基于K&C试验台的汽车动力总成惯性参数精确测试方法研究

汽车动力总成惯性参数(质量、质心位置和转动惯量)的精确测试一直是汽车行业内难点.如何设计汽车动力总成惯性参数高精度的测试方法,是整个汽车测试行业共同关注的问题.本文以中国汽车技术研究中心悬架KC试验台为基础,对汽车动力总成惯性参数测试方法进行了研究.通过杠杆原理和转动惯量平行轴移动定理对试验测得结果进行计算,得到汽车动力总成的惯性参数,并对测试结果精度进行了标定验证.结果表明该方法具有非常高的测试精度,可进行汽车动力总成惯性参数精确测试.     

离心泵快速启动过程瞬态性能测试系统的研制

离心泵在快速启动过程中表现出明显的瞬态特性,其瞬态水力性能与稳态运行过程的性能存在较大区别,快速启动的试验研究对于离心泵在特殊场合应用打下重要基础。由于其测试方法与一般水泵试验方法存在明显区别,因此专用试验台的研制是瞬态性能试验的重要基础。文中介绍试验系统的整体结构和数据采集系统,以及瞬时流量、扬程、转速等参数的测试方法和瞬态汽蚀特性的测试方法,同时还给出了各瞬态性能数据的描述方式和修正方法。通过在该试验台上进行的多次试验的结果可以看出,该试验台能较准确地测试离心泵的瞬态特性和稳态性能。     

数字舰炮随动系统精度测试分析

对数字舰炮随动系统跟踪精度的角差量测试方法及全角量测试方法进行了分析,并用典型的SDC(Synchro-to-Digital Conversion,同步机数字转换器,1700/2系列)模块,对角差量测试方法在MATLAB平台上进行了仿真试验,发现传统的角差量测量方法用于采用SDC模块的舰炮随动系统存在不可忽略的测量误差.提出了采用全角量测量方法,利用误差相消原理对舰炮随动系统输入信号进行变换、测量的方案,仿真试验结果表明:该方法可大大减小数字舰炮随动系统精度测试误差.     

透平膨胀机绝热效率的测试方法及误差计算

介绍透平膨胀机绝热效率测试中选用仪表精度、测试方法以及有关影响测试精度的因素和误差估算。指出按设计参数进行低温试验,最能表征其真实的绝热效率值。并列出了绝热效率综合误差的表达式。最后建议在作低温性能试验的同时,以同等精度作“热”态性能试验,每年复检时按“热”试数据对比,作为评定绝热效率值的依据。图2参11。     

对汽车制动性能检测误差的探讨

本文针对汽车制动性能检验经常出现误差的原因,从滚筒反力式制动试验台的结构参数、测试方法、操作规程方面进行了详细的分析和探讨.提出了改进措施,以便使检测结果更加准确、客观,使台试模拟技术更接近于实际.     

基于多基站激光跟踪仪的机器人位姿精度测试方法

针对机器人末端位姿精度测试的需求,提出了基于多基站激光跟踪仪的测试方法。该方法采用三靶球测量方案,通过非线性最小二乘法求解转站参数,并融合多基站测量数据实现机器人末端位姿精度的测试。通过直线导轨和转台标准器对该方法的测试效果进行实验验证,结果显示相对于单基站激光跟踪仪的测试方法,三基站测量的定位精度提升了38.5%,定点重复精度提升了42.2%。将该多基站测试方案在型号为IRB14000的工业机器人上进行了试验,根据工业机器人性能规范及其试验方法国标(GB/T 12642)要求进行操作,得到了机器人位姿精度的测试结果,证明了该多基站测试方案的可行性。     

基于工件面形精度的超精密机床误差建模与分析

在影响超精密加工工件面形精度的诸多因素中,机床的空间几何误差与运动误差往往占主要作用.在本单位一台新型超精密加工试验台的加工试验中,出现了较大的面形误差.为了辨识影响工件面形精度的主要误差,首先将机器人运动学理论与多体系统运动学理论相结合,建立新型超精密加工试验台的实际运动模型;其次,定量分析各个误差,如对刀误差、两轴不平行度误差和摆动中心定位误差等对工件面形精度的影响,得到工件面形精度(波峰-波谷值)随不同误差的变化规律;最后进行加工试验,并用PG I1240轮廓仪检测工件面形,将实际加工工件的检测结果与各个误差的分析结果进行相关性分析.通过上述分析,确定试验台两轴不平行是影响工件面形精度的主要误差因素.     

EHA汽车主动悬架试验台虚拟样机模型研究

提出了一种基于EHA的汽车主动悬架,建立了测试该悬架性能试验台的物理样机.在该物理样机的基础上,采用功率键合图方法和ANSYS-ADAMS-SIMULINK软件,建立了主动悬架试验台的复杂的机、电、液压、控制等多领域的虚拟样机.基于虚拟样机的仿真结果与基于物理样机的试验结果的对比表明:簧载质量的位移及加速度均方根值误差百分比均在8%以内,达到了工程上的要求.同时,加入PID控制后,簧载质量的位移和加速度都减小了30%左右.验证了所建立的机电液一体化系统虚拟样机模型的准确性.     

铁路客车空调机组检修中制冷压缩机排量的检验

简述了铁路客车空调压缩机排量试验台的设计参数和工作原理。设计的试验台为双循环系统,主要包括空气循环系统和制冷循环系统两部分。同时介绍了试验台的设计和试验情况,通过进行验证性试验,确定试验台的测试精度在10%以内。     

电子膨胀阀流量特性测试装置的研制

针对目前电子膨胀阀(EXV)测试设备的自动化程度低、测试结果不准确等缺点,遵照JB/T 10386-2002的测试方法,设计了一套适用于各类电子膨胀阀的流量特性测试系统.该装置采用了以单片机为核心的控制方案,并且开发了专用的电子膨胀阀驱动器.最后通过实验验证,该测试装置很好地实现了对电子膨胀阀流量特性的测试以及合格与否的初步判断,流量测试精度小于1.5%FS,测量参数指标达到技术要求.     

Blade protection and efficiency preservation of a turbine by a sacrificial material coating

In order to preserve the efficiency and power of a gas turbine, the clearances between rotating blades and the interior casing should be as small as possible. To obtain that, one sprays a sacrificial material by an atmospheric plasma spraying torch and obtains a coating layer. During their rotation, the blades scrape the coating and tear off fine layers, creating a functional gap between the blades and the casing seal. The combustion gases do not escape through the clearance and contribute to the power production. The aim of this work is to investigate the behavior of a particular sacrificial material and its effect on turbine blade wear under operating conditions. For this purpose, we use the abradability test rig in which three functional parameters are varied. Blade wear or material displacement is shown on various graphs and on the wear map, which indicates the other observed phenomena.     

Experimental study of cryogenic liquid turbine expander with closed-loop liquefied nitrogen system

A cryogenic liquid turbine expander is developed as a replacement for traditional Joule–Thomson valves used in the cryogenic systems for the purpose of energy saving. An experimental study was conducted to evaluate the performance of the turbine expander and is the subject of this paper. The test rig comprises a closed-loop liquefied nitrogen system, cryogenic liquid turbine expander unit, and its auxiliary and measuring systems. The test operating parameters of the turbine expander are determined on the basis of flow similarity rules. Pre-cooling of the liquid nitrogen system is first performed, and then the tests are conducted at different flow rates and speed ratios. The turbine expander flow rate, inlet and outlet pressure and temperature, rotational speed and shaft torque were measured. Experimental results and their uncertainties were analyzed and discussed. The following are demonstrated: (1) For both test cases, turbine expander peak isentropic efficiency is respectively 78.8% and 68.4% obtained at 89.6% and 92% of the design flow rate. The large uncertainties in isentropic efficiency are caused by the large enthalpy variations subjected to small measurement uncertainties in temperature and pressure. (2) Total efficiency and hydraulic efficiency of the turbine expander are obtained. They are essentially the same, since both include flow-related effects and also bearing losses. Comparisons of total efficiency and hydraulic efficiency were used to justify measurement uncertainties of different quantities, since the former involves the measured mass flow rate and enthalpy drop (being dependant on inlet and outlet temperature and pressure), while the latter involves the actual shaft power, volume flow rate, and inlet and outlet pressure. (3) Losses in flow passages and the shaft-bearing system have been inferred based on the measured turbine expander total efficiency, isentropic efficiency, and mechanical efficiency, which are respectively 57.6–74.8%, 62.1–78.8% and 89.5–96.4%. Uncertainty analysis is conducted for experimental isentropic efficiency, hydraulic efficiency, and total efficiency. The hydraulic efficiency seems to be the best measure for assessing the performance of cryogenic liquid turbine expander. (4) Isentropic efficiency versus speed ratio is obtained from the experimental data. The experimental isentropic efficiency increases with the speed ratio, and it reaches 78.8% at the largest experimental speed ratio. A higher efficiency would be achieved if the speed ratio could reach a larger value. This provides some guidance for an optimal operation of the turbine expander in the future.     

Early stage white etching crack identification using artificial neural networks

White Etching Cracks (WEC) in gearbox bearings is a major concern in the wind turbine industry, which can lead to a premature failure of the gearbox. Though many hypotheses regarding the generation of WEC have been proposed over the decades, the answer is still disputable. To trace back the failures to earlier stages before they occur, an innovative sensor-set has been utilized on a test rig to monitor the influencing factors that lead to WEC. This paperwork seeks to recognize abnormal patterns from recorded sensor data and derive statements of sensible sensor combinations in WEC early detection. A Long Short Term Memory (LSTM) network-based autoencoder is proposed for the anomaly detection (AD) task. Employing an auto-associative sequence-to-sequence predictor, a model is trained to reconstruct the normal time series data without WEC. The reconstruction error of testing time series data is evaluated for the determination of its anomaly. The results show that the specified LSTM autoencoder framework can qualitatively distinguish anomalies from collected multivariate time series data. Moreover, the anomaly score evaluated via reconstruction-error-based metrics can discriminate normal and abnormal behaviors in the study. This investigation’s results entail a significant step towards early WEC risk detection and more cost-efficient wind turbine technology if this approach can be further applied on stream data with plausible thresholds in monitoring system.

     

一种自调整的空间面轮廓度误差的评定方法

基于最小二乘法并结合二维样条插值函数和优化技术 ,提出一种用于空间面轮郭度误差评定的数据处理方法 ,其优点是在轮郭度误差评定过程中、能自动地实现被测轮廓与理论轮廓之间的适应性调整 ,从而能够分离并消除被测轮廓与其测量基准之间的位置误差对轮廓误差评定结果的影响。文中以汽轮机叶片轮廓的轮廓度误差评定为例 ,证实了这种评定方法的优越性。     

A Method for Determining X-ray Elastic Constants for the Measurement of Residual Stress

Abstract: The X-ray diffraction method is arguably the most convenient method of measuring residual stresses in terms of cost, spatial resolution, measurement time and the accuracy of measurement. The normal methods for calibrating X-ray diffractometers are not conveniently applied to automated scanning systems, however, and so a new approach is required. In this study, a scanning X-ray diffractometer was calibrated and the X-ray elastic constant for a steel alloy was determined using a customised four-point bending rig. The bending rig, in turn, was calibrated by dead loading. This study also described a simple alternative method for determining the X-ray elastic constant, without the use of specialised software. After calibration, the error band of the diffractometer was found to be less than ±10 MPa. As this is ±5% of the yield stress for a typical steel, this level of accuracy was deemed to be acceptable for the measurement of residual stress.     

纳米磁性膜微波磁谱测量微带线系统的优化设计

磁性薄膜微波磁导率的扫频测量对研究开发高频软磁材料和薄膜吸波材料都具有十分重要的意义.围绕微波磁谱测量微带线系统的优化设计,主要研究微带线短路法测量薄膜磁谱使用的测量夹具的设计与制作.首先根据测试要求确定夹具设计方案,再利用高频电磁场仿真软件HFSS对微带线结构夹具进行性能仿真与设计优化,最后按设计要求制作微带线结构夹具,并对测试效果进行了分析评价.结果表明,设计开发的微带线结构夹具能满足0.05～5GHz频段磁导率的测量精度要求,反射系数S11的测量误差小于1.4%.     

First comparison of the electrical properties of two grid emulators for UVRT test against field measurement

The technical rules for connecting turbines to the medium, high or extra-high voltage grid in Germany require the certification of the UVRT characteristics of wind turbines. The state-of-art voltage divider-based test equipment, also named UVRT-Container, is well equipped for executing UVRT tests in field. To conduct the UVRT in field the full wind turbine should be already installed. A second option to perform UVRT tests are system level test benches. They enable the testing of the nacelle. The components that are not actually present, such as the turbine tower or the blades, are emulated via a mechanical hardware in the loop (HiL) system. In this work, for the first time, the performance of two different grid simulators installed at the DyNaLab at Fraunhofer IWES and at the CWD at RWTH Aachen University is compared with a field measurement of the same type of wind turbine. Thus, not only a system test bench measurement is compared to a field measurement. Rather, two system test benches with individual technical approaches are additionally compared with each other. The focus of this work is to investigate the characteristics of the grid simulators within the steady-state range of the UVRT tests to replicate identical fault shapes on the test benches and in the field.

     

透平膨胀机气体轴承多功能实验台

在一个气体轴承常温动特性实验台的基础上，改建成了一个常温低温、静动特性气体轴承实验台，以满足开发气体轴承透平膨胀机的需要。实际应用显示，通过应用该实验台可有效地掌握透平膨胀机气体轴承的多方面性能。     

固态微波功率器件测量夹具及其校准技术研究

固态微波功率器件由于其封装形式的特殊性,测量过程中必须引入测量夹具作为桥梁,才能完成接口形式的转换,进而开展测试工作。针对固态微波功率器件微波电参数在测试中,测量夹具给测量结果带来影响的问题,对固态微波功率器件测量夹具及其校准技术进行了研究。文章介绍了采用TRL校准方法,并利用矢量网络分析仪的误差修正功能来去除测量夹具误差,从而得到被测器件的真实性能参数。通过具体试验数据表明,对测量夹具的校准和误差的去除是可行有效的,从而可以在测量结果中去除测量夹具的影响而得到被测器件的"净"参数。     

Dynamic weighing under nonzero initial conditions

The discrete output error (OE) model of second order is derived for the weighing system dynamics. Using the model and the recursive least squares (RLS) procedure, model parameters and then the mass being weighed can be estimated from a dynamic measurement signal of very short duration. The validity and the accuracy of this method are illustrated by digital simulation studies and real-life measurements