Measured Torsional Vibration Characteristics of a 100 Megawatt Wind Tunnel Drive Line

1999 ◽  
Author(s):  
James M. Corliss ◽  
H. Sprysl
Keyword(s):  
Steady State ◽  
Damping Ratio ◽  
Forced Response ◽  
Operating Conditions ◽  
Pulse Load ◽  
Torsional Vibrations ◽  
Variable Frequency Drive ◽  
Steady State Operation ◽  
Torque Measurements ◽  
Torsional Analysis

Abstract A new 100 MW (135,000 Hp) adjustable speed drive system has recently been installed in the NASA Langley National Transonic Facility. The 100 MW system is the largest of its kind in the world and consists of a salient pole synchronous motor powered by a 12-pulse Load Commutated Inverter variable frequency drive. During system commissioning the drive line torsional vibrations were measured with strain gages and a telemetry-based data acquisition system. The torque measurements included drive start-up and steady-state operation at speeds where the drive motor’s pulsating torques match the drive line’s torsional natural frequency. Rapid drive acceleration rates with short dwell times were effective in reducing torsional vibrations during drive starts. Measured peak torsional vibrations during steady-state operation were comparable to predicted values and large enough to produce noticeable lateral vibrations in the drive line shafting. Cyclic shaft stresses for all operating conditions were well within the fatigue limits of the drive line components. A comparison of the torque measurements to an analytical forced response model concluded that a 0.5% critical damping ratio was appropriately applied in the drive line’s torsional analysis.

Reduction of High-Amplitude Cogging Torque Response in a 12,000 Horsepower Synchronous Drive Motor

2003 ◽  
Author(s):  
James M. Corliss ◽  
Siddharth Pant ◽  
Kevin Hui ◽  
Larry Duddy ◽  
Jon Veno
Keyword(s):  
Steady State ◽  
Natural Frequency ◽  
Damping Ratio ◽  
Element Model ◽  
Forced Response ◽  
Response Analysis ◽  
Torsional Vibrations ◽  
Cogging Torque ◽  
Adjustable Speed Drive ◽  
Adjustable Speed

A new 12,000 horsepower adjustable speed drive system has recently been installed in the NASA Langley 14- by 22-Foot Subsonic Wind Tunnel. The new system consists of a salient pole synchronous motor powered by a 12-pulse cycloconverter adjustable speed drive. During system commissioning the drive line torsional vibrations were measured with strain gages and a telemetry-based data acquisition system. Torque measurements were taken during transient and steady-state operations at speeds where the drive motor’s pulsating torques matched the drive line’s torsional natural frequency. Measured peak torsional vibrations during steady-state operation were comparable to values predicted by a finite element model forced response analysis. An unexpected oscillating torque occurred during low speed operations where the motor’s cogging torque matched the torsional natural frequency. The oscillating torque was higher than the mean torque at this speed, and the motor’s electrical flux was tailored in this speed range to reduce the response to acceptable levels. A half-power bandwidth analysis of the torsional resonances concluded that the torsional critical damping ratio of the driveline was approximately 0.7%.

Asymptotic Analysis of a Narrow Gas-Lubricated, Flat Sector Thrust Bearing

1988 ◽  
Vol 110 (3) ◽  
pp. 427-433 ◽  
Author(s):  
J. J. Shepherd
Keyword(s):  
Steady State ◽  
Numerical Methods ◽  
Power Loss ◽  
Thrust Bearing ◽  
Center Of Pressure ◽  
Operating Conditions ◽  
Load Bearing Capacity ◽  
Steady State Operation ◽  
Bearing Number ◽  
Continuous Range

The method of matched expansions is employed to analyze the steady state operation of a finite gas-lubricated flat sector bearing for the case where the ratio of radial to circumferential dimensions is small and the relevant bearing number, Λ, is moderate. This technique yields general expressions for the pressure distribution, load bearing capacity, power loss and center of pressure location that are valid for a significant and continuous range of bearing dimensions, orientations and operating conditions. Comparisons are made, where possible, with the existing results from the literature obtained by numerical methods.

VPO Transient Oxidation Kinetics

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Gregory S. Patience ◽  
Maria-Jesus Lorences
Keyword(s):  
Steady State ◽  
Maleic Anhydride ◽  
Oxidation Rate ◽  
Circulating Fluidized Bed ◽  
Operating Conditions ◽  
Adsorption Sites ◽  
Carbon Adsorption ◽  
Reducing Conditions ◽  
Steady State Operation ◽  
Adsorbed Carbon

Transient and steady state reactor data for the partial oxidation of butane to maleic anhydride were collected in a fluid bed over DuPont commercial vanadium pyrophosphate catalyst (VPO) principally under butane rich, oxygen deficient operating conditions. Under moderate reducing conditions, oxygen becomes the determining factor for maleic anhydride productivity and selectivity. As the oxygen becomes depleted, minor changes in butane conversion impacts the selectivity substantially. However, when VPO catalyst is pre-exposed to oxygen for a substantial period of time (as practiced in Circulating Fluidized Bed technology), selectivity may be improved and maleic anhydride yields four times the steady state operation values are achieved. As the butane-to-oxygen ratio rises above 1, carbon deposits onto the surface of the catalyst, resulting in lower activity and selectivity. Based on a detailed reaction engineering model, the re-oxidation rate of the adsorbed carbon is 1st order with respect to the carbon adsorption sites and ½ order in oxygen. The re-oxidation rate of the reduced catalyst appears to be 1st order in sites and oxygen.

Steady-State Operation of a Loop Heat Pipe: Network Thermofluid Model and Results

2003 ◽  
Author(s):  
Nima Atabaki ◽  
B. Rabi Baliga
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Horizontal Tube ◽  
Operating Conditions ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Sintered Metal ◽  
Steady State Operation ◽  
Transport Line ◽  
Compensation Chamber

A network thermofluid model of a loop heat pipe (LHP) operating under steady-state conditions is presented. Attention is focused on a simple LHP, with one evaporator, a vapor transport line, a single condenser, a liquid transport line, and a compensation chamber. The evaporator is an internally grooved circular pipe, with a cylindrical wick installed on its inner surface. The wick is made of a sintered metal. The condenser is a horizontal tube covered with a high-thermal-conductivity sleeve, and the outer temperature of the sleeve is maintained at a constant sink temperature. Quasi one-dimensional mathematical models of the fluid flow and heat transfer in each of the elements of the LHP, and collectively of the entire LHP, are proposed and discussed. The working fluid considered in this work is ammonia, but the proposed model can work with any suitable fluid. Results pertaining to the LHP performance for a range of operating conditions are presented, compared (qualitatively) to corresponding results of an earlier experimental investigation in the literature, and discussed.

Long-Term Microturbine Exposure of an Advanced Alloy for Microturbine Primary Surface Recuperators

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Wendy J. Matthews ◽  
Karren L. More ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
National Laboratory ◽  
Operating Conditions ◽  
Normal Operation ◽  
Operating Environment ◽  
Protective Oxide ◽  
Oak Ridge ◽  
Steady State Operation ◽  
Alloy Oxidation

Haynes alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.) forms a protective oxide scale when exposed to the harsh operating environment of a microturbine primary surface recuperator. Primary surface recuperators manufactured from HR-120 are currently in use on the Capstone C65 MicroTurbine (MicroTurbine is a registered trademark of Capstone Turbine Corporation). Long-term microturbine tests of this alloy are currently being conducted at an elevated turbine exit temperature (∼100°F higher than that in a normal operation) at Capstone Turbine Corporation. Alloy samples that have been tested under steady-state microturbine operating conditions are removed after predetermined exposure intervals for characterization by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. Such evaluations include the characterization of surface oxide scales and the associated alloy compositional changes following a steady-state operation ranging from 1800 h to 14,500 h. Results from the microstructural and compositional analyses of these long-term steady-state engine-tested HR-120 samples are used to illustrate the progression of alloy oxidation in the microturbine operating environment.

Enhanced Heat Transfer Structure Design for Ion Dump of EAST-NBI System Based on Hypervapotron

2017 ◽  
Author(s):  
Ling Tao ◽  
Chundong Hu ◽  
Yuanlai Xie
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Energy Deposition ◽  
High Energy ◽  
Operating Conditions ◽  
Quasi Steady State ◽  
Enhanced Heat Transfer ◽  
Steady State Operation ◽  
The Future ◽  
Transfer Structure

Ion dump is an important functional component of the Neutral Beam Injection (NBI) system of Experimental Advanced Superconducting Tokamak (EAST) for absorbing un-neutralized particles deflected by deflection magnets during neutralization, and by means of the corresponding measurement and analyzing method on it, the total energy deposition value and instantaneous energy deposition distribution of the deflected ion beam can be obtained. According to the operation mechanism of the NBI system, ion dump is directly subjected to high-energy particle bombardment for long time, the corresponding heat-loaded on its plates is high, so the temperature rise control is demanding. In order to realize the running power of 2–4MW and running pulse length of more than 100s or even 1000s in the future NBI system, the structure of the ion dump must be designed in accordance with the quasi-steady state operation requirements to provide the guarantee for the steady state operation of EAST system. The Hypervapotron structure based on the subcooled boiling principle is used as an alternative structure to enhance the heat transfer of this high-heat-flux component. According to the operating requirements, space requirements, measurement requirements and beam power distribution characteristics, the engineering design and implementation of ion dump based on the enhanced heat transfer structure is realized for the future long pulse quasi-steady NBI system. The computational results of the heat-fluid-solid coupling simulation based on the two-phase heat transfer are also confirmed the feasibility of the proposed ion dump structure under quasi-steady-state operating conditions. This study is of great significance to explore the optimal heat transfer structure for quasi-steady ion dump to realize the high current, quasi-steady state and high power operation of EAST-NBI system.

scholarly journals DVR Control System for Voltage Sag/Swell Compensation for Sensitive Loads Protection

2020 ◽  
Vol 9 (11) ◽  
pp. 173-179
Keyword(s):  
Control System ◽  
Steady State ◽  
Voltage Drop ◽  
Reference Value ◽  
Operating Conditions ◽  
Resonance Problem ◽  
Transient Time ◽  
Steady State Operation ◽  
Lc Filter ◽  
Disturbance Detection

This paper introduces an enhanced control system to improve the transient response of the dynamic voltage restorer (DVR). The control strategy achieves superior response against voltage disturbance approximately within 400 µs. The control system comprises three terms: closed-loop feedback control signal, upstream disturbance detection error, and voltage drop over DVR term. The actual load voltage is compared with its reference value and is adapted by a PI controller. The upstream disturbance detection significantly enhances the transient time of the control system performance and improves its steady-state operation. In addition, the voltage drop over the DVR term represents the voltage drop caused by the DVR circuit component. Incorporating these effects in the control loop, fast and accurate response of the system are achieved. An L filter is used instead of the LC filter to overcome the inherent LC filter damping delay and resonance problem mentioned in previous studies. The system is simulated using MATLAB/ Simulink. The simulation results show excellent response in transient and steady-state operation for various operating conditions.

Torsional Vibrations in Rotor Shells

1998 ◽  
Vol 212 (4) ◽  
pp. 263-276 ◽  
Author(s):  
R Whalley ◽  
M Ebrahimi
Keyword(s):  
Cylindrical Shell ◽  
Manufacturing Process ◽  
High Speed ◽  
Damping Ratio ◽  
Operating Conditions ◽  
Torsional Vibrations ◽  
Thin Cylindrical Shell ◽  
Paper Manufacturing ◽  
Simulation Results ◽  
Transient Oscillations

Rotors comprising a motor-driven thin cylindrical shell with rigidly attached ends and torsional dampers, all of which are supported on bearings, are investigated. Analysis procedures enabling the variations in the model singularities with parameter changes are outlined. General results are derived indicating that the system damping ratio is maximized under specific operating conditions. A typical high-speed rotor for a paper manufacturing process is considered and analytical and simulation results are presented, confirming the predicted optimum damper settings and thereby minimizing the transient oscillations.

A High-Temperature Catalytic Combustor With Starting Burner

2000 ◽  
Vol 123 (3) ◽  
pp. 543-549 ◽  
Author(s):  
Y. Yoshida ◽  
K. Oyakawa ◽  
Y. Aizawa ◽  
H. Kaya
Keyword(s):  
Steady State ◽  
Catalytic Combustion ◽  
Cold Start ◽  
Heating System ◽  
Operating Conditions ◽  
Combustion System ◽  
Cold Starting ◽  
Steady State Operation ◽  
Wide Range ◽  
Catalytic Combustor

A catalytic combustion system has high potential to achieve low NOx emission level. When this combustion system is applied to a gas turbine, the required combustor performance must be maintained over a wide range of operating conditions. These conditions range from cold starting to steady-state operation. Particularly during the initial stage of cold starting when the catalyst is not yet activated, the catalyst must be heated by some means. This study proposes a new concept of a catalytic combustor with a direct heating system using vaporizing tube for starting burner in order to downsize the combustor and reduce the warm-up time during cold starts. The effectiveness of this concept is experimentally verified. Furthermore, NOx, CO, and HC emissions during startup can be reduced to a low level so as to achieve ultra-low pollution of the catalytic combustion over a wide range of operating conditions from cold start to steady-state operation. This paper outlines the operation concept covering cold start, verification of the concept through the experiments with flame visualization in the combustor, spray characteristics, construction of the combustor, and combustion characteristics that show low pollution in various operating conditions of the catalytic combustor.

Modeling and Simulation of a Cold-Engine Test Stand Driveline With Experimental Comparisons

2006 ◽  
Author(s):  
Kamran A. Gul ◽  
Douglas E. Adams
Keyword(s):  
Fuel Injection ◽  
Cold Test ◽  
Forced Response ◽  
Test Stand ◽  
Torsional Vibrations ◽  
Engine Test ◽  
Response Characteristics ◽  
Noise Characteristics ◽  
Torque Measurements ◽  
The Impact

There is a need to develop cold-engine test stands for use in diagnosing cylinder faults and measuring gear noise given the new quieter fuel injection systems in modern engines. When engines run hot, these characteristics are not easily measured. By running the unfired cold-engine as a load using an electric motor and driveline, torque measurements can be used to diagnose assembly faults, damage and noise characteristics. In this paper, two cold-engine test stand drivelines are considered. Both stands experience large torsional vibrations excited by the various engine harmonics. Engine fault diagnosis becomes a challenge when these torsional vibrations degrade the measured torque signals. To solve this problem of torsional vibrations, an engine test stand model is developed to understand the system dynamics and analyze the free and forced response characteristics of the system. The model is used to predict the impact of the changes made to the test stand driveline and the trends observed in the simulation results are compared with experimental results for model validation. It is shown that based on model sensitivity analysis the changes made to the driveline parameters help to reduce the amplitude of the driveline resonances considerably. The developed model can be used to design a cold test stand for production diagnostics.

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