低展弦比涡轮静叶栅叶片正弯曲作用的试验研究

对弯曲叶片研究中代表性的HIT涡轮静叶型重新开展了叶片弯曲对低展弦比涡轮静叶栅流场影响的试验研 究。测量了直叶片叶栅、+10°、+20°和+30°弯曲叶片叶栅的进、出口流场,分析了叶片弯曲对叶栅出口二次流、 总压损失和气流角的影响。结果表明:对该叶型叶栅,叶片正弯曲既不能大幅度降低叶栅二次流损失,也不能改 善叶栅出口气流角沿叶高的分布:叶栅出口二次流动、尾缘涡及壁角涡随叶片正弯曲角的增大而增强,而通道涡 强度和位置变化不大;该研究结果同以往有关文献的研究结果完全不同。     

Monte-Carlo simulation of industrial radiography images and experimental designs

In this article, we present a generic software for the simulation of gamma-ray radiography. This software simulates the entire radiographic system, from the source to the detector consisting of metallic screens and films. In an industrial context where the goal is to detect structural flaws in material like cracks, this simulator allows to compute gamma-ray images for different system parameters. By this way, engineers can choose an optimal set of parameters leading to the best image of flaws. We use Monte-Carlo techniques for the simulation of the whole system composed of a source, an object to inspect and a detector. The main contribution of this paper is to show that simulated images are coherent with real images although we use a simplified model for particle transport. Besides, we propose an acceleration technique to simulate the Markov chain of photon transport. Finally, an experimental design is performed leading to a linear model expressing the influence of the system parameters on image quality.     

汽车起重机用平衡阀静态特性仿真及试验研究

以汽车起重机起升机构系统中的某型流量为300 L/min平衡阀为研究对象,根据平衡阀的结构特点及工作原理,搭建数学模型,并对阀口模型进行精准过流面积计算。以数学模型为基础在AMESim中搭建仿真模型,分析负载压力、主阀流量、背压及控制特性曲线的静态特性;同时对平衡阀进行试验,试验结果对比仿真结果修正数学模型中参数值。结果表明：随着控制压力的增大,主阀口流量呈逐渐增大的趋势;当达到额定流量300 L/min时,主阀口流量保持不变;仿真模拟曲线与试验曲线最大误差为2.7%,验证了模型的可用性。     

基于液压支架用阀试验的ZJFJ 2型试验台液压系统的设计

介绍ZJFJ-2型液压支架用阀静压试验台的液压系统的总体设计,分别详细阐述了以乳化液、机械油两种不同介质作为液压动力源的双系统的设计过程及设计后液压系统的大致工作过程。按照给定的试验方案,对煤矿液压支架用阀进行了性能试验和出厂检验。试验结果表明:该液压系统运行稳定可靠、操作方便、数据测试准确,能够满足用户的要求。     

柔性反馈式液压破碎锤配流系统研究与实验

根据工程施工破碎锤实际工况需要,对柔性反馈式液压破碎锤配流系统进行理论研究。设计一套电液联合控制柔性反馈式液压破碎锤实验样机;搭建液压破碎锤实验测试平台,进行可行性与实际工况下实验。实验结果表明:液压破碎锤电液控制系统设计是可行性的,破碎性能符合要求;利用该系统可实现新型液压破碎锤冲击能与冲击频率的实时改变,采集并分析实际工况下的冲击性能参数。     

基于AMESim的低压铸造机液面加压系统的优化设计与分析

针对某型号低压铸造机在实际生产中,液面加压气动系统压力控制不精确的问题,对原有系统进行了改进,采用气动伺服阀闭环控制的形式来控制进入保温炉内的气体压力。借助AMESim软件对改进后的系统进行了建模,并对参数进行了严格的设置,使整个物理模型最大程度地接近实际系统。通过仿真分析和实验对比,验证改进后系统的压力控制情况要优于原系统。     

Effect of experimental conditions on the parameters used for evaluating the performance of the catalyst Mo/Al2O3 in diesel soot combustion

The literature reported different studies of soot combustion reaction under very distinct experimental conditions, which can include different values of catalyst:soot weight ratios, gas flow and heating rates. Therefore, avoiding screening of innumerable catalysts or empirical experiments, this work aims to present a general methodology based on a statistical experimental design of experiments with soot combustion, evaluating different reaction conditions and parameters that can be used for any other similar study. In this way, the effect of experimental conditions on the parameters used for evaluating the performance of Mo/Al₂O₃, a promising system previously studied, and Pt/Al₂O₃, a notorious catalytic system, were studied by a complete factorial experimental design. The results have shown that the experimental conditions strongly interfere with the parameters used for evaluating the catalytic performance and then it may generate incorrect conclusions.The effects of interaction between different conditions on the activity and mainly on the selectivity of CO₂ permitted to explain the performance of catalysts on soot combustion and to distinguish different pathways of catalytic and non-catalytic reactions under specific reaction conditions.The most appropriate conditions for studying soot combustion seem to be high cat:soot ratios, low heating rates and high gas flow rates, which, according to this work, must be equal to: 95:1, 2 K min⁻¹ and 115 mL min⁻¹, respectively.     

Experimental determination of gas holdup and volumetric mass transfer coefficient in a jet bubbling reactor

The hydrodynamics and mass transfer characteristics of a lab-scale jet bubbling reactor(JBR) including the gas holdup, volumetric mass transfer coefficient and specific interfacial area were assessed experimentally investigating the influence of temperature, p H and superficial gas velocity. The reactor diameter and height were 11 and 30 cm,respectively. It was equipped with a single sparger, operating at atmospheric pressure, 20 and 40℃, and two p H values of 3 and 6. The height of the liquid was 23 cm, while the superficial gas velocity changed within 0.010–0.040 m·s~(-1) range. Experiments were conducted with pure oxygen as the gas phase and saturated lime solution as the liquid phase. The liquid-side volumetric mass transfer coefficient was determined under unsteady-state oxygen absorption in a saturated lime solution. The gas holdup was calculated based on the liquid height change, while the specific interfacial area was obtained by a physical method based on the bubble size distribution(BSD) in different superficial gas velocities. The results indicated that at the same temperature but different p H, the gas holdup variation was negligible, while the liquid-side volumetric mass transfer coefficient at the p H value of 6 was higher than that at the p H = 3. At a constant p H but different temperatures, the gas holdup and the liquid-side volumetric mass transfer coefficients at 40℃ were higher than that of the same at 20℃. A reasonable and appropriate estimation of the liquid-side volumetric mass transfer coefficient(kla) in a pilot-scale JBR was provided which can be applied to the design and scale-up of JBRs.     

电静液作动器的建模仿真与试验研究

电静液作动集成技术是航空界未来航空器发展的五大关键技术之一。简述了电静液作动器EHA国内外发展动态,对定排量变转速型电静液作动器进行了原理分析、建模和仿真、试验验证。结果表明：所设计的电静液作动器满足技术要求,达到了预期目标,能实现高性能控制,但其某些方面还有待进一步的优化。仿真分析和试验结果为EHA的系统设计和工程优化提供参考。