Numerical and Experimental Investigations on Flexible Multi-bearing Rotor Dynamics

2004 ◽  
Vol 127 (4) ◽  
pp. 408-415 ◽  
Author(s):  
Q. Ding ◽  
A. Y. T. Leung
Keyword(s):  
Angular Acceleration ◽  
Rotor Dynamics ◽  
Dynamic Responses ◽  
Experimental Investigations ◽  
Test Rig ◽  
Theoretical Simulation ◽  
Speed Up ◽  
Simultaneous Existence ◽  
Stationary Bifurcation ◽  
The Mathematical Model

An experimental test rig is built to verify the dynamics of a multi-bearing rotor. It consists of two flexibly coupled shafts and is connected to a motor at one end via a flexible coupling. Each of the shafts is supported at the ends by two hydrodynamic bearings and is attached with two disks with equal and unequal masses, respectively. The mathematical model of the test rig is developed and is simulated numerically. The non-stationary dynamic responses of the system during speed-up with a constant angular acceleration are shown, respectively, by the non-stationary bifurcation diagrams, the selected time flows, and the spectrum cascades. Experiments are then carried out on the test rig. Generally, the numerical results are verified qualitatively by the experiments. Both results indicate that the non-synchronous whirls of the two shafts influence each other when flexibly coupled together. In particular, a new phenomenon is found for the four-bearing rotor system: the pre-existing non-synchronous whirl/whip resulted from the instability of one shaft can activate the onset of oil instability of another shaft. In the theoretical simulation, this phenomenon represents the rapid increase of the non-synchronous whirl orbit, whereas in the experiment, it represents the simultaneous existence of two whirl/whip frequencies in the spectra.

The Method of Harmonic Excitation for Determination of the Flexibility of the Support of Machine’s Rotor

2002 ◽  
Author(s):  
Jozef Rybczynski
Keyword(s):  
Rotor Dynamics ◽  
Harmonic Excitation ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Test Rig ◽  
Harmonic Force ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Made In

A series of experimental investigations were made in order to determine the set of coefficients of flexibility of construction supporting the rotor. The investigations were made on the test rig for the rotor dynamics investigation. A harmonic force of known amplitude was applied to all supports of the system to induce vibration of the system. Then the system’s reaction in the form of displacement in all connections at the same time was measured. On the bases of the experimental results a square 36-element (6×6) matrix of flexibility coefficients for each frequency of excitation was created. The matrices are the initial material to determine the modal masses, stiffness coefficients and damping coefficients in such form so that they could be the data to calculate the dynamics of the experimental rotor by means of computer programs. Moreover the experimental results are interesting information in the to analysis of the behavior of the test rig’s pedestals.

Experimental Investigations to Use Splash Lubrication for High-Speed Gears

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
A. Neurouth ◽  
C. Changenet ◽  
F. Ville ◽  
M. Octrue ◽  
E. Tinguy
Keyword(s):  
High Speed ◽  
Helical Gear ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Automotive Applications ◽  
Test Rig ◽  
Specific Test ◽  
Lubricant Oil ◽  
Speed Up ◽  
Run Up

In order to use electric motors which run up to 40,000 rpm in future automotive applications, this study aims to experimentally investigate if splash lubrication technique is worth considering for high-speed gears, i.e., for tangential gear speed up to 60 m/s. To this end, a specific test rig has been used to operate a single spur or helical gear in various operating conditions (lubricant, oil sump volume, temperature, etc.). Churning loss is measured and, as the fraction of air in the lubricant (namely, oil aeration) can be influential on this source of dissipation, a specific sensor is also employed for online monitoring of oil sump aeration. By inserting some moveable walls in the gearbox, it is demonstrated that churning losses and oil aeration can be significantly reduced by mounting these flanges at an appropriate distance to the gear lateral faces. Based on dimensional analysis, an engineering criterion is proposed to properly choose the clearance between the tested gear and the flanges.

Impact of Electric Vehicle Lateral Dynamics on the Battery Pack

2014 ◽  
Vol 590 ◽  
pp. 451-457
Author(s):  
Sen Nan Song ◽  
Fa Chao Jiang ◽  
Hong Shi
Keyword(s):  
Mathematical Model ◽  
Angular Acceleration ◽  
Simulation Software ◽  
The Body ◽  
Battery Pack ◽  
Vehicle Body ◽  
Rolling Motion ◽  
Rolling Angle ◽  
On The Road ◽  
The Mathematical Model

The present work is concerned with the rolling motion of the battery pack when EV travelling on the road. First McPherson suspension system was regarded as the research object with detailed analysis of its structural features and motion characteristics. Establish the mathematical model which could apply to calculating the rolling motion of the vehicle body. Through MATLAB/Simulink simulation software, we could calculate the rolling angle on passive suspension. On this basis, assume that the battery pack mounted on the vehicle body and make it passive connection and PID connection. When the body rolls, the battery pack will produce a certain angle then. Next establish the mathematical model to summarize the relationship between the two variables. Then we set the parameters and calculate the roll angle of battery pack in both cases for comparison. Simulation results show that road irregularities will make battery rotate an angle and PID controller can effectively reduce the angle, especially angular acceleration. This paper put forward a new idea that battery is connected with body by active control on EV, and proves the superiority in reducing the rolling angle.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

Experimental Investigation on the Dynamic Response of a Three Legged Articulated Type Offshore Wind Tower

2016 ◽  
Author(s):  
Chinsu Mereena Joy ◽  
Anitha Joseph ◽  
Lalu Mangal
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Renewable Energy Sources ◽  
Offshore Structures ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Experimental Investigations ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Study Results

Demand for renewable energy sources is rapidly increasing since they are able to replace depleting fossil fuels and their capacity to act as a carbon neutral energy source. A substantial amount of such clean, renewable and reliable energy potential exists in offshore winds. The major engineering challenge in establishing an offshore wind energy facility is the design of a reliable and financially viable offshore support for the wind turbine tower. An economically feasible support for an offshore wind turbine is a compliant platform since it moves with wave forces and offer less resistance to them. Amongst the several compliant type offshore structures, articulated type is an innovative one. It is flexibly linked to the seafloor and can move along with the waves and restoring is achieved by large buoyancy force. This study focuses on the experimental investigations on the dynamic response of a three-legged articulated structure supporting a 5MW wind turbine. The experimental investigations are done on a 1: 60 scaled model in a 4m wide wave flume at the Department of Ocean Engineering, Indian Institute of Technology, Madras. The tests were conducted for regular waves of various wave periods and wave heights and for various orientations of the platform. The dynamic responses are presented in the form of Response Amplitude Operators (RAO). The study results revealed that the proposed articulated structure is technically feasible in supporting an offshore wind turbine because the natural frequencies are away from ocean wave frequencies and the RAOs obtained are relatively small.

Experimental Study of Water Flow in Full-Size Test Rig for Water-Cooled Turbo-Generator Rotor

1966 ◽  
Vol 181 (1) ◽  
pp. 53-73 ◽  
Author(s):  
I. K. Csillag
Keyword(s):  
Operating Conditions ◽  
Experimental Investigations ◽  
Air Cooling ◽  
Test Rig ◽  
Full Size ◽  
Generator Rotor ◽  
Turbo Generator ◽  
Hydrogen Cooling ◽  
Major Factors ◽  
Design And Manufacture

The demand for electric power has doubled in the last decade. The most economical way to meet this demand is by building large-output generating units. The study of the major factors which determine the output of such generators shows that the only effective way to increase the output is by improving the cooling of their windings. For that reason design has progressed from air-cooling to indirect hydrogen-cooling, then to direct hydrogen-cooling. Now the trend is towards direct water-cooling where the water is in direct contact with the copper windings. The introduction of water into the stator winding was established in 1956 (1)† and was in fact directly responsible for the present increase in unit rating. The introduction of water to a rotating winding presents difficult problems in both design and manufacture. The test rig dealt with in this paper was built to study some of these problems and to carry out experimental investigations on a full size model of the special hydraulic features for a water-cooled turbo-generator rotor. The investigations were concentrated around the following five different problems which are dealt with in detail: (1) increase in pressure drop due to rotation; (2) free-rotating seal (inlet seal) (2); (3) vacuum-breaking device (water outlet) (3); (4) loss-distribution in the rotor; (5) measurement of the rotor vibrations in various operating conditions.

Dynamics of MEMS-Based Angular Rate Sensors Excited via External Electrostatic Forces

2020 ◽  
Author(s):  
Ibrahim F. Gebrel ◽  
Ligang Wang ◽  
Samuel F. Asokanthan
Keyword(s):  
Dynamic Behavior ◽  
Electrostatic Force ◽  
Angular Rate ◽  
Equations Of Motion ◽  
Ring Structure ◽  
Dynamic Responses ◽  
Actuator Dynamics ◽  
Vibratory Gyroscopes ◽  
Thin Ring ◽  
The Mathematical Model

Abstract This paper investigates the dynamic behavior of rotating MEMS-based vibratory gyroscopes which employs a thin ring as the vibrating flexible element. The mathematical model for the MEMS ring structure as well as a model for the nonlinear electrostatic excitation forces are formulated. Galerkin’s procedure is employed to reduce the equations of motion to a set of ordinary differential equations. Understanding the effects of nonlinear actuator dynamics is considered important for characterizing the dynamic behavior of such devices. A suitable theoretical model to generate nonlinear electrostatic force that acts on the MEMS ring structure is formulated. Dynamic responses in the driving and the sensing directions are examined via time responses, phase diagram, and Poincare’ map plots when the input angular motion and the nonlinear electrostatic force are considered simultaneously. The analysis is envisaged to aid fabrication of this class of devices as well as for providing design improvements in MEMS Ring-based Gyroscopes.

scholarly journals Design of a Measurement System for Six-Degree-of-Freedom Geometric Errors of a Linear Guide of a Machine Tool

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 5 ◽  
Author(s):  
Chien-Sheng Liu ◽  
Jia-Jun Lai ◽  
Yong-Tai Luo
Keyword(s):  
Degree Of Freedom ◽  
Geometric Errors ◽  
Light Path ◽  
Linear Guide ◽  
Positioning Errors ◽  
Speed Up ◽  
Analysis Design ◽  
Six Degree Of Freedom ◽  
Straightness Error ◽  
The Mathematical Model

This paper proposes a system utilizing a Renishaw XL80 positioning error measuring interferometer and sensitivity analysis design to measure six-degree-of-freedom (6 DOF) geometric errors of a machine tool’s linear guide. Each error is characterized by high independence with significantly reduced crosstalk, and error calculations are extremely fast and accurate. Initially, the real light path was simulated using Zemax. Then, Matlab’s skew ray tracing method was used to perform mathematical modeling and ray matching. Each error’s sensitivity to the sensor was then analyzed, and curve fitting was used to simplify and speed up the mathematical model computations. Finally, Solidworks was used to design the set of system modules, bringing the proposed system closer to a product. This system measured actual 6 DOF geometric errors of a machine tool’s linear guide, and a comparison is made with the Renishaw XL-80 interferometer measurements. The resulting pitch, yaw, horizontal straightness, and vertical straightness error deviation ranges are ±0.5 arcsec, ±3.6 arcsec, ±2.1 μm, and ±2.3 μm, respectively. The maximum repeatability deviations for the measured guide’s pitch, yaw, roll, horizontal straightness, vertical straightness, and positioning errors are 0.4 arcsec, 0.2 arcsec, 4.2 arcsec, 1.5 μm, 0.3 μm, and 3 μm, respectively.

Development and Experimental Testing of a Pilot Burner for DLN Combustors

2004 ◽  
Author(s):  
G. Riccio ◽  
S. Piazzini ◽  
P. Adami ◽  
F. Martelli ◽  
G. Tanzini ◽  
...  
Keyword(s):  
Experimental Testing ◽  
Isothermal Flow ◽  
Experimental Investigations ◽  
Test Rig ◽  
Electric Company ◽  
Low Emission ◽  
Analysis Design ◽  
Industrial Gas Turbine ◽  
D Model ◽  
Pilot Burner

Different geometrical modifications have been investigated and experimentally tested to improve a pilot burner for low emission industrial gas turbine combustors. Results of the ongoing collaboration between the DE of Florence and the Italian electric company ENEL are reported. The activity is dedicated to the improvement of the pilot burner to extend the operable margin of the engine and to reduce, at the same time, the emissions. The study has been performed mainly by means of experimental investigations both on isothermal flow as on combustion test rig. Results of the activity were employed both to obtain design information about the swirler and injection fuel holes for the pilot burner under investigation. Moreover the post-processing of the experimental data permitted the improvement of the correlation implemented into the 1-D model for the prediction of the injected fuel path. These results were implemented in the routine DoFHIS (Design of Fuel Holes Injection Systems) developed for the analysis/design of injection fuel systems.

Vibration characteristics simulation and comparison of traditional cab system model and seat–cab coupled model for trucks

2019 ◽  
Vol 10 (03) ◽  
pp. 1950013 ◽  
Author(s):  
Leilei Zhao ◽  
Yuewei Yu ◽  
Changcheng Zhou ◽  
Simon Feng
Keyword(s):  
Angular Acceleration ◽  
Coupled Model ◽  
Random Excitation ◽  
Vibration Characteristics ◽  
Dynamic Responses ◽  
System Model ◽  
Vertical Acceleration ◽  
Excitation Condition ◽  
Vertical Excitation ◽  
Excitation Conditions

To define the application fields of the traditional cab system model and the seat–cab coupled model, this paper mainly aims to investigate the differences of the vibration characteristics of the two models. First, the two models and their motion equations were introduced. Then, based on the mechanical parameters of the seat and cab system for a truck, the transmissibility characteristics of the two models were analyzed. The results show that the traditional model can relatively accurately predict the pitch and roll vibration characteristics of the real seat–cab system. However, it overvalues the vertical vibration transmitted from the front suspensions of the cab. Third, the typical excitation conditions and the measuring points were selected. Finally, under the typical excitation conditions, the dynamic responses of the measuring points were calculated. The results show that under the vertical excitation condition, the dynamic responses of the two models have obvious differences. Under the roll excitation condition and the pitch excitation condition, the roll responses and the pitch responses of the cab between the two models show almost no obvious difference. Under the random excitation condition, the vertical acceleration responses have relatively larger deviations between the two models, however, the angular acceleration responses are almost the same. For the preliminary design of the cab system, the traditional cab system model can be used. However, for the accurate design and the optimization of the seat–cab system, the seat–cab coupled model is recommended.

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