水和水蒸汽热力学物性参数及导数的计算与应用

本文针对现代换热设备设计、两相流动与传热研究的需要,介绍了可供科研使用的水和水蒸汽物性计算方法,完善了计算程序。根据超临界锅炉设计中的超临界水的物性计算,两相流研究和换热设备动态特性研究中对物性导数计算的需要,提供了两个算例,并进行了定性分析。     

Prediction of liquid level distribution in horizontal gas-liquid stratified flows with interfacial level gradient

A one-dimensional momentum equation has been derived based on a two-fluid model and used to predict the axial distribution of liquid level or void fraction in steady, cocurrent, gas-liquid stratified flows in horizontal circular pipes and rectangular channels. The equation is carefully formulated to incorporate the effect of interfacial level gradient. Two different critical liquid levels are found from the momentum equation and are adopted as a boundary condition to calculate the liquid level or void fraction distribution upstream of the channel exit. The predicted void fraction distributions are compared with the experimental data obtained in a rectangular channel in this work and other data reported for large-diameter pipes. Good agreement is shown for air-kerosene, air-water and stream-water stratified flows with a smooth gas-liquid interface.     

Vibro-Acoustic Response of a Pipe Excited by a Turbulent Internal Flow

This article presents an experimental study of the vibro-acoustic response of a pipe excited by a fully-developed turbulent air flow. First, the wall pressure field acting on the internal pipe wall is investigated. The power spectral density of the wall pressure fluctuations is analyzed after cancellation of contaminating background noise. The convection velocity and correlation lengths are calculated from measured cross-spectra, and the cross-spectra are expressed in Corcos model form. Second, the vibro-acoustic response of the pipe is analyzed by referring to the structural modes of the pipe. This revised version was published online in July 2006 with corrections to the Cover Date.     

Turbulent flow past a transverse cavity with inclined side walls. 1. Flow structure

The process of vortex formation in a cavity with inclined walls, which has a moderate aspect ratio, is experimentally studied, and the distribution of pressure coefficients is measured. The angle of inclination of the side walls ϕ is varied from 30 to 90°. It is found that the flow in the cavity becomes unstable in the range of inclination angles ϕ = 60–70°. Flow reconstruction occurs, which substantially alters the surface-temperature and static-pressure distributions. Large changes in these characteristics and their nonuniform distributions for these angles are observed across the cavity on its frontal wall and on the bottom. For small angles (ϕ = 30 and 45°), the pressure on the rear wall drastically increases, which leads to a small increase in pressure averaged over the entire cavity surface. __________ Translated from PrikladnayaMekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 5, pp. 68–76, September–October, 2006.     

Numerical investigation of hydroplaning characteristics of three-dimensional patterned tire

Hydroplaning characteristics of patterned tire on wet road are investigated by making use of finite volume and finite element methods. A detailed 3-D patterned tire model is constructed by our in-house modeling program and the rainwater flow is considered as incompressible and inviscid. Meanwhile, the fluid–structure interaction between the highly complicated tire tread and the rainwater flow is effectively treated by the general coupling method. Through the numerical experiments, the rainwater flow drained through tire grooves, hydrodynamic pressure and contact force are investigated and compared with those of the three-grooved tire model.     

主动隔振中气动压力跟踪的预测控制研究

气动伺服系统的压力跟踪是主动隔振系统中的一个重要环节。本文根据气动伺服系统的特点，建立了系统压力工作点的模型，应用基于状态空间的预测控制方法对系统压力进行了轨迹跟踪控制。首先，提出了一种控制器切换的方法来消除压力跟踪过程中的稳态误差；其次，通过对预测控制算法的改进减小了滞后对闭环系统动态性能和稳定性的影响。实验表明，本文提出的方法有效地解决了主动隔振系统中的气动压力跟踪问题。     

Contact interaction of a rigid heat-conducting punch with an elastic layer involving nonstationary frictional heating

A mathematical formulation is given and a solution is found to the quasistatic contact problem of thermoelasticity for a rigid heat-conducting punch moving over an elastic layer with fixed base. The interaction is accompanied by heating due to frictional forces obeying Amonton’s law. The problem is reduced to a system of integral equations with time-varying limits of integration. The structure of these equations depends on the type of thermal and physical conditions on the contact surface. An algorithm is proposed for the numerical solution of this kind of equations. The variation in the contact pressure and contact area with time is studied __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 12, pp. 35–46, December 2005.     

Elastoplastic analysis of nonlinearly hardening variable thickness annular disks under external pressure

Based on von Mises’ yield criterion, deformation theory of plasticity and Swift’s hardening law, elasto-plastic deformation of variable thickness annular disks subjected to external pressure is studied. A nonlinear shooting method using Newton’s iterations with numerically approximated tangent is designed for the solution of the problem. Considering a thickness profile in the form of a general parabolic function, the condition of occurrence of plastic deformation at the inner and outer edges of the annular disk is investigated. A critical disk profile is determined and the corresponding elastic–plastic stresses as well as the residual stress distribution upon removal of the applied pressure are computed and discussed.     

阻抗式和简单调压室甩荷时水位波动的显式计算方法

目前对调压室水位波动的研究主要有图解法和数值计算。尚未看到考虑阻力项后调压室水位波动随时间变化的显函数计算方法。本文从调压室的基本微分方程出发，采用泰勒级数展开式推导了阻抗式和简单式调压室甩荷时水位波动的显式计算方法。运用这种方法不仅可以计算调压室水位波动的过程，而且可以方便的计算调压室的最高涌浪和第二振幅。     

负压爆炸载荷和数据采集间隔对弹性开孔板动应力集中的影响

基于ANSYS 7.0/LS-DYNA程序,对3 m3 m四边简支,厚度0.025 m,中心开有0.3 m0.3 m方孔的弹性板,在正压和负压三角爆炸载荷作用下的应力响应进行了分析,利用能量密度时间分布函数（TDFED）确定了动应力集中因子,并给出其计算步骤。计算结果表明计算总时间和数据采集时间间隔对动应力集中因子影响较大,而负压荷载影响较小。