深海采矿输送软管几何非线性静力分析

根据矿石输送软管的挠度变化很大的特点,采用了几何非线性有限元理论对输送系统进行力学分析;根据输送管道在采矿船和采矿车的牵引下运动,同时受到管道和管内流体重力,以友浮力作用的情况,采用有限元分别对三种参数值的输送系统进行了计算分析。从计算结果的比较分析可知：简单输送系统不能满足深海采矿要求;在输送管道下端安装浮体,得到了一种十分理想的采矿系统;输送管道的密度对采矿系统的性能影响很大,应尽可能地采用密度小的输送管道。     

基于微孔限流孔板的超临界流体流量计量方法研究

文中介绍了应用微孔限流孔板进行限流的超临界流体输送系统的流体流量计量方法,详细阐述了用于计量的数学模型,并通过实验和MATLAB拟合确定出模型中的相应系数。通过这一数学模型建立了输送超临界流体的体积流量与输送压力、出口背压和限流孔板孔径之间的数学关系,这样在限流孔板固定和已知出口背压的情况下可通过设定超临界流体的输送压力获得预期的输送流量。     

EPC系统中气动传感器的非线性补偿

本文就带材输送设备中EPC系统的气动传感器问题作了非线性补偿的理论探讨,认为这种传感器的非线性可通过大挠度膜片来补偿,并提出了补偿公式.实验证明,非接触气动传感器经大挠度膜片补偿后,可获较满意效果.     

煤炭装卸系统增设筛分设备的改造方法

在简单介绍煤炭专业化连续输送系统和煤炭筛分设备知识的基础上,结合天津港煤码头公司卸车系统筛分设备改造的相关内容,阐述了在传统煤炭连续输送系统中进行煤炭筛分设备改造的方法。     

EPC系统中气动传感器的非线性补偿

本文就带材输送设备中ＥＰＣ系统的气动传感器问题作了非线性补偿的理论探讨，认为这种传感器的非线性可通过大挠度膜片来补偿，并提出了补偿公式。实验证明，非接触气动传感器经大挠度膜片补偿后，可获较满意效果。     

皮带输送设备在线监测系统的设计及应用

分析皮带输送设备在线监测系统主要功能,设计皮带输送设备在线监测系统整体结构,探讨皮带输送设备主要转态参数的监测方法以及原理等,在线监测系统能够有效提升了煤矿皮带输送设备的自动化程度,拥有良好应用前景。     

金属微粉体脉冲输送的微特性实验

采用以脉冲为微流动基本形态、脉冲当地惯性力为主动力的微流体数字化技术进行了金属微粉体(作为流体)脉冲输送微特性的实验,以解决激光金属粉体融覆沉积工艺中微粉体的精确稳定输送问题.建立了金属微粉体脉冲输送系统;以角形铬粉为实验材料,实验研究了驱动电压U、频率f、微喷嘴内径d、输送角度θ等4种系统参量对铬粉脉冲输送微特性(粉...     

流体高效输送技术在循环水系统节能改造中的应用

通过对三套循环水系统采用流体高效输送技术进行节能改造,更换旧泵为“量体定做”节能泵,消除了系统憋压和超负荷现象,改善了设备的运行状况,并取得了节电30％～40％的成果.     

流体机械可靠性预测的非线性数值方法

对承受流体动力作用的机械结构进行可靠性预测,在非线性流体激振理论基础上,提出了非线性振荡边界元数值方法。给出了流体激振可靠性分析的非线性振荡模型,建立起流体动力分析的边界积分方程及求解格式,提出了流体结构动力可靠度的计算方法。针对叶轮机械的叶片可靠性分析显示,该方法能快速、有效地预测结构承受流体激振的可靠性和安全性,开发的软件可应用于流体机械结构稳定性评定和管路系统振动分析等化工过程及动力工程问题。     

成功的连接

选择合适的连接装置可使流体输送过程更简捷、更安全甚至更智能化。在提高连接软管和管道的效益及降低其成本方面,融合流体输送的产品设计者们面临着诸多挑战。虽然摩托车、喷墨打印机、医疗设备或便携式水化装置上的所有流体输送通道均需要,如耦合器或接头之类     

Bifurcation analysis of flexible rotor supported by couple-stress fluid film bearings with non-linear suspension systems

This study analyzes the dynamic behavior of a flexible rotor supported by two couple-stress fluid film journal bearings with non-linear suspension systems. The analysis employs a short journal bearing assumption and considers the respective effects on the dynamic response of the system of the lubricant type (i.e. Newtonian or non-Newtonian), the bearing housing suspension system (i.e. linear or non-linear), the rotor speed and the degree of rotor unbalance. The behavior of the system is analyzed by reference to bifurcation diagrams, dynamic trajectory diagrams and Poincaré maps, respectively. In general, the results show that the dynamics of the system are significantly dependent on the rotor speed and the degree of rotor unbalance. Furthermore, it is found that the use of a couple-stress fluid lubricant enhances the dynamic stability of the rotor-bearing system considerably compared to that obtained when using a traditional Newtonian lubricant. Finally, the results show that the common assumption of a linear journal housing suspension system results in a significant underestimation of the vibrational amplitudes of both the rotor and the bearing and should therefore be replaced by a non-linear assumption.     

格子波尔兹曼方法及其应用

格子波尔兹曼方法为研究非线性复杂系统提供了一种新的手段。本文详细叙述了格子气自动机和格子波尔兹曼方法的基本原理以及其在流体力学中的应用     

APPLICATION OF FORCE-STATE MAPPING TO A NON-LINEAR FLUID–ELASTIC SYSTEM

The damping mechanisms associated with flow/structure interactions are, in general, considered to be non-linear. In this paper, the fluid–elastic instability of a tube in a heat exchanger is controlled using a tunable damper and the stiffness and damping associated with the flow-induced non-linearities are determined using the force-state mapping technique. The analysis of the results clearly indicates a linear destabilising fluid mechanism but also identifies non-linear damping and stiffness forces which are consistent with both the experimental behaviour and theoretical models for the instability.     

Non-linear vibrations and instabilities of orthotropic cylindrical shells with internal flowing fluid

In this work, Donnell’s non-linear shallow shell equations are used to study the dynamic instability of perfect simply supported orthotropic cylindrical shells with internal flowing fluid and subjected to either a compressive axial static pre-load plus a harmonic axial load or a harmonic lateral pressure. The fluid is assumed to be non-viscous and incompressible and the flow, isentropic and irrotational. An expansion with eight degrees of freedom, containing the fundamental, companion, gyroscopic, and four axi-symmetric modes is used to describe the lateral displacement of the shell. The Galerkin method is used to obtain the non-linear equations of motion which are solved by the Runge-Kutta method. A detailed parametric analysis clarifies the influence of the orthotropic material properties on the non-linear buckling and vibration characteristics of the shell. Numerical methods are used to identify the effect of the fluid flow and applied loads control parameters on the bifurcations and stability of the shell motions.     

The elastohydrodynamic lubrication of line contacts with pseudoplastic fluids

A new Reynolds equation, obtained by using the pseudoplastic model to express the non-newtonian fluid property, is derived for line contact elastohydrodynanic lubrication problems. The Reynolds equation results in a non-linear equation of high order which is derived by using an approximate method. The Newton-Raphson technique is utilized to solve the simultaneous system of modified Reynolds and elasticity equations. The results in this paper show that on increase in the coefficient of non-linearity, the pressure spike and film thickness decrease, and they approach a hertzian situation. With respect to the various loads and/or velocity values, the behaviours of the pressure spike and film thickness for non-newtonian fluids are almost the same as those of a newtonian fluid.     

The vibration of an artery-like tube conveying pulsatile fluid flow

A hybrid method for investigating pulsatile fluid flow in a long, thin, artery-like tube subjected to external excitations is presented. The non-linear partial differential equations governing the motion of the system, which incorporate the influence of circumferential strains, are solved by a combination of a finite element method, a finite difference method and a method of characteristics with interpolation. An initially axially stretched elastic tube conveying pulsating fluid, simply supported at both ends, is modelled to assess the effect of external harmonic excitation on the dynamic responses of the tube and the fluid flow. The results agree well with new experimental data. Comparison of the predicted results with those of a decoupled model demonstrates that it is necessary to consider the mechanism of fluid-structure interaction fully in the study of initially stretched cylindrical tubes conveying pulsatile fluid flow. An analysis of these coupling effects is presented for Womersley numbers alpha = 2.81 and 3.97 and a mean flow Reynolds number Re = 875.     

The unusual behaviour of a lubricant boundary layer

Oil starvation, finger formation and non-linear flow of the oil at the entry of a friction system are generally treated as problems of fluid dynamics. The present work attempts to show that an important, if not the most important, reason for these flow anomalies is the energetic interaction of the oil with the metallic surfaces and with the solid-like adsorbed layer. The experimental results obtained so far indicate that the behaviour of sliding bearings is inferior to that expected theoretically but that the gap can be sensibly reduced by modifying the interface relation between the contiguous phases that constitute the friction system.     

Design strategy for optimal iterative learning control applied on a deep drawing process

Metal forming processes in general can be characterised as repetitive processes; this work will take advantage of this characteristic by developing an algorithm or control system which transfers process information from part to part, reducing the impact of repetitive uncertainties, e.g. a gradual changes in the material properties. The process is highly non-linear and the system plant is modelled using a non-linear finite element and the gain factors for the iterative learning controller is identified solving a non-linear optimal control problem. The optimal control problem is formulated as a non-linear least square problem where the system response is evaluated using a non-linear finite element model of the process.     

A transient 2D-finite-element approach for the simulation of mixed lubrication effects of reciprocating hydraulic rod seals

This paper presents a method for the computation of soft elasto-hydrodynamic lubrication (EHL) based on the strong coupling of a non-linear finite-element model with the transient Reynolds equation for thin fluid films. This approach allows the usage of arbitrary non-linear elastic or inelastic material models for the finite deformations. The transient Reynolds equation is simultaneously solved within a finite-element computation. In order to account for the effect of surface roughness in the sealing contact, flow factors are incorporated into the transient Reynolds equation. The method is currently restricted to planar or axisymmetric geometries.     

A FREQUENCY DOMAIN METHOD FOR ESTIMATING THE PARAMETERS OF A NON-LINEAR STRUCTURAL DYNAMIC MODEL THROUGH FEEDBACK

A unifying perspective of non-linear structural dynamic systems as linear in the open loop with non-linear feedback in the closed loop has recently been revisited by the authors. The authors have previously used feedback to derive a new formulation of frequency response function matrices of non-linear systems, which are described as modulations of nominal linear systems. The modulation creates a pseudo-separation of the linear and non-linear dynamics of the system. The present article derives a new method for estimating parameters of non-linear parametric models that uses internal feedback to account for non-linearities. The main advantage of the new formulation of non-linear system identification is its simplicity. Moreover, the method estimates the linear frequency response matrix and non-linear system parameters at forced and unforced degrees of freedom of general multiple-degree-of-freedom non-linear systems simultaneously. This article demonstrates the implementation of this method on simulated data from single- and multiple-degree-of-freedom lumped parameter models.