THEORY OF THE FRACTIONAL COLLECTION EFFICIENCY FOR THE AXIAL FLOW CYCLONE DUST COLLECTOR

A cyclone dust collector is a simple device with no moving parts, so it is applied in many industrial fields. However there is still no satisfied theory to estimate the collection efficiency for a given cyclone with high reliability since it is very difficult to predict the movement of the fine solid particles in the three dimensional turbulent rotational flows in the cyclone. A new model of the fractional collection efficiency including the diffusion effect of the solid particles and the decay effect of the tangential velocity of gas flow along the concave wall surface has been derived. In order to confirm this model, a simplified axial flow cyclone of body diameter D₁ = 99 mm has been constructed and fly-ash particles were used as a test dust. The experimental results of collection efficiency were compared those predicted by the Ogawa model and the Fuchs model.     

RE-ENTRAINMENT OF DUSTS FROM THE DUST LAYER ON THE THE DEPOSITED DUSTS IN THE CYCLONE DUST COLLECTORS

There were many papers concerning the experimental results of the collection efficiency, but up to this time there are a few papers concerning the experimental results of the re-entrainment or dispersion of the dust particles from the dust layer by the turbulent rotational air flow in the dust bunker for the cyclone dust collector. Then in this paper, the author described the experimental results of the re-entrainment of the test dust ( talc X_R50 = 8.O µm ) for the four kinds of the throat diameter D₃ = 50, 80, 100 and 150 mm. Especially it is very importance to take into consideration of flow rate Qb into the dust bunker which is a function of D₃ and cyclone diameter D₁ and the maximum tangential velocity Vet in the dust bunker which depends on D₁,D₃ and Qb.     

圆柱壳中不连续管壁对振动功率流传播的影响

本文以一无限长弹性圆柱壳为研究对象,分析其自由振动特性及壳体中各内力传播的功率流,研究管壁接头对入射波的影响,从能量流的角度分析其振动控制效果.     

EFFECT OF MASS FLOWRATE ON POWDER FLOW VELOCITIES

The effect of mass flowrate on powder velocities during flow down a chute and in free fall from a hopper was studied using a microwave Doppler technique. The velocities on an inclined chute, which was either smooth or had its surface roughened by coating with a layer of the sample, increased as the mass flowrate increased; this effect was most significant at large angles of inclination. Free fall from a hopper also led to higher velocities being monitored as the mass flowrate increased.

The distribution of particle velocities was also estimated; during flow on a chute at high angles of inclination the distribution of velocities was greater for low flowrates while at low angles, where the powder only just managed to flow, the trend was reversed. There was no difference in the distribution of velocities measured for the free fall of particles as the mass flowrate varied.     

FLOW OF SAND-WATER MIXTURES AT VELOCITIES BELOW THE DEPOSITION CONDITION

An experimental study of sand-water flow in a horizontal pipeline has been conducted for the regime in which a stationary deposit was present. The particle diameter ranged between 0.2 mm and 0.01 mm and the particles were not flocculated. Axial pressure gradients and delivered concentrations were measured as functions of mean velocity and in-situ concentration.

A three layer model was found to be useful to predict the pipeline behavior at all but the lowest velocities. The Meyer-Peter sediment transport equation was satisfactory for very low velocities with the larger particles.     

用于气体流量控制的压电陶瓷阀的温度特性

采用PEV-1型压电陶瓷阀作为溅射气体Ar流量输出的驱动元件,用于真空磁控溅射镀膜中溅射气体恒压力控制.应用过程中发现压电陶瓷阀本身的迟滞特性和温度特性对气体输出流量有较大影响.试验分析得到压电陶瓷阀偏振电压变化过程中,气体输出流量的迟滞曲线.当压电陶瓷阀环境温度升高时,该迟滞特性会减弱,气体输出流量随偏振电压变化速率变大.     

复合材料层板中基体性能对层间应力分布的影响

本文分析了复合材料层板中基体性能的变化对层间应力的影响,差重讨论了层板自由边附近及层间界面上的应力分布.分析结果表明,基体性能的变化会对层间立力的分布产生显著的影响.因此,对于实际复合材料结构,有可能通过选用合适的基体来改变复合材料层板自由边附近的层间应力分布,从而减轻率合材料层板的分层破坏.      

GMT流动成型纤维取向研究

GMT材料流动成型后玻纤在平面内发生取向，导致模压件呈各向异性，本研究从成型后制品上取样烧尽树脂，由扫描仪获取纤维数值图像，用Photoshop软件将图像反相，增强，再利用MATLAB软件确定纤维取向分布，研究表明，GMT单向流动成型时纤维沿流动方向取向，随流动距离增大，取向趋向更为明显，而均匀双向拉伸流动纤维取向程度较小，与片材相比，材料力学性能沿取向方向增大，但垂直取向方向材料性能变差。     

毛细管两相流特性研究进展

毛细管是广泛使用于小制冷装置中的节流元件，主要介绍了毛细管内制冷工质两相流特性的实验研究及理论研究的国内外现状，阐述了目前研究存在的几个问题，探讨了这一领域内研究的几个发展方向。     

分布驱动系统对微型热声斯特林热机行波分量的研究

研究了微型热声斯特林热机声场行波分量的调节原理和调节方法,指出采用分布驱动系统就可以实现声场行波分量的调节,进而通过实验初步验证调节混合声场中行波分量的可行性.     

露天爆破毒气传播规律探讨

应用大气扩散理论探讨了露天爆破毒气的传播规律,并提出一种理论计算模型及计算公式．     

水环真空泵气体流量的测定

介绍了孔板测量流量方法的工作原理。说明了水环真空泵气体流量测量过程中各个参数的关系。     

大型高炉煤气重力除尘波纹管的失效分析

利用光学显微镜、扫描电镜和电子能谱等测试手段,从微观组织、断口形貌以及腐蚀产物成分等角度,分析了某大型高炉煤气重力除尘波纹管开裂失效的原因.结果表明,波纹管的失效是由于应力腐蚀开裂所致.提出了两方面的改进措施,即通过改进波纹管波形参数以增加疲劳寿命,以及通过改进波纹管材料以增加波纹管耐腐蚀性能.     

水压爆破圆柱薄壳结构物的动力响应分析

以爆炸力学理论为基础，对水压爆破圆柱形薄壁结构物在集中药包爆炸荷载作用下结构的动力响应特性和水压爆破机理进行了理论研究和分析，建立了不同材质的结构物在不同爆炸荷载作用下的药量计算公式。     

旋转式压缩机气流噪声研究综述和展望

回顾了旋转式压缩机气流噪声理论与应用的国内外研究现状。对气流噪声研究情况进行分类评述：储液器内气流噪声研究，涉及到计算方法和试验设计分析；排气阀的研究，包括流固耦合分析模型和可视化试验；消声器的研究，包括声学理论分析、试验技术和降噪改进方法；压缩机腔体内气流噪声研究，主要集中在声源识别，简化的集总参数模型和基于CFD的声学分析等3个方面。最后讨论了目前研究存在的一些问题和今后的研究方向。     

烟道内飘灰测量方法的研究

精确测量颗粒的大小，并对监测到的颗粒进行数学统计，从而实现对烟道内的飘灰颗粒进行实时监测。使用National Instruments公司的IMAQ可视化软件、Lab VIEW图片控制工具包、招待程序生成器和Lab VIEW开发出稳定可靠、经济灵活的现场烟道飘灰监测系统。     

加肋斜度对加肋壳稳定性的影响

本文从正交各向异性假设出发,推导了肋骨具有斜度时环加肋圆柱壳总体失稳的临界水压公式,并且用有限元分析软件ＡＬＧＯＲ进行了验证。在公式推导的过程中,考虑了加肋的实际分布情况,并编制了计算程序,对半圆环界面加肋圆柱壳和圆管加肋圆柱壳的临界水压进行了比较。算例表明,在消耗相同材料的情况下,半圆环加肋圆柱壳具有较好的抗水压性能;肋骨斜度增加,临界水压下降。     

爆炸焊接条件下炸药爆速的探针法测定

用探针法测量了几种混合炸药的爆速 ,绘制了它们沿爆轰方向的分布曲线 ,分析和讨论了试验结果。指出 ,炸药的爆轰和它的传播 (爆速 )有一个发生、发展、持续和消亡的过程 ,研究这个过程对于爆炸焊接来说有重要的理论和实际意义