KDF2滤棒成型机组纸盘架装置的改进

KDF2滤棒成型机组的纸盘架装置采用螺母锁紧定位,更换盘纸时操作不便且回转盘没有准确的定位装置,为此对纸盘架装置进行了改进.在不改变机座结构的前提下,将气缸与纸盘架设计成一体,气缸安装在回转盘上,纸盘锁紧装置通过轴承与活塞轴连接,使气缸活塞不随纸盘旋转,保证气缸活塞的密封性.控制气路设置在固定板上,通过浮动的连接装置连接气缸.纸盘架装置改进后,能够自动锁紧和释放纸盘,更换纸盘方便.增设的回转盘定位装置,保证了固定板与回转盘通气孔的准确接通,回转盘回转定位准确,避免了回转盘转动不到位现象的发生,生产过程运行平稳可靠.     

提高精梳机梳理度的探讨

根据定时潜力可适当放大三类精梳机锡林齿面角.顶梳插入深度受制于落棉隔距的放大.后退给棉比前进给棉对棉须丛多一次梳理循环.落棉率的大小不足以衡量精梳机梳理度的依据,重在精梳条含短绒率.     

超大口径PCCP内断丝对其承载能力影响研究

以南水北调中线工程为背景,进行PCCP断丝原型试验,基于试验结果,利用杆单元模拟钢丝,采用等效降温法施加钢丝预应力,建立PCCP承载数值计算分析模型,基于非线性有限元理论,选取混凝土塑性损伤模型,对超大口径PCCP断丝问题进行承载能力和受力状态分析.计算结果表明:PCCP管芯混凝土损伤开裂位置为断丝对应区域,断丝数增加加剧了管芯混凝土的开裂破坏;断丝数增加急剧降低了PCCP的承载性能;当断丝数达到一定根数时,管芯混凝土更易开裂,在有内水压力作用时,将加剧钢筒和钢丝层的腐蚀,影响PCCP长久运行.     

大型柴油机气缸套离心铸造

从铸件的设计、离心浇铸装置、工艺参数的选择以及浇铸过程的控制等几方面,介绍了大型柴油机气缸套的离心浇铸技术,在成功浇铸气缸套的基础上,总结了离心铸造气缸套的优点。     

有限元法在柴油机机体改进设计中的应用

本文应用有限元软件对某柴油机的机体的装配模型进行分析，与实测结果吻合较好，为该机体的改进设计提供可靠的理论依据。     

Experimental validation of a numerical model for the transport of firebrands

The paper deals with the experimental validation of a numerical model for the transport and combustion of cylindrical and disk-shaped firebrands. The model solves the conservation equations of brand mass, kinetic and angular momentum, and volume. Validation consists in predicting the mass and spatial distributions of glowing firebrands that were produced from the experimental generator developed by Manzello and coworkers [S.L. Manzello, J.R. Shields, T.G. Cleary, A. Maranghides, W.E. Mell, J.C. Yang, Y. Hayashi, D. Nii, T. Kurita, On the development and characterization of a firebrand generator, Fire Saf. J. 43 (2008) 258–268]. Ten thousand firebrands per run are released with initial conditions that are randomly generated according to probability distribution functions deduced from experimental mass and spatial distributions under no-wind conditions. Whatever the wind conditions considered, numerical results are found to be in good agreement with experimental data.     

Experimental study of the polytropic index of the compression stroke for a direct injection hydrogen engine

Hydrogen is regarded as a promising alternative fuel in the future. The direct-injection (DI) hydrogen engine has been demonstrated to offer large power without the risk of abnormal combustion. For the engine test of combustion analysis, the piezoelectric transducer measures the dynamic cylinder pressure data rather than the absolute one. The traditional method of absolute cylinder pressure correction is normally based on the polytropic index. This paper investigated the polytropic index effects by injection duration, start timing of injection and speed based on a 2.0 L direct-injection hydrogen engine. The experiments found that, since the injection of large volume hydrogen leads to approximately 0.8 bar increase of cylinder pressure in the compression stroke, the traditional correct method is not suitable for the DI hydrogen engine. What's more, the polytropic index drops from 2.2 to 1.22 with the changes of the crank angle and is sensitive to the concentration of the hydrogen. The study of the instantaneous polytropic index can not only be used to calculate the accurate heat release rate but also guide the research of the heat transfer of the DI hydrogen engine. The average polytropic index of 1.32 provides a new reference for the absolute cylinder pressure correction of the DI hydrogen engine.     

A Few Remarks About the Gurney Energy of Condensed Explosives

After reconsidering the definition and characteristics of the Gurney energy, we explain some points related to the evaluation and practical use of this quantity. We correct a recently published relationship between the detonation velocity of an explosive and its Gurney energy at infinite expansion. Then, in the framework of cylinder tests, we indicate that the Gurney energy gives only a rough evaluation of experimental results; it can, however, be reasonably used to compare the ability of explosives to accelerate metals. Besides, the value γ=3 classically evoked for the polytropic gamma of the detonation products generally leads to significant errors in the evaluation of the Gurney energy at infinite expansion.     

柱状药包岩石中爆炸的数值模拟

利用ANSYS/LS-DYNA3D对柱状药包在半无限岩石介质中爆炸情况进行了数值模拟,对柱状药包的爆炸在岩石内产生的应力变化进行了分析。给出了岩石弹性区内一点的应力变化时程曲线;并借助球形装药的经验公式对柱状装药的情况进行了分析比较,结果表明,应力波的峰值基本一致。该时程曲线可以用于多孔爆破计算。     

SIMULATED MATHEMATICAL MODEL FOR HIGH PRESSURE CYLINDER WALL TEMPERATURE OF HOMEMADE TURBINE

0 INTRODUCTIONThe problem of how to construct both simple and appliedsimulated mathematical model for the power plant simulator be-comes more and more important, along with the rapid develop-ment of exploitation and application of the simulators in the na…