旋涡风机内部流动的边界元解法

在旋涡风机内部流动分析的基础上，建立了计算叶轮内部流场的数学模型，并用边界元素法对模型进行了数值模拟，计算结果与理论分析基本一致。这表明该模型可以满意地描述旋涡风机内部流动。     

不同计算方法在轴流式风机数值模拟中的应用

基于MRF定常计算和SM非定常计算方法,对某轴流式风机进行了设计工况下的数值模拟。讨论了不同计算方法边界条件设置和收敛性判定的区别,分析了计算方法对风机全压效率的影响,研究了风机内部流场动静交界面上的静压分布、50%叶高截面静压和速度分布、叶片表面压力分布和叶轮出口动压分布等参数。数值结果表明,定常计算结果和非定常计算结果具有相同的变化趋势,但是存在一定的差异,这主要是由于定常计算没有考虑风机内部流动的非定常效应造成的;非定常计算能够更好地模拟动静交界区域的流动,比采用定常计算具有更好的数值结果。     

CFD仿真在轴流式灭火风机流场优化设计中的应用

应用计算流体动力学的方法对轴流式灭火风机内的三维湍流流动进行了建模和基于N-S方程的仿真分析,仿真采用有限体积法FVM和k-ε双方程模型来模拟湍流流动,得到了轴流式灭火风机在设计工况下的内部流场三维流动形态,分析了轴流式灭火风机内部的气流流动规律、流速和压力分布,以三维湍流场的仿真结果为依据,对轴流式灭火风机的内部风道进行了有效的改进和优化设计.结果表明锥形射流风筒采用整流栅板可以有效地提高出口风速,改善内部流动,更好地满足设计要求.     

贯流风机流场模拟与性能分析

利用计算流体力学(CFD)软件STAR-CD对贯流风机内部气体流动进行了数值模拟,研究了贯流风机的流动状态和结构参数变化对其产生的影响,分析了蜗舌间隙、进口角、蜗壳间隙、蜗舌位置角、出口角变化与贯流风机进、出口流速间的关系,从中寻找出结构参数变化对贯流风机流场影响的规律。同时,还将模拟计算结果与试验结果进行了比较,比较结果表明数值模拟的结果与试验结果基本吻合。     

蓖冷风机的数值模拟及内流场分析

对篦冷风机的三维内部流场进行了数值模拟,预测了风机的整体性能曲线,通过与试验数据比较表明了数值计算的可靠性.通过数值模拟,详细分析了风机子午平面和回转面的流动情况,分析了篦冷风机流场内射流-尾流、进风口与叶轮之间的间隙流动、叶轮流道内的二次流等局部流动特征.     

罗茨鼓风机内部流场的数值分析方法

以CFD软件FLUENT为工具,采用RNGk-ε湍流模型和PISO算法,对罗茨鼓风机内部气流流场进行了可压缩非定常流动的数值模拟,数值模拟与理论分析的对比结果验证了数值分析方法具有良好的准确度和可靠性。结果表明,基于动网格技术的风机内部流场的动态数值模拟,能较真实地反映风机内部湍流流动的流场分布和气流脉动的特征规律。     

单级后置导叶轴流通风机内部流场数值模拟与优化

借助FLUENT流动分析软件,根据计算流体力学理论,对一单级后置导叶轴流通风机的内部流场进行了全三维数值模拟,同时求解了叶轮、导叶（动区／静区）流场,获得了风机内部流场中重要的流动细节及规律,并在此基础上对该风机进行了流线型优化设计,使全压效率从74．12％提高到了77．11％。     

不同进口角度面板对贯流风幕机内流与噪声特性的影响

针对风幕机用贯流风机的降噪问题,采用了数值模拟与噪声试验结合的方法对其进行研究.将风机气动噪声作为优化目标,通过调整贯流风机进口面板的结构参数,改善贯流风机内部流动特性,达到降低气动噪声的目的.对4种不同进口面板结构的贯流风机,建立了三维CFD模型,模拟内部流动,分析其内流特性变化.在消声室进行噪声试验、在设计工况下,...     

轴流式通风机控制旋涡流型分析与试验研究

本文根据轴流式风机内部流动控制方程,进行了流型优化分析,提出了以K值为控制变量的最佳控制旋涡与流型的计算方法,给出了流动图形与计算结果。试验风机包括五种不同K值的叶轮。其系列产品已被推广与应用。文中评价了这些新型轴流式风机的理论分析与试验研究结果。     

基于RANS模型的不同边界条件风机三维流场模型应用研究

为了更加真实地分析风机流场，并缩短数值计算时间，分别建立不同参数（尺寸、转速）的轴流风机的三维流场模型，基于RANS模型中的Realizable k-ε模型，分别采用速度边界、Fan边界、3D Fan zone 3种边界条件对风机内部流场、射流通风流场进行稳态计算，并将计算结果与文献中风机试验数据进行了对比验证。为了进一步验证风机内部流场模拟结果的准确性，对1台SF3-4轴流式风机进行性能测试，结果表明：采用3D Fan zone和Fan边界条件计算内部流场的气动性能数据与试验值最接近，平均误差分别为1.59%和4.42%，但要求的网格数较多，计算时间长，而采用速度边界条件虽平均误差为10.3%，要求的网格数较少且计算时间短。在模拟风机射流通风流场时，采用3D Fan zone与Fan边界条件能实现流场边缘处的微小尺度旋流及流场各处的温度变化，而采用速度边界条件虽能实现流场中心处的大尺度射流，但无法实现流场其他位置的流动、传热现象；3种边界条件的计算结果都与风机内部流场的实际性能参数吻合度高，研究结果可为风机流场研究提供参考。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.