电磁阀的有限元法磁场分析及吸力计算

提出了电磁阀的吸力计算公式 ,建立了电磁阀的二维有限元模型 ,利用模型进行了计算软件的设计 .运用此软件对某公司生产的SRS电磁阀进行了磁场分析和电磁力计算 ,通过比较发现计算结果与测试结果吻合较好 .同时给出了电磁力和功耗随导线线径、匝数变化的关系曲线 ,讨论了电磁力和功耗与导线线径和匝数之间的关系 .

两个磁极面积大小不等时对电磁吸力计算的影响

两个磁极面积大小不等时对电磁吸力计算的影响（４３００７４）广州日报技术设备处左才工华中理工大学左全璋１前言一般文献大都探讨两个磁极面积相等的电磁吸力计算。本文讨论两个磁极面积不等时对吸力计算的影响，并提出考虑这种影响的计算图１方法。２气隙磁导与吸力计...

基于非饱和土压强度计算模型的水利工程土湿吸力计算

采用非饱和土压强度计算模型对水利工程设计土湿吸力进行计算,并分析其影响因素。结果表明:非饱和土压强度计算模型在土湿吸力计算时具有较好的精度,误差低于5%。含水率是土体湿吸力主要影响因素,随着含水率增加土湿吸力逐渐减小,呈现负相关性;土体抗剪强度随着土湿吸力增加而递增,呈现正相关性。

基质吸力对黄河大堤非饱和土渗透能力的影响

针对测定非饱和土基质吸力计算较难的问题,制作了非饱和土三轴仪测定非饱和土吸力,采用直接与间接法测定非饱和土渗透系数。以黄河大堤险工段饱和非饱和土为例,分析了基质吸力、含水率及渗流系数间的关系,获得了基质吸力对非饱和土渗透能力的影响,为堤防渗透稳定性评价及预测提供了依据。

烟酒物流配送系统分拣机械手的搬运稳定性的应用分析

工业机器人或称机械手,在物流配送分拣领域也得到了广泛的应用。真空技术常用于机械手夹持抓取工件的部位;机械手夹持装置安装于机械手的末端,和工件直接接触,夹持装置的性能直接影响到机械手的性能,对生产效率影响很大。影响机械手搬运稳定性的关键因素为搬运动力来源和搬运平台机构,因此,本文研究的重点放在了机械手的真空系统和搬运平台机构这两个方面。

CFD simulation of ammonia-based CO_2 absorption in a spray column

A comprehensive computational fluid dynamics（CFD） model is developed based on the gas-liquid two-phase hydrodynamics,gas-liquid mass-transfer theory and chemical reaction kinetics,and the ammonia-based CO2 absorption in a spray column is numerically studied.The Euler-Lagrange model is applied to describe the behavior of gas-liquid twophase flowand heat transfer.The dual-film theory and related correlations are adopted to model the gas-liquid mass transfer and chemical absorption process.The volatilization model of multi-component droplet is utilized to account for ammonia slippage.The effect of operation parameters on CO2 removal efficiency is numerically studied.The results showa good agreement with the previous experimental data,proving the validity of the proposed model.The profile studies of gasphase velocity and CO2 concentration suggest that the flowfield has a significant impact on the CO2 concentration field.Also,the local CO2 absorption rate is influenced by both local turbulence and the local liquid-gas ratio.Furthermore,the velocity field of gas phase is optimized by the method of adjusting the orifice plate,and the results showthat the CO2 removal efficiency is improved by approximately 4%.

Effects of expanding zone parameters of vacuum dust suction mouth on flow simulation results

Based on the parametric analysis of the expanding zone of the vacuum dust suction mouth,the flow in the vacuum dust suction mouth was simulated by computational fluid dynamics(CFD)software,Fluent.The effects of the expanding zone parameters on flow simulation were analyzed.The results show that simulation effects depend on threshold values of the expanding zone parameters of the dust suction mouth,and the threshold values of the expanding zone can be obtained according to the different structures of the vacuum dust suction mouth and be selected as the geometric parameters in calculating,and also corners of the expanding zone make unobvious difference in calculation accuracy and in computational efficiency compared with no corner.The simulation results provide practical guidance to the flow simulation on the dust suction mouth.

Rotordynamic forces generated by discharge-to-suction leakage flows in centrifugal pumps

In order to investigate the flow-induced vibration in the shroud passage of centrifugal pump and predict rotordynamic forces of centrifugal pump rotor system, an analysis of rotordynamic forces arising from shrouded centrifugal pump is presented. CFD techniques were utilized to analyze the full three-dimensional viscous, primary/secondary flow field in a centrifugal pump impeller to determine rotordynamic forces. Multiple quasisteady solutions of an eccentric three-dimensional model at different whirl frequency ratios yielded the rotordynamic forces. The skew-symmetric stiffness, damping, and mass matrices were obtained by second-order leastsquares analysis. Simulation of the coupled primary/secondary flow field was conducted, and the complex flow characteristics in the flow field of a shroud passage were achieved including the mean velocity and pressure, as well as the eddy in a large scale of flow field due to viscosity. The rotordynainic force coefficients were calculated, and the resuhs were in good agreement with those of experiment except for the direct inertial coefficient without the consideration of whirling forces from the impeller primary flow passage.

Computational fluid dynamics simulation on the longwall gob breathing

In longwall mines, atmospheric pressure fluctuations can disturb the pressure balance between the gob and the ventilated working area, resulting in a phenomenon known as ‘‘gob breathing". Gob breathing triggers gas flows across the gob and the working areas and may result in a condition where an oxygen deficient mixture or a methane accumulation in the gob flows into the face area. Computational Fluid Dynamics(CFDs) modeling was carried out to analyze this phenomenon and its impact on the development of an explosive mixture in a bleeder-ventilated panel scheme. Simulation results indicate that the outgassing and ingassing across the gob and the formation of Explosive Gas Zones(EGZs) are directly affected by atmospheric pressure changes. In the location where methane zones interface with mine air, EGZ fringes may form along the face and in the bleeder entries. These findings help assess the methane ignition and explosion risks associated with fluctuating atmospheric pressures.

Numerical simulation of particle deposition in obstructive human airways

To investigate airflow pattern and its impact on particle deposition, finite-volume based computational fluid dynamics （CFD） simulations were conducted in the diseased triple-bifitrcation airways. Computations were carried out for twenty Reynolds numbers ranging from 100 to 2 000 in the step of 100. Particles in the size range of 1-10 μm were conducted. Two particle deposition mechanisms （gravitational sedimentation and inertial impaction） were considered. The results indicate that there are strong relationship between airflow structures and particle deposition patterns. Deposition efficiency is different for different particles in the whole range of the respiratory rates. Particles in different sizes can deposit at different sites. Smaller particles can be uniformly deposited at the inside wall of the considered model. Larger particles can be mainly deposited in the proximal bifurcations. Deposition fraction varies a lot for different inlet Reynolds numbers. For lower Reynolds numbers, deposition fraction is relatively small and varies a little with varying the diameters. For Reynolds number to target the aerosols at the specific site. higher Reynolds numbers, there is a most efficient diameter for each

Reducing the Gas Pressure Drop in Suction Mufflers of Hermetic Reciprocating Compressors

The suction muffler of hermetic reciprocating compressors is installed in order to attenuate the noise generated by the gas pulsation of the flow through the suction valve. However, the installation of the suction muffler affects the operation of the compressor owing to gas pressure drop, which causes volumetric and energetic efficiency loss due to the gas specific volume augmentation. Therefore, there is a compromise between sound attenuation and pressure drop increase, which has to be taken into account by compressor designers. In this work, it presents a numerical solution to the flow through a suction muffler in order to analyze the pressure field and point out the main contributions to the overall pressure drop of the flow. A commercial CFD （computational fluid dynamics） code was used to perform the numerical simulations and the results were validated by using experimental data. After analyzing the pressure field, the geometry of the muffler was modified intending to decrease the flow pressure drop. The geometric modification produced a 28% reduction on the overall pressure drop, without influencing the sound attenuation.

Deng-Fan Potential for Relativistic Spinless Particles—an Ansatz Solution

Deng-Fan potential originally appeared many years ago as an attractive proposition for molecular systems. On the contrary to the ground state of one-dimensional Schr6dinger equation, this potential fails to admit exact analytical solutions for arbitrary quantum number in both relativistic and nonrelativistic regime. Because of this complexity, there exists only few papers, which discuss this interesting problem. Here, using an elegant ansatz, we have calculated the system spectra as well as the eigenfunctions in the general case of unequal vector and scalar potentials under Klein-Gordon equation.