带壳JH-14C传爆药烤燃实验及响应特性数值模拟

为了探究受外部不同温度影响下带壳JH-14C传爆药的响应特性，设计了一套慢速烤燃下可测量JH-14C传爆药温度变化和壳体应变的实验装置，获取了不同升温速率下弹体内部温度随时间变化曲线、慢烤响应过程中装药壳体径向应变历程曲线，揭示了带壳JH-14C传爆药的慢速烤燃响应特性，将烤燃实验中弹体径向应变测试结果和炸药反应烈度相关联，提出了一种弹药烤燃实验反应等级的判定方法；基于热力学和装药化学反应，建立了带壳装药烤燃热传导模型和Arrhenius模型，采用BP神经网络反演了JH-14C传爆药热的热反应参数，对不同升温速率下弹体内部的温度场进行了研究。结果表明：升温速率越低，装药的响应温度越高，响应越剧烈；随着升温速率的降低，炸药的点火区域从炸药两端外缘逐渐向炸药内部转移。     

油水重力分离实验模拟系统的研制

所研制的油水重力分离实验模拟系统，由介质循环、乳化液制备、激光片光源、图象采集及设备模型等部分组成，可对系统流量、介质物性、分散相含量、乳化状态、设备结构等多种因素进行实验模拟，从而能有效地将实际介质在工程设备中的流动与分离过程再现到实验室中．该系统与ＰＩＶ、停留时间分布等有关检测技术相配合，可对多种油田地面分离设备进行多工况、多参数的流动诊断分析，为揭示介质在设备中的流动与分离规律、研究设备工作理论、优化设备结构等提供了重要手段．     

液压换向阀的耦合水击振动特性研究

以某型舵机操纵液压换向阀为例,运用特征线法,对其由于自激振动以及启闭动作产生水击诱发非线性耦合振动现象的机理进行理论分析,获得换向阀水击振动的动态特性.通过实验验证,换向阀控制口水击压力幅值与计算结果偏差为2.87%,且压力变化趋势与计算结果基本一致.该结果可为掌握液压系统的振动特性、采取振动控制措施以及换向阀的设计和改进提供理论依据.     

传爆药静态压缩力学性能及损伤特性研究

为研究聚黑-14C（JH-14C）传爆药静态压缩力学性能及损伤特性,开展准静态压缩实验,获得了不同应变率下的应力-应变曲线,建立了描述不同应变率下JH-14C力学行为的非线性本构模型;利用扫描电镜（SEM）对回收试样进行细微形貌观测,获得了准静态压缩JH-14C损伤特性的表征。结果表明:JH-14C压缩强度随应变率的升高而提高;实验与计算结果对照验证了本构模型的有效性;准静态压缩实验中,JH-14C主要损伤模式为脱湿和穿晶断裂。     

布置方式对U形管不稳定性的影响

从实验和理论两方面研究了不同布置方式对加热Ｕ型管不稳定性的影响。实验在氟利昂－１１３试验台上进行，研究了不同布置Ｕ这在三种压力工况，六种加热工况及各种流量下的流动不稳定性。     

多路程控网络讯号源数据采集和控制

为研究材料的冲击特性而进行的爆轰实验测试中,用多路程控网络讯号源给电探针供电及漏电检查,电探针导通时产生脉冲信号。为测试仪器自动化的需要,设计了一种利用RS-485总线把PC机和多台网络讯号源互联构成小型集散系统,实现了分布式程控网络讯号源数据采集和控制。     

破碎岩石气体渗透性的试验测定方法

为了测试采矿工程中松散破碎岩体的气体渗透特性,设计了与MTS815.02岩石力学伺服机配套的气体渗透仪和测试系统。依靠MTS伺服机改变压力和位移条件,渗透仪用以稳定破碎岩石并连接气体测试系统,接入气源、组成回路和测试气透特性等由测试系统完成。通过对几组破碎砂岩岩样氮气渗透性能的测试,结合考虑状态方程的渗透率换算公式,得出破碎砂岩气体渗透率随压力和粒径条件的变化规律。该测试方法和测试结果在研究采动破碎岩体瓦斯等气体流动规律方面具有重要意义。     

布置方式对U型管不稳定性的影响

从实验和理论两方面研究了不同布置方式对加热Ｕ型管不稳定性的影响。实验在氟利昂－１１３试验台上进行，研究了不同布置Ｕ型管在三种压力工况，六种加热工况及各种流量下的流动不稳定性。理论研究得出了系统稳定性的判据，比较了不同布置方式Ｕ型管的脉动起始边界；并对实际工业现场的Ｕ型管布置方式进行了模拟数值计算，比较了在较高系统压力下不同布置方式Ｕ型管的脉动起始边界     

一种实用着靶模拟测试技术

为了研究弹引系统的动态特性参数，在反弹道测试技术的基础上，发展了一种新的动态着靶模拟测试技术：碰前接电技术。设计加工了实验弹及弹上接电装置；根据原理性实验，求出信号建立时间，据此设计了靶前接电装置，进而组成了碰前接电技术测试系统；将此系统用于靶场实验，获得了在实际载荷下雷管部位的冲击加速度响应曲线；对加速度曲线进行最大熵谱估计，确定了测得的信号是完整的；利用小波变换消除噪声，提取特征频率重构了加速度曲线。     

旋转式一孔测压管及其应用1）

由圆柱三孔型二元复合测压管的测速原理出发，提出用一孔测压管通过旋转实现平面气流速度大小与方向的自动测量，建立了相应的测试系统．通过大量实验，研究了该系统的性能．在多种回流和旋流流场测量中进行了应用．结果表明该系统测量原理正确，重复性好，精度高     

Local stress measurement using the thermoelastic effect

A technique for measuring local stresses in metallic specimens is proposed and tested. The technique depends on the experimental measurement of temperature changes in stressed members due to adiabatic elastic deformation. At a free boundary in a body under plane stress, these temperature changes are directly related to the value of the tangential principal stress. The technique is suited for measurement of stress-concentration effects, since the temperature changes can be measured with thermocouples featuring extremely small junctions. A simple stress-concentration geometry, the finitewidth strip with a central circular hole, is chosen as a model system for this study. Heat transfer in this geometry due to the temperature gradients produced by elastic deformation is analyzed. It is shown that the ratio of the temperature change at a reference section to the change at the locale of the stress concentration can be used to determine the stress-concentration factor, allowing for heat-transfer effects. An experimental measurement system capable of obtaining reproducible results with the thermal-measurement technique is described, and experimental results are given for the model geometry which agree favorably with theoretical predictions. Application of the technique to other problems is discussed.     

A concise method for determining a valve flow coefficient of a valve under compressible gas flow

This work presents a novel method of determining a valve flow coefficient for a valve and transient mass flow rate of compressible gas discharged from a reservoir. The proposed method consists of a set of equations to express the physical phenomena and measurement equipment to measure the indispensable data used in the above equations. Regardless of the kind of valve, the valve flow coefficient can be obtained efficiently and feasibly. The results of this study indicate not only that the valve flow characteristics of the diaphragm valve significantly differ from those of the ball valve, but also that the C_v flow equation conventionally used is no longer valid for the diaphragm valve. The valve flow coefficient of the ball valve determined by the proposed method is about 48 and the representative one proposed by the ANSI/ISA is about 56. In addition, the mass flow rate of gas flow through a valve under transient process can be estimated without using a flow meter. Moreover, the cumulated masses discharged predicted by the method proposed herein are consistent well with those of the experimental results. The deviations are smaller than 6%.     

Experimental investigation of the flow pattern,pressure drop and void fraction of two-phase flow in the corrugated gap of a plate heat exchanger

The two-phase flow in the corrugated gap created by two adjacent plates of a plate heat exchanger was investigated experimentally. One setup consisting of a transparent corrugated gap was used to visualize the two-phase flow pattern and study the local phenomena of phase distribution, pressure drop and void fraction. Saturated two-phase R365mfc and an air-water mixture were used as working fluids.In a second experimental setup, the heat transfer coefficients and the pressure drop inside an industrial plate heat exchanger during the condensation process of R134a are determined. Both experimental setups use the same type of plates, so the experimental results can be connected and a flow pattern model for the condensation in plate heat exchangers can be derived. In this work the results of the flow pattern visualization, the two-phase pressure drop in the corrugated gap and the void fraction analysis by measurement of the electrical capacity are presented. A new pressure drop correlation is derived, which takes into account different flow patterns, that appear during condensation. The mean deviation of the presented pressure drop model compared to the experimental data and data from other experimental works is 18.9%. 81.7% of the calculated pressure drop lies within ±30% compared to the experimental data.     

Time delay in a semi-active damper: modelling the bypass valve

Ride comfort and handling of off-road vehicles can be significantly improved by replacing the normal passive dampers in the vehicle suspension system with controllable, two-state, semi-active dampers. The hydraulic valve, which enables the semi-active damper characteristics to be controlled, is a critical component of a semi-active damper and has a marked influence on suspension performance. Models of the dynamics of a hydraulic bypass valve used on semi-active suspension systems for heavy vehicles were investigated. It is envisaged that similar models will eventually be incorporated into a full vehicle, three-dimensional simulation study. Valve response time (or time delay) is used as a measure of model accuracy because it is an important parameter in the performance of a semi-active damper. Models were created with AMESim, a commercial fluid power simulation environment, and MATLAB. AMESim was found to be capable of dealing with detailed and complex fluid power models. Attempts to solve models of similar complexity in the MATLAB environment were unsuccessful due to numerical stiffness. Experimental work was conducted to obtain dynamic performance data with which to validate model integrity. Several external factors influenced the valve behaviour during experiments. Test bench dynamics significantly influences results and obscures the absolute accuracy of the models and the experimental data. The investigation demonstrated an approach to creating fluid power models for this application that can be used in simulation, but also indicated that substantial effort is required in the process. The accuracy of the current model is not sufficient for design purposes.     

The effect of internal surface modification on flow instabilities in forced convection boiling in a horizontal tube

This paper presents the experimental result of a study on the effects of heat transfer enhancement on two-phase flow instabilities in a horizontal in-tube flow boiling system. Five different heat transfer surface configurations and five different inlet temperatures are used to observe the effect of heat transfer enhancement and inlet subcooling. All experiments are carried out at constant heat input, system pressure and exit restriction. Dynamic instabilities, namely pressure-drop type, density-wave type and thermal oscillations are found to occur for all the investigated temperatures and enhancement configurations, and the boundaries for the appearance of these oscillations are found. The effect of the enhancement configurations on the characteristics of the boiling flow dynamic instabilities is studied in detail. The comparison between the bare tube and the enhanced tube configurations are made on the basis of boiling flow instabilities. Differences among the enhanced configurations are also determined to observe which of them is the most stable and unstable one. The amplitudes and periods of pressure-drop type oscillations and density-wave type oscillations for tubes with enhanced surfaces are found to be higher than those of the bare tube. The bare tube is found to be the most stable configuration, while tube with internal springs having bigger pitch is found to be the most unstable one among the tested tubes. It is found that system stability increases with decreasing equivalent diameter for the same type heater tube configurations; however, on the basis of effective diameter there is no single result such as stability increase/decrease with increasing/decreasing effective diameter.     

土体水分传输的温度效应试验系统设计与应用

自制了一套用于研究温度作用下土体水分传输机制的室内试验模拟系统.采用水浴加热替代电阻丝直接加热的方案,解决加热不均匀且不容易控制温度的难题.应用串行通讯接口技术把智能温度控制仪表和微机连接,实现了温度自动控制和采集的自动化.开展了7组试验耗时接近1年,试验结果表明,该系统性能稳定、部件之间兼容性较好,连续工作30天温度...     

The measurement of water vapour transfer rate through clothing system with air gap between layers

The experiments described in this paper are designed to test the water vapour transfer rates through outdoor clothing system with air gap between layers under conditions more closely actual wear. It was adopted distance of 5 mm to ensure no disturbance of the air gap thickness between layers throughout the measurement period with all fabrics. The results have indicated that the water vapour transfer rates of clothing system decrease very slightly with time, it is shown that they approached nearly equilibrium state throughout the experiment. It is revealed that the water vapour transfer rates of the clothing system were ordered into groups determined by the type of waterproof breathable fabric as a shell layer being ordered.     

大型结构变形监测摄像测量研究进展

桥梁、隧道、舰船等大型结构变形的全场、高精度、动态测量,是其动态性能实验和质量监测的基本要求。摄像测量具有非接触、高精度、可测点多、实时动态测量等特点,在大型结构的变形监测方面有独特的优势。本文介绍了作者所在科研团队近年来利用摄像测量技术在大型结构变形监测方面的研究新成果和典型应用,包括提出位移传递像机串联网络摄像测量方法与技术,用于自动监测高速铁路、隧道等大型结构的路基沉降;研制天线基座变形摄像测量系统,实时、连续、长时间测量我国远望号测量船的天线基座变形等。     

Residual stress measurement for injection molded components

Residual stress induced during manufacturing of injection molded components such as polymethyl methacrylate(PMMA) affects the mechanical and optical properties of these components. These residual stresses can be visualized and quantified by measuring their birefringence. In this paper, a low birefringence polariscope(LBP) is used to measure the whole-field residual stress distribution of these injection molded specimens. Detailed analytical and experimental study is conducted to quantify the residual stress measurement in these materials. A commercial birefringence measurement system was used to validate the results obtained to our measurement system. This study can help in material diagnosis for quality and manufacturing purpose and be useful for understanding of residual stress in imaging or other applications.     

Experimental investigation of parameters effect on heat transfer of spray cooling

The effects of spray height, nozzle spray angle, inlet pressure and spray incident angle on heat transfer of spray cooling were studied by an experimental method. Multi-points thermocouples and infrared imaging device were used to measure temperature distribution on heating surface. A Doppler anemometry and a camera were applied to study the spray flow field. The mechanism of heat transfer of spray cooling was concluded on the basis of experimental data and spray characteristics. It is showed that parameters affect heat transfer by way of changing the flow field on the heating surface. Heat transfer performance can be optimized by a smaller spray angle nozzle, which sprays at a smaller spray height and a higher inlet pressure. The effect of incident angle on heat transfer depends on nozzle spray angle and the definition of distance of nozzle to surface.