scholarly journals Dynamic Modeling and Simulation of a Super-High-Speed Circumferential-Flux Hysteresis Motor

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
A. Halvaei Niasar ◽  
M. Zare ◽  
H. Moghbelli
Keyword(s):  
Steady State ◽  
Dynamic Modeling ◽  
Gas Turbines ◽  
High Speed ◽  
Dynamic Performance ◽  
Input Power ◽  
Information Storage ◽  
Steady State Condition ◽  
Steady State Model ◽  
Industry Applications

There is an interest in super-high-speed motors in industry applications such as gyroscope, micro gas turbines, centrifuge, machine tool spindle drives, and information storage disk drives. This paper presents the dynamic performance characteristics of hysteresis motors using a Matlab/Simulink software. A nonlinear mathematical model based on ad-qaxis theory in the rotor reference frame is applied to study the starting and synchronization processes of a hysteresis machine with a circumferential-flux-type rotor. The steady-state and transient responses of the motor to different changes such as the variation in the load torque are provided. The calculation method of the motor parameters in dynamic modeling based on a steady-state model of the motor is presented. The simulation results such as the current,the input power, and power factor are compared with some experimental results in steady-state condition.

On The Steady State and Dynamic Performance Characteristics of Floating Ring Bearings

1981 ◽  
Vol 103 (3) ◽  
pp. 389-397 ◽  
Author(s):  
Chin-Hsiu Li ◽  
S. M. Rohde
Keyword(s):  
Steady State ◽  
Linear Theory ◽  
High Speed ◽  
Dynamic Performance ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Journal Bearings ◽  
Transient Problem ◽  
The Stability ◽  
Bearing System

An analysis of the steady state and dynamic characteristics of floating ring journal bearings has been performed. The stability characteristics of the bearing, based on linear theory, are given. The transient problem, in which the equations of motion for the bearing system are integrated in real time was studied. The effect of using finite bearing theory rather than the short bearing assumption was examined. Among the significant findings of this study is the existence of limit cycles in the regions of instability predicted by linear theory. Such results explain the superior stability characteristics of the floating ring bearing in high speed applications. An understanding of this nonlinear behavior, serves as the basis for new and rational criteria for the design of floating ring bearings.

Analysis on Dynamic Performance of Hydrodynamic Tilting-Pad Gas Bearings Using Partial Derivative Method

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Yang Lihua ◽  
Qi Shemiao ◽  
Yu Lie
Keyword(s):  
Analytical Method ◽  
Gas Turbines ◽  
High Speed ◽  
Dynamic Performance ◽  
Gas Bearings ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Dynamic Performances ◽  
Perturbation Frequency ◽  
San Andres

Tilting-pad gas bearings are widely used in high-speed rotating machines due to their inherent stability characteristics. This paper advances the analytical method for prediction of the dynamic performances of tilting-pad gas bearings. The main advantage of the analytical method is that the complete set of dynamic coefficients of tilting-pad gas bearings can be obtained. The predictions show that the perturbation frequency has the strong effects on the dynamic coefficients of gas bearings. In general, at lower perturbation frequency, the equivalent direct stiffness coefficients increase with frequency, whereas equivalent direct damping coefficients dramatically reduce. For higher perturbation frequency, the dynamic coefficients are nearly independent of the frequency. Moreover, the equivalent dynamic coefficients of four-pad tilting-pad gas bearing obtained by the method in this paper are in good agreement with those obtained by Zhu and San Andres [(2007), “Rotordynamic Performance of Flexure Pivot Hydrostatic Gas Bearings for Oil-Free Turbomachinery,” ASME J. Eng. Gas Turbines Power, 129(4), pp. 1020–1027] in the published paper. The results validate the feasibility of the method presented in this paper in calculating the dynamic coefficients of gas-lubricated tilting-pad bearings.

Squeeze film dampers supporting high-speed rotors: Rotordynamics

2020 ◽  
pp. 135065012092208
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbines ◽  
High Speed ◽  
Squeeze Film ◽  
Jet Engines ◽  
Transient Vibration ◽  
Element Analysis ◽  
Squeeze Film Damper ◽  
The Time Domain

This work develops a finite element based multi-mass flexible rotor model for theoretical investigation of the influence of the squeeze film damper lubricant inertia on the unbalance-induced steady-state and transient vibration amplitudes of high speed turbomachinery. The rotordynamic model is developed by applying the principles of finite element analysis to discretize the rotor components, including the rotor shaft and disk, into local elements with mass, stiffness, and gyroscopic matrices. Subsequently, the local matrices are assembled together to develop the global model of the rotordynamic system. The influence of squeeze film damper lubricant inertia is incorporated into the model by using short-length cavitated damper models with retaining springs executing circular-centered orbits. Additionally, the rotordynamic model incorporating the nonlinear squeeze film damper models is iteratively solved in the time domain by applying a predictor-corrector transient modal integration numerical method and the steady-state and transient motions of the rotor system are investigated under different rotor and squeeze film damper parameters. The results of the study verify the substantial influence of squeeze film damper lubricant inertia on attenuating the vibrations of high-speed turbomachinery. Furthermore, the developed rotordynamic model delivers an efficient and powerful platform for the analysis of high-speed turbomachinery, including jet engines and gas turbines.

scholarly journals Dynamic Modeling of Single-Shaft Industrial Gas Turbine

1996 ◽  
Author(s):  
R. Bettocchi ◽  
P. R. Spina ◽  
F. Fabbri
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Dynamic Modeling ◽  
Operating Conditions ◽  
Steady State Condition ◽  
On Line ◽  
Working Parameters ◽  
Industrial Gas Turbine ◽  
And Control ◽  
Measurement And Control

In the paper the dynamic non-linear model of single shaft industrial gas turbine was developed as the first stage of a methodology aimed at the diagnosis of measurement and control sensors and gas turbine operating conditions. The model was calibrated by means of reference steady-state condition data of a real industrial gas turbine and was used to simulate various machine transients. The model is modular in structure and was carried out in simplified form, but not so as to compromise its accuracy, to reduce the calculation time and thus make it more suitable for on-line simulation. The comparison between values of working parameters obtained by the simulations and measurements during some transients on the gas turbine in operation provided encouraging results.

Thermal Management of Electronic Chips in a Channel Using Input Power to Control Flow Velocity

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Esam M. Alawadhi
Keyword(s):  
Steady State ◽  
Pressure Drop ◽  
Thermal Management ◽  
Heat Generation ◽  
Electronic Device ◽  
Thermal Characteristics ◽  
Input Power ◽  
Control Flow ◽  
Steady State Condition ◽  
Average Temperature

In this research, thermal management of an electronic device using the input power is investigated numerically using the finite element method. The considered geometry consists of a horizontal channel with three volumetrically heated chips mounted on the bottom wall of the channel. The magnitude of the channel’s inlet velocity is varied with the variation of heat generation in the chips. The thermal characteristics of the system are presented, and compared with thermal characteristics of a system at a steady state condition. The effect of the Reynolds number and the oscillating period of the heat generation on the chips’ average temperature and Nusselt number is presented. The pressure drop in the channel is also calculated. The results indicated that the transient operating condition causes temperature to be higher than steady state by more than 45%, and difference between the transient and steady operations is reduced if the frequency is high. However, flow frequency has nearly no effect on the pressure drop in the channel.

Performance of a Turboshaft Engine for Helicopter Applications Operating at Variable Shaft Speed

2012 ◽  
Author(s):  
Gianluigi Alberto Misté ◽  
Ernesto Benini
Keyword(s):  
Steady State ◽  
Engine Performance ◽  
Engine Fuel ◽  
Main Rotor ◽  
Steady State Condition ◽  
Power Turbine ◽  
Steady State Model ◽  
Optimization Routine ◽  
Turboshaft Engine ◽  
The Impact

An off-design steady state model of a generic turboshaft engine has been implemented to assess the influence of variable free power turbine (FPT) rotational speed on overall engine performance, with particular emphasis on helicopter applications. To this purpose, three off-design flight conditions were simulated and engine performance obtained with different FTP rotational speeds were compared. In this way, the impact on engine performance of a particular speed requested from the main helicopter rotor could be evaluated. Furthermore, an optimization routine was developed to find the optimal FPT speed which minimizes the engine specific fuel consumption (SFC) for each off-design steady state condition. The usual running line obtained with constant design FPT speed is compared with the optimized one. The results of the simulations are presented and discussed in detail. As a final simulation, the main rotor speed Ω required to minimize the engine fuel mass flow was estimated taking into account the different requirements of the main rotor and the turboshaft engine.

Real-Time Dynamics Modeling of Cryogenic Ball Bearings With Thermal Coupling

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Pradeep K. Gupta ◽  
Howard G. Gibson
Keyword(s):  
Steady State ◽  
Real Time ◽  
Dynamic Modeling ◽  
Heat Generation ◽  
Step Change ◽  
Operating Conditions ◽  
Thermal Time ◽  
Ball Bearings ◽  
Thermal Coupling ◽  
Steady State Condition

Abstract Real-time dynamic modeling of cryogenic ball bearings, where the rotating inner race accelerates to the operating speed, is based on integration of classical differential equations of motion of bearing elements, when experimentally measured ball/race traction behavior is used to compute the imposed acceleration on the rolling elements. The dynamic performance simulation provides a realistic coupling between traction behavior in the ball-to-race contacts and dynamics of bearing element motion as the bearing goes through the transient speed variation. However, due to vastly different mechanical and thermal time scales, heat generation in the bearing is time-averaged over a relatively large thermal time-step to model temperature fields as a step change, while the bearing motion is simulated in real-time. The emphasis is on dynamic modeling with thermal coupling in a static sense. Under stable conditions, the step change in temperature field converges to operating value as the bearing approaches a dynamic steady-state condition, which demonstrates acceptable significance of the dynamic simulation with coupled thermal interactions. Both all steel and hybrid ball bearings for liquid oxygen (LOX) turbo pump applications are modeled. Bearing performance simulations are closely modeled over experimental time cycles in both transient and steady-state domains. Steady-state solutions are shown to be independent of initial conditions to demonstrate acceptable convergence of time domain integrations. Model predictions of heat transferred to circulating LOX is within the range of variation in experimental data. Parametric evaluation of bearing performance as a function of operating conditions demonstrate that while the ball/race contact stress is higher in a hybrid bearing, contact heat generation is significantly lower in comparison with that in the all steel bearings.

The Effect of Treated High-Vanadium Fuel on Gas Turbine Load, Efficiency, and Life

1958 ◽  
Author(s):  
Bruce O. Buckland
Keyword(s):  
Steady State ◽  
Natural Gas ◽  
Gas Turbines ◽  
Complete Recovery ◽  
Magnesium Content ◽  
Vanadium Content ◽  
Residual Oil ◽  
Steady State Condition ◽  
Load Variations ◽  
Compressor Inlet

Tests were run on four inter-cooled regenerative high-temperature gas turbines of like design to measure the effect of burning several different residual fuels. Some of the tests were made with the help and co-operation of the Central Vermont Public Service Corporation on two of their units at Rutland, Vermont. Other tests were made at Bangor, Maine, with the help and co-operation of The Esso Research and Engineering Company, and the Bangor Hydroelectric Company, on the two units in the Graham Station. The results of the tests can be summarized as follows: 1. After a few hundred hours of intermittent operation, the first-stage nozzle area reaches a steady-state condition wherein it oscillates between zero and a maximum of about 8 percent reduction in area due to oil ash. The maximum reduction varies from 4 percent to 8 percent, depending on the fuel; 2. With continuous operation the first-stage nozzle area does not reach a steady-state value in 100 hours but plugs more or less continuously at rates varying from 5 to 24 percent per hundred hours, depending on the fuel. The load decreases also at rates varying from one to twenty percent in the same period; 3. Increasing the magnesium content of the fuel with respect to its vanadium content increases the deposition rate, but increasing the aluminum with respect to the vanadium content has the opposite effect; 4. Substantial temperature changes due to load variations and changes of firing temperature have little or no effect on dislodging the ash, but shutdowns in excess of two hours duration cause recoveries of over 70 percent in the area and over 50 percent in the load; 5. Introducing about 15 pounds of spent refinery catalyst into the low-pressure compressor inlet results in more than 40 percent recovery in the nozzle area and about the same recovery in the load. This cleaning operation, followed by a shutdown, results in practically complete recovery in both load and area during subsequent operation. A test was run for 2400 hours with a single residual fuel containing about 360 ppm of vanadium following 2700 hours operation on distillate fuel. Comparisons of the gas-path parts with those of two other units of the same design, one using a residual oil having 80 ppm of vanadium and the other using natural gas, lead to the following conclusions: 1. The life of the gas-path parts is no different whether a high vanadium or a low vanadium residual fuel is used; 2. The corrosion of the nozzles and buckets is not much greater with treated residual oil than with natural gas.

SOFC/mGT Coupling: Different Options With Standard Boosters

2013 ◽  
Author(s):  
Luca Larosa ◽  
Mario L. Ferrari ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
Steady State ◽  
Hybrid System ◽  
Cost Reduction ◽  
Gas Turbines ◽  
Point Of View ◽  
Inlet Pressure ◽  
Substantial Cost ◽  
Micro Gas Turbine ◽  
Steady State Model ◽  
The University

In this paper an innovative SOFC hybrid system is proposed, equipped with ejector-based cathodic recirculation. The cathodic flow is preheated by recirculating hot exhausts. However, this approach needs higher pressure values than those available with commercial micro gas turbines (mGT): a possible but expensive solution could be to design a completely new mGT. Another option could be to use a booster with the function of re-compressor installed between the mGT compressor and the ejector (in order to increase ejector inlet pressure). This choice allows the use of commercial machines with a substantial cost reduction by comparison with designing a new micro gas turbine. Moreover, this layout is able to separate the compressor ratio of the mGT from the ejector inlet pressure, generating more flexibility from the point of view of the control system. In this paper, a thermodynamic study of this machine coupling is carried out considering the hybrid system emulator developed by TPG at the University of Genoa. For this purpose, three different boosting approaches were examined with a steady-state model built in Matlab-Simulink environment. The results presented here were obtained to show emulator performance and flexibility. Available power and thermal aspects are discussed in detail.

A dynamic modeling approach for a high-speed winding system with twin-rotor coupling

2020 ◽  
Vol 90 (21-22) ◽  
pp. 2533-2551
Author(s):  
Xi Hou ◽  
Yongxing Wang ◽  
Pei Feng ◽  
Haiyan Yu ◽  
Xunxun Ma ◽  
...  
Keyword(s):  
Dynamic Modeling ◽  
High Speed ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Beam Theory ◽  
Element Model ◽  
Heavy Load ◽  
Modeling Approach ◽  
Contact Roller ◽  
Twin Rotor

This paper continues the previous study and presents a dynamic modeling approach for a high-speed winding system. To meet the requirements of high-speed winding, a twin-rotor coupling structure is adopted in the winding system. It is a complex spindle system, due to its high speed, heavy load, frequency-dependent coupling parameters, and time-varying rotational speed. In this paper, an approach to establishing a finite element model of the winding system is proposed to predict its dynamic behavior characteristics during the winding process. First, the spindle and contact roller models of the discrete single component are developed based on Timoshenko beam theory. Bending, transverse shear effects, and gyroscopic moment are considered in the models. The contact stiffness between the contact roller and the packages to be wound on the spindle is simplified by a nonlinear spring. The contact stiffness is identified by dynamics analysis in ANSYS® 17.0. Next, a fully dynamic model of the winding system, which consists of the spindle subsystem, the contact roller, and the flexible coupling elements, is established. Third, the Newmark method is used to develop the program to solve the dynamic equations in MATLAB® 2013b. Finally, the effects of the supporting system and contact state on the winding system's dynamic response are investigated. The results indicate the model of the winding system presented in this paper is suitable for predicting dynamic performance during the winding process.

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