scholarly journals Hardware in the Loop Test-Rig for Identification and Control Application on High Speed Pantographs

2004 ◽  
Vol 11 (3-4) ◽  
pp. 445-456 ◽  
Author(s):  
A. Collina ◽  
A. Facchinetti ◽  
F. Fossati ◽  
F. Resta
Keyword(s):  
High Speed ◽  
Real Life ◽  
Operating Conditions ◽  
Hardware In The Loop ◽  
Test Rig ◽  
Dynamical Interaction ◽  
Contact Wire ◽  
The Real ◽  
Current Collection ◽  
Set Up

Trains current collection for traction motors is obtained by means of a sliding contact between the overhead line (OHL) and the collector strips mounted on the pantograph head. The normal force by which the collector presses against the contact wire ensures the contact pressure for the electrical contact. As the train speed increases, the variation of contact force between pantograph and catenary increases, and the pantograph-OHL dynamic interaction becomes greater. This condition causes excessive mechanical wear and contact wire uplift (for high values of contact forces), and leads to high percentage of contact loss, arcing and electrically related wear.The topic of actively controlled pantograph is gaining more interest as a tool to increase the performance of the current collection at high speed. In the last few years, it appears possible to transfer the knowledge based on numerical experiments, to the real operating condition. An important step in this direction is the set up of a laboratory hardware in the loop test-rig in which the control strategies and the actuation can be tested, before tests performing in real life conditions, in order to demonstrate their actual feasibility. The present paper describes an hardware in the loop (HIL) test-rig developed by the authors, which allows to reproduce the dynamical interaction between overhead lines and pantograph in high speed railways. Using the described laboratory set-up, experimental investigation on the problems related with pantograph-OHL interaction can be performed, very similarly to the real life operating conditions, with the advantage of varying test parameters and conditions easily.

Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates

2017 ◽  
Author(s):  
B. R. Nichols ◽  
R. L. Fittro ◽  
C. P. Goyne
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Operating Conditions ◽  
System Stability ◽  
Supporting Evidence ◽  
Test Rig ◽  
Flow Rates ◽  
Oil Supply ◽  
Bending Mode ◽  
Wide Range

Many high-speed, rotating machines across a wide range of industrial applications depend on fluid film bearings to provide both static support of the rotor and to introduce stabilizing damping forces into the system through a developed hydrodynamic film wedge. Reduced oil supply flow rate to the bearings can cause cavitation, or a lack of a fully developed film layer, at the leading edge of the bearing pads. Reducing oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses due to shear forces. While machine efficiency may be improved with reduced lubricant flow, little experimental data on its effects on system stability and performance can be found in the literature. This study looks at overall system performance of a test rig operating under reduced oil supply flow rates by observing steady-state bearing performance indicators and baseline vibrational response of the shaft. The test rig used in this study was designed to be dynamically similar to a high-speed industrial compressor. It consists of a 1.55 m long, flexible rotor supported by two tilting pad bearings with a nominal diameter of 70 mm and a span of 1.2 m. The first bending mode is located at approximately 5,000 rpm. The tiling-pad bearings consist of five pads in a vintage, flooded bearing housing with a length to diameter ratio of 0.75, preload of 0.3, and a load-between-pad configuration. Tests were conducted over a number of operating speeds, ranging from 8,000 to 12,000 rpm, and bearing loads, while systematically reducing the oil supply flow rates provided to the bearings under each condition. For nearly all operating conditions, a low amplitude, broadband subsynchronous vibration pattern was observed in the frequency domain from approximately 0–75 Hz. When the test rig was operated at running speeds above its first bending mode, a distinctive subsynchronous peak emerged from the broadband pattern at approximately half of the running speed and at the first bending mode of the shaft. This vibration signature is often considered a classic sign of rotordynamic instability attributed to oil whip and shaft whirl phenomena. For low and moderate load conditions, the amplitude of this 0.5x subsynchronous peak increased with decreasing oil supply flow rate at all operating speeds. Under the high load condition, the subsynchronous peak was largely attenuated. A discussion on the possible sources of this subsynchronous vibration including self-excited instability and pad flutter forced vibration is provided with supporting evidence from thermoelastohydrodynamic (TEHD) bearing modeling results. Implications of reduced oil supply flow rate on system stability and operational limits are also discussed.

Empirical investigation of wireless sensor network performance in noisy environments

2014 ◽  
Vol 12 (1) ◽  
pp. 29-38
Author(s):  
Silvanus Teneng Kiyang ◽  
Robert Van Zyl
Keyword(s):  
Ambient Noise ◽  
Network Performance ◽  
Signal To Noise Ratio ◽  
Real Life ◽  
Wireless Sensor ◽  
Mathematical Tool ◽  
Content Type ◽  
The Real ◽  
Test Platform ◽  
Set Up

Purpose – The purpose of this work is to assess the influence of ambient noise on the performance of wireless sensor networks (WSNs) empirically and, based on these findings, develop a mathematical tool to assist technicians to determine the maximum inter-node separation before deploying a new WSN. Design/methodology/approach – A WSN test platform is set up in an electromagnetically shielded environment (RF chamber) to accurately control and quantify the ambient noise level. The test platform is subsequently placed in an operational laboratory to record network performance in typical unshielded spaces. Results from the RF chamber and the real-life environments are analysed. Findings – A minimum signal-to-noise ratio (SNR) at which the network still functions was found to be of the order 30 dB. In the real-life scenarios (machines, telecommunications and computer laboratories), the measured SNR exceeded this minimum value by more than 20 dB. This is due to the low ambient industrial noise levels observed in the 2.4 GHz ISM band for typical environments found at academic institutions. It, therefore, suggests that WSNs are less prone to industrial interferences than anticipated. Originality/value – A predictive mathematical tool is developed that can be used by technicians to determine the maximum inter-node separation before the WSN is deployed. The tool yields reliable results and promises to save installation time.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

scholarly journals Hardware in the Loop Platform for Testing Photovoltaic System Control

2020 ◽  
Vol 10 (23) ◽  
pp. 8690
Author(s):  
Víctor Samano-Ortega ◽  
Alfredo Padilla-Medina ◽  
Micael Bravo-Sanchez ◽  
Elías Rodriguez-Segura ◽  
Alonso Jimenez-Garibay ◽  
...  
Keyword(s):  
Control Systems ◽  
Operating Conditions ◽  
Real System ◽  
Photovoltaic System ◽  
Hill Climbing ◽  
Integration Time ◽  
System Control ◽  
Hardware In The Loop ◽  
The Real ◽  
Point Tracking

The hardware in the loop (HIL) technique allows you to reproduce the behavior of a dynamic system or part of it in real time. This quality makes HIL a useful tool in the controller validation process and is widely used in multiple areas including photovoltaic systems (PVSs). This study presents the development of an HIL system to emulate the behavior of a PVS that includes a photovoltaic panel (PVP) and a DC-DC boost converter connected in series. The emulator was embedded into an NI-myRIO development board that operates with an integration time of 10 µs and reproduces the behavior of the real system with a mean percent error of 2.0478%, compared to simulation results. The implemented emulator is proposed as a platform for the validation of control systems. With it, the experimental stage is carried out on two controllers connected to the PVS without having the real system and allowing to emulate different operating conditions. The first controller is based on the Hill Climbing algorithm for the maximum power point tracking (MPPT), the second is a proportional integral (PI) controller for voltage control. Both controllers generate settling times of less than 3 s; the MPPT controller generates variations in the output in steady state inherent to the algorithm used. For both cases, the comparison of the experimental results with those obtained through software simulation show that the platform fulfills its usefulness when evaluating control systems.

Sealing Technology: Rub Test Rig for Abrasive/Abradable Systems

2007 ◽  
Author(s):  
Ulrich Rathmann ◽  
Sven Olmes ◽  
Alex Simeon
Keyword(s):  
High Speed ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Rig ◽  
Visual Appearance ◽  
Major Interest ◽  
Rubbing Behavior ◽  
Blade Tip ◽  
Detailed Assessment ◽  
The University

Performance and efficiency optimization is one of the major tasks in the turbo machinery industry. Therefore efforts for scientific and technical improvements focus on optimization and reduction of losses. Secondary losses are of major interest because of their parasitic character related to stage efficiency and power output. One of these losses is over tip leakage of blades. Common practice is a minimization of this clearance with abrasive/abradable combinations. With this technique the blade tip (abrasive material) can rub into its counterpart (heat-shield, abradable material on casings or liners) and therefore minimize the operating tip-clearance. This technology is well established in compressor and turbine engineering since many years [1]. Field experience shows that abrasive/abradable systems do not always work as intended. In some cases rubbing conditions are reversed so that the intended abradable cuts into the abrasive. Any benefit on operating tip-clearance will then be minor at best or even negative. Rubbing behavior is difficult to predict, especially for new materials or geometries where no experience is available. In close cooperation with the University of Applied Sciences Rapperswil (Switzerland), ALSTOM has developed a test rig that allows simulating engine-operating conditions and therefore evaluate abrasive/abradable combinations before actual implementation into an engine. The rig is designed to reproduce circumferential velocities and incursion rates that are typical for gas turbine engines in the compressor as well as in the turbine. Forces and temperatures are measured as quantitative data, visual appearance and metallographic condition of test specimens are recorded as qualitative data that allow a more detailed assessment of material combinations and operating conditions. This paper describes the design of a high-speed wear rig facility to test single blade and fully shrouded rub configurations. In addition the validation of the test rig against real engine experience and knowledge is shown.

Simulation of Laboratory Jets and Full Scale Exhaust Plumes (Keynote Paper)

2003 ◽  
Author(s):  
Sanford M. Dash
Keyword(s):  
High Speed ◽  
Scale Up ◽  
Turbulence Models ◽  
Operating Conditions ◽  
Data Sets ◽  
Fighter Aircraft ◽  
The Real ◽  
Exhaust Plumes ◽  
Rans Turbulence Models ◽  
The Subject

Recent activities at CRAFT Tech related to the simulation of high speed laboratory jets, their control via passive actuation, and the scale-up and revisions required for real engines and operation at flight are discussed. We focus on aircraft applications related to jet noise reduction with activities pertinent to varied missile jet/plume applications the subject of other review papers. Laboratory jet experiments have served to validate the RANS turbulence models utilized and are supplemented by LES studies to provide data sets not readily obtainable in the laboratory such as temperature fluctuation data needed for thermal transport modeling. Applications for a military fighter aircraft indicate that laboratory experiments cannot replicate the real exhaust environment and thus can only suggest actuation concepts that are promising. CFD is required to revise and scale-up these concepts for the real engine and to provide estimates of their performance in flight. Studies presented show the differences between laboratory plumes and real plumes, as well as the effects of plume/plume and plume/aerodynamic interactions which are quite appreciable and show a markedly different structure than that of the isolated jet under the same operating conditions.

scholarly journals Tractor accelerated test on test rig

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
M. Mattetti ◽  
Giovanni Molari ◽  
A. Vertua ◽  
A. Guarnieri
Keyword(s):  
Real Life ◽  
Weather Condition ◽  
Experimental Tests ◽  
Acceleration Factor ◽  
Test Rig ◽  
The Real ◽  
Structural Part ◽  
Ground Testing ◽  
Post Test ◽  
Structural Tests

The experimental tests performed to validate a tractor prototype before its production, need a substantial financial and time commitment. The tests could be reduced using accelerated tests able to reproduce on the structural part of the tractor, the same damage produced on the tractor during real life in a reduced time. These tests were usually performed reproducing a particular harsh condition a defined number of times, as for example using a bumpy road on track to carry out the test in any weather condition. Using these procedures the loads applied on the tractor structure are different with respect to those obtained during the real use, with the risk to apply loads hard to find in reality. Recently it has been demonstrated how, using the methodologies designed for cars, it is possible to also expedite the structural tests for tractors. In particular, automotive proving grounds were recently successfully used with tractors to perform accelerated structural tests able to reproduce the real use of the machine with an acceleration factor higher than that obtained with the traditional methods. However, the acceleration factor obtained with a tractor on proving grounds is in any case reduced due to the reduced speed of the tractors with respect to cars. In this context, the goal of the paper is to show the development of a methodology to perform an accelerated structural test on a medium power tractor using a 4 post test rig. In particular, several proving ground testing conditions have been performed to measure the loads on the tractor. The loads obtained were then edited to remove the not damaging portion of signals, and finally the loads obtained were reproduced in a 4 post test rig. The methodology proposed could be a valid alternative to the use of a proving ground to reproduce accelerated structural tests on tractors.

Near-Earth Unmanned Aerial Vehicles: Sensor Suite Testing and Evaluation

2006 ◽  
Author(s):  
Vefa Narli ◽  
Paul Y. Oh
Keyword(s):  
Performance Metrics ◽  
High Fidelity ◽  
Hardware In The Loop ◽  
Test Rig ◽  
Math Model ◽  
The Real ◽  
Sensor Performance ◽  
Six Degree Of Freedom ◽  
World Environment ◽  
Testing And Evaluation

This paper describes a test rig that is used to design and test sensor suites for unmanned air vehicles (UAV) operating in near-earth like environments such as forests, caves and urban canyons. The test rig employs a six degree-of-freedom gantry. Inside its workspace is a full-scale diorama of the environment. Surrounding the gantry are lamps, fans, and generators to reproduce lighting, rain and obscurants typical of such environments. A sensor pod is mounted at the gantry end-effector. The acquired data is fed into a high-fidelity math model of the real UAV. The output is then used to drive the gantry to move the sensor pod in the real world environment. The net effect is a hardware-in-the-loop system that emulates the real UAV’s motions and responses in near-Earth environments. The test rig is important because there is little to no data on sensor performance metrics of UAV in near-Earth environments.

scholarly journals Investigations on Oil Flow Rates Projected on the Casing Walls by Splashed Lubricated Gears

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
G. Leprince ◽  
C. Changenet ◽  
F. Ville ◽  
P. Velex
Keyword(s):  
Spur Gear ◽  
Operating Conditions ◽  
Test Rig ◽  
Variable Size ◽  
Flow Measurements ◽  
Flow Rates ◽  
Lubricant Flow ◽  
Wide Range ◽  
Oil Flow ◽  
Set Up

In order to investigate the oil projected by gears rotating in an oil bath, a test rig has been set up in which the quantity of lubricant splashed at several locations on the casing walls can be measured. An oblong-shaped window of variable size is connected to a tank for flow measurements, and the system can be placed at several locations. A series of formulae have been deduced using dimensional analysis which can predict the lubricant flow rate generated by one spur gear or one disk at various places on the casing. These results have been experimentally validated over a wide range of operating conditions (rotational speed, geometry, immersion depth, etc.).

Design of a High-Speed Rotating Test Rig for Adaptive Seal Systems

2015 ◽  
Author(s):  
Laura S. Beermann ◽  
Corina Höfler ◽  
Hans-Jörg Bauer
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Parameter Study ◽  
Test Rig ◽  
Swirl Chamber ◽  
Mass Flows ◽  
Gap Width

Gas turbine engines are subject to increased performance and improved efficiency, which leads to rising core temperatures with additional cooling needs. Reducing the parasitic leakage in the secondary flow system is important to meet the challenging requirements. New seal designs have to be tested and optimized at engine like conditions, like high pressure of up to 9 bar and surface speed of up to 280 m/s as well as an adjusted flow field. Flexible seal designs are an innovative approach to reduce leakage mass flows significantly. Axial and radial movements during transient operating conditions can be compensated easily, thus allowing a smaller gap width and minimizing rub and heat load. This paper describes the design and construction of a new rotating test rig facility. To the knowledge of the authors, this is the only test rig with an adjustable gap width and flow field in a high pressure and speed range. The facility is capable of up to 8 bar differential pressure across the seal and up to 4 bar back pressure. The high revolution engine facilitates a surface speed of up to 280 m/s. A traversable casing allows a quick change of the gap width during operation and simulates radial and axial rotor/stator movements in the engine. The seal movement as well as the resulting gap width are measured during operation to fully understand the seal behavior. An important feature of the new test rig is the continuously adjustable pre-swirl system. It has been designed to cover the different flow conditions in the real engine. Therefore, a RANS parameter study of the pre-swirl chamber has been conducted, which shows the adjustability of different pre-swirl ratios for constant and changing inlet mass flows.

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