三通换向阀阀内泥浆冲蚀磨损数值模拟研究

针对泥水盾构机接管系统中三通换向阀阀芯及管道易受泥浆冲蚀磨损问题,应用计算流体动力学中DPM(Discrete Phase Model)模型对阀芯缩径弯管与等径弯管进行对比分析。研究结果表明:泥浆流经等径弯管时对管壁造成的冲蚀磨损程度比流经缩径弯管时的冲蚀磨损程度严重;缩径弯管中凸台可以起到有效的扰流作用,消耗泥浆流体具有的动能,有利于减缓泥浆对弯管外壁面的冲蚀磨损;泥浆流经不同变直径管道时,对管壁造成的冲蚀磨损程度不同;其中泥浆从缩径弯管流向等径弯管处的冲蚀磨损率小于从等径弯管流向缩径弯管处的冲蚀磨损率。     

基于场协同原理的管道经济管径计算新方法

管道输送中管道直径直接影响管道的投资成本、输送费用和维护费用,然而现有经济管径的确定方法计算繁琐、物理意义不明确。从流体速度与管道材料消耗的协调出发,提出了的概念,作为反映管道安全与能效协调性或管道收益合理性的指标,提供了一条综合考虑输送总能量与管道材料用量、管道收益与投入等因素的确定经济管径的途径,揭示流体输送的物理机制,得出了常温流体输送过程中反映管道的数学式,并通过具体算例验证了这一指标的有效性与合理性,对管道输送经济管径的确定和管道的经济运行具有指导意义。     

精矿浆体管道输送流量检测研究

针对精矿浆体管道输送流量难以准确检测的问题,在浆体管道输送试验基地进行输运试验与研究。分析精矿流体特性与浆体浓度变化及气泡等对电磁流量计检测流量的影响。设计一种基于多传感器信息融合的流量检测系统,给出其检测系统结构框图。提取流体状态的特征量:差压波动系数、流量波动系数、浆体密度等,并研究其与流量的相关性。将精矿浆体管道输送过程划分为5个阶段,根据特征量识别所获数据所处阶段。采用分层产生式规则的专家系统对每个阶段检测的流量进行真伪辨别和融合修正处理。给出了带浆停泵再启动与多泵串联批量输送铁精矿浆体的流量试验曲线,说明系统能在各种工况下准确地检测输送流量。     

基于双环电阻传感器的管道内壁腐蚀监测技术研究

为实现管道内壁腐蚀的全周向在线监测并提高测量精度,在传统电阻法的基础上提出一种基于双环电阻探针的腐蚀监测方法。双环电阻探针解决了由于几何限制和管道内外壁温差所带来的测量误差。通过对双环探针进行多象限分区,求解各分区的电阻比值,实现了管道全方位的在线腐蚀监测。通过双环探针可以同时实现对管道内外壁的温差计算与实时监测,为湿蒸汽管道冷凝液膜的形成起到预报作用。基于以上研究基础,在实验室X65模拟管路中,分别布置四象限分区双环电阻传感器、传统丝状电阻传感器和高精度热电偶对管道的腐蚀和内外壁温差进行实时监测。试验结果表明：基于新型双环探针的管道内壁腐蚀监测方法,可以完成管道内外壁温差和局部分区腐蚀状态的在线监测,并在腐蚀深度和腐蚀速率的测量上比传统丝状电阻探针具有更高的监测精度。     

含固体颗粒流体用安全阀的自动冲洗装置及冲洗过程数值模拟

针对煤液化工业油煤浆输送管路中安全阀不能可靠关闭问题,提出一种安全阀自动冲洗装置.在安全阀与输送主管路连接管路上增设气液直接接触式蓄势器冲洗装置,蓄势器内充入一定量冲洗油,并通过冲洗油支路与安全阀入口管路相连.冲洗油管路上设置自控阀门,以安全阀阀瓣动作为控制信号.当阀瓣有回座动作时,自控阀门自动打开,冲洗油对安全阀进行自动冲洗.为分析方案的可行性,以油煤浆为输送流体、溶剂油为冲洗介质,运用FLUENT软件的双欧拉模型对安全阀内煤颗粒的冲洗过程进行三维数值模拟.计算结果表明,冲洗装置可有效地清除安全阀内的固相颗粒,保证安全阀可靠关闭.分析表明,冲洗过程瞬间完成,相对于主流体而言,仅有少量与主流体相容的冲洗油进入流体输送管路,不会影响液化工艺过程的稳定性.     

物料管道输送的减阻问题

为了提高输送效率和节约能源，使用振动减阻的方法来实现物料的输送减阻，尾砂试验表明，振动减阻是切实可行的，而浆体的浓度和输送速度是两个关键性因素，通过应力液的反射与透射分析，认为应力波在管道垂直方向上传播时逐渐衰减，迫使下层颗粒向上作微波移动，降低了浆体的粘性阻力损失，管道振动对层流附面层有较大影响，使边壁浆体的速度梯度减小，并导致边壁剪切应的降低。同时，使附面层的厚度加大，中性稳定雷诺数增加，阻止流态的转捩。应力波的作用以及附面层的改变，最终导致输送阻力的降低。     

A new method for field test of the heating capacity of air source heat pumps

The operation performance measurement of the air source heat pumps in the field, in which conditions are complicated and the accuracy could not be ensured, is very crucial for its performance evaluation and improvement. In this investigation, a novel method for measuring the heating capacity of the air source heat pump is established. An auxiliary electric heater is installed along the pipeline between the compressor and the condenser, and the refrigerant temperature difference caused by the heater is gathered to calculate the refrigerant mass flow rate based on the energy conservation. The heating capacity is calculated with the measured data of the refrigerant enthalpy at the inlet and outlet of the condenser and the refrigerant mass flow rate of the compressor discharge pipe. The validation results in laboratory tests show that the measured heating capacity accuracy is within 9.2%. It is also found that the impact of the novel test method on the heating capacity of the air source heat pumps is below 1.7%, and the power consumption of the tested units is increasing of within 1.8% compared with it when the electric heater is off. The refrigerant enthalpy difference method with an electric heater presented in this research can be applied to measure the heating capacity of different air source heat pump air heaters accurately in the field, which will be much helpful to improve the performance for cleaning heating in northern China.     

Detection of gas pipe wall thickness based on electromagnetic flux leakage

Based on electromagnetic flux leakage (EMFL), a nondestructive testing (NDT) technique for the detection of gas pipe wall thickness is presented, and its principle and feasibility is evaluated by means of equivalent magnetic circuit analysis and finite element analysis. An online NDT device adopting this technique is developed, and its structure and working principle are introduced in detail. This device is composed of a detector array with 32 pipe wall thickness sensors that employ a Hall element as the element for sensing the magnetic flux density, and it can be adapted to pipe diameters from Ø400mm to Ø650 mm. On the basis of the experimental investigation for this device, the influences of some factors on thickness measurement, namely the excitation current, excitation coil turns, gap distance, concentrator of the magnetic field, magnetization time, and number of sensors in the detector array, are revealed and the optimal excitation voltage for the sensors of the detector array is selected. The measuring calibration is given to establish the relationship between the pipe wall thickness and the output voltage of the sensors. The results show that the proposed EMFL for measuring the wall thickness of ferromagnetic pipe is feasible, the technical parameters of the sensor are important for improvement of measurement precision and resolution, and the developed device has precision, resolution, and a linear output curve. Carried by the developed gas pipeline inspection robot through a universal joint, this NDT device can move inside the gas pipeline and monitor the state of the pipe wall.     

管道壁缺陷超声波在役检测的量化分析研究

介绍了管道壁缺陷超声波在役检测原理和技术性能，指出超声波在役检测技术具有直接测量和量化的特点，特别适用于管道壁腐蚀减薄缺陷和其它减薄缺陷的在役检测，对管道壁厚度的检测精度高。介绍了管道壁缺陷的超声波在役检测方法，给出了四种典型的管道壁缺陷型式，指出建立并完善管道壁缺陷超声波在役检测的量化分析模型，对于提高检测精度具有十分重要的意义。在对四种典型管道壁缺陷型分析的基础上，通过对四次反射回波时间和相对幅值的分析识别，建立了管道壁缺陷超声波在役检测的量化分析模型，并给出了计算框图。最后，对四种典型管道壁缺陷型式进行了模拟试验分析。     

A system to estimate coarse particle velocities at the pipe wall in settling slurry flow

Understanding and modelling of coarse particle (settling) slurries in laminar flow in pipes is still not complete. Better analytical procedures will enable more efficient pipeline operation which could result in significant power savings in the transport of coarse materials. The depth and velocity of the settled bed significantly affect the pressure gradients required to pump these slurries and knowledge of these parameters is of importance. Existing measurement techniques that can be used for monitoring of these complex fluid systems are either very expensive, not easy to implement or mostly used under controlled laboratory conditions. A new measurement system was developed that is capable of detecting the deposition of solids, the depth of a settled bed and the velocity of coarse particles at the pipe wall, around the pipe circumference. Particle velocities were determined by cross-correlating modulated signals from pairs of electrodes mounted flush with the pipe wall, in contact with the slurry. Tests were conducted using a mixture of acetal beads in water, at bulk velocities between 0.5 and 4 m/s. Estimated particle velocities from the cross-correlation analyses were compared with those obtained using a 30 fps video camera combined with visual inspection, and found to be within ±6%, thus validating the viability of the system. Particle velocity resolution using the cross-correlation technique is limited by block size, sample rate and the measurement distance between electrode pairs. Further test work with a range of real slurries (different particle sizes, solids concentrations and rheologies) needs to be conducted, along with more extensive verification of the results, to establish the limits of the system. Initial testing and evaluation of the system, which is capable of coarse particle flow monitoring in real time, showed significant potential for development of a new commercial sliding bed detector that can be used in a wide range of industrial applications in which particles are transported hydraulically.     

Determining the position of hydrate blocks in gas pipelines by a radiowave method

A radiowave method of detecting and positioning hydrate blocks in pipelines is considered. The method consists in probing a pipeline with a high-frequency nanosecond-duration radio pulse with subsequent measurement of its travel time to the hydrate block and back. Results of a natural experiment and flow charts of a device for determining the position of a hydrate block imitator (ice) in a stub pipe with a diameter of 273 mm. A Gunn diode is used as a generator of microwave pulses with a duration of 10 ns and a basic frequency of 10 GHz. The decay of microwave pulses in the pipe and the potential of the radiowave method are estimated.     

含体积型缺陷管线表面应力应变状态的有限元模型分析及试验验证

腐蚀是影响油气管道安全运行的主要因素,确定预测腐蚀管道的剩余强度和其剩余寿命的方法有重要意义。应用ANSYS软件对含内腐蚀缺陷管道的三种模型进行有限元分析,得到采用1/4模型计算更简便、高效;由两种边界条件的模拟结果可知,自由边界条件下缺陷中心处的应变数值较高。管道外壁周向应变峰值分别与缺陷直径呈线性关系,与缺陷深度呈指数关系。并利用电阻应变片测量的值,与相同条件下模拟值的偏差不超过5.3%,结果表明,该建模方法是可靠的。     

基于湿含量计算模型的管道空气流量在线微机测量系统

空气测量准确性对热工设备燃烧效率、热效率以及气氛控制有非常重要的影响。湿空气中水蒸汽含量对空气测量准确性有较大的影响。随着节能工作的日益加强，对助燃用空气测量准确性提出了更高要求。针对目前管道空气流量在线测量系统测量精度较低和控制滞后的问题，本文基于蒸汽压方程，建立了工况下管道空气流量测量新模型和在线测量系统，实现了管道空气流量的完全在线测量，提高了测量的精度和速度。本测试系统已成功地应用于生产实际，取得了较好的节能效果。     

Review of certain key issues in indirect measurements of the mass flow rate of solids in pneumatic conveying pipelines

On-line mass flow measurement of particulate solids in pneumatic conveying pipeline is a technically challenging area, where mass flow measurement presents a range of problems. These problems are not normally relevant to a single phase flow, but are always involved in gas–solids two-phase flows, like inhomogeneous distribution of solids over the pipe cross section, irregular velocity profiles, variations in particle size, moisture content, and deposition of fine particles on the inner wall of the pipeline. These variables may affect the response of a solids flow meter in ill-defined ways. All of these make the design and the calibration of solids’ mass flowmeter more difficult. Based on a review of non-invasive mass flow measurements of particulate solids, this paper summarizes and highlights several key issues, which often rely on structures of sensors or measurement methods, in indirect mass flow metering of pneumatically conveyed solids. They are: (i) spatial filtering effect; (ii) averaging effect; (iii) measurement resolution and sensitivity of array structures in tomography sensors.     

Hydraulics conveyances of mud slurry by a spiral pipe

Indonesia particularly East Java has been suffering from eruption of gas and mud slurry, caused by oil and gas exploration. Everyone calls this disaster as Sidoarjo mud or Lapindo mud. Mud slurry is essentially a mixture of a carrying fluid and solid particles held in suspension. When the mud slurry flow speed is not sufficiently high the particles will not be maintained in suspension. In spiral pipe twisted with a constant pitch in relation to the axis a swirling flow occurs when fluids flow in the pipe. The aim of this study is to examine characteristics of the hydraulic transport of mud slurry flowing in the spiral pipe with three-shape groove pipe walls. The shear stress and the shear strain are calculated by measuring the pressure drop and the volumetric flow rate in circular pipe, respectively. The power law exponent were about 0.93–1.0 for mud slurry solution of 45%, 30% and 20% of weight concentrations. The diameter of particles was 0.95 mm and the density was 2.19 × 10³ (kg/m³). The apparent viscosity of mud slurry solution is not constant to the shear strain but the relationship is approximated by model of power law. The friction factor of mud slurries in a spiral pipe with ratio pitch per diameter 6.7 is lower than circular pipe and spiral pipe with P/Di= 3.9 and 4.3. It was shown that the spiral pipe caused drag reduction in flowing of mud slurries. The drag reduction ratio of spiral pipe was about 28% for Cw=30% at Re’=32 × 10³. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Yanuar received his B.S. degree in Mechanical Engineering from Indonesia University, Indonesia, in 1986. He then received his Master of Eng. and Doctor of Eng. in Mechanical Engineering from University of Tokyo Metropolitan, Japan, in 1995 and 1998, respectively. Professor at Mechanical Engineering at University of Indonesia in Jakarta, Indonesia.     

电网电容电流外加信号单频测量法的研究与应用

针对高压电力系统发生单相接地时,流经故障点的电流急剧增加,产生很强的间隙弧光接地过电压问题,对电网电容电流外加信号测量控制器的方法进行了详细的分析,充分论证了测量电网电容电流的必要性,对电网电容电流外加信号单频测量控制器的方法进行了研究,将外加信号单频测量法的原理计算分析与其他测量方法进行了比较。研究结果表明,电容电流外加信号单频测量法具有测量准确,特别是电网系统阻尼大,回路Q值低或位移电压很小时,更能显示外加信号单频测量法的优势,为进一步进行优化电网电容电流测量法的设计与应用奠定了基础。     

Simulation and experimental study of the sensor emitting frequency for ultrasonic tomography system in a conducting pipe

Ultrasonic tomography techniques provide flow visualization capability, non-invasively and non-intrusively, to enhance the understanding of complex flow processes. There is limited ultrasonic research in tomography imaging systems in the tomogram analysis of fluid flow in a conducting pipe because of a high acoustic impedance mismatch, which means that very little ultrasonic energy can be transmitted through the interface. The majority of industrial pipelines are constructed from metallic composites. Therefore, the development and improvement of ultrasonic measurement methods to accommodate a stainless steel pipe are proposed in this paper. Experimental and simulation distribution studies of the ultrasonic emitting frequency in acrylic versus stainless steel pipes were studied, measured and analyzed. During the simulation, ultrasonic transducers were placed on the surface of the investigated pipe to inspect the ultrasonic sensing field. The distribution of the sound wave acoustic pressure was simulated based on the physical dimensions and parameters of the actual experimental hardware set-up. We developed ultrasonic acoustic models using the finite element method with COMSOL software, and experiments were carried out to validate the simulation results. Finally, by performing the static phantoms tests, a feasibility study of ultrasonic tomography system was presented to investigate the void fraction of liquid column inside a stainless steel pipe.     

挖泥船泥浆管道输送工况点的在线动态优化方法

分析挖泥船泥浆管道输送系统的构成、特性以及边界约束条件。提出一种以比能耗为优化目标的泥浆管道输送工况点在线动态优化方法。既克服以产量最大化为优化目标时能耗过高、效率偏低的弊病,又很好地解决现有离线静态优化方法不适合应用到泥浆管道输送过程中进行工况点连续优化的问题。提出的工况点在线优化方法以实时检测的系统过程参数为基础,利用模糊决策方法进行工况点优化,不依赖于对系统设备特性的准确描述,特别适合于疏浚施工过程中土质和系统特性不断发生变化的场合应用。在浙江临海疏浚施工现场对所提出的方法和传统的手动疏浚作业方法进行对比试验,试验结果证明了该优化方法的有效性,不但提高了疏浚产量,而且减少了泥浆流速和浓度的波动,降低比能耗,提高泥浆管道输送系统的效率。     

整流式流量计设计与开发

随着国家标准GB／T2624-2006在石油、化工、电力、冶金等行业的推广。在实际应用中很多企业遇到了现场直管段长度不能满足GB／T2624-2006标准要求,造成节流装置测量精度降低甚至无法给出测量精度的问题。市场急需一种能够准确测量流量,而且直管段长度要求较短的差压式流量仪表。天津市润泰自动化仪表有限公司通过一年多的研制实验,开发出整流式流量计产品,该产品具有所需直管段短、测量精度高、永久压力损失小等特点。是一种节能、经济、可靠的流量仪表,对我国工业企业流量测量将起到重要作用。     

Freezing of aqueous specimens: an X-ray diffraction study

The effects on water of two cooling methods, immersion in a liquid cryogen and high-pressure freezing, were studied by X-ray cryodiffraction on different sucrose solutions. The nature of the ice formed by each method depends on both the sucrose concentration and the specimen thickness. In order to compare the two methods, we mainly studied specimens having a thickness of 0.2 mm. Under these conditions, freezing by immersion gives rise to hexagonal (IH), cubic (IC) and amorphous (IV) ices when the sucrose concentration (weight/weight) has a value within the range 0–30%, 30–60%, 60% and higher, respectively. The temperature of the phase transitions IV–IC, IC–IH depends on the sucrose concentration. High-pressure freezing gives rise to two specific forms of ice: an amorphous and a crystalline ice (ice III). Ice III is observed when pure water samples are high-pressure frozen provided that the sample temperature does not rise above −150 °C. Above this temperature, ice III transforms into hexagonal ice. Amorphous ice is formed when the sucrose concentration is higher than 20%. The amorphous ice formed under high pressure has a similar, but not identical, X-ray diffraction pattern to that of amorphous ice formed at atmospheric pressure. While the X-ray diffraction pattern of amorphous ice formed at atmospheric pressure (IV) shows a broad ring at a position corresponding to 0.37 nm, that of high-pressure amorphous ice (IVHP) shows a broader ring, located at 0.35 nm. IVHP presents a phase transition (IVHP–IV) at temperatures that depend on the sucrose concentration. We also observed that some precautions have to be taken in order to minimize the alcohol contamination of high-pressure frozen samples. The ice-phase diagram presented in this paper should be taken into account in all methods dedicated to the structural study of frozen biological specimens.