mean values of interfacial tension at 190 °C, 200 °C, and 210 °C are 6.8 ± 0.7 mN/m, 3.9 ± 0.3 mN/m,
and 3.7 ± 0.2 mN/m, respectively. A method of estimating whether elastic effects will significantly affect the estimated interfacial
tension value during retraction for the given polymer pair is provided.
Received: 6 August 1999 Accepted: 2 January 2001 相似文献
19.
20.
Sayed Z. Mohammady 《Rheologica Acta》2007,46(8):1109-1119
To determine the impact of molecular architecture on the molecular dynamics of the glass relaxation processes of soft blocks
in different types of block copolymers, model block copolymers with a variation in both molecular architecture and chemical
composition were studied. Four block copolymer models, namely, two styrene–butadiene–styrene (S-B-S) block copolymers and
two styrene–styrene butadiene–styrene (S-SB-S) were chosen. In each pair of block copolymers, one is linear triblock and the
other is star asymmetric. For the sake of comparison, two polybutadiene (PB) homopolymer samples, having similar chain lengths
of the PB blocks present in the S-B-S block copolymers, have been investigated. Dynamic mechanical measurements have been
carried out for the real and imaginary parts of the complex shear modulus (G′, G”) in the temperature and frequency ranges from −110 to 30 °C and from 10−2 to 15.9 Hz, respectively. Complete master curves have been constructed for all samples investigated. Moreover, broadband
dielectric spectroscopy has been carried out to cover wide temperature and frequency windows, −120 to 0 °C and 10−1 to 107 Hz, respectively. The results showed that the molecular dynamics of the glass relaxation process of the PB or statistical
PSB soft phases in the block copolymers is dramatically changed when compared to the PB homopolymer. In addition, the molecular
architecture is found to be an important factor in determining the molecular mobility of the soft blocks. The results are
discussed in terms of the applied confinement of the counter PS hard phase, block lengths, domain thicknesses and the type
of end-to-end junctions between the different polymeric blocks.
Paper presented 3rd Annual European Rheology Conference (AERC 2006) April 27–29, 2006, Crete, Greece. 相似文献