An Experimental Technique for the Analysis of Slug Flows in Pneumatic Pipelines Using Pressure Measurements

An experimental technique has been developed to measure the flow characteristics of slugs in dense phase pneumatic conveying using pressure measurements. This method is based on the unique characteristics of slug flows in pipes, i.e., an axial pressure fluctuation along the pipeline and a pressure difference in the radial direction at the back of a slug. Standard differential pressure transducers were used in this study and the influence of the finite response time of these transducers was considered. Experiments were conducted over a range of gas-solids flow conditions and experimental data were analyzed to describe the behavior of solids slugs through pipes. The calculated slug velocity and length using axial pressure measurements were confirmed by video recordings, and the synthesis between axial and radial pressure signals showed reasonable agreement in flow pattern analysis. This relatively simple measuring technique has been found effective in detecting solids slugs traveling through horizontal pipes and will distinguish various flow regimes. It provides a useful and easily applied tool for system optimizing and benchmarking in industrial applications.     

An Experimental Technique for the Analysis of Slug Flows in Pneumatic Pipelines Using Pressure Measurements

An experimental technique has been developed to measure the flow characteristics of slugs in dense phase pneumatic conveying using pressure measurements. This method is based on the unique characteristics of slug flows in pipes, i.e., an axial pressure fluctuation along the pipeline and a pressure difference in the radial direction at the back of a slug. Standard differential pressure transducers were used in this study and the influence of the finite response time of these transducers was considered. Experiments were conducted over a range of gas-solids flow conditions and experimental data were analyzed to describe the behavior of solids slugs through pipes. The calculated slug velocity and length using axial pressure measurements were confirmed by video recordings, and the synthesis between axial and radial pressure signals showed reasonable agreement in flow pattern analysis. This relatively simple measuring technique has been found effective in detecting solids slugs traveling through horizontal pipes and will distinguish various flow regimes. It provides a useful and easily applied tool for system optimizing and benchmarking in industrial applications.     

并联贮箱不平衡输送试验系统的设计

根据伯努利方程建立并联贮箱推进剂输送的数学模型,分析了并联贮箱不平衡输出的主要影响因素在于两路减压阀出口压力偏差和金属膜片贮箱膜片压差散布,提出以水替代有毒推进剂作为试验工质的计算方法。根据理论分析模型设计出并联贮箱不平衡输送试验系统,利用定流量的推进剂输送系统解决金属膜片的翻转压力时刻变化的问题,保证推进剂输送流量的稳定,从而验证了试验系统的可行性,为新一代运载火箭上面级并联贮箱设计提供了试验支撑。     

差分飞行时间法精密测量高压液体声速的研究

基于差分飞行时间法建立了一套可直接测量高压液体声速的实验装置,自主设计和研制了双超声腔体,建立了精密声速测量系统、高压液体充注系统、精密压力和温度测量系统以及数据采集和分析系统。在此系统上,开展了303～353K,压力高至10MPa的纯水声速测量研究,声速测量相对标准不确定度为0.018% (k=1),纯水声速测量结果与国际标准状态方程及已有实验数据具有良好的一致性。研究成果为后续开展其他液体如海水、新型燃料等工质的精密声速测量奠定了基础。     

Turbulent Flow Around an Oscillating Body in Superfluid Helium: Dissipation Characteristics of the Nonlinear Regime

By examining the resonance curves of an oscillator submerged in superfluid liquid helium, it is found that their shape is affected by two distinct dissipation regimes when the amplitude is large enough to generate turbulence in the liquid. In a resonance curve, the central part close to resonance, may be in a turbulent regime, but the response is of much lower amplitude away from the resonance frequency, so that the oscillation can still be in the linear regime for frequencies not exactly at resonance. This introduces an ambiguity in estimating the inverse quality factor Q ^?1 of the oscillator. By analyzing experimental data we consider a way of matching the two ways of estimating Q ^?1 and use the information to evaluate the frictional force as a function of velocity in a silicon paddle oscillator generating turbulence in the superfluid.     

Mechanical Characterization of an Alternative Technique to Embed Sensors in Composite Structures: The Monitoring Patch

Sensor embedding is one of the main operations in dealing with composites in-core instrumentation. In this work, an alternative encapsulation technique called “monitoring patch” is proposed to achieve correct sensor embedding, to facilitate the industrialised instrumentation procedure and to adapt the sensors according to the geometry and material heterogeneities required of the composite structures. The monitoring patch is mainly developed with the aim to reduce the variability effects produced if the sensor alone is placed. In this initial study, a first patch’s configuration is manufactured with CTMI pre-impregnate epoxy–woven glass, hosting two kinds of silicon prism sensors. The monitoring patch is then placed in the thick middle plane of an epoxy-carbon M21 T700GC quasi-isotropic plate. The plates are instrumented with strain gauges and tested using digital image correlation (DIC). The strain field maps are calculated to analyse the over-strain zones and to infer fracture paths. At the same time, a FEM model is developed to compare the numerical and the experimental observations. The results show that the mechanical strength of the instrumented plates is not significantly affected by the presence of the patch. The failure path of the instrumented plates with monitoring patch is found along the patch perimeter; therefore, the sensors can be recovered without damage even after the failure of the instrumented structure. The feasibility of the monitoring patch is discussed with other embedding techniques. In further studies, the monitoring patch will host a streaming sensor with an aim to carry out in-core strain measurements.     

Numerical Analysis of the Characteristics of an Arc in Laminar and Turbulent Gas Flows

The equations of magnetic gas dynamics are used to calculate the characteristics of an electric arc in a plasmotron channel versus the gas flow rate. The results obtained with the aid of the laminar and the two-parameter k– model of turbulence with allowance for deviations from equilibrium in the plasma and for the swirling of the gas are compared with experimental data. The stability of a laminar flow to the effect of weak hydrodynamic perturbations is investigated.     

Analysis of the Internal Pressure in Tube Hydroforming and Its Experimental Investigation

The internal pressure of the process was studied theoretically and experimentally. The external load character and internal stress character of tube hydroforming were discussed first. Then, according to the characters, the function and classification of internal pressure were presented in general. Base on the stress analysis, its effect on the yield criterion and calculation formula were also researched and derived. To verify the correction of the theoretical analysis and derived formula, experiments with different internal pressures were carried out and the result was compared and discussed. It demonstrates that internal pressure plays an important role in tube hydroforming and theory and formula discussed and derived by this paper are feasible in practice.     

Residual Stresses in a Cu–CFC Component for Thermonuclear Application: Numerical Prediction and Experimental Evaluation Using an Indentation Technique

Abstract: The present work concerns the assessment of residual stresses (RS) in a component for thermonuclear applications, made by casting of copper on a carbon fibre‐reinforced carbon composite and intended to be subjected to severe cycles of thermal, mechanical and neutron loads. The magnitude of RS left at the interface between the two materials in the production process, due to thermal expansion mismatch, has to be carefully assessed. In the present investigation, the likely spatial distribution of the RS has been predicted first using numerical analysis and has been validated experimentally, then, on the basis of the results of indentation tests performed at the micron scale on the metal layer. It is shown that this simple and fast methodology can return reliable results in the present context.     

Evaluation of Cryogenic Flow Meters: An Example in Non-Standard Experimental Design and Analysis

A number of difficult problems in experimental design and analysis were afforded by an experiment to evaluate the precision and accuracy of a new facility for calibrating cryogenic flow meters. Time order was an important variable, but could not be economically randomized. The design space was not rectangular and two important variables were intrinsically highly correlated. The resulting data had outliers, cycles, unexpected shifts and other dilticultics. This report chronicals the evolution of the design of the experiments and the analysis of the results.     

Experimental Measurements of the Speed of Sound in n-Hexane from 293 to 373 K and up to 150 MPa

Speed-of-sound measurements were performed at pressures up to 150 MPa in the temperature range from 293 to 373 K on n-hexane in the liquid state. Theses data were then used to evaluate the isentropic and isothermal compressibility in the same range of pressures and temperatures. The speed-of-sound measurements, as well as the related compressibility coefficients, compare very well with the values calculated from the correlation of Randzio et al. Volumetric properties also compare very well with the direct measurements reported in the standard reference data tables.     

Drop Tower Experiment to Study the Capillary Flow in Symmetrical and Asymmetrical Channels: Experimental Set-up and Preliminary Results

Owing to the development of the space exploration activities, the in-orbit management of fluids such as the transportation of propellant liquid in microgravity becomes the important direction of microgravity fluid research, and one of main problems is the stability behaviors of free surface flow in capillary channel of PMD. In the present study, an experiment set-up of the fluid transport with two different capillary channels has been developed on the Beijing Drop Tower platform. Both symmetrical and asymmetrical flow channels, with the same cross-sectional areas and lengths and different cross-sectional geometries were used and HFE-7500 is chosen as test liquid. 10 times of the drop-down experiments were performed for investigation of the capillary flow characters in different volumetric flow rates, and the three main patterns of capillary flows: subcritical flow, critical flow and supercritical flow were found in experiments, these patterns are distinguished by the movement of the point of lowest surface over time. Meanwhile, the critical flow rates at which free surface becomes instable observed in our experiments are (1) 2.7 ±0.2ml/s for the critical flow rate of asymmetrical channel; and (2) 2.2 ±0.2ml/s for symmetrical channel flow, respectively.     

Characterization and Experimental Verification of the Nonlinear Distortion in a Technique for Measuring the Relative Velocity Between Micromachined Structures in Normal Translational Motion

Applications exist for microelectromechanical systems (MEMS) devices where the measurement or estimation of the relative velocity, or at least the direction of instantaneous relative velocity, between two microstructures in normal translational motion is required. A technique for directly measuring the relative velocity has not been available. This paper presents a technique for directly measuring the relative velocity between two microstructures in normal translational motion. The technique consists of measuring the current flowing into the capacitance formed between the two microstructures when a constant voltage is applied across them. The technique and the resulting nonlinear distortion in the velocity measurement are characterized. A prototype relative velocity sensor is fabricated and evaluated to verify the measurement technique     

利用模态参数识别技术与分层建模理论修改分析模型

本文根据分层建模理论,在计算机上实现了利用由模态参数识别技术得到的模态参数,对分析模型进行修正。计算结果表明,这一方法很好地反映了实验中的精度问题,不失为联系实验测试与数值分析之间的一座新的桥梁。     

双球体挠性接管充压泄漏故障原因分析与测定

针对双球体挠性接管某次充压试验发生泄漏故障,对故障原因和故障测定进行了研究。通过对挠性接管安装、挠性接管密封面的损坏情况以及胶管帘子布损坏部位勘验,结合KST-F(0)G挠性接管的结构分析,测定发生泄漏的原因是接管安装不合理造成,并通过试验再现了故障,验证了分析结果。由此进一步规范了双球体挠性接管安装要求。     

Numerical and Experimental Determination of the Feeding Distance of Aluminum Alloys in Gravity Die Casting Using an Optimized Riser Shape

A finite difference thermal model was utilized to analyze the solidification process and to predict the maximum feeding distance in gravity die casting of aluminum alloys with an optimal riser shape. Predictions are verified experimentally for both pure aluminum and A1-12% Si alloy. The experimental maximum feeding distance for castings made from A1-12% Si alloy in gravity diecastings was found to be 10 times the casting thickness, compared to 9.1 times the casting thickness from numerical predictions. For pure aluminum, the experimental maximum feeding distance was 7 times the casting thickness, compared to 6.2 times the casting thickness from numerical analysis.     

Industrial Ecosystems and Food Webs: An Ecological-Based Mass Flow Analysis to Model the Progress of Steel Manufacturing in China

Materials and energy are transferred between natural and industrial systems, providing a standard that can be used to deduce the interactions between these systems. An examination of these flows is an essential part of the conversation on how industry impacts the environment. We propose that biological systems, which embody sustainability, provide methods and principles that can lead to more useful ways to organize industrial activity. Transposing these biological methods to steel manufacturing is manifested through an efficient use of available materials, waste reduction, and decreased energy demand with currently available technology. In this paper, we use ecological metrics to examine the change in structure and flows of materials in the Chinese steel industry over time by means of a systems-based mass flow analysis. Utilizing available data, the results of our analysis indicate that the Chinese steel manufacturing industry has increased its efficiency and sustainable use of resources over time at the unit process level. However, the appropriate organization of the steel production ecosystem remains a work in progress. Our results suggest that through the intelligent placement of cooperative industries, which can utilize the waste generated from steel manufacturing, the future of the Chinese steel industry can better reflect ecosystem maturity and health while minimizing waste.     

浅析实施标准战略对经济社会科学发展的助推作用--以广州市实施标准化战略工作为例

本文以广州市实施标准化战略工作为例,探讨标准化战略对经济社会发展的助推机理、可能遇到的问题,以及如何更好地发挥标准化战略的助推作用。