共查询到19条相似文献,搜索用时 750 毫秒
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俞勤泰 《制冷空调与电力机械》1982,(2)
近年来,水利水电工程中已广泛应用散装水泥,散装水泥车作为水泥的一种主要运输手段,其需要也随之增加。以往散装水泥车除立罐形式外多用倾斜尾卸式气卸车,在车上装成斜罐形式或用自卸车改装,这种型式由于车辆重心较高,在山区使用受到一定限制。为此,去年杭州机械设计研究所受有关单位委托,设计了利用奔茨2626型卡车底盘改装的上卸式 SB-13散装水泥车,现已 相似文献
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罐车制动过程中,液体晃动产生的水击压力对罐车的安全性能具有很大的影响。基于此,本文运用FLUENT软件中的VOF模块模拟研究罐车在制动过程中罐内液体水击产生过程,并研究了罐车液体充装率、密度和黏度对罐体水击压强的影响。研究表明:制动过程中液体晃动水击内壁压力随着充装率的增加先增大后减小,充装率为0.85时,达到最大。且液体晃动水击内壁压力随着液体密度的增加而增大,随着液体黏度的增加而减小。按实际刹车制动过程液体晃动水击内壁压力计算的液化气体罐式集装箱的罐体最大应力要比按JBT4781-2005标准计算的最大应力增加33.2%,应依据实际刹车制动过程液体晃动水击内壁压力进行强度设计. 相似文献
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一、概述
JJG140-2008《铁路罐车容积》检定规程适用于装运液体产品的铁路罐车(不包括液化气体铁路罐车和粉尘货物铁路罐车)的首次检定和后续检定。JJG140-2008的检定条件、检定设备(测量竖直径、横直径、内总长、内总高、外周长、外横直径、外总长等)、检定项目、检定方法、附录C《铁路罐车容积计算公式》(V=V1+V2-V3,式中:V——罐体容积,L;V1——筒体容积,L;V2——封头容积,L;V3——缺圆圈体体积,L),以及附录H《检定记录表》(h1、h2、h3)中的容积,均与铁路罐车罐体容积有关,但是JJG140-2008附录A《铁路罐车主要车型基本参数一览表》中并未列出罐体容积,只是列出标记容积。 相似文献
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针对部分充液罐车转向或制动过程中罐体内液体的晃动问题,建立了液罐车内液体晃动的三维力学模型,通过与准静态模型以及罐体内液体晃动的试验结果进行对比,验证了模型的有效性。研究了防波板的几何参数(开孔的大小、形状及位置等)对液体瞬态晃动时的载荷转移及晃动力的影响。评估了防波板不同的几何参数下,作用在罐体端面以及单个防波板上的力。发现了在中等或高充液比的情况下,在防波板和罐体端面或者相邻防波板之间的密闭空间将产生很大的空气压力。研究结果表明,防波板的几何参数对液体载荷的载荷转移量、晃动产生的作用力以及俯仰力矩均有很大的影响。空气压力可以减小液体的载荷的纵向转移量,从而抑制液体的晃动,提高车辆的制动性能。 相似文献
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《Advanced Powder Technology》2019,30(9):1789-1804
In order to solve the problem of dust pollution caused by ore unloading in ore pass, this paper, taking Li Lou Mining as a case study, conducted the wind speed variation law in the fluid domain and the impact of the collision between the ore in the unloading process on the fluid to determine the key dust control point based on the CFD-DEM coupling software. By Fluent software, the air curtain dust-proof efficiency under the action of unloading airflow is analyzed, and the relationship between the dust-control wind speed and the impinging airflow is known. And an experimental model of gas water spray is established to analyze the effect of spray dust removal. By analyzing the impact airflow and dust migration caused by ore unloading and the effect of air curtain dust control through numerical simulation, it can be seen that when the ore discharging quantity Mo = 4000 kg, the dust production is mainly concentrated in the fourth middle section. By high-pressure air shield assisting dust removal, dust diffusion can be better controlled when the ratio of impact wind speed of ore pass wellhead (denoted as λ) to high-pressure air curtain wind speed (denoted as ζ) is at least 1:8. When the dust removal effect is optimal, the ratio δ of the water supply amount ql and the gas supply amount Qg is determined by the gas water spray dust control experimental platform. 相似文献
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利用Fluent软件对贴附射流与辐射板复合空调系统进行模拟计算,分析其舒适性,并根据壁面温度计算其辐射不对称性。结合模型设置和模拟结果提出3种改善其辐射不对称性的方案并进行模拟计算。结果表明,侧壁辐射板布置于正对送风口方向以及与送风口所在壁面相邻壁面的下部空间,辐射不对称性可降低1.5~2.0℃,且不会有结露的风险,温度均匀性优于原方案。 相似文献
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Eliades T Papadopulos JS Eliades G Silikas N Watts DC 《Journal of materials science. Materials in medicine》2003,14(11):967-972
The purpose of this study was to assess the chemical composition, structure and degree of double bond conversion of retrieved bone cement from 29 total hip replacement revision arthroplasties, employing a multi-technique approach. Scanning electron microscopy revealed a porous cement surface, which replicated the characteristics of bone or femoral stem surface irregularities. Fourier transform infrared spectroscopy indicated that the retrieved bone cement samples were covered by a well-organized proteinaceous film rich in amides and alcohols, probably because of the adsorption of species from body tissues and fluids. X-ray fluorescence spectrometry showed the presence of potassium, sodium, calcium and phosphorus, implying the development of a mineralization process of the adsorbed biofilm. X-ray microtomography demonstrated a dense porous network in the bulk material comprised of macropores with a mean diameter >1 mm. FTIR analysis of the degree of double bond conversion of retrieved samples was in the order of 70%, similar to that of samples prepared in vitro in air, but 30% lower relative to their counterparts mixed in vitro and set in water. The effect of the adsorption of species onto bone cement surface on the reactivity of the material with the surrounding tissues and materials, is currently unknown. The results of this investigation reveal that the in vivo aging pattern of bone cements may involve alterations, which cannot be simulated under current in vitro protocols, emphasizing the necessity for adopting in vivo approaches including retrieval studies in assessing bone cement properties. ©;2003 Kluwer Acadamic Publishers 相似文献
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目的 获得多喷嘴风冷过程的界面换热系数,并研究风冷工艺参数对界面换热的影响规律.方法 基于Fluent软件对三喷嘴强制风冷传热过程进行"气-固"耦合分析,获得高压气流的流速场和钢板表面温度场.基于"气-固"耦合分析得到钢板表面平均温度曲线,利用自开发的反传热软件计算得到"气-固"耦合界面换热系数,并将界面换热系数以第三类边界条件施加在钢板表面进行瞬态传热分析.结果 对于直径为4 mm的喷嘴,当喷嘴间距为10~16 mm时,喷嘴间距对高压气体的流速场影响较大,气流的卷吸效应随着喷嘴距离的增大而增强;喷嘴间距对界面换热系数影响较小,喷嘴至钢板表面的距离对界面换热系数影响较大;随着喷嘴至钢板表面距离的增大,各股气流逐渐汇合为一股,各股气流的滞止区也逐渐汇合,钢板表面温度更加均匀;将界面换热系数以第三类边界条件施加在钢板表面进行瞬态传热分析,得到的钢板表面温度与"气-固"耦合分析得到的钢板表面平均温度曲线吻合得较好.结论 获得的界面换热系数可为多喷嘴风冷过程数值模拟提供可靠的数据,保证温度场的求解精度. 相似文献
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