自振射流喷嘴振荡腔内信号检测方法

为了获取喷嘴振荡腔内的压力脉动信号,提出一种新的检测方法.首先分析自振射流的特性,设计了产生自振射流的喷嘴结构;结合计算流体动力学分析喷嘴腔内动压分布,确定测压点位置;运用流体网络理论分析自振射流的频率特性,在此基础上确定用于实验的微型高响应压力传感器;考虑到腔内振荡信号的非平稳性,采用希尔伯特-黄变换（HHT）信号分析方法.实验结果表明,腔内振荡信号主要集中于40~60 Hz、110~150 Hz和200~310 Hz三个频带,且组成频率成分所对应的幅值差异明显;距离喷嘴出口较近处,自振信号振幅较大,频带窄.     

高压水射流破碎高围压岩石损伤场的数值模拟

利用ALE(arbitrary lagrange-euler)算法,考虑到一般情况下岩石处于高围压状态,建立了高压水射流冲击高围压岩石的数值模型.分析了高压水射流冲击下高围压岩石的损伤演化过程,指出岩石破碎过程呈阶跃式;通过对比无围压状态下岩石和高围压状态下岩石在高压水射流作用下破碎坑演化情况,指出处于高围压状态下的岩石损伤沿轴向的演化速率明显低于无围压状态下的岩石,沿径向的损伤演化受围压影响较小.通过分析4个典型单元在不同速度射流冲击下损伤演化情况,表明在提高射流速度可明显提高射流破岩效率,并在理论上对射流速度与射流破岩性能的关系进行了解释.     

粉料气动输送中的流动状态及管道磨损的研究

粉料气动输送中的气流速度由高到低变化时,气—固两相流的流动状态依次出现均匀流,层状流,脉动流和塞状流。在粉料输送管道磨损问题中,研究了粉料粒度、输送浓度和输送气体压力对磨损量的影响。试验中测定了气—固两相流的射流膨胀角及冲击面积,探讨了中心射流与外层射流的分布及其影响因素。     

冶金用喷粉罐喷粉速率控制的冷态模拟试验

 为实现冶金用喷粉罐喷粉速率的稳定控制，通过冷态模拟试验，测定喷粉罐不同喷吹参数对罐内压力和输粉管路压力的影响规律，研究了罐内压力与输粉管路压力的差值Δp对喷粉速率的控制规律。研究结果表明，正常喷粉状态下，罐内压力主要由罐顶充压和流化气压力共同决定。输粉管路压力主要由载气流量决定，其值随载气流量的增大而增大。通过设置罐顶充压、流化气压力和载气流量的不同参数组合来改变Δp，可实现对喷粉速率的稳定控制。在载气流量相同条件下，喷粉速率随Δp的增大而增大；在Δp相同条件下，载气流量值越大，喷粉速率越大。     

金属锂还原罐内化学反应与传热耦合特性

为了分析真空热还原制取金属锂的还原效率和还原率,综合考虑罐内球团传热和化学反应,建立了传热与反应动力学耦合模型.利用该模型对单球团和还原罐内球团还原过程进行数值模拟,得到了球团温度及还原率的时间分布,并分析了罐外换热系数对球团还原过程的影响.结果表明：球团低导热率和反应等效热汇是影响还原过程的主要因素,罐中心区域和罐壁处的温度和反应速率存在较大差值;还原初期传热为还原过程的主要控制因素,而反应后期化学反应为主要控制因素;罐外换热系数对还原过程影响不大,增强罐内传热是提高还原效率的有效途径.     

自循环粒子射流钻井提速工具机理研究

粒子射流钻井技术能够有效解决深井与超深井钻井效率低的问题。基于文丘里效应相关理论,设计了井下自循环粒子射流钻井工具,建立了流体在工具内部流动的压力模型,分析模型因素对钻头喷嘴射流压力的影响。结果表明:流体的雷诺数与管壁粗糙度对能量损失影响最大,加速粒子所需要的能耗其次,固液之间摩擦能耗较小。随着上喷嘴直径、岩屑质量分数与岩屑直径的变大,射流压力先增加后减小,存在最优值;随着喉管直径的变大射流压力逐渐变小;喉管长度的大小对射流压力没有影响。     

环境压力对超音速氧气射流特性影响的数值模拟

超音速氧气射流技术是炼钢精炼过程中的重要环节,关于常压条件下超音速氧气射流的特性已进行了大量的研究,但对真空精炼过程中低压环境下的超音速氧气射流特性目前研究较少。通过数值模拟的方法研究了不同环境压力条件下超音速氧气射流的特性,并与试验结果进行了对比分析。研究结果表明：低压环境条件与高压环境条件相比,超音速氧气射流速度的衰减受到抑制,射流核心段的长度得到延长;不同环境压力条件下,射流压力与射流速度分布趋势一致,均沿轴向不断降低,但压力衰减程度大于速度衰减的程度;不同环境压力条件下,氧气射流的温度随着氧气射流的扩散不断升高,最终趋于环境温度。     

液压驱动隔膜泵的研究与设计

长距离、高扬程、高浓度浆体管道输送是适合中国国情的运输方式,高压浆体泵是实现这种运输方式的核心设备。液动隔膜泵是一种新型的高压浆体泵,具有压力高、效率高、无流量脉动、易损件使用寿命长、无混浆、自动化程度高等特点。介绍了液动隔膜泵的组成、工作原理,对该泵设计中的有关问题进行了研究,并提出了解决措施。     

萍钢高炉用镁砂清除冷却壁结垢

萍乡钢铁厂314m~3高炉冷却壁结垢严重,在第一代炉龄停炉中修时对炉底炉缸三层冷却壁采用镁砂(炼钢转炉用)高压冲洗,取得了良好效果。冲洗设备由0.04m~3的简易料罐(上下有阀门控制)及高压(0.5MPa)风动输送管道组成。镁砂要筛除泥砂和粗粒部分,取3～5mm 粒级装入罐内。冲洗前冷却壁水管先用压缩空气冲刷吹干,然后通过开、关料罐的下阀门断续地向喷管     

两种异形入口突扩腔体喷嘴出口射流流动特性研究

运用PIV(Particle Image Velocity,粒子图像测速)技术对菱形与王字形入口突扩腔体喷嘴的出口段射流流场进行测量,分析了两种不同腔体入口形状对自激振荡射流的流动特性的影响。结果表明:对于腔体入口膨胀率D/De=2.75、长径比L/D=1.82的菱形入口与王字形入口突扩腔体喷嘴出口射流,它们的流动混合率和速度衰减基本一致,但王字形入口突扩腔体喷嘴出口射流的脉动速度和湍动能均大于菱形射流,由此得出王字形入口突扩腔体喷嘴射流较菱形射流具有更强的湍流混合率,并能卷吸更多的周围流体,因而对燃烧器性能的改善作用将更为明显。     

Pipeline Column Separation Flow Regimes

A generalized set of pipeline column separation equations is presented describing all conventional types of low-pressure regions. These include water hammer zones, distributed vaporous cavitation, vapor cavities, and shocks (that eliminate distributed vaporous cavitation zones). Numerical methods for solving these equations are then considered, leading to a review of three numerical models of column separation. These include the discrete vapor cavity model, the discrete gas cavity model, and the generalized interface vaporous cavitation model. The generalized interface vaporous cavitation model enables direct tracking of actual column separation phenomena (e.g., discrete cavities, vaporous cavitation zones), and consequently, better insight into the transient event. Numerical results from the three column separation models are compared with results of measurements for a number of flow regimes initiated by a rapid closure of a downstream valve in a sloping pipeline laboratory apparatus. Finally, conclusions are drawn about the accuracy of the modeling approaches. A new classification of column separation (active or passive) is proposed based on whether the maximum pressure in a pipeline following column separation results in a short-duration pressure pulse that exceeds the magnitude of the Joukowsky pressure rise for rapid valve closure.     

Pipeline Network Features and Leak Detection by Cross-Correlation Analysis of Reflected Waves

This paper describes progress on a new technique to detect pipeline features and leaks using signal processing of a pressure wave measurement. Previous work (by the present authors) has shown that the analysis of pressure wave reflections in fluid pipe networks can be used to identify specific pipeline features such as open ends, closed ends, valves, junctions, and certain types of bends. It was demonstrated that by using an extension of cross-correlation analysis, the identification of features can be achieved using fewer sensors than are traditionally employed. The key to the effectiveness of the technique lies in the artificial generation of pressure waves using a solenoid valve, rather than relying upon natural sources of fluid excitation. This paper uses an enhanced signal processing technique to improve the detection of leaks. It is shown experimentally that features and leaks can be detected around a sharp bend and up to seven reflections from features/leaks can be detected, by which time the wave has traveled over 95?m. The testing determined the position of a leak to within an accuracy of 5%, even when the location of the reflection from a leak is itself dispersed over a certain distance and, therefore, does not cause an exact reflection of the wave.     

Evaluation of Unsteady Flow Resistances by Quasi-2D or 1D Models

This note considers the evaluation of resistances in unsteady flow by means of a 1D unsteady friction model. The model is applied for the case of a water hammer, both in a single gravity pipeline and in a single pumped pipeline. Comparisons with experimental results show that the model does not predict the exact shape of the oscillation, but it gives, with high precision, the maximums and minimums of the pressure head oscillation if correct values of the parameter of the model are used. Because experimental evaluations can be made only for a few cases and can give rise to very different values depending on experimental conditions, the sensitivity of the model to physical and numerical parameters that influence the phenomenon is examined by comparison with the results of a quasi-2D model previously proposed.     

高银铜铁钙载金炭高温高压解吸电解试验与实践

针对原矿成分复杂,全泥氰化炭浆工艺吸附后载金炭泥质重,银、铜、钙、铁等杂质品位高,高温高压解吸电解载金炭生产中解吸电解循环管道易结垢堵塞,金、银解吸率偏低,解吸时间长,金泥难冶炼等问题,进行了解吸电解工艺试验研究与生产实践。结果表明:在高铜、铁、钙载金炭高温高压解吸电解生产过程中,采用氢氧化钠质量分数2%,氰化钠质量分数0.25%,除垢剂0.2%的组合解吸药剂配液制度,解吸电解温度控制:一段125℃恒温5h,最高温度控制155℃,解吸流量控制在2.25倍炭床体积,贫炭酸洗率控制80%,可解决解吸管道易堵塞难题,解吸电解流量得到稳定保障,管道筛网拆换频次由原来的一天一拆换提高到15天一拆换;金解吸率由83.83%提高到87.15%,银解吸率由95.41%提高到98.37%;解吸电解时间由每柱19.15h缩短至16.67h。加快氰化金银吸附速率,氰化尾槽金银浓度实现科学控制,提升金、银综合回收率。     

阿尔及利亚南部某市供水工程设计

阿尔及利亚南部城市某供水工程输水管道横跨撒哈拉沙漠737 km,经过路线地形复杂。管道流态包含重力流和压力流,同时具有长距离、大流量、高扬程的特点。本文介绍了该供水工程中的管道设计,对输水管线进行了正常状态和过渡状态水力计算,有效地保证了供水系统的安全性及可靠性。     

二次冷轧机组乳化液管路直接混合润滑系统开发

 针对传统直喷润滑系统不能实现乳化液流量与浓度的同时在线调整,造成二次冷轧机组升降速与钢种切换过程中轧制不稳定、板厚与板形质量不佳、轧制能耗与油耗总成本较高等问题,结合二次冷轧机组的设备及工艺特点,在搭建的试验平台上完成了乳化液管路直接混合润滑系统关键设备选型,提出了一套适合于二次冷轧机组的乳化液管路直接混合润滑系统设计方案、对管路直接混合与混合箱搅拌混合乳化液特性进行了对比,并将该润滑系统应用到某钢铁企业1 220二次冷轧机组的生产实践,有效提升了轧制稳定性、带钢厚度与板形质量、降低了轧制能耗与油耗总成本。     

Time-frequency analysis of transient pressure signals for a mechanical heart valve cavitation study

A series of transient pressure signals (TPSs) can be measured using a miniature pressure transducer mounted near the tip of the inflow side of a mechanical heart valve (MHV) occluder during closure. A relationship appears to exist between the intensity and pattern of the TPS and the cavitation potential of a MHV. To study the relationship between MHV cavitation and the TPSs, we installed an MHV in a valve testing chamber of a digitally controlled burst test loop. A charge coupled device (CCD) camera and a personal computer based image grabbing program was used to visualize cavitation bubbles appearing on or near the occluder surface. One bileaflet MHV was used as the model for this study. Cavitation bubbles were observed within 300 microsec of the leaflet/housing impact. The valve was tested at various driving pressures between 100 and 1,300 mmHg. MHV cavitation bubble intensities were qualitatively classified into three categories: 1) strong, 2) weak, and 3) none. Digital images of the MHV occluder inflow surface were recorded simultaneously with the TPSs. TPSs were studied by the time-frequency analysis method (spectrogram) and correlated to MHV cavitation potential. The intensity of the cavitation bubbles was found to be associated with burst test loop driving pressures during leaflet closure.     

Study of Transient Vapor Cavitation in Series Pipe Systems

The phenomenon of vapor cavitation due to water hammer in steel and plastic pipes (polyethylene and PVC) is investigated experimentally using high frequency pressure transducers. A wave character with a gradually increasing frequency of pressure oscillations is found to be associated with vapor cavitation. The influence of wall elasticity, liquid evaporation duration, and steady-state losses on the maximum cavitation pressure is shown. A growing pressure reduction is accompanied by gas desorption from the liquid. The liberated air reduces the amplitude of the pressure increase and prolongs the period of oscillations. The maximum cavitation pressure increase, directly proportional to the pressure wave velocity, can be many times higher than the maximum water hammer pressure amplitude. For the short liquid evaporation duration (below 0.06 s) considered in the experiment, the first maximum increase is also distinctly higher than previously published. The frequency of the vapor cavitation pressure wave depends on the duration of the oscillations. For the test cases, the frequency increases during the cavitation from about 400 to 900 Hz for steel pipes and from about 300 to 600 Hz for plastic pipes.     

双缓冲腔环形间隙对凿岩机缓冲系统动态特性的影响

分析了液压凿岩机双缓冲系统的结构特点,应用孔口节流理论确定了缓冲活塞的静平衡位置,基于应力波传递原理得到了缓冲活塞的回弹速度,考虑油液的压缩特性推导出一级缓冲腔压力公式,由间隙流量公式得到了二级缓冲腔压力,在此基础上建立了缓冲活塞的运动微分方程.应用Matlab工具对双缓冲系统的动态特性进行了仿真,分析了不同环形间隙下缓冲活塞的运动规律,探讨了环形间隙对一级和二级缓冲腔压力的影响.提出与环形间隙和活塞最大行程的比值相关的间隙行程系数η.仿真结果表明,间隙行程系数与双缓冲系统的特性密切相关,存在最优范围.搭建了实验台,通过实验对缓冲系统的数学模型进行了验证.