共查询到20条相似文献,搜索用时 171 毫秒
1.
2.
3.
4.
5.
6.
基于多松弛格子Boltzmann模型,对竖直细长微通道内颗粒自由沉降过程进行模拟,分析气体稀薄效应、初始位置以及颗粒间相互作用对微颗粒沉降特性的影响.研究表明:随Knudsen数增大,微通道内气体稀薄效应增强,颗粒表面气体滑移速度增大,气相流体有效粘度减小,颗粒相同运动状态下受到气体阻力相应减小,颗粒沉降平衡速度明显增大;不同初始位置颗粒沉降过程存在明显差异,初始位置偏离中心线颗粒将发生水平方向位移且呈振荡趋势,最终稳定于中心线平衡位置;在微尺度双颗粒沉降DKT现象过程中,气体稀薄效应影响颗粒运动特性,后颗粒跟随过程明显增长. 相似文献
7.
以微钝尖锥为飞行器前缘模型,采用基于分子运动论的DSMC方法模拟不同前缘曲率半径的尖锥在高超声速来流下的气动热环境,计算驻点热流率,并与Fay-Riddell公式和其他修正理论作对比,研究具有局部稀薄气体效应的高超声速尖锥气动加热特征及其变化规律.发现修正的Cheng参数适合作为工程上判断驻点区域稀薄气体效应影响大小的判据. 相似文献
8.
9.
10.
11.
Mehdi Baniasadi Saeed Amir Aslanzadeh Maryam Baniasadi Sattar Ghader 《Journal of Engineering Thermophysics》2016,25(1):143-150
A new equation of state (IR EOS) recently reported for liquids and gases has been utilized to predict the densities of some energy carriers at different temperatures, pressures. The ability of IR EOS is examined by comparing its results with experimental data for some energy carriers in homogeneous gas, homogeneous liquid and gas–liquid transition region from low to very high pressures. The IR EOS gives excellent results in homogenous gas and homogeneous liquid region while its predictions in gas–liquid transition have more deviations. The average absolute deviation between calculated and experimental densities for 968 data points of 12 energy carriers is 0.33% over the entire range of data with a maximum pressure of 1000 MPa. 相似文献
12.
13.
Dwain E. Diller 《Physica A》1980,104(3):417-426
The shear viscosity coefficient of compressed gaseous and liquid methane has been measured at temperatures between 100 and 300 K and at pressures up to 30 MPa (4350 psia) with a torsionally oscillating quartz crystal viscometer. The estimated precision and accuracy of the measurements are about 0.5% and 2%, respectively. The measurements have been compared with an equation previously proposed for calculating the viscosity of gaseous and liquid methane. Most of the differences between the equation and the measurements reported here are within our experimental error. Larger differences (up to 6%) are reported at the lowest temperature (100 K) and high pressures, and along a supercritical isotherm at 200 K (T ≈ 1.05 Tc). 相似文献
14.
Evan H. Abramson 《高压研究》2013,33(4):544-548
A rolling-sphere technique has been used to measure shear viscosities of (supercritical) fluid argon in the diamond-anvil cell between the temperatures of 294 and 673 K, up to a maximum pressure of 5 GPa. At these pressures, the viscosities can be fit to a modified free-volume expression. A single correlation between reduced viscosity and reduced residual entropy is shown to give a good account of the current high pressure data, data at lower pressures and those for the sub-critical liquid. 相似文献
15.
The values of the shear viscosity of simple dense gases at room temperature up to 6000 bar, measured by the authors, have been compared to values calculated with statistical models: Lennard-Jones, Van-der-Waals and hard sphere dense fluids. The values from molecular dynamic modeling of Couette flow, for a Lennard-Jones system, along temperature) are in agreement with the experimental values of shear viscosity of helium and neon.With the hard sphere model the difference between the values calculated from the Kubo relation with the equilibrium molecular-dynamic calculations and experimental values for the noble gases has not the same representation according as the gas is at high or low reduced temperature. For this model some corrections have been calculated. 相似文献
16.
17.
Abstract The dynamic viscosity η of the binary mixture tridecane + 2,2,4,4,6,8-heptamethyl-nonane has been measured in the temperature range 293.15-353.15K (in progressive 10 K steps) at pressures 0.1,20,40,60,80 and 100 MPa. The system is described by 9 molar fractions (0 to 1 in 0.125 progressive steps). The density ρ has been measured at pressures from 0.1 to 65 MPa in progressive 5 MPa steps. The whole set of experimental data represents 378 points for η and 882 for ρ. The measurements of η allow to determine the excess viscosity ηE and the excess activation energy of viscous flow ΔGE versus pressure, temperature and composition. 相似文献
18.
The thermal conductivity of gaseous nitrogen, methane and carbon dioxide has been measured at room temperature and at pressures up to 35 MPa in the cases of nitrogen and methane and up to 5 MPa in the case of carbon dioxide. A transient hot-wire technique was used, which has been described previously. The curves of thermal conductivity versus density for all three gases are found not to be expressible as a polynomial expansion, which is probably due to changes in energy-relaxation behavior with pressure. In the case of carbon dioxide, which was studied close to its critical temperature, some vestiges of anomalous behavior associated with the critical point can be seen. Accurate Eucken factors for the three gases are given. In the case of nitrogen, the experimental value is found to be somewhat below recent predictions. 相似文献
19.
根据热力学面上流体无量纲化剩余迁移性质曲线与对比密度曲线的相似性,通过关联无量纲化剩余导热系数和粘度与对比密度的方程,提出了一个推算卤代烃制冷工质稠密流体迁移性质状态方程。在常压下迁移性质计算的基础上,应用该方程只要已知物质的临界参数、分子量和偏心因子便可以计算稠密流体(气相或液相)的导热系数和粘度。该方法的提出使得迁移性质的计算像平衡性质一样通过状态方程便可以求出。与实验数据比较,本方法计算导热系数的总平均偏差为 4.8%,最大偏差为18.0%;计算粘度的总平均偏差为4.4%,最大偏差为 15.6%。 相似文献
20.
DING Chunfeng & XING Da Institute of Laser Life Science South China Normal University Guangzhou China 《中国科学G辑(英文版)》2004,47(4):513-520
Large oscillations of gas and vapor filled bubbles in liquid during acoustic cavitation. This highly nonlinear bubble motion is accompanied by the emission of light-sonoluminescence (SL)[1, 2]. The noble gases inside the bubble can influence the SL[3—5]. At an acoustic pressure, the intensity of SL increases with the molecular mass of noble gas inside the bubbles[6]. There are several kinds of theories about SL mechanism. At present, the bremsstrahlung mechanism is widely admitted. The b… 相似文献