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%.

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.

The Finite Element Analysis and Optimization for the Grinder Based on the Joint Surface

2013 ◽  
Vol 281 ◽  
pp. 165-169 ◽  
Author(s):  
Xiang Lei Zhang ◽  
Bin Yao ◽  
Wen Chang Zhao ◽  
Ou Yang Kun ◽  
Bo Shi Yao
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Element Model ◽  
Joint Surface ◽  
Weak Links ◽  
Response Analysis ◽  
Element Analysis ◽  
Static And Dynamic Analysis ◽  
Harmonic Response Analysis ◽  
Grinding Machine

Establish the finite element model for high precision grinding machine which takes joint surface into consideration and then carrys out the static and dynamic analysis of the grinder. After the static analysis, modal analysis and harmonic response analysis, the displacement deformation, stress, natural frequency and vibration mode could be found, which also helps find the weak links out. The improvement scheme which aims to increase the stiffness and precision of the whole machine has proposed to efficiently optimize the grinder. And the first natural frequency of the optimized grinder has increased by 68.19%.

scholarly journals Design optimization of vehicle asynchronous motors based on fractional harmonic response analysis

2021 ◽  
Vol 12 (1) ◽  
pp. 689-700
Author(s):  
Ao Lei ◽  
Chuan-Xue Song ◽  
Yu-Long Lei ◽  
Yao Fu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequency ◽  
Asynchronous Motor ◽  
Element Model ◽  
Design Parameters ◽  
Response Analysis ◽  
Harmonic Response ◽  
First Order ◽  
Harmonic Response Analysis

Abstract. To make vehicles more reliable and efficient, many researchers have tried to improve the rotor performance. Although certain achievements have been made, the previous finite element model did not reflect the historical process of the motor rotor well, and the rigidity and mass in rotor optimization are less discussed together. This paper firstly introduces fractional order into a finite element model to conduct the harmonic response analysis. Then, we propose an optimal design framework of a rotor. In the framework, objective functions of rigidity and mass are defined, and the relationship between high rigidity and the first-order frequency is discussed. In order to find the optimal values, an accelerated optimization method based on response surface (ARSO) is proposed to find the suitable design parameters of rigidity and mass. Because the higher rigidity can be transformed into the first-order natural frequency by objective function, this paper analyzes the first-order frequency and mass of a motor rotor in the experiment. The results proved that not only is the fractional model effective, but also the ARSO can optimize the rotor structure. The first-order natural frequency of asynchronous motor rotor is increased by 11.2 %, and the mass is reduced by 13.8 %, which can realize high stiffness and light mass of asynchronous motor rotors.

Investigation of Damping Potential of Strip Damper on a Real Turbine Blade

2016 ◽  
Author(s):  
M. Afzal ◽  
I. Lopez Arteaga ◽  
L. Kari ◽  
V. Kharyton
Keyword(s):  
Boundary Conditions ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
Iterative Solution ◽  
Element Model ◽  
Forced Response ◽  
Contact Forces ◽  
Response Analysis ◽  
Bladed Disk ◽  
Different Types

This paper investigates the damping potential of strip dampers on a real turbine bladed disk. A 3D numerical friction contact model is used to compute the contact forces by means of the Alternate Frequency Time domain method. The Jacobian matrix required during the iterative solution is computed in parallel with the contact forces, by a quasi-analytical method. A finite element model of the strip dampers, that allows for an accurate description of their dynamic properties, is included in the steady-state forced response analysis of the bladed disk. Cyclic symmetry boundary conditions and the multiharmonic balance method are applied in the formulation of the equations of motion in the frequency domain. The nonlinear forced response analysis is performed with two different types of boundary conditions on the strip: (a) free-free and (b) elastic, and their influence is analyzed. The effect of the strip mass, thickness and the excitation levels on the forced response curve is investigated in detail.

The Mechanism on Prediction of Transient Maximum Amplitude for Tuned and Mistuned Blisks

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Luohui Ouyang ◽  
Hai Shang ◽  
Hua Chen ◽  
Qingzhen Bi ◽  
Li-Min Zhu
Keyword(s):  
Damping Ratio ◽  
Maximum Amplitude ◽  
Element Model ◽  
Forced Response ◽  
Lumped Parameter Model ◽  
Fundamental Parameter ◽  
Reduced Order ◽  
Lumped Parameter ◽  
Engine Order ◽  
Acceleration And Deceleration

Abstract Blisks are subjected to frequent acceleration and deceleration, which leads to a transient forced response; however, there is limited understanding of this response. In this work, the mechanism on prediction of transient maximum amplitude is found. An analytical link is proposed between the transient maximum amplitude and a fundamental dimensionless parameter which combines the damping ratio, natural frequency, acceleration, and engine order of the system to reveal the mechanism of the transient maximum amplitude. Therefore, the transient maximum amplitudes of tuned and mistuned blisks are predicted analytically. First, a lumped parameter model is used to study the mechanism of the transient maximum amplitude for a tuned blisk, and an approximated analytical expression is derived between the fundamental parameter and the transient amplification factor of a 1DOF (degree-of-freedom) model. The relationship is also applicable to a reduced order, tuned finite element model (FEM). Second, the mechanism of the transient response for a mistuned blisk is studied in the decoupled modal space of the blisk, based on the 1DOF transient relationship. The transient maximum amplitude in a reduced order, mistuned FEM is predicted. Two lumped parameter models and a FEM are employed to validate the prediction.

A Case Study of the Unsteady Response of a Hingeless Helicopter Rotor Blade

2019 ◽  
Author(s):  
Pratik Sarker ◽  
Uttam K. Chakravarty
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Rotor Blade ◽  
Degrees Of Freedom ◽  
Forced Response ◽  
Helicopter Rotor ◽  
Mode Shapes ◽  
Response Analysis ◽  
Steady State Condition ◽  
Helicopter Rotor Blade

Abstract The helicopter is an essential means of transport for numerous tasks including carrying passengers and equipment, providing air medical services, firefighting, and other military and civil tasks. While in operation, the nature of the unsteady aerodynamic environment surrounding the rotor blades gives rise to a significant amount of vibration to the helicopter. In this study, the unsteady forced response of the Bo 105 hingeless helicopter rotor blade is investigated at the forward flight in terms of the coupled flapping, lead-lag, and torsional deformations. The mathematical model for the steady-state response of the rotor blade is modified to include the unsteady airfoil behavior by using the Theodorsen’s lift deficiency function for three degrees of freedom of motion. The nonlinear mathematical model is solved by the generalized method of lines in terms of the time-varying deflections of the rotor blade. The unsteady airloads are found to create larger deformations compared to that of the steady-state condition for a given advance ratio. The azimuth locations of the peak loadings also vary with different degrees of freedom. The first three natural frequencies and mode shapes of the rotor blade are presented. The model for the forced response analysis is validated by finite element results.

Mistuned Forced Response Predictions of an Embedded Rotor in a Multistage Compressor

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Fanny M. Besem ◽  
Robert E. Kielb ◽  
Paul Galpin ◽  
Laith Zori ◽  
Nicole L. Key
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Aerodynamic Performance ◽  
Forced Response ◽  
Response Analysis ◽  
Data Set ◽  
Multistage Compressor ◽  
The Individual ◽  
Decoupled Method ◽  
Tremendous Impact

This paper covers a comprehensive forced response analysis conducted on a multistage compressor and compared with the largest forced response experimental data set ever obtained in the field. The steady-state aerodynamic performance and stator wake predictions compare well with the experimental data, although losses are underestimated. Coupled and uncoupled unsteady simulations are conducted on the stator–rotor configuration. It is shown that the use of a decoupled method for forced response cannot yield accurate results for cases with strong inter-row interactions. The individual and combined contributions of the upstream and downstream stators are also assessed. The downstream stator is found to have a tremendous impact on the forced response predictions due to the constructive interactions of the two stator rows. Finally, predicted mistuned blade amplitudes are compared to mistuned experimental data. The average amplitudes match the experiments very well, while the maximum response amplitude is underestimated.

scholarly journals Numerical and Experimental Investigations on a Friction Ring Damper for a Flywheel

2021 ◽  
Author(s):  
Xiaodong He ◽  
Zhiwei Zheng ◽  
Xiuchang Huang ◽  
Sen Wang ◽  
Xinsheng Wei ◽  
...  
Keyword(s):  
Vibration Amplitude ◽  
Damping Ratio ◽  
Nonlinear Dynamic Analysis ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Experimental Investigations ◽  
Response Analysis ◽  
Contact Interface ◽  
Friction Contact ◽  
Stick Slip

Abstract A damping strategy using a friction ring damper for an industrial flywheel was numerically and experimentally investigated. The friction ring damper, located on the arms of the flywheel, was experimentally found to effectively reduce the vibration amplitude of the flywheel. The vibration energy is dissipated when relative motions occur at the friction contact interfaces. Nonlinear dynamic analysis based on a lumped-parameter model of a flywheel equipped with a friction ring damper was conducted. A dimensionless parameter, κ, defined as the ratio of the critical friction force to the amplitude of harmonic force, was used to evaluate the damping performance. For several values of κ, steady-state responses under harmonic excitation and nonlinear modes were obtained using the harmonic balance method (HBM) combined with the alternating frequency–time domain method (AFT). The forced response analysis proved the existence of an optimal value of κ, which can minimize the vibration amplitude of the flywheel. The nonlinear modal analysis showed that all the damping ratio–frequency curves are completely coincident even for different κ, and the frequency corresponding to the maximum damping ratio is equal to the frequency at the intersection of the forced response curves under the fully slip and the fully stick states of the friction contact interface. By analyzing the behaviors of the friction contact interface, it is shown that the friction contact interface provides damping in the combined stick–slip state. The forced response under random excitation was calculated using the Runge–Kutta method and the friction interface behaviors were analyzed. Finally, spectral testing was conducted to verify the numerical results.

A Forced Response Method for Annular Combustors Excited by Traveling Acoustic Pressure Waves

2008 ◽  
Author(s):  
Sanghum Baik ◽  
Mehmet Dede
Keyword(s):  
Finite Element ◽  
Pressure Wave ◽  
Acoustic Pressure ◽  
Response Prediction ◽  
Element Model ◽  
Forced Response ◽  
Response Analysis ◽  
Element Analysis ◽  
Variable Theory ◽  
Response Method

Recent progress in the development of an industry level tool for computing forced response of annular combustors is presented. Hereby, in addressing productivity issues caused by huge finite element model of full-wheel combustor, the theoretical framework of cyclic symmetry is introduced. The complex-variable theory, which originated for capturing natural frequency and mode shape characteristics of rotationally periodic structure, was extended for real-number-based finite element analysis (FEA) to solve forced response problem; specifically, a systematic method was developed to create cyclic domain replica of traveling pressure wave loading on full-wheel combustor. In this paper, theoretical descriptions of the physics-based, practical forced response analysis technique will be provided, and its implementation into building the tool of industrial level will be discussed. The technology developed herein will be verified using a simple cylindrical structure that is excited by acoustic pressure wave that travels in circumferential direction with a certain number of nodal diameter. In the end, a practical application to forced response prediction of a combustor component will be presented.

LATERAL-FLEXURAL AND TORSIONAL VIBRATIONS OF FLEXIBLE RING FOR ELECTROMECHANICAL INTEGRATED ELECTROSTATIC HARMONIC ACTUATOR

2009 ◽  
Vol 09 (03) ◽  
pp. 391-409
Author(s):  
LIZHONG XU ◽  
YAOWU LI
Keyword(s):  
Natural Frequency ◽  
Dynamic Equation ◽  
Forced Response ◽  
Dynamic Responses ◽  
Torsional Vibrations ◽  
Vibration Modes ◽  
System Parameters ◽  
Electromechanical Integrated ◽  
Flexible Ring ◽  
Electromechanical Coupled

This paper presents an electromechanical coupled dynamic equation for the lateral-flexural and torsional vibrations of a flexible ring for an electromechanical integrated electrostatic harmonic actuator as well as the equation of the forced response of the electromechanical integrated electrostatic harmonic actuator to voltage excitation. By solving these equations, the natural frequency and vibration modes of the flexible ring for the actuator are investigated. Changes in the natural frequency with respect to the main system parameters are also examined and the dynamic responses of the actuator to voltage excitation obtained.

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