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221.
绿色金属加工用油的开发与发展趋势 总被引:3,自引:0,他引:3
本文论述了绿色金属加工油液的发展概况,开发的必要性和可能性,介绍了几种绿色金属加工油液和几种添加剂的性能测试结果,并提出了相关建议. 相似文献
222.
The combined effects of couple stresses and surface roughness on the performance characteristics of hydrodynamic lubrication of slider bearings with various film shapes, such as plane slider, exponential, secant and hyperbolic, are studied. A stochastic random variable with non-zero mean, variance and skewness is used to mathematically model the surface roughness of the slider bearing’s. The Stokes couple stress fluid model is used to characterize the rheological behavior of the lubricant with polymer additives. The modified expressions for the bearing characteristics, namely pressure, load carrying capacity, center of pressure, frictional force are obtained for the general lubrication film shape on the basis of Stokes microcontinuum theory for couple stress fluids. Results are computed numerically for various film shapes under consideration. It is observed that, for all the lubricant film shapes under consideration, the negatively skewed surface roughness increases the load carrying capacity, frictional force and temperature rise, while it reduces the coefficient of friction. On the contrary, the reverse trend is observed for positively skewed surface roughness. Further, these effects are more pronounced for the couple stress fluids. 相似文献
223.
224.
A systematic research about the liquefaction of alkali lignin in supercritical ethanol using ZSM‐5 zeolite catalysts is reported, which includes the synergistic effect of temperature, catalytic content, and reaction time on product yield and distribution. Fourier transform infrared and gas chromatography‐mass spectrometry analysis were carried out to evaluate the compositions of bio‐oil and solid residue. Under moderate condition, maximum conversion and yield of bio‐oil were satisfactorily high. With the help of ZSM‐5 catalyst, lignin could be successfully converted into aromatic compounds. 相似文献
225.
为了研究磁流变液在圆筒剪切模型中的流变特性,建立了以圆筒剪切模型为基础的实验装置。首先,通过理论分析得到了磁流变液在圆筒剪切模型中的层间传力模型,切应力和剪切速率测量方法。其次,通过ANSYS对圆筒剪切模型中磁流变液的磁场强度进行了仿真模拟,并以实验测量验证,得到了磁场强度分布。最后以理论分析为基础,通过实验测量得到了切应力与剪切速率和磁场强度之间的关系,并得到了拟合公式。实验表明,磁流变液流切应力与磁场强度的比值为0.162k Pa/m T,与剪切度率的比值为0.00026k Pa·s,磁场强度的增强能够较大地提升磁流变液的工作能力。 相似文献
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227.
This paper describes a methodology for measuring rheological flow properties in-line, in real-time, based on simultaneous measurements of velocity profiles using an ultrasound velocity profiling (UVP) technique with pressure difference (PD) technology. The methodology allows measurements that are rapid, non-destructive and non-invasive and has several advantages over methods presented previously. The set-up used here allows direct access to demodulated echo amplitude data, thus providing an option to switch between time domain algorithms and algorithms based on FFT for estimating velocities, depending on the signal-to-noise ratio (SNR) and time resolution required. Software based on the MATLAB® graphical user interface (GUI) has been developed and provides a powerful and rapid tool for visualizing and processing the data acquired, giving rheological information in real-time and in excellent agreement with conventional methods. This paper further focuses on crucial aspects of the methodology: implementation of low-pass filter and singular value decomposition (SVD) methods, non-invasive measurements and determination of the wall positions using channel correlation and methods based on SVD. Measurements of sound velocity and attenuation of ultrasound in-line were introduced to increase measurement accuracy and provide an interesting approach to determine particle concentration in-line. The UVP-PD methodology presented may serve as an in-line tool for non-invasive, real-time monitoring and process control. 相似文献
228.
In this work, the annular (tangential) flow of Newtonian and non‐Newtonian fluids in tube bundles has been studied experimentally. Extensive pressure drop data has been obtained embracing wide ranges of the Reynolds number (13–6600) and for two test modules of different geometrical arrangements, but of similar overall void fraction. Preliminary experiments suggest that the pressure drop is mainly determined by the overall void fraction of the bundle and is relatively insensitive to the detailed geometrical configuration of the bundle. A simple predictive correlation has been developed which reconciles the present results for Newtonian and power law fluids with acceptable levels of reliability. 相似文献
229.
Nonequilibrium molecular dynamics calculations of the shear viscosity of supercritical carbon dioxide along the 313 K isotherm are reported. Three different intermolecular potential models of increasing complexity are considered: a spherically symmetric Lennard-Jones potential, a two-site Lennard-Jones potential, and a three-site potential which includes a quadrupole-quadrupole moment. Results for the three potentials are compared with experimental data.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A. 相似文献
230.
The controllability of the magneto-rheological fluid (MRF) flowing through a micro-pipeline is analyzed. The coupled formulas
for MRF are deduced by analyzing the property of the flow field and magnetic field. Then, the relationship between the flow
speed of MRF and the special shear stress under the effect of the magnetic field is founded. The model of the MRF and micro-pipeline
is established by using multi-physics software of Comsol, the curve of V - A in an ideal condition is attained by modifying parameters, and by adding the boundary condition of the model. This paper
provides a theoretical proof of the controllability of MRF flowing through the micro-pipeline and explores MRF’s application
on the micro-drive and control field. 相似文献