基于层流流量计的航发燃油流量动态测量技术研究

为解决航空发动机过渡态燃油测量问题,研究了基于层流流量计(LFM)的航空燃油流量动态测量技术.设计了一款量程为0～3 000 mL/min的液体LFM,在小型涡轮喷气式发动机试车台上对其进行了试验,并与科里奥利流量计(CMF)进行了比对,试验结果显示LFM具有优秀的动态特性.当发动机处于稳态时,LFM测量结果与CMF吻...     

某型航空发动机双转子系统动力学特性计算

针对双转子航空发动机的动力学特性问题展开研究,以传递矩阵法为基础,建立数学计算模型,引用经实验验证的算法,结合某型航空发动机双转子的实际结构,对其动力学特性进行理论计算,对结果进行分析,得出结论,为航空发动机转子动力学特性的调整和发动机的故障诊断提供了一些理论参考。计算结果表明:该发动机转子在额定工作转速范围内存在一阶临界转速,但临界转速远离工作转速,说明柔性转子设计合理。双转子系统中由于中介轴承的耦合作用,一个转子的临界转速随另一个转子转速的增加而增加。     

航空发动机燃油系统温升特性研究

为发挥航空发动机燃油的最大使用效益,充分利用燃油对发动机滑油及飞机交流发电机(IDG)滑油的冷却作用,利用多种分析方法对某型航空发动机燃油温升特性进行研究,给出了发动机典型工作状态下的燃油温升特性,并与试验结果进行对比。结果表明提出的分析方法能够有效的计算航空发动机各工作状态下的燃油温升特性。     

基于GasTurbTM的双转子涡扇发动机性能研究

基于国内外涡扇发动机及其部件特性研究结果，本文旨在以双转子高涵道比涡扇发动机E³某型号为研究对象，通过GasTurb^TM仿真平台，建立动态部件模型。基于相似理论及模化原理，在核心机工作点匹配约束条件下，对其部件特性进行研究，从而获得航空发动机在非稳定工况下的整机性能和工作特性。研究结果表明：在其他条件一定的情况下，双转子发动机的核心机效率和流量随高低压转子转速的增大而增大，伴随着涡轮前温度的升高，推力逐渐增大，耗油率先增大后减小；高压压气机的增压比偏离设计值的程度对油耗影响较为明显。     

航空发动机燃油喷嘴关键件配合精度研究

基于流体体积(Volume of Fluid,VOF)方法和realizable k-ε湍流模型,对航空发动机双油路离心式喷嘴的主油路进行数值模拟,通过仿真与实验结果相结合对关键件的尺寸公差和配合尺寸进行了调整。通过实验加工出了不同尺寸公差的配合试件,并在不同工况条件下进行测试,对比主油路的雾化性能,验证燃油喷嘴关键件的配合精度对主油路雾化性能的影响,找到了导致燃油喷嘴出现油膜过厚、喷雾锥角偏大和流量偏小等性能不达标的影响因素,为优化航空发动机燃油喷嘴雾化性能和提高整套喷嘴性能一致性提供了参考。     

航空发动机转子系统动力特性的研究

航空发动机作为高速旋转机械,其振动特性直接影响到飞机的整机性能,而转子系统是发动机的主要振源。在试车过程中,发现某型涡扇双转子航空发动机频频发生振动故障,为了查出影响发动机振动的主要因素,以某型涡扇双转子发动机为研究对象,应用ANSYS有限元软件计算了转子系统的临界转速和振型,并利用多体动力学仿真软件ADAMS建立转子系统的刚柔耦合虚拟样机模型,在转速维持恒定的情况下,进行了动力学仿真,得到了转子系统的不平衡响应,为减振工作提供了技术支持。     

孔口流量计正压测试夹具和可膨胀系数的研究

孔口流量计是标准孔板流量计的特殊使用形式,为环境监测领域中常用流量测量元件。孔口流量计在校准时按上游入口压力的不同,其校准方法分为微正压和微负压两种校准工况。两种工况均为国家标准和规范推荐方法,但校准出的流量系数差距达10%。夹具引入的附加差压和仪表流量系数线性度误差是导致两种校准工况流量系数偏差的原因。通过CFD仿真研究,设计对被校准孔口流量计上游压力影响较小的夹具形式和结构参数。在仿真数据的基础上计算得到适用于常用管径和雷诺数范围的孔口流量计的可膨胀修正系数公式。运用上述成果并进行试验验证,正压和负压校准流量系数的差距减小至±0.5%以内。校准流量范围内孔口流量计流量系数线性度也有0.1%左右的提升。     

双转子航空发动机振动信号的分离测试技术

阐述了用FFT(快速傅立叶变换)分离法和盲源分离法,对双转子航空发动机振动信号进行分离的原理和实现,并应用FastICA算法,对某型双转子航空发动机高、低压转子实测振动信号进行了盲源分离实践,分离结果验证了该方法的可行性和有效性,从而为双转子发动机振动监测与故障诊断提供了一种可行的信号处理方法。     

航空发动机双转子系统碰摩故障振动特性研究

航空发动机转子系统的振动对飞机的飞行安全具有重要影响。文中针对某型航空发动机无中介轴承的双转子系统的结构特征,采用集中质量法建立了双转子-轴承-机匣耦合的动力学模型,分别对内外转子碰摩故障进行了仿真,通过轴心轨迹图、时域波形图、频谱图、庞加莱图分析了双转子系统耦合振动响应特性,提取了内外转子碰摩故障特征。研究成果可以为航空发动机振动状态监测和故障诊断系统提供理论支持。     

基于AMESim的主燃油控制系统仿真与频域分析

为确定某型航空发动机数控系统中主燃油控制系统特性，采用力平衡和流量连续方程方程，并结合AMESim软件建立主燃油计量模块、等压差模块、停车控制模块和整个系统的仿真模型。与试验结果对比，通过模型部件调试和模块优化确定高精度仿真模型；并利用AMESim线性分析和模态分析工具对主燃油控制系统的频域特性和固有频率进行了计算。结果表明：所建主燃油控制系统仿真模型特性与试验结果比较误差小于5%,系统固有频率与实测结果一致，可为主燃油控制装置系统的优化设计提供理论依据。     

复合型流量计的测量模型

在无载液压缸动态特性良好的基础上,将其与伺服电机控制的计量泵并联连接,设计一种复合型动态流量计,可实现对连续偏置的动态流量精确测量。计量泵调节无载液压缸的活塞位置的同时测量偏置稳态流量,无载液压缸测量高频的动态流量,解决了无载液压缸的行程受限问题。结合复合型动态流量计的结构特性,提出了一种新的泵控缸动平衡控制方案来调节液压缸的活塞位置,提高了活塞的控制和响应速度;同时针对流量测量中的流体泄漏建立流量泄漏补偿模型,使动态流量的测量更精确。搭建实验系统,利用LabVIEW编写实验程序,结合涡轮流量计进行稳态流量测量校准。实验结果表明:复合型流量计方案可行,在稳态流量的测量中可以实现高精度的测量,在动态流量测量中,动态性能良好。     

Performance tests of flowmeters for fuel consumption measurements in fishing vessels

In the study, we developed a flowmeter to be mounted on fishing vessels to measure their fuel consumption in the sea, and evaluated the performance of the flowmeter under the dynamic conditions of a fishing vessel. In order to analyze the dynamic behavior of the fishing vessel in the sea, dynamic motions (pitch and heave) based on the speed of the fishing vessel were obtained through simulation and field test. In the presence of vibration, the uncertainty of the ultrasonic flowmeter increased from 0.12% to 0.5%. The measurement error of the ultrasonic flowmeter also increased from 0.5% up to 2% when dynamic behavior motions (pitch and heave) increased with the speed of the fishing vessel. The results confirmed that the measurement errors of ultrasonic flowmeter were consistent at the same flow rate and speed of the fishing vessel in the dynamic test bed and sea field test. Additionally, to confirm the long-term stability of the developed flowmeter, a long-term test of the flowmeter was performed for three days in actual fishing conditions. The results indicated that the ultrasonic flowmeter developed in the study can measure the fuel consumption of an actual fishing vessel. To the best of the authors’ knowledge, this is the first study to measure the fuel consumption in the sea via mounting a flowmeter on an actual fishing vessel.     

气体涡轮流量计性能优化的模拟与实验研究

以TRZ80气体涡轮流量计为研究对象,采用数值模拟与实验测试相结合的方法,提出了前整流器和后导流体的结构优化方案。通过对结构优化前后流量内部流场特征的分析,揭示了流量计结构与性能优化背后确切的流体力学机制。研究结果表明：前整流器和后导流体区域的压降突变与后导流体尾部的涡旋结构和回流现象是影响流量计计量性能的主要机制。优化的流量计结构可以明显减弱压降突变、涡旋结构与回流现象。优化的流量计结构既可以显著降低流量计的压力损失,又可以明显提高流量计的测量精度与稳定性,其压力损失和线性度误差分别降低了约48.58%和32.43%。研究结果有助于为今后开发与量产计量性能更好的气体涡轮流量计提供理论指导和技术支持。     

Evaluation of flowmeters for heat metering

Heat flowmeters are expected to be reasonably priced, be very reliable, and have high measurement accuracy. Various types of heat flowmeters have been developed and they are widely used in large residential and industrial buildings. In this study, three types of heat flowmeters (turbine, electromagnetic and ultrasonic) were tested for accuracy, effect of installation position and vibration, durability and performance in the field for several installation positions and in the presence of vibration. We used a liquid flow standard system and a customized durability test system in accordance with the International Organization of Legal Metrology (OIML) R 75-2 heat meter testing method. The field test was conducted in eight different locations from winter to summer. All flowmeters were calibrated before and after the field test, and the measurement deviation and the relative expanded uncertainty were calculated. The mean deviations obtained were–0.21%,–0.07%, and 0.11%, with the relative expanded uncertainties 0.48%, 0.17%, and 0.40% for turbine, electromagnetic, and ultrasonic flowmeters, respectively. The results of position and rotation tests, mean deviations by rotation angles at 90°, 180°and 270°relative to 0°(horizontal position) were–1.24%,–1.07% and–0.80%, respectively. For the vibration tests at 1 m/s² and 5 m/s² vibration acceleration, the turbine flowmeter, the electromagnetic flowmeter and the ultrasonic flowmeter showed deviations that ranged from −0.2% to −0.5%, −0.6% (2.6 m³/h), and 0.0% (negligible), respectively. In the durability tests, the accuracy of all three types of heat flowmeters remained at ±1% or less, showing sufficient durability. In the field test, the deviation of the turbine flowmeter and the ultrasonic flowmeter showed ±2.5% or less deviation. However, the electromagnetic flowmeter seems to be inaccurate below 6.9% of the maximum flow rate.     

Field test of a swirlmeter for gas flow measurement

In this paper the experimental results of a field test in natural gas measurement are presented. A vortex precession meter (swirlmeter) has been tested by means of a master–slave calibration technique, using, as reference, a turbine gas meter for custody transfer. The main aim of this study is to assess the metrological behaviour and the sensibility to the installation effects of a vortex precession flowmeter (swirlmeter), which, although well known in the control of the process industry, is quite a new instrument in natural gas applications. The experimental results here reported can be considered as only a first but necessary step to realise an exhaustive metrological analysis of this meter, since field tests must always be combined with laboratory tests in order to reach a comprehensive knowledge.     

Analysis of viscosity effect on turbine flowmeter performance based on experiments and CFD simulations

Viscosity effect is one important factor that affects the performance of turbine flowmeter. The fluid dynamics mechanism of the viscosity effect on turbine flowmeter performance is still not fully understood. In this study, the curves of meter factor and linearity error of the turbine flowmeter changing with fluid viscosity variations were obtained from multi-viscosity experiments (the viscosity range covered is 1.0×10^–6 m²/s–112×10^–6 m²/s). The results indicate that the average meter factor of turbine flowmeter decreases with viscosity increases, while the linearity error increases. Furthermore, Computational Fluid Dynamics (CFD) simulation was carried out to analyze three-dimensional internal flow fields of turbine flowmeter. It was demonstrated that viscosity changes lead to changes of the wake flow behind the upstream flow conditioner blade and the flow velocity profile before fluid entering turbine rotor blade, which affect the distribution of pressure on the rotor blades, so impact the turbine flowmeter performance.     

Developing a model for prediction of helical turbine flowmeter performance using CFD

In this article, a numerical model for prediction of turbine flowmeter performance is proposed. This model is consists of a novel iterative algorithm, based on torque balance theory. Despite previous studies, the effect of bearings drag torque on finding balance point is considered. Using an in-house code, the bearings torque of the flowmeter is calculated based on the finite difference method. The three-dimensional steady state internal flow field of turbine flowmeter is obtained from the Computational Fluid Dynamics (CFD) simulations. For evaluation of the model׳s accuracy the experiments on a 6 in. helical turbine flowmeter has been carried out for crude oil and water. Consequently, the K-factor and also linearity error for cases of fluids are achieved. The results were compared with experimental data and it is found that the numerical model results are reasonably accurate. Therefore, by using the proposed model, the heavy cost of design and optimization of turbine flowmeters can be reduced.     

Performance test and component characteristics evaluation of a micro gas turbine

This study aims to analyze engine performance and component characteristics of a micro gas turbine based on detailed measurement of various parameters. A test facility to measure performance of a micro gas turbine was set up and performance parameters such as turbine exit temperature, exhaust gas temperature, engine inlet temperature, compressor discharge pressure and temperature, and fuel and air flow rates were measured. The net gas turbine performance (power and efficiency based on the gas turbine shaft end) was isolated and analyzed. With the aid of measurement based simulation, component characteristic parameters such as turbine inlet temperature, compressor efficiency, turbine efficiency and recuperator effectiveness were estimated. Behaviors of the estimated characteristic parameters with operating condition change were examined and sensitivities of estimated parameters to the measured parameters were analyzed.     

Uncertainty estimation in calibration of instruments of model turbine test facility

The experimental testing of the reduced scale model turbine is an important phase to obtain the performance characteristics of the prototype because the characteristics are difficult to obtain from theoretical calculations. A specially designed hydraulic test facility following the guidelines of international standards is generally used to obtain the performance characteristics of model turbine. These characteristics are transposable to the prototype turbines. The model turbine test facility is also used for the research and development work by the designers and scientists. The accuracy of the results obtained is entirely dependent on the instrumentation, calibration and uncertainty estimation. In the present study, the instrumentation and calibration procedure of a model Francis turbine test facility is presented by following the guidelines of international electrotechnical commission. The instruments such as flow meter, inlet and differential pressure transducers, torque sensors, angular position sensors and temperature sensors are calibrated using primary and secondary methods. The calibration curves and uncertainties involved in different instruments are obtained and presented. Both systematic and random uncertainties involved in hydraulic efficiency measurements are also presented. The maximum total uncertainty is ±0.15% in the hydraulic efficiency of model Francis turbine at best efficiency point.     

Response and flow characteristics of a dual-rotor turbine flowmeter

The technical problems of flow measurement in hypersonic flight could be mitigated through dual-rotor turbine flowmeters (DRT-FMs). In this study, a visual experiment platform was designed to reproduce the flow of a 1.3 cm diameter DRT-FM. A mathematical model considering two rotors was developed to perform a parameterised study and evaluate the rotor responses. Further, the entire flow passage was numerically simulated through an added automatic iterative rotor-dynamic calculation based on the angular momentum balance theory. According to the experimental results, the response range of the rotational speeds was divided into three stages: unresponsive, unstable, and stable. The downstream rotor responded at a lower flow rate, increasing the measurement range of the rotor turbine flowmeter. Considering the region of linear increase in the rotor speed in stable state under different flow media, tip clearances, and number of blades, the mathematical results indicated that the downstream rotor exhibited a compensation effect of the rotational speed on the calculation of rotational speed at the current flow rate conditions, which mitigates the measurement instability of the upstream rotor. Through the simulations, the rotation speed difference of the two rotors resulted in a slight periodic disturbance to the downstream rotor, which was alleviated after flowing through the spacer and could be ignored. Moreover, the high vorticity regions appeared around the rotors and areas of abrupt structural changes in the flow passage; the distribution gradually extended as the vorticity decreased. The present study provides an understanding of the DRT-FM and some recommendations to improve its characteristics.