Predesign study for a modern 4-bladed rotor for the NASA rotor systems research aircraft
Bishop, H. E.; Burkam, J. E.; Heminway, R. C.; Keys, C. N.; Smith, K. E.; Smith, J. H.; Staley, J. A.
1981-01-01
Trade-off study results and the rationale for the final selection of an existing modern four-bladed rotor system that can be adapted for installation on the Rotor Systems Research Aircraft (RSRA) are reported. The results of the detailed integration studies, parameter change studies, and instrumentation studies and the recommended plan for development and qualification of the rotor system is also given. Its parameter variants, integration on the RSRA, and support of ground and flight test programs are also discussed.
Duval, R. W.; Bahrami, M.
1985-01-01
The Rotor Systems Research Aircraft uses load cells to isolate the rotor/transmission systm from the fuselage. A mathematical model relating applied rotor loads and inertial loads of the rotor/transmission system to the load cell response is required to allow the load cells to be used to estimate rotor loads from flight data. Such a model is derived analytically by applying a force and moment balance to the isolated rotor/transmission system. The model is tested by comparing its estimated values of applied rotor loads with measured values obtained from a ground based shake test. Discrepancies in the comparison are used to isolate sources of unmodeled external loads. Once the structure of the mathematical model has been validated by comparison with experimental data, the parameters must be identified. Since the parameters may vary with flight condition it is desirable to identify the parameters directly from the flight data. A Maximum Likelihood identification algorithm is derived for this purpose and tested using a computer simulation of load cell data. The identification is found to converge within 10 samples. The rapid convergence facilitates tracking of time varying parameters of the load cell model in flight.
RESEARCH ON KNOWLEDGE-BASED CAPP SYSTEM FOR ROTOR FORGING
Wang Leigang; Deng Dongrnei; Liu Zhubai
2000-01-01
Guided by developing forging technology theory,designing rules on rotor forging process are summed up.Knowledge-based CAPP system for rotor forging is created.The system gives a rational and optimum process.
A rotor-mounted digital instrumentation system for helicopter blade flight research measurements
Knight, V. H., Jr.; Haywood, W. S., Jr.; Williams, M. L.
1978-01-01
A rotor mounted flight instrumentation system developed for helicopter rotor blade research is described. The system utilizes high speed digital techniques to acquire research data from miniature pressure transducers on advanced rotor airfoils which are flight tested on an AH-1G helicopter. The system employs microelectronic pulse code modulation (PCM) multiplexer digitizer stations located remotely on the blade and in a hub mounted metal canister. As many as 25 sensors can be remotely digitized by a 2.5 mm thick electronics package mounted on the blade near the tip to reduce blade wiring. The electronics contained in the canister digitizes up to 16 sensors, formats these data with serial PCM data from the remote stations, and transmits the data from the canister which is above the plane of the rotor. Data are transmitted over an RF link to the ground for real time monitoring and to the helicopter fuselage for tape recording. The complete system is powered by batteries located in the canister and requires no slip rings on the rotor shaft.
A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research
Coleman, Colin P.
1997-01-01
The recent appearance of the Kamov Ka-50 helicopter and the application of coaxial rotors to unmanned aerial vehicles have renewed international interest in the coaxial rotor configuration. This report addresses the aerodynamic issues peculiar to coaxial rotors by surveying American, Russian, Japanese, British, and German research. (Herein, 'coaxial rotors' refers to helicopter, not propeller, rotors. The intermeshing rotor system was not investigated.) Issues addressed are separation distance, load sharing between rotors, wake structure, solidity effects, swirl recovery, and the effects of having no tail rotor. A general summary of the coaxial rotor configuration explores the configuration's advantages and applications.
Churchill, G. B.; Gerdes, R. M.
1984-01-01
The design criteria and control and handling qualities of the Automatic Flight Control System (AFCS), developed in the framework of the XV-15 tilt-rotor research aircraft, are evaluated, differentiating between the stability and control criteria. A technically aggressive SCAS control law was implemented, demonstrating that significant benefits accrue when stability criteria are separated from design criteria; the design analyses for application of the control law are presented, and the limit bandwidth for stabilization in hovering flight is shown to be defined by rotor or control lag functions. Flight tests of the aircraft resulted in a rating of 3 on the Cooper-Harper scale; a possibility of achieving a rating of 2 is expected if the system is applied to the yaw and heave control modes.
Churchill, G. B.; Gerdes, R. M.
1984-01-01
The design criteria and control and handling qualities of the Automatic Flight Control System (AFCS), developed in the framework of the XV-15 tilt-rotor research aircraft, are evaluated, differentiating between the stability and control criteria. A technically aggressive SCAS control law was implemented, demonstrating that significant benefits accrue when stability criteria are separated from design criteria; the design analyses for application of the control law are presented, and the limit bandwidth for stabilization in hovering flight is shown to be defined by rotor or control lag functions. Flight tests of the aircraft resulted in a rating of 3 on the Cooper-Harper scale; a possibility of achieving a rating of 2 is expected if the system is applied to the yaw and heave control modes.
A real-time, dual processor simulation of the rotor system research aircraft
Mackie, D. B.; Alderete, T. S.
1977-01-01
A real-time, man-in-the loop, simulation of the rotor system research aircraft (RSRA) was conducted. The unique feature of this simulation was that two digital computers were used in parallel to solve the equations of the RSRA mathematical model. The design, development, and implementation of the simulation are documented. Program validation was discussed, and examples of data recordings are given. This simulation provided an important research tool for the RSRA project in terms of safe and cost-effective design analysis. In addition, valuable knowledge concerning parallel processing and a powerful simulation hardware and software system was gained.
Dynamic Characteristics and Experimental Research of Dual-Rotor System with Rub-Impact Fault
Hongzhi Xu
2016-01-01
Full Text Available Rub-impact fault model for dual-rotor system was further developed, in which rubbing board is regarded as elastic sheet. Sheet elastic deformation, contact penetration, and elastic damping support during rubbing of sheet and wheel disk were considered. Collision force and friction were calculated by utilizing Hertz contact theory and Coulomb model and introducing nonlinear spring damping model and friction coefficient. Then kinetic differential equations of rub-impact under dry rubbing condition were established. Based on one-dimensional finite element model of dual-rotor system, dynamic transient response of overall structure under rub-impact existing between rotor wheel and sheet was obtained. Meanwhile, fault dynamic characteristics and impact of rubbing clearance on rotor vibration were analyzed. The results show that, during the process of rub-impact, the spectrums of rotor vibration are complicated and multiple combined frequency components of inner and outer rotor fundamental frequencies are typical characteristic of rub-impact fault for dual-rotor system. It also can be seen from rotor vibration response that the rubbing rotor’s fundamental frequency is modulated by normal rotor double frequency.
Dynamic Model and Fault Feature Research of Dual-Rotor System with Bearing Pedestal Looseness
Nanfei Wang
2016-01-01
Full Text Available The paper presents a finite element model of dual-rotor system with pedestal looseness stemming from loosened bolts. Dynamic model including bearing pedestal looseness is established based on the dual-rotor test rig. Three-degree-of-freedom (DOF planar rigid motion of loose bearing pedestal is fully considered and collision recovery coefficient is also introduced in the model. Based on the Timoshenko beam elements, using the finite element method, rigid body kinematics, and the Newmark-β algorithm for numerical simulation, dynamic characteristics of the inner and outer rotors and the bearing pedestal plane rigid body motion under bearing pedestal looseness condition are studied. Meanwhile, the looseness experiments under two different speed combinations are carried out, and the experimental results are basically the same. The simulation results are compared with the experimental results, indicating that vibration displacement waveforms of loosened rotor have “clipping” phenomenon. When the bearing pedestal looseness fault occurs, the inner and outer rotors vibration spectrum not only contains the difference and sum frequency of the two rotors’ fundamental frequency but also contains 2X and 3X component of rotor with loosened support, and so forth; low frequency spectrum is more, containing dividing component, and so forth; the rotor displacement spectrums also contain fewer combination frequency components, and so forth; when one side of the inner rotor bearing pedestal is loosened, the inner rotor axis trajectory is drawn into similar-ellipse shape.
Rotor balancing apparatus and system
Lyman, Frank (Inventor); Lyman, Joseph (Inventor)
1976-01-01
Rotor balancing apparatus and a system comprising balance probes for measuring unbalance at the ends of a magnetically suspended rotor are disclosed. Each balance probe comprises a photocell which is located in relationship to the magnetically suspended rotor such that unbalance of the rotor changes the amount of light recorded by each photocell. The signal from each photocell is electrically amplified and displayed by a suitable device, such as an oscilloscope.
Superconductor rotor cooling system
Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.
2002-01-01
A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.
Variable Speed Rotor System Project
National Aeronautics and Space Administration — Variable speed rotors will give helicopters several advantages: higher top speed, greater fuel efficiency, momentary emergency over-power, resonance detuning...
A new approach to helicopter rotor blade research instrumentation
Knight, V. H., Jr.
1978-01-01
A rotor-blade-mounted telemetry instrumentation system developed and used in flight tests by the NASA/Langley Research Center is described. The system uses high-speed digital techniques to acquire research data from miniature pressure transducers on advanced rotor airfoils which are flight tested using an AH-1G helicopter. The system employs microelectronic PCM multiplexer-digitizer stations located remotely on the blade and in a hub-mounted metal canister. The electronics contained in the canister digitizes up to 16 sensors, formats this data with serial PCM data from the remote stations, and transmits the data from the canister which is above the plane of the rotor. Data is transmitted over an RF link to the ground for real-time monitoring and to the helicopter fuselage for tape recording.
Robust stabilization of rotor-active magnetic bearing systems
Li, Guoxin
Active magnetic bearings (AMBs) are emerging as a beneficial technology for high-speed and high-performance suspensions in rotating machinery applications. A fundamental feedback control problem is robust stabilization in the presence of uncertain destabilizing mechanisms in aeroelastic, hydroelastic dynamics, and AMB feedback. As rotating machines are evolving in achieving high speed, high energy density, and high performance, the rotor and the support structure become increasingly flexible, and highly coupled. This makes rotor-AMB system more challenging to stabilize. The primary objective of this research is to develop a systematic control synthesis procedure for achieving highly robust stabilization of rotor-AMB systems. Of special interest is the stabilization of multivariable systems such as the AMB supported flexible rotors and gyroscopic rotors, where the classical control design may encounter difficulties. To this end, we first developed a systematic modeling procedure. This modeling procedure exploited the best advantages of technology developed in rotordynamics and the unique system identification tool provided by the AMBs. A systematic uncertainty model for rotor-AMB systems was developed, eliminating the iterative process of selecting uncertainty structures. The consequences of overestimation or underestimation of uncertainties were made transparent to control engineers. To achieve high robustness, we explored the fundamental performance/robustness limitations due to rotor-AMB system unstable poles. We examined the mixed sensitivity performance that is closely related to the unstructured uncertainty. To enhance transparency of the synthesis, we analyzed multivariable controllers from classical control perspectives. Based on these results, a systematic robust control synthesis procedure was established. For a strong gyroscopic rotor over a wide speed range, we applied the advanced gain-scheduled synthesis, and compared two synthesis frameworks in
Investigation of rotor control system loads
Sun Tao; Tan Jianfeng; Wang Haowen
2013-01-01
This paper concentrates on the aeroelasticity analysis of rotor blade and rotor control systems. A new multi-body dynamics model is established to predict both rotor pitch link loads and swashplate servo loads. Two helicopter rotors of UH-60A and SA349/2, both operating in two critical flight conditions, high-speed flight and high-thrust flight, are studied. The analysis shows good agreements with the flight test data and the calculation results using CAMRAD II. The mechanisms of rotor control loads are then analyzed in details based on the present predictions and the flight test data. In high-speed conditions, the pitch link loads are dominated by the integral of blade pitching moments, which are generated by cyclic pitch control. In high-thrust conditions, the positive pitching loads in the advancing side are caused by high collective pitch angle, and dynamic stall in the retreating side excites high-frequency responses. The swashplate servo loads are predominated by the rotor pitch link loads, and the inertia of the swashplate has significant effects on high-frequency harmonics of the servo loads.
Jordon, D. E.; Patterson, W.; Sandlin, D. R.
1985-01-01
The XV-15 Tilt Rotor Research Aircraft download phenomenon was analyzed. This phenomenon is a direct result of the two rotor wakes impinging on the wing upper surface when the aircraft is in the hover configuration. For this study the analysis proceeded along tow lines. First was a method whereby results from actual hover tests of the XV-15 aircraft were combined with drag coefficient results from wind tunnel tests of a wing that was representative of the aircraft wing. Second, an analytical method was used that modeled that airflow caused gy the two rotors. Formulas were developed in such a way that acomputer program could be used to calculate the axial velocities were then used in conjunction with the aforementioned wind tunnel drag coefficinet results to produce download values. An attempt was made to validate the analytical results by modeling a model rotor system for which direct download values were determinrd..
Diagnosis of wind turbine rotor system
Niemann, Hans Henrik; Mirzaei, Mahmood; Henriksen, Lars Christian
2016-01-01
This paper describes a model free method for monitoring and fault diagnosis of the elements in a rotor system for a wind turbine. The diagnosis as well as the monitoring is done without using any model of the wind turbine and the applied controller or a description of the wind profile. The method...... is based on available standard sensors on wind turbines. The method can be used both on-line as well as off-line. Faults or changes in the rotor system will result in asymmetries, which can be monitored and diagnosed. This can be done by using the multi-blade coordinate transformation. Changes in the rotor...... system that can be diagnosed and monitored are: actuator faults, sensor faults and internal blade changes as e.g. change in mass of a blade....
STABILITY OF ROTOR-BEARING SYSTEMS
Uğur YÜCEL
2003-03-01
Full Text Available In various industrial applications there is a need for higher speed, yet reliably operating rotating machinery. A key factor in achieving this type of machinery continues to be the ability to accurately predict the dynamic response and stability of a rotor-bearing system. This paper introduces and explains the nature of rotordynamic phenomena from comparatively simple analytic models. Starting with the most simple rotor model that is supported in two rigid bearings at its ends, the more realistic and more involved cases are considered by incorporating the effects of flexible bearings. Knowledge of these phenomena is fundamental to an understanding of the behavior of complex models, which corresponds to the real rotors of turbomachines.
An Empirical Study of Overlapping Rotor Interference for a Small Unmanned Aircraft Propulsion System
Mantas Brazinskas
2016-10-01
Full Text Available The majority of research into full-sized helicopter overlapping propulsion systems involves co-axial setups (fully overlapped. Partially overlapping rotor setups (tandem, multirotor have received less attention, and empirical data produced over the years is limited. The increase in demand for compact small unmanned aircraft has exposed the need for empirical investigations of overlapping propulsion systems at a small scale (Reynolds Number < 250,000. Rotor-to-rotor interference at the static state in various overlapping propulsion system configurations was empirically measured using off the shelf T-Motor 16 inch × 5.4 inch rotors. A purpose-built test rig was manufactured allowing various overlapping rotor configurations to be tested. First, single rotor data was gathered, then performance measurements were taken at different thrust and tip speeds on a range of overlap configurations. The studies were conducted in a system torque balance mode. Overlapping rotor performance was compared to an isolated dual rotor propulsion system revealing interference factors which were compared to the momentum theory. Tests revealed that in the co-axial torque-balanced propulsion system the upper rotor outperforms the lower rotor at axial separation ratios between 0.05 and 0.85. Additionally, in the same region, thrust sharing between the two rotors changed by 21%; the upper rotor produced more thrust than the lower rotor at all times. Peak performance was recorded as a 22% efficiency loss when the axial separation ratio was greater than 0.25. The performance of a co-axial torque-balanced system reached a 27% efficiency loss when the axial separation ratio was equal to 0.05. The co-axial system swirl recovery effect was recorded to have a 4% efficiency gain in the axial separation ratio region between 0.05 and 0.85. The smallest efficiency loss (3% was recorded when the rotor separation ratio was between 0.95 and 1 (axial separation ratio was kept at 0
Eigenvalue assignment strategies in rotor systems
Youngblood, J. N.; Welzyn, K. J.
1986-01-01
The work done to establish the control and direction of effective eigenvalue excursions of lightly damped, speed dependent rotor systems using passive control is discussed. Both second order and sixth order bi-axis, quasi-linear, speed dependent generic models were investigated. In every case a single, bi-directional control bearing was used in a passive feedback stabilization loop to resist modal destabilization above the rotor critical speed. Assuming incomplete state measurement, sub-optimal control strategies were used to define the preferred location of the control bearing, the most effective measurement locations, and the best set of control gains to extend the speed range of stable operation. Speed dependent control gains were found by Powell's method to maximize the minimum modal damping ratio for the speed dependent linear model. An increase of 300 percent in stable speed operation was obtained for the sixth order linear system using passive control. Simulations were run to examine the effectiveness of the linear control law on nonlinear rotor models with bearing deadband. The maximum level of control effort (force) required by the control bearing to stabilize the rotor at speeds above the critical was determined for the models with bearing deadband.
Time Frequency Features of Rotor Systems with Slowly Varying Mass
Tao Yu
2011-01-01
Full Text Available With the analytic method and numerical method respectively, the asymptotic solutions and finite element model of rotor system with single slowly varying mass is obtained to investigate the time frequency features of such rotor system; furthermore, with given model of slowly varying mass, the rotor system with dual slowly varying mass is studied. For the first order approximate solution is used, there exists difference between the results with analytic method and numerical method. On the base of common characteristics of rotor system with dual slowly varying mass, the general rules and formula describing the frequency distribution of rotor system with multiple slowly varying mass are proposed.
The Second Generation High Speed Rotor Head Mounted Instrumentation System
Lewis, John; Reynolds, R. S. (Technical Monitor)
1997-01-01
NASA Ames Research Center has been investigating the air pressure flow of a rotor blade on a UH-60 Black Hawk helicopter in-flight. This paper will address the changes and improvements due to additional restrictions and requirements for the instrumentation system. The second generation instrumentation system was substantially larger and this allowed greatly improved accessibility to the components for ease of maintenance as well as improved gain and offset adjustment capabilities and better filtering.
Numerical Analysis of Nonlinear Rotor-bearing-seal System
CHENG Mei; MENG Guang; JING Jian-ping
2008-01-01
The system state trajectory, Poincaré maps, largest Lyapunov exponents, frequency spectra and bifurcation diagrams were used to investigate the non-linear dynamic behaviors of a rotor-bearing-seal coupled system and to analyze the influence of the seal and bearing on the nonlinear characteristics of the rotor system. Various nonlinear phenomena in the rotor-bearing-seal system, such as periodic motion, double-periodicmotion, multi-periodic motion and quasi-periodic motion were investigated. The results may contribute to a further understanding of the non-linear dynamics of the rotor-bearing-seal coupled system.
Jenks, Mark; Haslim, Leonard
1988-01-01
The final results of the Advanced Flight Research Rotor (AFRR) study, a NASA sponsored research program, are summarized. First, the results of the initial phase of the AFRR program, consisting of the definition of a conventional rotor with planform and prescribed twist distributions, are briefly reviewed. The mechanism of the calculated performance benefit is then explained, and a detailed analysis of the prescribed twist distribution is presented. Recommendations are made on the practical means of approximating the prescribed twist on the actual rotor.
Stability of Rotor Systems: A Complex Modelling Approach
Kliem, Wolfhard; Pommer, Christian; Stoustrup, Jakob
1996-01-01
A large class of rotor systems can be modelled by a complex matrix differential equation of secondorder. The angular velocity of the rotor plays the role of a parameter. We apply the Lyapunov matrix equation in a complex setting and prove two new stability results which are compared with the resu......A large class of rotor systems can be modelled by a complex matrix differential equation of secondorder. The angular velocity of the rotor plays the role of a parameter. We apply the Lyapunov matrix equation in a complex setting and prove two new stability results which are compared...
某超高速转子系统减振结构研究%Research on vibration absorber for a super-high speed rotor system
陈巍; 杜发荣; 丁水汀; 韩树军; 李云清
2011-01-01
为解决某超高速转子系统的失稳碰摩问题,以干摩擦阻尼耗散转子涡动能量理论为依据,采用一种自由安装式干摩擦片减振结构(干摩擦阻尼器).该结构在转轴上安装波形弹性垫片及干摩擦片,通过螺母预紧力矩向波形弹性垫片及各干摩擦片提供轴向正压力.干摩擦片随转子振动并产生相对运动,从而耗散转子涡动能量,达到减振、增强转子稳定性的目的.通过实验不同数量的干摩擦片和不同预紧力矩的组合寻找满足工程稳定性的减振器结构参数.结果表明:干摩擦阻尼器适用于高速、轻载转子系统的减振、增稳,可以有效降低转子振动,控制转子涡动发散的趋势;所用实验方法有助于快速获得满足工程稳定性的减振结构参数.%A kind of freely assembled dry friction vibration absorber was presented to solve the problems of instability and rubbing faults for a super-high speed rotor system based on theory of dry friction dissipating energy from rotor vibration. In this structure, a waveshaped elastic pad and some dry friction pads were freely assembled on shaft, and axial normai force was provided for elastic pad and dry friction pads by pre-loaded moment for nut.When friction pads moved with shaft, the relative movements between them could dissipate vibration energy from rotor system, absorb vibration and enhance system stability. The configuration format meeting the stability in engineering for the damper of the studied rotor system has been acquired by testing different groups of dry friction pads and pre-loaded moment. The results show that dry friction damper is suitable for high speed and light loaded rotor system to restrain vibration and enhance its stability. The testing routine is helpful to find a comfortable configuration format in engineering of dry friction damper.
Thermal modeling of a mini rotor-stator system
Dikmen, Emre; Hoogt, van der Peter; Boer, de André; Aarts, Ronald; Jonker, Ben
2009-01-01
In this study the temperature increase and heat dissipation in the air gap of a cylindrical mini rotor stator system has been analyzed. A simple thermal model based on lumped parameter thermal networks has been developed. With this model the temperature dependent air properties for the fluid-rotor i
The Effects of Crack on the Transmission Matrix of Rotor Systems
Z.K. Peng
2011-01-01
Full Text Available The dynamic behavior of rotor containing crack is a subject of particular interest and has been extensively investigated by researchers. The effects of crack on the natural frequencies and modal shapes and motion orbits of rotor systems have already been well explored by researchers. In the present study, the infl uence of crack on the transmission matrices of the rotor systems is investigated by using the FEM (finite element method analysis and the HBM (harmonic balance method technique. It is for the first time revealed that there are differences between the transmission matrices for the fundamental frequency components and the transmission matrices for the super-harmonic components, and the differences are mainly determined by the crack location. The results are validated by numerical experiments where the system responses of a rotor system are obtained using Runge-Kutta method. The results are of significance for the development of effective crack detection methods in practice.
Effect of the Rotor Crank System on Cycling Performance
Jobson, Simon A.; Hopker, James; Galbraith, Andrew; Coleman, Damian A.; Nevill, Alan M.
2009-01-01
The aim of this study was to evaluate the impact of a novel crank system on laboratory time-trial cycling performance. The Rotor system makes each pedal independent from the other so that the cranks are no longer fixed at 180°. Twelve male competitive but non-elite cyclists (mean ± s: 35 ± 7 yr, Wmax = 363 ± 38 W, VO2peak = 4.5 ± 0.3 L·min-1) completed 6-weeks of their normal training using either a conventional (CON) or the novel Rotor (ROT) pedal system. All participants then completed two 40.23-km time-trials on an air-braked ergometer, one using CON and one using ROT. Mean performance speeds were not different between trials (CON = 41.7 km·h-1 vs. ROT = 41.6 km·h-1, P > 0.05). Indeed, the pedal system used during the time-trials had no impact on any of the measured variables (power output, cadence, heart rate, VO2, RER, gross efficiency). Furthermore, the ANOVA identified no significant interaction effect between main effects (Time-trial crank system*Training crank system, P > 0.05). To the authors’ knowledge, this is the first study to examine the effects of the Rotor system on endurance performance rather than endurance capacity. These results suggest that the Rotor system has no measurable impact on time-trial performance. However, further studies should examine the importance of the Rotor ‘regulation point’ and the suggestion that the Rotor system has acute ergogenic effects if used infrequently. Key points The Rotor crank system does not improve gross efficiency in well-trained cyclists. The Rotor crank system has no measurable impact on laboratory 40.23-km time-trial performance. A 6-week period of familiarisation does not increase the effectiveness of the Rotor crank system. PMID:24150012
Fault detection in rotor bearing systems using time frequency techniques
Chandra, N. Harish; Sekhar, A. S.
2016-05-01
Faults such as misalignment, rotor cracks and rotor to stator rub can exist collectively in rotor bearing systems. It is an important task for rotor dynamic personnel to monitor and detect faults in rotating machinery. In this paper, the rotor startup vibrations are utilized to solve the fault identification problem using time frequency techniques. Numerical simulations are performed through finite element analysis of the rotor bearing system with individual and collective combinations of faults as mentioned above. Three signal processing tools namely Short Time Fourier Transform (STFT), Continuous Wavelet Transform (CWT) and Hilbert Huang Transform (HHT) are compared to evaluate their detection performance. The effect of addition of Signal to Noise ratio (SNR) on three time frequency techniques is presented. The comparative study is focused towards detecting the least possible level of the fault induced and the computational time consumed. The computation time consumed by HHT is very less when compared to CWT based diagnosis. However, for noisy data CWT is more preferred over HHT. To identify fault characteristics using wavelets a procedure to adjust resolution of the mother wavelet is presented in detail. Experiments are conducted to obtain the run-up data of a rotor bearing setup for diagnosis of shaft misalignment and rotor stator rubbing faults.
Finite element analysis of two disk rotor system
Dixit, Harsh Kumar
2016-05-01
A finite element model of simple horizontal rotor system is developed for evaluating its dynamic behaviour. The model is based on Timoshenko beam element and accounts for the effect of gyroscopic couple and other rotational forces. Present rotor system consists of single shaft which is supported by bearings at both ends and two disks are mounted at different locations. The natural frequencies, mode shapes and orbits of rotating system for a specific range of rotation speed are obtained by developing a MATLAB code for solving the finite element equations of rotary system. Consequently, Campbell diagram is plotted for finding a relationship between natural whirl frequencies and rotation of the rotor.
V/STOL tilt rotor aircraft study. Volume 2: Preliminary design of research aircraft
1972-01-01
A preliminary design study was conducted to establish a minimum sized, low cost V/STOL tilt-rotor research aircraft with the capability of performing proof-of-concept flight research investigations applicable to a wide range of useful military and commercial configurations. The analysis and design approach was based on state-of-the-art methods and maximum use of off-the-shelf hardware and systems to reduce development risk, procurement cost and schedules impact. The rotors to be used are of 26 foot diameter and are the same as currently under construction and test as part of NASA Tilt-Rotor Contract NAS2-6505. The aircraft has a design gross weight of 12,000 lbs. The proposed engines to be used are Lycoming T53-L-13B rated at 1550 shaft horsepower which are fully qualified. A flight test investigation is recommended which will determine the capabilities and limitations of the research aircraft.
Surface-Mount Rotor Motion Sensing System Project
National Aeronautics and Space Administration — A surface-mounted instrumentation system for measuring rotor blade motions on rotorcraft, for use both in flight and in wind tunnel testing, is proposed for...
A Surface-Mounted Rotor State Sensing System Project
National Aeronautics and Space Administration — A surface-mounted instrumentation system for measuring rotor blade motions on rotorcraft, for use both in flight and in wind tunnel testing, is proposed for...
Huang, Zhiwei; Zhou, Jianzhong; Yang, Mengqi; Zhang, Yongchuan [Huazhong University of Science and Technology, College of Hydraulic and Digitalization Engineering, Wuhan, Hubei Province (China)
2011-07-15
The object of this research aims at the hydraulic generator unit rotor system. According to fault problems of the generator rotor local rubbing caused by the parallel misalignment and mass eccentricity, a dynamic model for the rotor system coupled with misalignment and rub-impact is established. The dynamic behaviors of this system are investigated using numerical integral method, as the parallel misalignment, mass eccentricity and bearing stiffness vary. The nonlinear dynamic responses of the generator rotor and turbine rotor with coupling faults are analyzed by means of bifurcation diagrams, Poincare maps, axis orbits, time histories and amplitude spectrum diagrams. Various nonlinear phenomena in the system, such as periodic, three-periodic and quasi-periodic motions, are studied with the change of the parallel misalignment. The results reveal that vibration characteristics of the rotor system with coupling faults are extremely complex and there are some low frequencies with large amplitude in the 0.3-0.4 x components. As the increase in mass eccentricity, the interval of nonperiodic motions will be continuously moved forward. It suggests that the reduction in mass eccentricity or increase in bearing stiffness could preclude nonlinear vibration. These might provide some important theory references for safety operating and exact identification of the faults in rotating machinery. (orig.)
Xiangbo Xu
2015-08-01
Full Text Available Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs, offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously.
Xu, Xiangbo; Chen, Shao
2015-08-31
Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs), offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously.
Flywheel system using wire-wound rotor
Chiao, Edward Young; Bender, Donald Arthur; Means, Andrew E.; Snyder, Philip K.
2016-06-07
A flywheel is described having a rotor constructed of wire wound onto a central form. The wire is prestressed, thus mitigating stresses that occur during operation. In another aspect, the flywheel incorporates a low-loss motor using electrically non-conducting permanent magnets.
Rotor Systems of Aircraft Jet Engines
Ján Kamenický
2000-01-01
engine's both coaxial rotors, their supports (including their hydrodynamic dampers, and its casing as well. Besides the short description of the engine design peculiarities and of its calculating model, there is also a short description of the used method of calculations, with focus on its peculiarities as well. Finally, some results of calculations and conclusions that follow from them are presented.
Progress in Open Rotor Research: A U.S. Perspective
Van Zante, Dale E.
2015-01-01
In response to the 1970s oil crisis, NASA created the Advanced Turboprop Project (ATP) to mature technologies for high-speed propellers to enable large reductions in fuel burn relative to turbofan engines of that era. Both single rotation and contra- rotation concepts were designed and tested in ground based facilities as well as flight. Some novel concepts/configurations were proposed as part of the effort. The high-speed propeller concepts did provide fuel burn savings, albeit with some acoustics and structural challenges to overcome. When fuel prices fell, the business case for radical new engine configurations collapsed and the research emphasis returned to high bypass ducted configurations. With rising oil prices and increased environmental concerns there is renewed interest in high-speed propeller based engine architectures. Contemporary analysis tools for aerodynamics and aeroacoustics have enabled a new era of blade designs that have both high efficiency and lower noise characteristics. A recent series of tests in the U.S. have characterized the aerodynamic performance and noise from these modern contra-rotating propeller designs. Additionally the installation and noise shielding aspects for conventional airframes and blended wing bodies have been studied. Historical estimates of 'propfan' performance have relied on legacy propeller performance and acoustics data. Current system studies make use of the modern propeller data and higher fidelity installation effects data to estimate the performance of a contemporary aircraft system. Contemporary designs have demonstrated high net efficiency, approximately 86%, at 0.78 Mach, and low noise, greater than 15 EPNdB cumulative margin to Chapter 4 when analyzed on a NASA derived aircraft/mission. This paper presents the current state of high-speed propeller/open rotor research within the U.S. from an overall viewpoint of the various efforts ongoing. The remaining technical challenges to a production engine include
QUANTITATIVE METHODOLOGY FOR STABILITY ANALYSIS OF NONLINEAR ROTOR SYSTEMS
ZHENG Hui-ping; XUE Yu-sheng; CHEN Yu-shu
2005-01-01
Rotor-bearings systems applied widely in industry are nonlinear dynamic systems of multi-degree-of-freedom. Modem concepts on design and maintenance call for quantitative stability analysis. Using trajectory based stability-preserving and dimensional-reduction, a quanttative stability analysis method for rotor systems is presented. At first, an n-dimensional nonlinear non-autonomous rotor system is decoupled into n subsystems after numerical integration. Each of them has only onedegree-of-freedom and contains time-varying parameters to represent all other state variables. In this way, n-dimensional trajectory is mapped into a set of one-dimensional trajectories. Dynamic central point (DCP) of a subsystem is then defined on the extended phase plane, namely, force-position plane. Characteristics of curves on the extended phase plane and the DCP's kinetic energy difference sequence for general motion in rotor systems are studied. The corresponding stability margins of trajectory are evaluated quantitatively. By means of the margin and its sensitivity analysis, the critical parameters of the period doubling bifurcation and the Hopf bifurcation in a flexible rotor supported by two short journal beatings with nonlinear suspensionare are determined.
Study of nonlinear dynamic characteristics of rotor-bearing systems
焦映厚; 陈照波; 曲秀全
2004-01-01
Based on the short-bearing model, the stability of a rigid Jeffcott rotor system is studied in a relatively wide parameter range by using Poincare maps and the numerical intrgration method. The results of the calculation show that the period doubling bifurcation, quasi-periodic and chaotic motions may occur. In some typical system are acquired with the numerical integration method. They demonstrate some motion state of the system.The fractal dimension concept is used to determine whether the system is in a state of chaotic motion. The analysis result of this paper provides the theoretical basis for qualitatively controlling the stable operating states ofthe rotors.
Control of flexible rotor systems with active magnetic bearings
Lei, Shuliang; Palazzolo, Alan
2008-07-01
An approach is presented for the analysis and design of magnetic suspension systems with large flexible rotordynamics models including dynamics, control, and simulation. The objective is to formulate and synthesize a large-order, flexible shaft rotordynamics model for a flywheel supported with magnetic bearings. A finite element model of the rotor system is assembled and then employed to develop a magnetic suspension compensator to provide good reliability and disturbance rejection. Stable operation over the complete speed range and optimization of the closed-loop rotordynamic properties are obtained via synthesis of eigenvalue analysis, Campbell plots, waterfall plots, and mode shapes. The large order of the rotor model and high spin speed of the rotor present a challenge for magnetic suspension control. A flywheel system is studied as an example for realizing a physical controller that provides stable rotor suspension and good disturbance rejection in all operating states. The baseline flywheel system control is determined from extensive rotordynamics synthesis and analysis for rotor critical speeds, mode shapes, frequency responses, and time responses.
EFFECT OF THE ROTOR CRANK SYSTEM ON CYCLING PERFORMANCE
Simon A. Jobson
2009-09-01
Full Text Available The aim of this study was to evaluate the impact of a novel crank system on laboratory time-trial cycling performance. The Rotor system makes each pedal independent from the other so that the cranks are no longer fixed at 180°. Twelve male competitive but non-elite cyclists (mean ± s: 35 ± 7 yr, Wmax = 363 ± 38 W, VO2peak = 4.5 ± 0.3 L·min-1 completed 6-weeks of their normal training using either a conventional (CON or the novel Rotor (ROT pedal system. All participants then completed two 40.23-km time-trials on an air-braked ergometer, one using CON and one using ROT. Mean performance speeds were not different between trials (CON = 41.7 km·h-1 vs. ROT = 41.6 km·h-1, P > 0.05. Indeed, the pedal system used during the time-trials had no impact on any of the measured variables (power output, cadence, heart rate, VO2, RER, gross efficiency. Furthermore, the ANOVA identified no significant interaction effect between main effects (Time-trial crank system*Training crank system, P > 0.05. To the authors' knowledge, this is the first study to examine the effects of the Rotor system on endurance performance rather than endurance capacity. These results suggest that the Rotor system has no measurable impact on time-trial performance. However, further studies should examine the importance of the Rotor 'regulation point' and the suggestion that the Rotor system has acute ergogenic effects if used infrequently
Dynamic Vibration Absorber with Negative Stiffness for Rotor System
Hongliang Yao
2016-01-01
Full Text Available To suppress the vibration of a rotor system, a vibration absorber combining negative stiffness with positive stiffness together is proposed in this paper. Firstly, the negative stiffness producing mechanism using ring type permanent magnets is presented and the characteristics of the negative stiffness are analyzed. Then, the structure of the absorber is proposed; the principles and nonlinear dynamic characteristics of the absorber-rotor system are studied numerically. Finally, experiments are carried out to verify the numerical conclusions. The results show that the proposed vibration absorber is effective to suppress the vibration of the rotor system, the nonlinearity of the negatives stiffness affects the vibration suppression effect little, and the negative stiffness can broaden the effective vibration control frequency range of the absorber.
Research on Design Technology of the Planetary Gear System for Open Rotor Engine%开式转子发动机齿轮传动系统设计技术研究
侯明曦; 信琦; 王飞鸣
2013-01-01
等速对转行星齿轮传动系统是对转风扇开式转子发动机的关键技术。与齿轮驱动单级风扇（GTF）发动机的行星齿轮传动系统相比较，该系统的结构更为复杂，工作条件更恶劣。本文以对转风扇开式转子发动机齿轮传动系统概念设计为基础，开展了行星齿轮传动系统初步设计、齿轮疲劳强度分析、行星轴承寿命分析和传动系统润滑设计技术研究，为开式转子发动机的发展提供参考。%As the key technology of the open rotor engine with counter-rotating fans, the planetary gear system with the same counter-rotating speeds owns more complicated conifguration and bears poorer working environment compared with the single fan of geared turbofan engine. Based on the concept design of gear driven system for the open rotor engine with counter-rotating fans, the preliminary design of planetary gear system, gear tooth strength analysis, planetary bearing life analysis and lubrication design technology research were accomplished in this paper, which contribute to the development and experience accumulation of the open rotor engine.
Savonius rotor using swinging blades as an augmentation system
Aldos, T. K.
The power output from a Savonius rotor can be improved by reducing the drag force on the up-wind blades. A new method of doing this is experimentally investigated in the present work. The method depends on allowing the rotor blades to swing back when they are on the upwind stroke. A high and real power augmentation may be achieved by the new system at an optimum angle of swing. The system is independent of wind direction, is simple to construct, and requires no additional accessories.
Transverse vibration of a rotor system driven by two cardan joints
Saigo, M.; Iwatsubo, T.
1987-05-01
The torque-induced transverse vibration of a rotor system driven by two Cardan joints is analyzed and the effects of the stiffness asymmetry of the rotor shaft supports, the damping force in the joints and the gyroscopic moment of the rotor on the dynamic stability of the system are evaluated. The analysis proves that both parametric and self-excited vibrations can occur due to the transmitted torque when the driving shaft and the driven shaft (rotor shaft) are inclined; the stiffness asymmetry of rotor supports does not always have the stabilizing effect which has been observed in a rotor system driven by a single Cardan joint [1
E. E. Ovsiannikova
2015-01-01
Full Text Available The article studies dynamics of rotor on active magnetic bearings within the mathematical model development of rotor in artificial ventricle. The problem of stabilization of rigid titanium rotor with magnetic inserts on active magnetic bearings is analyzed.The relevance of the research field is caused by high percent of people who are suffering from heart disease. The purposes of work are to create a mathematical model of the rigid rotor and position its center to meet specified requirements for displacement of no more than 0.2 millimeter while rotating with the speed from 5 000 rpm to 10 000 rpm in constant blood flow. The work of AMBs is based on the principle of active magnetic pendant of ferromagnetic solid. The stabilization in adjusted position is accomplished by magnetic forces, which affect the solid from the control electromagnets.The article presents initial data, design scheme, assumptions accepted to solve the problem and derivation of dynamic equation of rotating rigid rotor on AMBs. The decentralized control of magnetic pendant was implemented. The PD control – proportional differential control - was chosen as the base of control system. Its application is widespread due to the simplicity, industrial use and operation stability. The use of decentralized control in dynamics modeling of a rigid rotor in AMBs is physically occurred and has some advantages. One of the most important advantages is the calculation of control parameters by selection of appropriate values of rigidity and damping parameters.The analysis of rotor dynamics was conducted in MATLAB© software package.The modeling was performed to allow observing the system action while the parameters were varied.The conducted research showed that to meet the specified requirements of maximal rotor displacement no more than 0.2 mm the following values of coefficients were required: and The stabilization of the rotor
Assessment of research needs for wind turbine rotor materials technology
1991-01-01
Wind-driven power systems is a renewable energy technology that is still in the early stages of development. Wind power plants installed in early 1980s suffered structural failures chiefly because of incomplete understanding of wind forces (turbulent), in some cases because of poor product quality. Failures of rotor blades are now somewhat better understood. This committee has examined the experience base accumulated by wind turbines and the R and D programs sponsored by DOE. It is concluded that a wind energy system such as is described is within the capability of engineering practice; however because of certain gaps in knowledge, and the presence of only one major integrated manufacturer of wind power machines in the USA, a DOE R and D investment is still required.
Meshing Force of Misaligned Spline Coupling and the Influence on Rotor System
Guang Zhao
2008-01-01
Full Text Available Meshing force of misaligned spline coupling is derived, dynamic equation of rotor-spline coupling system is established based on finite element analysis, the influence of meshing force on rotor-spline coupling system is simulated by numerical integral method. According to the theoretical analysis, meshing force of spline coupling is related to coupling parameters, misalignment, transmitting torque, static misalignment, dynamic vibration displacement, and so on. The meshing force increases nonlinearly with increasing the spline thickness and static misalignment or decreasing alignment meshing distance (AMD. Stiffness of coupling relates to dynamic vibration displacement, and static misalignment is not a constant. Dynamic behaviors of rotor-spline coupling system reveal the following: 1X-rotating speed is the main response frequency of system when there is no misalignment; while 2X-rotating speed appears when misalignment is present. Moreover, when misalignment increases, vibration of the system gets intricate; shaft orbit departs from origin, and magnitudes of all frequencies increase. Research results can provide important criterions on both optimization design of spline coupling and trouble shooting of rotor systems.
Nonlinear dynamic behaviors of ball bearing rotor system
WANG Li-qin; CUI Li; ZHENG De-zhi; GU Le
2009-01-01
Nonlinear forces and moments caused by ball bearing were calculated based on relationship of displacement and deflection and quasi-dynamic model of bearing. Five-DOF dynamic equations of rotor supported by ball bearings were estimated. The Newmark-β method and Newton-Laphson method were used to solve the equations. The dynamic characteristics of rotor system were studied through the time response, the phase portrait, the Poincar? maps and the bifurcation diagrams. The results show that the system goes through the quasiperiodic bifurcation route to chaos as rotate speed increases and there are several quasi-periodic regions and chaos regions. The amplitude decreases and the dynamic behaviors change as the axial load of ball bearing increases; the initial contact angle of ball bearing affects dynamic behaviors of the system obviously. The system can avoid non-periodic vibration by choosing structural parameters and operating parameters reasonably.
WANG Shan-yuan; CHEUNG H.W.; LO M.T.
2002-01-01
This paper describes systematic measurement of fiber migration and distribution pattern of twist at different radial positions of rotor spun yarn mixed tracer fiber by Hi- Scope Video Microscope System. The positions of tracer fibers were measured in three dimensions accurately, and the migration index and the twist distribution at different radial positions of rotor yarn were calculated and analyzed. This research result serves structural mechanics of rotor spun yarn.
Rotor blade online monitoring and fault diagnosis technology research
Tesauro, Angelo; Pavese, Christian; Branner, Kim
Rotor blade online monitoring and fault diagnosis technology is an important way to find blade failure mechanisms and thereby improve the blade design. Condition monitoring of rotor blades is necessary in order to ensure the safe operation of the wind turbine, make the maintenance more economical...
Dynamic response of a rub-impact rotor system under axial thrust
An, Xueli; Zhou, Jianzhong; Xiang, Xiuqiao; Li, Chaoshun; Luo, Zhimeng [Huazhong University of Science andTechnology, College of Hydroelectric and Digitalization Engineering, Wuhan, Hubei (China)
2009-11-15
A model of a rigid rotor system under axial thrust with rotor-to-stator is developed based on the classic impact theory and is analyzed by the Lagrangian dynamics. The rubbing condition is modeled using the elastic impact-contact idealization, which consists of normal and tangential forces at the rotor-to-stator contact point. Mass eccentricity and rotating speed are used as control parameters to simulate the response of rotor system. The motions of periodic, quasi-periodic and chaotic are found in the rotor system response. Mass eccentricity plays an important role in creating chaotic phenomena. (orig.)
Complex Critical Exponents in Diluted Systems of Quantum Rotors
Fernandes, Rafael; Schmalian, Jörg
2011-03-01
In this work, we investigate the effects of the Berry phase 2 πρ on the critical properties of XY quantum-rotors that undergo a percolation transition. This model describes a variety of randomly-diluted quantum systems, such as interacting bosons coupled to a particle reservoir, quantum planar antiferromagnets under a perpendicular magnetic field, and Josephson-junction arrays with an external bias-voltage. Focusing on the quantum critical point at the percolation threshold, we find that, for rational ρ , one recovers the power-law behavior with the same critical exponents as in the case with no Berry phase. However, for irrational ρ , the low-energy excitations change completely and are given by emergent spinless fermions with fractal spectrum. As a result, critical properties that cannot be described by the usual Ginzburg-Landau-Wilson theory of phase transitions emerge, such as complex critical exponents, log-periodic oscillations, and dynamically-broken scale invariance. Research supported by the U.S. DOE, Office of BES, Materials Science and Engineering Division.
Nonlinear dynamic analysis of a rotor-bearing-seal system under two loading conditions
Ma, Hui; Li, Hui; Niu, Heqiang; Song, Rongze; Wen, Bangchun
2013-11-01
The operating speed of the rotating machinery often exceeds the second or even higher order critical speeds to pursue higher efficiency. Thus, how to restrain the higher order mode instability caused by the nonlinear oil-film force and seal force at high speed as far as possible has become more and more important. In this study, a lumped mass model of a rotor-bearing-seal system considering the gyroscopic effect is established. The graphite self-lubricating bearing and the sliding bearing are simulated by a spring-damping model and a nonlinear oil-film force model based on the assumption of short bearings, respectively. The seal is simulated by Muszynska nonlinear seal force model. Effects of the seal force and oil-film force on the first and second mode instabilities are investigated under two loading conditions which are determined by API Standard 617 (Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services, Seventh Edition). The research focuses on the effects of exciting force forms and their magnitudes on the first and second mode whips in a rotor-bearing-seal system by using the spectrum cascades, vibration waveforms, orbits and Poincaré maps. The first and second mode instability laws are compared by including and excluding the seal effect in a rotor system with single-diameter shaft and two same discs. Meanwhile, the instability laws are also verified in a rotor system with multi-diameter shaft and two different discs. The results show that the second loading condition (out-of-phase unbalances of two discs) and the nonlinear seal force can mainly restrain the first mode instability and have slight effects on the second mode instability. This study may contribute to a further understanding about the higher order mode instability of such a rotor system with fluid-induced forces from the oil-film bearings and seals.
Effect of Vane Opening on Aerodynamic Performance of the Ram-rotor Test System
HAN Ji-ang; GUAN Jian; ZHONG Jingjun; YUAN Chenguang
2016-01-01
In order to research the influence of adjustable vane on the aerodynamic performance of the ram-rotor test system,FLUENT software has been adopted to simulate the flow passage of the ram-rotor test system numerically.The vane opening is controlled by changing the stagger angle of the vane blades.Results show that flow uniformity of vane outlet is influenced by the vane openings,which has an impact on the aerodynamic loss to some extent.Total pressure ratio,adiabatic efficiency and mass flow rate can be regulated by different openings of the vane.Compared with-8° vane opening,top efficiency of the ram-rotor increases by about 13.8％ at +6° opening.And total pressure ratio drops by 5.87％.The rising opening increases the relative Mach number at inlet of the ram-rotor and weakens the intensity of the tip clearance leakage,which comes to a decreasing aerodynamic loss.
Dynamic balance of unsymmetrical rotor-bearing system
黄森林; 刘占生; 苏杰先
2003-01-01
The formula is derived for calculating correction weights from motion equations of unsymmetrical ro-tor-bearing system. Two trial weights are required in two trial operations for ea ch balancing plane, and forwardprecession of trial responses are used to calculate the correction weights. Comparative experiments between thismethod and the conventional method are carried out on the test bench. Moreover, this method was used to bal-ance a 600 MW generator-bearing system, it decreased the balancing time and improved the balance accuracy.This method has been proved valid for balancing unsymmetrical rotor-bearing system.
Structural analysis of wind turbine rotors for NSF-NASA Mod-0 wind power system
Spera, D. A.
1976-01-01
Preliminary estimates are presented of vibratory loads and stresses in hingeless and teetering rotors for the proposed NSF-NASA Mod-0 wind power system. Preliminary blade design utilizes a tapered tubular aluminum spar which supports nonstructural aluminum ribs and skin and is joined to the rotor hub by a steel shank tube. Stresses in the shank of the blade are calculated for static, rated, and overload operating conditions. Blade vibrations were limited to the fundamental flapping modes, which were elastic cantilever bending for hingeless rotor blades and rigid-body rotation for teetering rotor blades. The MOSTAB-C computer code was used to calculate aerodynamic and mechanical loads. The teetering rotor has substantial advantages over the hingeless rotor with respect to shank stresses, fatigue life, and tower loading. The hingeless rotor analyzed does not appear to be structurally stable during overloads.
Dynamic Characteristics of Flow Induced Vibration in a Rotor-Seal System
Nan Zhang
2011-01-01
Full Text Available Flow induced vibration is an important factor affecting the performance of the rotor-seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the fluid force, which is induced by the interaction between the unstable fluid flow in the seal and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear models. Various nonlinear phenomena of flow induced vibration in the rotor-seal system, such as synchronization phenomenon and amplitude mutation, are reproduced.
挤压阻尼减振滑动轴承—刚性转子系统的研究%Research on a Rigid Rotor-Sliding Bearing System with a Squeeze Film Damper
陆永忠; 廖道训; 黄其柏
2001-01-01
In this paper, a dynamic model on a rigid rotor-sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor-sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.
Transverse vibration of a rotor system driven by a Cardan joint
Iwatsubo, T.; Saigo, M.
1984-07-01
The transverse vibration of a rotor system driven by a Cardan joint is analyzed and the effect of the transmitted torque on the dynamic stability of the system evaluated. As a result of the analysis, the following facts are proved: when the driving shaft and driven shaft (rotor shaft) are included, both parametric and self-excited vibrations arise due to transmitted torque; asymmetrical stiffness of the rotor supports has the effect of stabilizing this self-excited vibration.
2016-01-01
Full Text Available The paper presents numerical results analysis of main rotor vibration due to helicopter main rotor thrust pulsation.The calculation method, the object of research and numerical research results with the aim to reduce the amplitude of the vibrations transmitted to the hub from the helicopters main rotor by the individual blade control in azimuth by the installation angle of blades cyclic changes are set out in the article. The individual blades control law for a five-blade main rotor based on the blade frequencies is made. It allows reducing the vibration from thrust. Research takes into account the main rotor including and excluding the blade flapping motion. The minimal vibrations regime is identified.Numerical study of variable loads caused by unsteady flow around the main rotor blades at high relative speeds of flight, which transmitted to the rotor hub, is made. The scheme of a thin lifting surface and the rotor vortex theory are used for simulation of the aerodynamic loads on blades. Non - uniform loads caused by the thrust, decomposed on the blade harmonic and its overtones. The largest values of deviation from the mean amplitude thrust are received. The analysis of variable loads with a traditional control system is made. Algorithms of higher harmonics individual blade control capable of reducing the thrust pulsation under the average value of thrust are developed.Numerical research shows that individual blade control of high harmonics reduces variable loads. The necessary change in the blade installation is about ± 0,2 degree that corresponds to the maximum displacement of the additional con- trol stick is about 1 mm.To receive the overall picture is necessary to consider all six components of forces and moments. Control law with own constants will obtained for each of them. It is supposed, that each of six individual blade control laws have an impact on other components. Thus, the problem reduces to the optimization issue. The
Dynamic balancing of dual-rotor system with very little rotating speed difference
杨健; 贺世正; 王乐勤
2003-01-01
Unbalanced vibration in dual-rotor rotating machinery was studied with numerical simulations and experiments. A new method is proposed to separate vibration signals of inner and outer rotors for a system with very little difference in rotating speeds. Magnitudes and phase values of unbalance defects can be obtained directly by sampling the vibration signal synchronized with reference signal. The balancing process is completed by the reciprocity influence coefficients of inner and outer rotors method. Results showed the advantage of such method for a dual-rotor system as compared with conventional balancing.
Li, Chaofeng; Yu, Hexing; Zhou, Shihua; Wen, Bangchun
2013-11-01
In the classical process for stability studies on the rotor-bearing system with crack faults, the simple discrete model is adopted for research on such problems, which neglect some needful dynamical influence factor, such as the material damping, shearing effect and gyroscopic effects, etc. Therefore, it is necessary to find a precise calculation model for simulation of the rotor-bearing system with cracks faults. In this paper, instead of the traditional simple discrete model, finite element (FE) model is adopted to investigate the motion stability of a nonlinear rotor system with crack fault. According to finite element theory, the FE model of the cracked rotor system is established firstly. It should be pointed out that the element where the crack occurs is modeled by a particular crack element and the supports at both ends are simulated by two nonlinear loads. Then, based on dimensionless and dimensionality reduction, the Newmark-β method and the shooting method are employed to study the effect of eccentricity and the depth of crack on instability speed and bifurcation feature. Furthermore, the simulation results are verified by some corresponding experiments. The simulation and experimental results show that instability speed does not change monotonically, but decreases firstly and then increases when the amount of eccentricity increases. Moreover, as the type of instability changes, the instability speed jumps concomitantly. Additionally, the presence of crack fault can disturb the oil whirl, as a result, instability speed tends to increase slightly, but it does not affect the type of instability and jumping phenomenon. This research presents an effective and convenient method which uses the finite element method (FEM) to research the motion stability of the nonlinear rotor-bearing system with cracked faults and other nonlinear force, and the proposed method can provide a theoretical reference for stability analysis and vibration control in more complex
Rotor dynamic considerations for large wind power generator systems
Ormiston, R. A.
1973-01-01
Successful large, reliable, low maintenance wind turbines must be designed with full consideration for minimizing dynamic response to aerodynamic, inertial, and gravitational forces. Much of existing helicopter rotor technology is applicable to this problem. Compared with helicopter rotors, large wind turbines are likely to be relatively less flexible with higher dimensionless natural frequencies. For very large wind turbines, low power output per unit weight and stresses due to gravitational forces are limiting factors. The need to reduce rotor complexity to a minimum favors the use of cantilevered (hingeless) rotor configurations where stresses are relieved by elastic deformations.
Zhentao Wang
2012-01-01
Full Text Available Fault detection and isolation (FDI in rotor systems often faces the problem that the system dynamics is dependent on the rotor rotary frequency because of the gyroscopic effect. In unbalance excited rotor systems, the continuously distributed unbalances are hard to be determined or estimated accurately. The unbalance forces as disturbances make fault detection more complicated. The aim of this paper is to develop linear time invariant (LTI FDI methods (i.e., with constant parameters for rotor systems under consideration of gyroscopic effect and disturbances. Two approaches to describe the gyroscopic effect, that is, as unknown inputs and as model uncertainties, are investigated. Based on these two approaches, FDI methods are developed and the results are compared regarding the resulting FDI performances. Results are obtained by the application in a rotor test rig. Restrictions for the application of these methods are discussed.
14 CFR 29.923 - Rotor drive system and control mechanism tests.
2010-01-01
... limitations either preclude repeated use of this power or would result in premature engine removals during the... addition, a level of safety equal to that of the main rotors must be provided for— (1) Each component in the rotor drive system whose failure would cause an uncontrolled landing; (2) Each component...
Stringer, David Blake
The overarching objective in this research is the development of a robust, rotor dynamic, physics based model of a helicopter drive train as a foundation for the prognostic modeling for rotary-wing transmissions. Rotorcrafts rely on the integrity of their drive trains for their airworthiness. Drive trains rely on gear technology for their integrity and function. Gears alter the vibration characteristics of a mechanical system and significantly contribute to noise, component fatigue, and personal discomfort prevalent in rotorcraft. This research effort develops methodologies for generating a rotor dynamic model of a rotary-wing transmission based on first principles, through (i) development of a three-dimensional gear-mesh stiffness model for helical and spur gears and integration of this model in a finite element rotor dynamic model, (ii) linear and nonlinear analyses of a geared system for comparison and validation of the gear-mesh model, (iii) development of a modal synthesis technique for potentially providing model reduction and faster analysis capabilities for geared systems, and (iv) extension of the gear-mesh model to bevel and epicyclic configurations. In addition to model construction and validation, faults indigenous to geared systems are presented and discussed. Two faults are selected for analysis and seeded into the transmission model. Diagnostic vibration parameters are presented and used as damage indicators in the analysis. The fault models produce results consistent with damage experienced during experimental testing. The results of this research demonstrate the robustness of the physics-based approach in simulating multiple normal and abnormal conditions. The advantages of this physics-based approach, when combined with contemporary probabilistic and time-series techniques, provide a useful method for improving health monitoring technologies in mechanical systems.
Quasimodes instability analysis of uncertain asymmetric rotor system based on 3D solid element model
Zuo, Yanfei; Wang, Jianjun; Ma, Weimeng
2017-03-01
Uncertainties are considered in the equation of motion of an asymmetric rotor system. Based on Hill's determinant method, quasimodes stability analysis with uncertain parameters is used to get stochastic boundaries of unstable regions. Firstly, A 3D finite element rotor model was built in rotating frame with four parameterized coefficients, which is assumed as random parameters representing the uncertainties existing in the rotor system. Then the influences of uncertain coefficients on the distribution of the unstable region boundaries are analyzed. The results show that uncertain parameters have various influences on the size, boundary and number of unstable regions. At last, the statistic results of the minimum and maximum spin speeds of unstable regions were got by Monte Carlo simulation. The used method is suitable for real engineering rotor system, because arbitrary configuration of rotors can be modeled by 3D finite element.
Analysis on Dynamic Performance for Active Magnetic Bearing—Rotor System
YANHui－yan; WANGXi－ping; 等
2001-01-01
In the application of active magnetic bearings(AMB),one of the key problems to be solved is the safety and stabiltiy in the sense of rotor dynamics,The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings,and studies its rotor dynamics performance,including calculation of the natural frequencies with their distribution characteristics,and the critical speeds of the system.one of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magntic bearing-rotor systemby combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.
Hybrid Configuration of Darrieus and Savonius Rotors for Stand-alone Power Systems
Wakui, Tetsuya; Tanzawa, Yoshiaki; Hashizume, Takumi; Nagao, Toshio
The suitable hybrid configuration of Darrieus lift-type and Savonius drag-type rotors for stand-alone wind turbine-generator systems is discussed using our dynamic simulation model. Two types of hybrid configurations are taken up: Type-A installs the Savonius rotor inside the Darrieus rotor and Type-B installs the Savonius rotor outside the Darrieus rotor. The computed results of the output characteristics and the dynamic behaviors of the system operated at the maximum power coefficient points show that Type-A, which has fine operating behavior to wind speed changes and can be compactly designed because of a shorter rotational shaft, is an effective way for self-controlled stand-alone small-scale systems.
Structural Considerations of a 20MW Multi-Rotor Wind Energy System
Jamieson, P.; Branney, M.
2014-12-01
The drive to upscale offshore wind turbines relates especially to possiblereductions in O&M and electrical interconnection costs per MW of installed capacity.Even with best current technologies, designs with rated capacity above about 3 MW are less cost effective exfactory per rated MW(turbine system costs) than smaller machines.Very large offshore wind turbines are thereforejustifiedprimarily by overall offshore project economics. Furthermore, continuing progress in materials and structures has been essential to avoid severe penalties in the power/mass ratio of large multi-MW machines.The multi-rotor concept employs many small rotors to maximise energy capture area withminimum systemvolume. Previous work has indicated that this can enablea very large reduction in the total weight and cost of rotors and drive trains compared to an equivalent large single rotor system.Thus the multi rotor concept may enable rated capacities of 20 MW or more at a single maintenancesite. Establishing the cost benefit of a multi rotor system requires examination of solutions for the support structure and yawing, ensuring aerodynamic losses from rotor interaction are not significant and that overall logistics, with much increased part count (more reliable components) and less consequence of single failuresare favourable. This paper addresses the viability of a support structure in respect of structural concept and likely weight as one necessary step in exploring the potential of the multi rotor concept.
Wang, Aiming; Cheng, Xiaohan; Meng, Guoying; Xia, Yun; Wo, Lei; Wang, Ziyi
2017-03-01
Identification of rotor unbalance is critical for normal operation of rotating machinery. The single-disc and single-span rotor, as the most fundamental rotor-bearing system, has attracted research attention over a long time. In this paper, the continuous single-disc and single-span rotor is modeled as a homogeneous and elastic Euler-Bernoulli beam, and the forces applied by bearings and disc on the shaft are considered as point forces. A fourth-order non-homogeneous partial differential equation set with homogeneous boundary condition is solved for analytical solution, which expresses the unbalance response as a function of position, rotor unbalance and the stiffness and damping coefficients of bearings. Based on this analytical method, a novel Measurement Point Vector Method (MPVM) is proposed to identify rotor unbalance while operating. Only a measured unbalance response registered for four selected cross-sections of the rotor-shaft under steady-state operating conditions is needed when using the method. Numerical simulation shows that the detection error of the proposed method is very small when measurement error is negligible. The proposed method provides an efficient way for rotor balancing without test runs and external excitations.
王弢; 帅健; 刘焰明
2012-01-01
The dynamic systems, such as generator rotors and ship propulsion shafts, include transmission shafts, bearings and seals, which is a typical rotor-bearing-seal dynamic system. When the system is running, some factors, including shaft mass eccentricity, bearing lubrication properties and seal force, change the system running stability and make it into different movement conditions. The dynamic equations are given in the paper. With the numerical integral method, the influences of shaft mass eccentricity, bearing lubrication properties and seal force on the dynamic system are investigated. Some relationships between the factors with the system running stability are offered in the paper, which are very significant in theory.%建立了转子-轴承-密封动力学模型,通过数值积分模拟方法,研究了轴系对中偏心、轴承支承润滑特性、密封力等动态因素对系统振动的影响,其运动行为和各因素对系统运动稳定性的影响,得出了各种因素与系统运动行为之间的相互关系.
Research on flight stability performance of rotor aircraft based on visual servo control method
Yu, Yanan; Chen, Jing
2016-11-01
control method based on visual servo feedback is proposed, which is used to improve the attitude of a quad-rotor aircraft and to enhance its flight stability. Ground target images are obtained by a visual platform fixed on aircraft. Scale invariant feature transform (SIFT) algorism is used to extract image feature information. According to the image characteristic analysis, fast motion estimation is completed and used as an input signal of PID flight control system to realize real-time status adjustment in flight process. Imaging tests and simulation results show that the method proposed acts good performance in terms of flight stability compensation and attitude adjustment. The response speed and control precision meets the requirements of actual use, which is able to reduce or even eliminate the influence of environmental disturbance. So the method proposed has certain research value to solve the problem of aircraft's anti-disturbance.
Chaos control and impact suppression in rotor-bearing system using magnetorheological fluid
Piccirillo, V.; Balthazar, J. M.; Tusset, A. M.
2015-11-01
In this paper a general dynamic model of a rotor-bearing system using magnetorheological fluid (MR) is presented. The mathematical model of the rotor-bearing system results from a Jeffcott rotor with two-degrees of freedom and discontinuous supports. The effect of magnetorheological fluid on vibration is investigated based on a model of a modified LuGre dynamical friction model. A comparison with equivalent rotor-bearing system is made to verify the contribution of MR in this system. In this study two different implementations of the control procedure are presented, one eliminating the chaotic behavior and the second suppressing the unbalancing vibration so as to avoid impact in rotor-bearing system. First, to control the undesirable chaos in rotor-bearing system a damped passive control methodology is used. On the other hand, to suppressing the impact vibration, the Fuzzy Logic Control is considered. Results demonstrate that undesirable behaviors of rotor can be avoided by varying the damping force.
Dynamics of High-Speed Precision Geared Rotor Systems
Lim Teik C.
2014-07-01
Full Text Available Gears are one of the most widely applied precision machine elements in power transmission systems employed in automotive, aerospace, marine, rail and industrial applications because of their reliability, precision, efficiency and versatility. Fundamentally, gears provide a very practical mechanism to transmit motion and mechanical power between two rotating shafts. However, their performance and accuracy are often hampered by tooth failure, vibrations and whine noise. This is most acute in high-speed, high power density geared rotor systems, which is the primary scope of this paper. The present study focuses on the development of a gear pair mathematical model for use to analyze the dynamics of power transmission systems. The theory includes the gear mesh representation derived from results of the quasi-static tooth contact analysis. This proposed gear mesh theory comprising of transmission error, mesh point, mesh stiffness and line-of-action nonlinear, time-varying parameters can be easily incorporated into a variety of transmission system models ranging from the lumped parameter type to detailed finite element representation. The gear dynamic analysis performed led to the discovery of the out-of-phase gear pair torsion modes that are responsible for much of the mechanical problems seen in gearing applications. The paper concludes with a discussion on effectual design approaches to minimize the influence of gear dynamics and to mitigate gear failure in practical power transmission systems.
THE DESIGN OF AXIAL PUMP ROTORS USING THE NUMERICAL METHODS
Ali BEAZIT
2010-06-01
Full Text Available The researches in rotor theory, the increasing use of computers and the connection between design and manufacturing of rotors, have determined the revaluation and completion of classical rotor geometry. This paper presents practical applications of mathematical description of rotor geometry. A program has been created to describe the rotor geometry for arbitrary shape of the blade. The results can be imported by GAMBIT - a processor for geometry with modeling and mesh generations, to create a mesh needed in hydrodynamics analysis of rotor CFD. The results obtained are applicable in numerical methods and are functionally convenient for CAD/CAM systems.
Interaction of Parametric and Forced Vibrations in High Speed Rotor-Bearing-Systems
Weyh, Bernhardt
1997-01-01
... and the manifold of inhomogeneous solutions are discussed. The application to a realisation of a high speed twin-disc rotor-bearing-system of a textile spinning turbine illustrates the resonance effects...
Nonlinear Dynamics Analysis of Tilting Pad Journal Bearing-Rotor System
Jiayang Ying
2011-01-01
Full Text Available The nonlinear dynamics theory is increasingly applied in the dynamics analysis of tilting pad journal bearing-rotor system. However, extensive work on system dynamics done previously neglects the influence caused by the moment of inertia of the pad. In this paper, a comparison is made between the responses of the rotor in the bearings with and without pad inertia effect. Taking the Jeffcott rotor system as an example, the characteristics of bearing-rotor system, such as bifurcation diagram, cycle response, frequency spectrum, phase trajectories, and Poincaré maps, were attained within a certain rotation rate range. The pivotal oil-film force of tilting pad journal bearing was calculated by database method. The results directly demonstrate that considering the influence of the pad moment of inertia, system dynamics characteristics are found more complicated when rotor-bearing system works around natural frequency and system bifurcation is observed forward when rotor-bearing system works on high-speed range.
Model updating of rotor systems by using Nonlinear least square optimization
Jha, A. K.; Dewangan, P.; Sarangi, M.
2016-07-01
Mathematical models of structure or machineries are always different from the existing physical system, because the approach of numerical predictions to the behavior of a physical system is limited by the assumptions used in the development of the mathematical model. Model updating is, therefore necessary so that updated model should replicate the physical system. This work focuses on the model updating of rotor systems at various speeds as well as at different modes of vibration. Support bearing characteristics severely influence the dynamics of rotor systems like turbines, compressors, pumps, electrical machines, machine tool spindles etc. Therefore bearing parameters (stiffness and damping) are considered to be updating parameters. A finite element model of rotor systems is developed using Timoshenko beam element. Unbalance response in time domain and frequency response function have been calculated by numerical techniques, and compared with the experimental data to update the FE-model of rotor systems. An algorithm, based on unbalance response in time domain is proposed for updating the rotor systems at different running speeds of rotor. An attempt has been made to define Unbalance response assurance criterion (URAC) to check the degree of correlation between updated FE model and physical model.
Fault Feature Analysis of a Cracked Gear Coupled Rotor System
Hui Ma
2014-01-01
Full Text Available Considering the misalignment of gear root circle and base circle and accurate transition curve, an improved mesh stiffness model for healthy gear is proposed, and it is validated by comparison with the finite element method. On the basis of the improved method, a mesh stiffness model for a cracked gear pair is built. Then a finite element model of a cracked gear coupled rotor system in a one-stage reduction gear box is established. The effects of crack depth, width, initial position, and crack propagation direction on gear mesh stiffness, fault features in time domain and frequency domain, and statistical indicators are investigated. Moreover, fault features are also validated by experiment. The results show that the improved mesh stiffness model is more accurate than the traditional mesh stiffness model. When the tooth root crack appears, distinct impulses are found in time domain vibration responses, and sidebands appear in frequency domain. Amplitudes of all the statistical indicators ascend gradually with the growth of crack depth and width, decrease with the increasing crack initial position angle, and firstly increase and then decrease with the growth of propagation direction angle.
Wireless Sensors System for Broken Rotor bar Fault Monitoring using Wavelet Analysis
Rezazadeh Mehrjou, Mohammad; Mariun, Norman; Karami, Mahdi; Misron, Norhisam; Amran Mohd Radzi, Mohd
2015-11-01
Accurate condition monitoring prevents unexpected failures in electrical systems including induction machines, and hence improves their performance significantly. To enhance the reliability of condition monitoring systems, wireless sensor systems are developed. In the recent years, researchers have placed considerable emphasis on developing cost-effective scheme using wireless sensor systems for fault diagnosis of equipments in industry. As broken rotor bar is one of the main causes of malfunction in electrical motors, this paper proposes a method for early detection of this failure in induction machines using wireless sensor system. In this respect, a test bed is developed where a sensor measures the motor current and then a microcontroller connected to this current sensor read and send the data to wireless sensor for remote real time data analysis. In the receiver unit, a Lab VIEW based program is developed to store data in a database and MATLAB is used for signal processing and fault.
Finite Element Harmonic Solution of the Coupled Rotor-bearing System
无
2002-01-01
Fluid-solid interaction problems have been studied q uite extensively in the past years. Rotor-bearing system is a typical example. Fluid field is changed under the exciting of rotor vibration. On the same ti me, a net force caused by fluid pressure exerts on rotor, which will change roto r vibration. So, the fluid-solid coupled analysis method must be used. Traditionally, numerical difference method was used to solve fluid problems. The coupled fluid-solid equation could not be set up based on the me...
A Study of Coaxial Rotor Performance and Flow Field Characteristics
2016-01-22
A Study of Coaxial Rotor Performance and Flow Field Characteristics Natasha L. Barbely Aerospace Engineer NASA Ames Research Center Moffett Field...The pressure field generated by the two airfoils aided our interpretation of the more complex coaxial rotor system flow field. The pressure fields...velocity (ft/sec) Z vertical distance between rotors (ft) αS pitch angle (deg), negative pitch down κint coaxial rotor induced power interference
DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well
2013-01-01
This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean
Liu, Shibing; Yang, Bingen
2017-10-01
Flexible multistage rotor systems with water-lubricated rubber bearings (WLRBs) have a variety of engineering applications. Filling a technical gap in the literature, this effort proposes a method of optimal bearing placement that minimizes the vibration amplitude of a WLRB-supported flexible rotor system with a minimum number of bearings. In the development, a new model of WLRBs and a distributed transfer function formulation are used to define a mixed continuous-and-discrete optimization problem. To deal with the case of uncertain number of WLRBs in rotor design, a virtual bearing method is devised. Solution of the optimization problem by a real-coded genetic algorithm yields the locations and lengths of water-lubricated rubber bearings, by which the prescribed operational requirements for the rotor system are satisfied. The proposed method is applicable either to preliminary design of a new rotor system with the number of bearings unforeknown or to redesign of an existing rotor system with a given number of bearings. Numerical examples show that the proposed optimal bearing placement is efficient, accurate and versatile in different design cases.
Control Law Design for Twin Rotor MIMO System with Nonlinear Control Strategy
M. Ilyas
2016-01-01
Full Text Available Modeling of complex air vehicles is a challenging task due to high nonlinear behavior and significant coupling effect between rotors. Twin rotor multi-input multioutput system (TRMS is a laboratory setup designed for control experiments, which resembles a helicopter with unstable, nonlinear, and coupled dynamics. This paper focuses on the design and analysis of sliding mode control (SMC and backstepping controller for pitch and yaw angle control of main and tail rotor of the TRMS under parametric uncertainty. The proposed control strategy with SMC and backstepping achieves all mentioned limitations of TRMS. Result analysis of SMC and backstepping control schemes elucidates that backstepping provides efficient behavior with the parametric uncertainty for twin rotor system. Chattering and oscillating behaviors of SMC are removed with the backstepping control scheme considering the pitch and yaw angle for TRMS.
Allred, Charles Jefferson
Since the advent of Health and Usage Monitoring Systems (HUMS) in the early 1990's, there has been a steady decrease in the number of component failure related helicopter accidents. Additionally, measurable cost benefits due to improved maintenance practices based on HUMS data has led to a desire to expand HUMS from its traditional area of helicopter drive train monitoring. One of the areas of greatest interest for this expansion of HUMS is monitoring of the helicopter rotor head loads. Studies of rotor head load and blade motions have primarily focused on wind tunnel testing with technology which would not be applicable for production helicopter HUMS deployment, or measuring bending along the blade, rather than where it is attached to the rotor head and the location through which all the helicopter loads pass. This dissertation details research into finding methods for real time methods of estimating rotor blade motion which could be applied across helicopter fleets as an expansion of current HUMS technology. First, there is a brief exploration of supporting technologies which will be crucial in enabling the expansion of HUMS from the fuselage of helicopters to the rotor head: wireless data transmission and energy harvesting. A brief overview of the commercially available low power wireless technology selected for this research is presented. The development of a relatively high-powered energy harvester specific to the motion of helicopter rotor blades is presented and two different prototypes of the device are shown. Following the overview of supporting technologies, two novel methods of monitoring rotor blade motion in real time are developed. The first method employs linear displacement sensors embedded in the elastomer layers of a high-capacity laminate bearing of the type commonly used in fully articulated rotors throughout the helicopter industry. The configuration of these displacement sensors allows modeling of the sensing system as a robotic parallel
A 5-DOF Model for Aeroengine Spindle Dual-rotor System Analysis
HU Qinghua; DENG Sier; TENG Hongfei
2011-01-01
This paper develops a five degrees of freedom (5-DOF) model for aeroengine spindle dual-rotor system dynamic analysis.In this system, the dual rotors are supported on two angular contact ball bearings and two deep groove ball bearings, one of the latter-mentioned bearings works as the inter-shaft bearing.Driven by respective motors, the dual rotors have different co-rotating speeds.The proposed model mathematically formulates the nonlinear displacements, elastic deflections and contact forces of beatings with consideration of 5-DOF and coupling of dual rotors.The nonlinear equations of motions of dual rotors with 5-DOF are solved using Runge-Kutta-Fehlberg algorithm.In order to investigate the effect of the introduced 5-DOF and nonlinear dynamic bearing model, we compare the proposed model with two models: the 3-DOF model of this system only considering three translational degrees of freedom (Gupta, 1993, rotational freedom is neglected); the 5-DOF model where the deep groove ball bearings are simplified as linear elastic spring (Guskov, 2007).The simulation results verify Gupta's prediction (1993) and show that the rotational freedom of rotors and nonlinear dynamic model of bearings have great effect on the system dynamic simulation.The quantitative results are given as well.
Open Rotor Tone Shielding Methods for System Noise Assessments Using Multiple Databases
Bahr, Christopher J.; Thomas, Russell H.; Lopes, Leonard V.; Burley, Casey L.; Van Zante, Dale E.
2014-01-01
Advanced aircraft designs such as the hybrid wing body, in conjunction with open rotor engines, may allow for significant improvements in the environmental impact of aviation. System noise assessments allow for the prediction of the aircraft noise of such designs while they are still in the conceptual phase. Due to significant requirements of computational methods, these predictions still rely on experimental data to account for the interaction of the open rotor tones with the hybrid wing body airframe. Recently, multiple aircraft system noise assessments have been conducted for hybrid wing body designs with open rotor engines. These assessments utilized measured benchmark data from a Propulsion Airframe Aeroacoustic interaction effects test. The measured data demonstrated airframe shielding of open rotor tonal and broadband noise with legacy F7/A7 open rotor blades. Two methods are proposed for improving the use of these data on general open rotor designs in a system noise assessment. The first, direct difference, is a simple octave band subtraction which does not account for tone distribution within the rotor acoustic signal. The second, tone matching, is a higher-fidelity process incorporating additional physical aspects of the problem, where isolated rotor tones are matched by their directivity to determine tone-by-tone shielding. A case study is conducted with the two methods to assess how well each reproduces the measured data and identify the merits of each. Both methods perform similarly for system level results and successfully approach the experimental data for the case study. The tone matching method provides additional tools for assessing the quality of the match to the data set. Additionally, a potential path to improve the tone matching method is provided.
Zhang, Xuening; Han, Qinkai; Peng, Zhike; Chu, Fulei
2015-05-01
A great deal of research work has been done on the dynamic behaviors of the rotor-bearing system. However, the important effects of load and variation of contact angle on the bearing performance have not been focused on sufficiently. In this paper, a five-degree-of-freedom load distribution model is set up considering the bearing preload and the loads due to the rotor imbalance. Utilizing this model, the variation of the bearing contact angle is investigated thoroughly. The comparisons of the obtained contact angle against the results from literature validate that the proposed load distribution model is effective. With this model, the static ball deformations are obtained considering variation of the contact angle. Through resolving the dynamic displacements of the rotor, the dynamic ball deformations could also be obtained. Then the total restoring forces and moments of the bearings could be formulated. By introducing these nonlinear forces and moments into the rotating system, a new dynamic model considering the preload and the variation of contact angle is set up. The present analyses indicate that the bearing contact angle will be changed remarkably with the effect of bearing load. The deflection vibration of the rotor-bearing system will be underestimated without considering the varying contact angle. With the effect of varying contact angle, the ball passage frequency and its combinations with the shaft rotating frequency become more noticeable. The main resonance regions for the rotor-bearing system shift to the lower speed ranges when the variation of contact angle is taken into account.
Sivachandran Paulsamy
2014-01-01
Full Text Available In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG for direct coupled stand alone wind energy systems (SAWES. Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.
Paulsamy, Sivachandran
2014-01-01
In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.
Crack location identification of rotating rotor systems using operating deflection shape data
ZHANG; ChunLin; LI; Bing; YANG; ZhiBo; XIAO; WenRong; HE; ZhengJia
2013-01-01
Crack location identification, as one key destination of structural health monitoring, is still a challenge for operating rotor systems. The operating deflection shape (ODS), which represents a visual description of the structural vibration patterns under operating conditions, has been gaining importance for structure damage detection in recent years. The ODS carries damage information of a structure, however, it is also difficult to detect weak cracks of rotor directly. The approximate waveform capacity dimension (AWCD) method was successfully applied to damage detection of plates and beam-like structures. In this paper,a strategic approach that combines ODS and weighted AWCD is proposed for crack location identification of the rotating rotor.To eliminate the false peaks of AWCD and obtain desirable results, a weight factor and ODS curvature data are introduced to the expression of the weighted AWCD. The effectiveness of the proposed method is validated by numerical simulation and experimental investigation in a cracked rotor system. The results indicate that the proposed approach not only provides good identifying performance for incipient rotor cracks, but also effectively eliminates the fault peaks introduced by the inflexion locations of ODSs. Moreover, the proposed approach proves promising in detecting crack locations of rotating rotor systems.
Design and Optimization Method of a Two-Disk Rotor System
Huang, Jingjing; Zheng, Longxi; Mei, Qing
2016-04-01
An integrated analytical method based on multidisciplinary optimization software Isight and general finite element software ANSYS was proposed in this paper. Firstly, a two-disk rotor system was established and the mode, humorous response and transient response at acceleration condition were analyzed with ANSYS. The dynamic characteristics of the two-disk rotor system were achieved. On this basis, the two-disk rotor model was integrated to the multidisciplinary design optimization software Isight. According to the design of experiment (DOE) and the dynamic characteristics, the optimization variables, optimization objectives and constraints were confirmed. After that, the multi-objective design optimization of the transient process was carried out with three different global optimization algorithms including Evolutionary Optimization Algorithm, Multi-Island Genetic Algorithm and Pointer Automatic Optimizer. The optimum position of the two-disk rotor system was obtained at the specified constraints. Meanwhile, the accuracy and calculation numbers of different optimization algorithms were compared. The optimization results indicated that the rotor vibration reached the minimum value and the design efficiency and quality were improved by the multidisciplinary design optimization in the case of meeting the design requirements, which provided the reference to improve the design efficiency and reliability of the aero-engine rotor.
Research on pattern recognition for marine steam turbine rotor axis orbit
ZHANG Yan; YANG Zhi-da; XIA Hong
2003-01-01
The structure,function and recognition method of an axis orbit auto-recognizing system are presented in this paper.In order to make the best use of information of format and dynamic characteristics of marine steam turbine axis orbit,the structure and functions or neural network are applied to this system,which can be used to auto-recognize axis orbit of the system turbine rotor using BP neural network.
Investigation of the effect of controllable dampers on limit states of rotor systems
Zapoměl J.
2012-06-01
Full Text Available The unbalance and time varying loading are the principal sources of lateral vibrations of rotors and of increase of forces transmitted through the coupling elements into the stationary part. These oscillations and force effects can be considerably reduced if damping devices are added to the coupling elements placed between the rotor and its casing. The theoretical studies and practical experience show that to achieve their optimum performance their damping effect must be controllable. This article focuses on investigation of influence of controlled damping in the rotor supports on its limit state of deformation, fatigue failure and on magnitude of the forces transmitted into the stationary part. The analysed system is a flexible rotor with one disc driven by an electric DC motor and loaded by the disc unbalance and by technological forces depending on the rotor angular position. In the computational model the system vibration is governed by a set of nonlinear differential equations of the first and second orders. To evaluate the fatigue failure both the flexural and torsional oscillations are taken into account. The analysis is aimed at searching for the intervals of angular speeds, at which the rotor can be operated without exceeding the limit states.
Rotor anisotropy as a blade damage indicator for wind turbine structural health monitoring systems
Tcherniak, Dmitri
2016-06-01
Structural damage of a rotor blade causes structural anisotropy of the rotor. In rotor dynamic, the anisotropy affects the symmetry of the rotor mode shapes, and the latter can be utilized to detect the blade damage. The mode shape symmetry can be characterized by relative blades' magnitude and phase. The study examines the potential use of these parameters as rotor damage indicators. Firstly the indicators are studied analytically using a simple 6 degrees-of-freedom model of a rotating rotor. Floquet analysis is used due to the time periodic nature of the considered system. Floquet analysis allows one to perform analytical modal decomposition of the system and study the sensitivity of the damage indicators to the amount of damage. Secondly, operational modal analysis (OMA) is involved to extract the same damage indicators from simulated experimental data, which was synthesized via numerical simulations. Finally, the same procedure was applied to operating Vestas V27 wind turbine, first using the simulated experimental data obtained by using aeroelastic simulation code HAWC2 and then using the data acquired during the measurement campaign on a real wind turbine. The study demonstrates that the proposed damage indicators are significantly more sensitive than the commonly used changes in natural frequency, and in contrast to the latter, can also pinpoint the faulty blade. It is also demonstrated that these indicators can be derived from blades vibration data obtained from real life experiment.
Magnetostatic analysis of a rotor system supported by radial active magnetic bearings
Ferfecki P.
2009-06-01
Full Text Available The development and the design of a radial active magnetic bearing (AMB reflects a complex process of the multidisciplinary rotor dynamics, electromagnetism and automatic control analysis. Modelling is performed by application of the physical laws from different areas, e.g. Newton's laws of motion and Maxwell's equations. The new approach in the numerical modelling of radial AMB and design methodology allowing automatic generation of primary dimensions of the radial AMB is proposed. Instead of the common way of computation of electromagnetic forces by linearizing at the centre position of the rotor with respect to rotor displacement and coil current, the finite element computation of electromagnetic forces is used. The heteropolar radial AMB consisting of eight pole shoes was designed by means of the built up algorithms for rotor system with two discs fixed on the cantilever shaft. A study of the influence of the nonlinear magnetization characteristics of a rotor and stator material on the equilibrium position of a rotor system is carried out. The performed numerical study shows that results obtained from the analytical nonlinear relation for electromagnetic forces can be considerably different from forces computed with magnetostatic finite element analysis.
邓豪; 潘存云; 徐海军; 张湘
2012-01-01
为大幅度提高活塞式发动机的功率密度,提出一种双转子活塞发动机,其功率传输系统主要由能量转换组件和差速驱动组件构成.能量转换组件包含气缸体以及同轴交叉安装在气缸体中的两个转子,转子上均布有多个叶片活塞,两组叶片活塞在气缸体内相互间隔,与气缸体共同形成多个密闭的独立工作腔.差速驱动组件利用内摆线机构和曲柄摇杆机构组合而成,并负责约束气缸中的两个转子以周期性波动的角速度作差速转动,使得工作腔容积周期性地增大、减小.研究该发动机的构成及工作原理,得出发动机能量转换组件部分的基本几何关系及进、压、爆、排条件,推导出发动机排量和瞬时流量的计算公式,建立差速驱动组件部分的运动学模型并进行分析.分析结果表明,由于具备在主轴旋转一周过程中的较多的做功次数和动态扩容等特点,双转子活塞发动机理论上将比现有活塞式发动机的排量更大、功率密度更高、运转更为平稳.%In order to increase the power density of the piston engine, the power transmission system of a twin-rotor piston engine is proposed, which is composed of an energy conversion assembly and a differential velocity drive mechanism assembly. The major parts of the energy conversion assembly include a housing and two interdigitated rotors each having plurality of diagonally opposed vane pistons which separate the housing and form working chambers. The differential velocity drive mechanism is composed of the hypocycloidal mechanism and the crank rock mechanism, which constrain the two rotors fixed inside the housing rotating with periodical nonuniform velocity. Thus the volume of the working chambers varies, and opens and closes periodically. The structure and the working principle of the engine are discussed. The mathematical modeling of the energy conversion assembly and the conditions of intake
李忠刚; 陈予恕
2012-01-01
研究了转子-密封系统在气流激振力作用下的低频振动——1∶2亚谐共振现象.利用流体计算动力学(CFD)方法对转子-密封系统进行了流场模拟计算,辨识出适用于气流流场的Muszynska模型参数,并建立了转子-密封系统动力学方程.采用多尺度方法将系统进行3次截断,并得到系统响应.采用奇异性理论研究了系统的1∶2亚谐共振,进一步得到系统亚谐共振的分岔方程和转迁集,根据转迁集给出了在不同奇异性参数空间内的分岔图.同时,由分岔方程得到了亚谐共振非零解存在的条件.其分析结果对抑制转子-密封系统的亚谐振动有重要的工程意义.%The 1:2 subharmonic resonance of the labyrinth seals/rotor systems was investigated, which the low-frequency vibration of stream turbines could be caused by the gas exciting force in. The empirical parameters of gas exciting force of Muszynska model were obtained by using the results of Computational Fluid Dynamics ( CFD). Based on multiple scale method, the 1:2 subharmonic resonance response of the dynamic system was gained by truncating the system with three orders. The transition sets and the local bifurcations diagrams of the dynamics system were presented by employing singular theory analysis. Meanwhile, the existence conditions of subharmonic resonance non-zeros solutions of the dynamic system were obtained, which provides a new theoretical basis in recognizing and protecting the rotor from the subharmonic resonant failures in the turbine machinery.
Van Zante, Dale E.; Rizzi, Stephen A.
2016-01-01
The ERA project executed a comprehensive test program for Open Rotor aerodynamic and acoustic performance. System studies used the data to estimate the fuel burn savings and acoustic margin for an aircraft system with open rotor propulsion. The acoustic measurements were used to produce an auralization that compares the legacy blades to the current generation of open rotor designs.
Theodore, Colin R.; Tischler, Mark B.
2010-01-01
An automatic rotor trim control system was developed and successfully used during a wind tunnel test of a full-scale UH-60 rotor system with Individual Blade Control (IBC) actuators. The trim control system allowed rotor trim to be set more quickly, precisely and repeatably than in previous wind tunnel tests. This control system also allowed the rotor trim state to be maintained during transients and drift in wind tunnel flow, and through changes in IBC actuation. The ability to maintain a consistent rotor trim state was key to quickly and accurately evaluating the effect of IBC on rotor performance, vibration, noise and loads. This paper presents details of the design and implementation of the trim control system including the rotor system hardware, trim control requirements, and trim control hardware and software implementation. Results are presented showing the effect of IBC on rotor trim and dynamic response, a validation of the rotor dynamic simulation used to calculate the initial control gains and tuning of the control system, and the overall performance of the trim control system during the wind tunnel test.
马文琦; 黄鑫; 刘海艳
2012-01-01
In order to overcome the problem that the aerostatic bearing-rotor system vibrates severely near the critical speed region,a large number of experimental studies about the effects of supply pressure on stability of high-speed aerostatic bearing-rotor system were carried out.In this paper,with turbine driven and the control of the electrical proportional valve,vibration of this system was tested and analyzed on various working conditions.The results demonstrate that the critical speed is increased with the increase of the bearing supply pressure.However,the change of the vibration amplitude is opposite,which is reduced with the increase of the bearing supply pressure.The method of secondary controlling the supply pressure can sufficiently inhibit the vibration amplitude of the critical speed region within a certain range,and the system stability can be corresponding improved.%为解决气浮轴承在经过临界转速的剧烈振动不稳定这一问题,进行了供气压力对气体轴承-转子系统稳定性影响的实验研究.基于涡轮驱动和电器比例阀压力控制,搭建了基于高速静压气体轴承-转子系统实验台,对不同供气压力工况组合下系统振动进行了测试与分析.结果表明:在一定供气压力范围内,临界转速值随着轴承供气压力增大而升高,振动幅值随着轴承供气压力增大而降低,合理控制临界转速区域附近供气压力可一定程度内抑制振动幅值,达到提高系统稳定性的目的.
Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers
无
2009-01-01
To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy- namical equations of the rotor, with other equations of blades. In this way, the original system with 16+4n (n≥3) degrees of freedom (DoF) is reduced to a system with 24 DoF only. Then the parametric excitation terms in the blade-overhang rotor-SFD model are simplified in terms of periodic transforma- tions. The coupling equations are numerically solved and the solutions are used to analyze the dy- namic behavior of the system in terms of the bifurcation diagram, whirl orbit, Poincaré map and spec- trum plot. A variety of motion types are found such as multi-periodic, quasi-periodic, and chaotic mo- tions. Moreover, the typical nonlinear dynamic evolutions including the periodic-doubling bifurcation and reverse bifurcation are noted. It is noticed that there exist apparent differences in the dynamic behavior between the blade-overhang rotor-SFD models without and with considering the effect of blades.
Model-Based Degree Estimation of Unbalance and Misalignment in Flexible Coupling-rotor System
LI Changyou; XU Minqiang; GUO Song; WANG Yuewu; WANG Rixin
2009-01-01
The condition of rotor system must be assessed in order to develop condition-based maintenance for rotating machinery. It is determined by multiple variables such as unbalance degree, misalignment degree, the amount of bending deformation of the shaft, occurrence of shaft crack of rotor system and so on. The estimation of the degrees of unbalance and misalignment in flexible coupling-rotor system is discussed. The model-based approach is employed to solve this problem. The models of the equivalent external loads for unbalance and misalignment are derived and analyzed. Then, the degrees of unbalance and misalignment are estimated by analyzing the components of the equivalent external loads of which the frequencies are equal to the 1 and 2 times running frequency respectively. The equivalent external loads are calculated according to the dynamic equation of the original rotor system and the differences between the dynamical responses in normal case and the vibrations when the degree of unbalance or misalignment or both changes. The denoise method based on bandpass filter is used to decrease the effect of noise on the estimation accuracy. The numerical examples are given to show that the proposed approach can estimate the degrees of unbalance and misalignment of the flexible coupling-rotor system accurately.
Advanced turbocharger rotor for variable geometry turbocharging systems
Stafford, R.J.; Mulloy, J.M.; Yonushonis, T.M.; Weber, H.G.; Patel, M.J. [Cummins Engine Co., Inc., Columbus, IN (United States)
1997-12-31
Turbocharging of diesel engines has enhanced fuel economy and reduced diesel engine emissions. The initial applications of turbochargers to heavy duty diesel engines during the early 1970`s reduced Bosch smoke (a measure of particulate matter used at the time) from 2.4 to 0.6 units. Current turbochargers are optimized at one set of engine conditions and by necessity, at the off-design conditions or transient conditions the fuel economy and emissions performance are penalized. A rotor was designed and a prototype fabricated which showed as much as a 10% efficiency improvement at off-design conditions. The leading edges are blunt and rounded to accept the flow from the turbine nozzles at a variety of inlet conditions with a minimum of losses. The rotor efficiency is better at all conditions and the advantage improves as it operates at conditions further from the design point. Unfortunately, the conventional materials from which this turbine rotor was constructed had inadequate strength to allow its use on engines, and had such high rotational inertia that transient response would have been severely compromised.
Higher harmonic control analysis for vibration reduction of helicopter rotor systems
Nguyen, Khanh Q.
1994-01-01
An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor
Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers
CAO DengQing; WANG LiGang; CHEN YuShu; HUANG WenHu
2009-01-01
To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy-namical equations of the rotor, with other equations of blades. In this way, the original system with 16+4n (n≥3) degrees of freedom (DoF) is reduced to a system with 24 DoF only. Then the parametric excitation terms in the blade-overhang rotor-SFD model are simplified in terms of periodic transforma-tions. The coupling equations are numerically solved and the solutions are used to analyze the dy-trum plot. A variety of motion types are found such as multi-periodic, quasi-periodic, and chaotic mo-tions. Moreover, the typical nonlinear dynamic evolutions including the periodic-doubling bifurcation and reverse bifurcation are noted. It is noticed that there exist apparent differences in the dynamic behavior between the blade-overhang rotor-SFD models without and with considering the effect of blades.
Bifurcation analysis of coupled lateral/torsional vibrations of rotor systems
Lee, Kyoung-Hyun; Han, Hyung-Suk; Park, Sungho
2017-01-01
This paper presents a numerical method to analyze the bifurcation of coupled lateral/torsional vibrations of rotor systems. Based on a Hamiltonian approach, a three degree-of-freedom dynamic model of a rotor is derived. Nonlinear ordinary differential equations are derived from the dynamic model. The stability of the equilibrium and linear normal modes (LNMs) are analyzed using a linearized matrix of the system equation. For bifurcation analysis of the periodic orbits, a nonlinear normal modes (NNMs) computation algorithm is performed using multiple shooting methods and pseudo-arclength continuation. Multiple shooting points are continued from LNMs near equilibrium, bifurcation points of the NNMs are detected from the stability change of the periodic orbits during the continuation. The proposed stability analysis, an NNMs computation of coupled lateral/torsional vibration, is demonstrated using two different rotor models: a system with strong eccentricity, and a system with weak eccentricity.
Dynamics analysis of a cracked dual-disk over-hung rotor-bearing system
CHEN Hong; LI He; ZHANG Xiao-wei; WEN Bang-chun
2006-01-01
A dynamic model of a dual-disk vertical over-hung rotor-bearing system is developed,taking into account nonlinear oil-film force.Its dynamic behaviors are investigated by numerical Runge-Kutta method.Its bifurcation and chaos characteristics are analyzed with crack fault and without crack fault.By analyzing the bifurcation plot,Poincare section plots and amplitude spectra,we found that the crack greatly influences the dynamic characteristics of the rotor-bearing system.Because of the strong effect of the nonlinear oil-film force and crack to the system,1/2 times,1/3 times frequency components appear in the response spectrum map.The results may bring up theoretical references for fault diagnosis of rotor-beating systems.
STUDY ON INFLUENCE OF BENDING-TORSION COUPLING IN AN IMPACTING-RUB ROTOR SYSTEM
孙政策; 徐健学; 周桐; 谭宁
2003-01-01
A mathematical model of an impacting-rub rotor system with bending-torsion coupling was established. It was compared with the model without bending-torsion coupling through the nodern nonlinear dynamic theory. It is observed that periodical, chaotic,period adding phenomena in them and the two models have a similar bifurcation process in their bifurcation figures. But the influence of bending-torsion on the dynmaic characteristics of the system is not neglected. The results have considerable meanings to analyze and improve the characteristics of an impacting-rub rotor system.
Actuators of active tribotechnical systems of the rotor-bearing type
Savin, L.; Shutin, D.; Kuzavka, A.
2017-08-01
The article describes the perspectives of using active bearings in rotor-bearing systems. The principal scheme of a mechatronic tribotechnical system anв classification of actuators used in such system are shown. Piezo actuators are considered from the point of view of use as actuators in active bearings. The comparative characteristics of different types of actuators
Ducted fan inlet/exit and rotor tip flow improvements for vertical lift systems
Akturk, Ali
The current research utilized experimental and computational techniques in 5" and 22" diameter ducted fan test systems that have been custom designed and manufactured. Qualitative investigation of flow around the ducted fan was also performed using smoke flow visualizations. Quantitative measurements consisted of 2D and 3D velocity measurements using planar and Stereoscopic Particle Image Velocimetry (PIV and SPIV), high resolution total pressure measurements using Kiel total pressure probes and real time six-component force and torque measurements. The computational techniques used in this thesis included a recently developed radial equilibrium based rotor model(REBRM) and a three dimensional Reynolds-Averaged Navier Stokes (RANS) based CFD model. A radial equilibrium based rotor model (REBRM) developed by the author was effectively integrated into a three-dimensional RANS based computational system. The PIV measurements and computational flow predictions using (REBRM) near the fan inlet plane were in a good agreement at hover and forward flight conditions. The aerodynamic modifications resulting from the fan inlet flow distortions in forward flight regime were clearly captured in 2D PIV results. High resolution total pressure measurements at the downstream of the fan rotor showed that tip leakage, rotor hub separation, and passage flow related total pressure losses were dominant in hover condition. However, the losses were dramatically increased in forward flight because of inlet lip separation and distortion. A novel ducted fan inlet flow conditioning concept named "Double Ducted Fan" (DDF) was developed. The (DDF) concept has a potential to significantly improve the performance and controllability of VTOL UAVs and many other ducted fan based vertical lift systems. The new concept that will significantly reduce the inlet lip separation related performance penalties used a secondary stationary duct system to control "inlet lip separation" occurring especially at
黄晓东; 王卫卫; 蒋玮光
2012-01-01
直升机旋翼系统是直升机的核心部件,弹性轴承将桨叶与桨毂相连,提供桨叶的挥舞、摆振和变距自由度,刚度特性是其主要的力学性能.通过采用松紧螺套驱动半圆形夹具转动来测试弹性轴承压缩、扭转和弯曲刚度特性,结果表明该试验方法新颖独特,具有一定的通用性,能准确判定弹性轴承是否合格,可为不同机型的弹性轴承提供装机前试验的方法.%Rotor system is the core component of the helicopter, flexible blade with the spherical thrust bearing connected to provide the wielding, shimmy and pitch degrees of freedom, the stiffness characteristics is one of the main mechanical properties. Test the spherical thrust bearing compression, torsion and bending stiffness characteristics by twisting the screw to drive the semicircular fixture. These results indicated that the test method is distinctive and general. It can accurately determine whether the spherical thrust bearing is qualified and provide a test before installing for different type of spherical thrust bearings.
Xiaoyan Ye
2014-05-01
Full Text Available In order to study the water lubricated bearing-rotor system in seawater desalination pump, this paper is based on the coupling between the lubricating flow field and the rotor dynamics. The fluid-solid interaction (FSI method, Rigid Body, was adopted to study the journal orbit of the bearing-rotor system under the periodic unbalancing load. The influences of geometric and working parameter to the journal orbit were combined to analyze the stability and reliability of the bearing-rotor system. The result shows that increasing the rotating speed would increase the journal whirling amplitude and the system sensitivity to the external excitation and unbalancing load were promoted; increasing the aspect ratio would reduce the journal whirling amplitude and cause the system to be more unstable; increasing the inlet pressure would reduce the journal whirling amplitude and cause the system to be more unstable; increasing the unbalancing load would reduce the stability margin and the system is easy to be unstable if obstructed; increasing the radial clearance would reduce the journal whirling amplitude and cause the system to be more unstable. The attitude angle has no influence on the journal whirling amplitude but would influence the stability of system and the value of attitude angle should not be large.
Arbab Nighat Khizer
2015-01-01
Full Text Available This paper presents a time-domain approach for identification of longitudinal dynamics of single rotor model helicopter. A frequency sweep excitation input signal is applied for hover flying mode widely used for space state linearized model. A fully automated programmed flight test method provides high quality flight data for system identification using the computer controlled flight simulator X-plane©. The flight test data were recorded, analyzed and reduced using the SIDPAC (System Identification Programs for Air Craft toolbox for MATLAB, resulting in an aerodynamic model of single rotor helicopter. Finally, the identified model of single rotor helicopter is validated on Raptor 30-class model helicopter at hover showing the reliability of proposed approach
Instantaneous Purified Orbit: A New Tool for Analysis of Nonstationary Vibration of Rotor System
Shi Dongfeng
2001-01-01
Full Text Available In some circumstances, vibration signals of large rotating machinery possess time-varying characteristics to some extent. Traditional diagnosis methods, such as FFT spectrum and orbit diagram, are confronted with a huge challenge to deal with this problem. This work aims at studying the four intrinsic drawbacks of conventional vibration signal processing method and instantaneous purified orbit (IPO on the basis of improved Fourier spectrum (IFS to analyze nonstationary vibration. On account of integration, the benefits of short period Fourier transform (SPFT and regular holospectrum, this method can intuitively reflect vibration characteristics of’a rotor system by means of parameter analysis for corresponding frequency ellipses. Practical examples, such as transient vibration in run-up stages and bistable condition of rotor show that IPO is a powerful tool for diagnosis and analysis of the vibration behavior of rotor systems.
Flywheel Rotor Safe-Life Technology
Ratner, J. K. H.; Chang, J. B.; Christopher, D. A.; McLallin, Kerry L. (Technical Monitor)
2002-01-01
Since the 1960s, research has been conducted into the use of flywheels as energy storage systems. The-proposed applications include energy storage for hybrid and electric automobiles, attitude control and energy storage for satellites, and uninterruptible power supplies for hospitals and computer centers. For many years, however, the use of flywheels for space applications was restricted by the total weight of a system employing a metal rotor. With recent technological advances in the manufacturing of composite materials, however, lightweight composite rotors have begun to be proposed for such applications. Flywheels with composite rotors provide much higher power and energy storage capabilities than conventional chemical batteries. However, the failure of a high speed flywheel rotor could be a catastrophic event. For this reason, flywheel rotors are classified by the NASA Fracture Control Requirements Standard as fracture critical parts. Currently, there is no industry standard to certify a composite rotor for safe and reliable operation forth( required lifetime of the flywheel. Technical problems hindering the development of this standard include composite manufacturing inconsistencies, insufficient nondestructive evaluation (NDE) techniques for detecting defects and/or impact damage, lack of standard material test methods for characterizing composite rotor design allowables, and no unified proof (over-spin) test for flight rotors. As part of a flywheel rotor safe-life certification pro-ram funded b the government, a review of the state of the art in composite rotors is in progress. The goal of the review is to provide a clear picture of composite flywheel rotor technologies. The literature review has concentrated on the following topics concerning composites and composite rotors: durability (fatigue) and damage tolerance (safe-life) analysis/test methods, in-service NDE and health monitoring techniques, spin test methods/ procedures, and containment options
A comprehensive vibration analysis of a coupled rotor/fuselage system
Yeo, Hyeonsoo
A comprehensive vibration analysis of a coupled rotor/fuselage system for a two-bladed teetering rotor using finite element methods in space and time is developed which incorporates consistent rotor/fuselage structural, aerodynamic, and inertial couplings and a modern free wake model. A coordinate system is developed to take into account a teetering rotor's unique characteristics, such as teetering motion and undersling. Coupled nonlinear periodic blade and fuselage equations are transformed to the modal space in the fixed frame and solved simultaneously. The elastic line and detailed 3-D NASTRAN finite element models of the AH-1G helicopter airframe from the DAMVIBS program are integrated into the elastic rotor finite element model. Analytical predictions of rotor control angles, blade loads, hub forces, and vibration are compared with AH-1G Operation Load Survey flight test data. The blade loads predicted by present analysis show generally fair agreement with the flight test data, especially blade chord bending moment estimation shows good agreement. Calculated 2/rev vertical vibration levels at pilot seat show good correlation with the flight test data both in magnitude and phase, but 4/rev vibration levels show fair correlation only in magnitude. Lateral vibration results show more disagreement than vertical vibration results. Pylon flexibility effect is essential in the two-bladed teetering rotor vibration analysis. The pylon flexibility increases the first lag frequency by about 14%, and decreases 2/rev longitudinal and lateral hub forces by more than half. Rotor/fuselage coupling reduces 2/rev vertical and lateral vibration levels by 60% to 70% and has a small effect on 4/rev vibration levels. Modeling of difficult components (secondary structures, doors/panels, etc) is essential in predicting airframe natural frequencies. Refined aerodynamics such as free wake and unsteady aerodynamics have an important role in the prediction of vibration. For example, free
RESEARCH OF DYNAMIC PARAMETERS OF THE ELECTRIC DRIVE ON THE BASIS OF ROLLING ROTOR MOTOR
G. V. Kulinchenko
2016-12-01
Full Text Available Purpose. Development and investigation of a dynamic model of electric drive on the base of the rolling rotor motor (RRM which reflects the positioning of the actuator of the locking and regulating equipment in time. Methodology. Analytical description of electromagnetic and mechanical processes in the electric drive during the RRM shaft movement by using a system of differential equations. Numerical imitation modeling with the processes visualization in the Matlab environment of the RRM rotor displacement with mechanical load in time. Results. It is shown that the degree of influence of the value of the load inertia on the dynamics of the object obtained by the waveform changes the rotation angle of the rotor and motor speed in time. The degree of influence of the value of the electromagnetic time constant of the dynamics of the positioning of the actuator, and the nature of transients during acceleration and fixing position of the rotor with a predetermined moment of inertia for different values of inductance. The effect of the ratio of electromechanical and electromagnetic time constants of the nature of the transition processes accompanying jog mode angular displacement of the drive shaft on the base of RRM. Originality. The lack of technical means to ensure acceptable accuracy time measurement of angular displacement shaft of the actuator in jog mode offset by using a laser meter which gives the opportunity to assess the adequacy of the dynamic model of the RRM. Practical value. The results of investigations allow to create a tool for optimization of structural, technical and hardware and software solutions for the improvement and modernization of the projected electric locking and regulating equipment. The direction for improving the dynamics of the drive on the basis of RRM is indicated providing for an increase in its torque characteristics of the motor by reducing the influence of the parameters of transients.
Influence of the Mechanical Seals on the Dynamic Performance of Rotor-Bearing Systems
XU Hua; ZHU Jun
2006-01-01
In this Paper,to consider the effects of mechanical seals.a lumped-mass modeJ and the transfer matric method are used to establish the equations for the dynamics performance of rotor-bearing system.The general inverted iteration method is also used to solve the eigenvalue problem of these equations.To check the response of the rotorbearing system under unbalance motivation,the Gauss method is used to calculate the dynamic response of the constrained vibration.The results,based on the dynamic properties calculation of a typical mechanical spiral seal,such as stiffness coefficients and damping coefficients.exert the influence of the mechanical seal on the rotorbeating system of the high-speed machinery.Meanwhile,some structure parameters that may affect the dynamic performance and forced vibration under unbalance motiVation of the rotor-bearing system considering mechanical seals are analyzed in the Paper.The analysis results show that the mechanical seal more or less has effects on the rotor-bearing system.The mechanical seal has much more effects on the flexible rotor-bearing system than on the rigid one.For instance,in a certain case,ifthe effects of the mechanical seal were taken into account,the system's critical speed may increase by 70-80%.
Innovative multi rotor wind turbine designs
Kale, S.A.; Sapali, S.N. [College of Engineering. Mechanical Engineering Dept, Pune (India)
2012-07-01
Among the renewable energy sources, today wind energy is the most recognized and cost effective. Developers and researchers in this sector are optimistic and continuously working innovatively to improve the technology. The wind power obtained is proportional to the swept area of wind turbine. The swept area is increased by using a single rotor of large diameter or multi rotors in array. The rotor size is growing continuously with mature technology. Multi rotor technology has a long history and the multi rotor concept persists in a variety of modern innovative systems but the concept has fallen out of consideration in mainstream design from the perception that is complex and unnecessary as very large single rotor units are now technically feasible. This work addresses the evaluation of different multi rotor wind turbine systems. These innovative wind turbines are evaluated on the basis of feasibility, technological advantages, security of expected power performance, cost, reliability, impact of innovative system, comparison with existing wind turbine design. The findings of this work will provide guidelines for the practical and economical ways for further research on the multi rotor wind turbines. (Author)
Instability analysis procedure for 3-level multi-bearing rotor-foundation systems
Zhou, S.; Rieger, N. F.
1985-01-01
A procedure for the instability analysis of a three-level multispan rotor systems is described. This procedure is based on a distributed mass elastic representation of the rotor system in several eight-coefficient bearings. Each bearing is supported from an elastic foundation on damped, elastic pedestals. The foundation is represented as a general distributed mass elastic structure on discrete supports, which may have different stiffness and damping properties in the horizontal and vertical directions. This system model is suited to studies of instability threshold conditions for multirotor turbomachines on either massive or flexible foundations. The instability conditions is found by obtaining the eigenvalues of the system determinant, which is obtained by the transfer matrix method from the three-level system model. The stability determinant is solved for the lowest rotational speed at which the system damping becomes zero in the complex eigenvalue, and for the whirl frequency corresponding to the natural frequency of the unstable mode. An efficient algorithm for achieving this is described. Application of this procedure to a rigid rotor in two damped-elastic bearings and flexible supports is described. A second example discusses a flexible rotor with four damped-elastic bearings. The third case compares the stability of a six-bearing 300 Mw turbine generator unit, using two different bearing types. These applications validate the computer program and various aspects of the analysis.
Frankenstein, B.; Froehlich, K.J.; Lieske, U.; Schuber, L. [Fraunhofer Institut Zerstoerungsfreie Pruefverfahren (IZFP), Institutsteil Dresden (Germany)
2007-07-01
The Fraunhofer Institute of Non-Destructive Testing Dresden (IzfP-D) uses condition monitoring systems, which by permanent monitoring e.g. of wind rotors, aircraft components, or pipelines are to ensure high availability of the object. This way, damage (e.g. crack initiation and propagation, delamination) can be detected early, and early repair measures will lengthen the life of the components and reduce standstill times during repair. Guided elastic waves are used for wind rotor monitoring, which are induced by piezo fibre converters. The contribution describes the method and measuring instrumentation for generation and detection of acoustic waves in composite materials. The focus is on static load tests of rotor blades, of which the status and trends are presented. (orig.)
Studies on dynamic characteristics of the joint in the aero-engine rotor system
Shuguo, Liu; Yanhong, Ma; Dayi, Zhang; Jie, Hong
2012-05-01
The joint as a major part of the aero-engine rotating shafts directly influences its rotordynamics and state stability. This paper studies the dynamic effects of structure parameters and the external load on the stiffness and contact state of the rotor joints with nonlinear finite-element method and experiments. And a sensitivity analysis of critical speeds and vibration modes with respect to typical parameters (stiffness of the spline joints) is performed with finite difference methods, through two approaches, i.e. relative sensitivity analysis and absolute sensitivity analysis. The study results show that the stiffness and contact state of joints vary with external loads and geometry structures, and affect the rotor system operating. It is advisable to consider the influence of the position, structural parameter and external load of the rotor joints on aero-engine structure dynamics design.
Design study of a feedback control system for the Multicyclic Flap System rotor (MFS)
Weisbrich, R.; Perley, R.; Howes, H.
1977-01-01
The feasibility of automatically providing higher harmonic control to a deflectable control flap at the tip of a helicopter rotor blade through feedback of selected independent parameter was investigated. Control parameters were selected for input to the feedback system. A preliminary circuit was designed to condition the selected parameters, weigh limiting factors, and provide a proper output signal to the multi-cyclic control actuators. Results indicate that feedback control for the higher harmonic is feasible; however, design for a flight system requires an extension of the present analysis which was done for one flight condition - 120 kts, 11,500 lbs gross weight and level flight.
Control system design for flexible rotors supported by actively lubricated bearings
Nicoletti, Rodrigo; Santos, Ilmar
2008-01-01
This article presents a methodology for calculating the gains of an output feedback controller for active vibration control of flexible rotors. The methodology is based on modal reduction. The proportional and derivative gains are obtained by adjusting the first two damping factors of the system...... and keeping the lengths of the two eigenvalues constant in the real-imaginary plane. The methodology is applied to an industrial gas compressor supported by active tilting-pad journal bearings. The unbalance response functions and mode shapes of the flexible rotor with and without active control are presented...
Detection of a fatigue crack in a rotor system using full-spectrum based estimation
C Shravankumar; Rajiv Tiwari
2016-02-01
The force due to crack switching has multiple harmonic components of the spin speed. These components excite the rotor both in the same and reverse directions of the rotor spin. A full-spectrum method using complex Fast Fourier transform equations is developed to obtain force coefficients and displacement coefficients (forward and reverse). These coefficients are then used as an input to developed identification algorithms. Fault parameters identified are the additive stiffness due to crack, disc eccentricity due to unbalance, and system viscous damping. An extended algorithm estimates the crack forces. The algorithms are numerically tested.
NONLINEAR DYNAMIC CHARACTERISTICS OF HYDRODYNAMIC JOURNAL BEARING-FLEXIBLE ROTOR SYSTEM
Lu Yanjun; Yu Lie; Liu Heng
2005-01-01
The nonlinear dynamic behaviors of flexible rotor system with hydrodynamic bearing supports are analyzed. The shaft is modeled by using the finite element method that takes the effect of inertia and shear into consideration. According to the nonlinearity of the hydrodynamic journal bearing-flexible rotor system, a modified modal synthesis technique with free-interface is represented to reduce degrees-of-freedom of model of the flexible rotor system. According to physical character of oil film, variational constrain approach is introduced to continuously revise the variational form of Reynolds equation at every step of dynamic integration and iteration. Fluid lubrication problem with Reynolds boundary is solved by the isoparametric finite element method without the increasing of computing efforts. Nonlinear oil film forces and their Jacobians are simultaneously calculated and -Newton-Floquet (PNF) method. A method, combining the predictor-corrector mechanism to the PNF method, is presented to calculate the bifurcation point of periodic motions to be subject to change of system parameters. The local stability and bifurcation behaviors of periodic motions are obtained by Floquet theory. The chaotic motions of the beating-rotor system are investigated by power spectrum.The numerical examples show that the scheme of this study saves computing efforts but also is of good precision.
Open Rotor - Analysis of Diagnostic Data
Envia, Edmane
2011-01-01
NASA is researching open rotor propulsion as part of its technology research and development plan for addressing the subsonic transport aircraft noise, emission and fuel burn goals. The low-speed wind tunnel test for investigating the aerodynamic and acoustic performance of a benchmark blade set at the approach and takeoff conditions has recently concluded. A high-speed wind tunnel diagnostic test campaign has begun to investigate the performance of this benchmark open rotor blade set at the cruise condition. Databases from both speed regimes will comprise a comprehensive collection of benchmark open rotor data for use in assessing/validating aerodynamic and noise prediction tools (component & system level) as well as providing insights into the physics of open rotors to help guide the development of quieter open rotors.
An identification method for damping ratio in rotor systems
Wang, Weimin; Li, Qihang; Gao, Jinji; Yao, Jianfei; Allaire, Paul
2016-02-01
Centrifugal compressor testing with magnetic bearing excitations is the last step to assure the compressor rotordynamic stability in the designed operating conditions. To meet the challenges of stability evaluation, a new method combining the rational polynomials method (RPM) with the weighted instrumental variables (WIV) estimator to fit the directional frequency response function (dFRF) is presented. Numerical simulation results show that the method suggested in this paper can identify the damping ratio of the first forward and backward modes with high accuracy, even in a severe noise environment. Experimental tests were conducted to study the effect of different bearing configurations on the stability of rotor. Furthermore, two example centrifugal compressors (a nine-stage straight-through and a six-stage back-to-back) were employed to verify the feasibility of identification method in industrial configurations as well.
Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems
Christensen, Rene Hardam; Santos, Ilmar
2003-01-01
In rotor-blade systems basis as well as parametric vibration modes will appear due to the vibration coupling among flexible rotating blades and hub rigid body motion. Parametric vibration will typically occur when the hub operates at a constant angular velocity. Operating at constant velocity...
A novel identification method of Volterra series in rotor-bearing system for fault diagnosis
Xia, Xin; Zhou, Jianzhong; Xiao, Jian; Xiao, Han
2016-01-01
Volterra series is widely employed in the fault diagnosis of rotor-bearing system to prevent dangerous accidents and improve economic efficiency. The identification of the Volterra series involves the infinite-solution problems which is caused by the periodic characteristic of the excitation signal of rotor-bearing system. But this problem has not been considered in the current identification methods of the Volterra series. In this paper, a key kernels-PSO (KK-PSO) method is proposed for Volterra series identification. Instead of identifying the Volterra series directly, the key kernels of Volterra are found out to simply the Volterra model firstly. Then, the Volterra series with the simplest formation is identified by the PSO method. Next, simulation verification is utilized to verify the feasibility and effectiveness of the KK-PSO method by comparison to the least square (LS) method and traditional PSO method. Finally, experimental tests have been done to get the Volterra series of a rotor-bearing test rig in different states, and a fault diagnosis system is built with a neural network to classify different fault conditions by the kernels of the Volterra series. The analysis results indicate that the KK-PSO method performs good capability on the identification of Volterra series of rotor-bearing system, and the proposed method can further improve the accuracy of fault diagnosis.
Vibration transmission through rolling element bearings. Part III: Geared rotor system studies
Lim, T. C.; Singh, R.
1991-11-01
This paper extends the proposed bearing matrix formulation of Parts I and II to analyze the overall dynamics of a geared rotor system which includes a spur gear pair, shafts, rolling element bearing, a prime mover and a load (attached to the geared rotor system through flexible torsional couplings), a rigid or flexible casing, and compliant or massive mounts. Linear time-invariant, discrete dynamic models of a generic geared rotor system with proportional viscous damping are developed, by using lumped parameter and dynamic finite element techniques, which are then used to predict the vibration transmissibility through bearings and mounts, casing vibration motion, and dynamic response of the internal rotating system. Each rotating shaft is modeled as an Euler beam in the lumped parameter model and as a Timoshenko beam in the dynamic finite element model, but the gyroscopic moment is not included. Eigensolution and forced harmonic response studies due to rotating mass unbalance or kinematic transmission error excitation for the following example cases are obtained by using the formulation, and the results are compared with those of simple models currently available in the literature and/or experiment: case I, a single-stage rotor system with flexibly mounted rigid casing consisting of two bearings as a special case of the geared rotor system; case II, a spur gear pair drive supported by four bearings installed in a flexibly mounted rigid casing; and case III, an experimental set-up consisting of a high-precision gear and pinion, and four identical rolling element bearings contained in a flexible casing mounted rigidly on a massive foundation. Analytical predictions show that the theory is indeed capable of predicting bearing and mount moment transmissibilities in addition to the force transmissibilities. Also, flexural vibrations of the casing plate are predicted well as the theory is in good agreement with measurements made on case III; such predictions are not
Neural Network Control of a Magnetically Suspended Rotor System
Choi, Benjamin B.
1998-01-01
Magnetic bearings offer significant advantages because they do not come into contact with other parts during operation, which can reduce maintenance. Higher speeds, no friction, no lubrication, weight reduction, precise position control, and active damping make them far superior to conventional contact bearings. However, there are technical barriers that limit the application of this technology in industry. One of them is the need for a nonlinear controller that can overcome the system nonlinearity and uncertainty inherent in magnetic bearings. At the NASA Lewis Research Center, a neural network was selected as a nonlinear controller because it generates a neural model without any detailed information regarding the internal working of the magnetic bearing system. It can be used even for systems that are too complex for an accurate system model to be derived. A feed-forward architecture with a back-propagation learning algorithm was selected because of its proven performance, accuracy, and relatively easy implementation.
Nonlinear Vibration Induced by the Water-film Whirl and Whip in a Sliding Bearing Rotor System
ZHAI Liming; LUO Yongyao; WANG Zhengwei; KITAUCHI Seishiro; MIYAGAWA Kazuyoshi
2016-01-01
Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips have attracted many studies while the water-film whips in the water lubricated sliding bearing have been little researched with the mechanism still an open problem. The dynamic fluid film forces in a water sliding bearing are investigated numerically with rotational, whirling and squeezing motions of the journal using a nonlinear model to identify the relationships between the three motions. Rotor speed-up and slow-down experiments are then conducted with the rotor system supported by a water lubricated sliding bearing to induce the water-film whirl/whip and verify the relationship. The experimental results show that the vibrations of the journal alternated between increasing and decreasing rather than continuously increasing as the rotational speed increased to twice the first critical speed, which can be explained well by the nonlinear model. The radial growth rate of the whirl motion greatly affects the whirl frequency of the journal and is responsible for the frequency lock in the water-film whip. Further analysis shows that increasing the lubricating water flow rate changes the water-film whirl/whip characteristics, reduces the first critical speed, advances the time when significant water-film whirling motion occurs, and also increases the vibration amplitude at the bearing center which may lead to the rotor-stator rub-impact. The study gives the insight into the water-film whirl and whip in the water lubricated sliding bearing.
Nonlinear vibration induced by the water-film whirl and whip in a sliding bearing rotor system
Zhai, Liming; Luo, Yongyao; Wang, Zhengwei; Kitauchi, Seishiro; Miyagawa, Kazuyoshi
2016-03-01
Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips have attracted many studies while the water-film whips in the water lubricated sliding bearing have been little researched with the mechanism still an open problem. The dynamic fluid film forces in a water sliding bearing are investigated numerically with rotational, whirling and squeezing motions of the journal using a nonlinear model to identify the relationships between the three motions. Rotor speed-up and slow-down experiments are then conducted with the rotor system supported by a water lubricated sliding bearing to induce the water-film whirl/whip and verify the relationship. The experimental results show that the vibrations of the journal alternated between increasing and decreasing rather than continuously increasing as the rotational speed increased to twice the first critical speed, which can be explained well by the nonlinear model. The radial growth rate of the whirl motion greatly affects the whirl frequency of the journal and is responsible for the frequency lock in the water-film whip. Further analysis shows that increasing the lubricating water flow rate changes the water-film whirl/whip characteristics, reduces the first critical speed, advances the time when significant water-film whirling motion occurs, and also increases the vibration amplitude at the bearing center which may lead to the rotor-stator rub-impact. The study gives the insight into the water-film whirl and whip in the water lubricated sliding bearing.
Silva Navarro, Gerardo; Cabrera Amado, Alvaro [Cinvestav, IPN, Mexico, D.F. (Mexico)
2007-11-15
This paper deals with the problem of semiactive balancing control of a rotor-bearing system, where one journal bearings is supported on two radial Magneto-Rheological (MR) dampers. The mathematical model of the rotor-bearing system results from an orthotropic Jeffcott-like model and the dynamics associated to the MR dampers, whose rheological properties depend on the current inputs. For control purposes we use the Choi-Lee-Park polynomial for the MR dampers, which is quite consistent with the tpical nonlinear and complex hysteresis behavior and also simplifies the physical implementation on an experimental setup. The semiactive control scheme for the unbalance reponse of the rotor-bearing system is synthesized using sliding-mode control techniques. Some numerical and experimental results are included to illustrate the dynamic performance and robustness of the overall system. [Spanish] En este trabajo se abora el problema de control semiactivo del desbalance en un sistema rotor-chumacera, donde una de las chumaceras convencionales se monta sobre una suspension con dos amortiguadores Magneto-Reologicos (MR) radiales. El modelo matematico del sistema rotorchumacera se obtiene de un modelo tipo Jefcott ortotropico y la dinamica de los amortiguadores MR, cuyas propiedades reologicas dependen de las corrientes electricas de alimentacion. Para propositos de control se emplea el modelo polinomial de Choi-Lee-Park para los dos amortiguadores MR, el cual es consistente con el tipico comportamiento no-lineal y de histeresis, permitiendo simplificar su implementacion fisica en una plataforma experimental. El esquema de control semiactivo de la respuesta al desbalance, en el sistema rotor-chumacera, se basa en las tecnicas de control por modos deslizantes. Se presentan algunos resultados de simulacion numerica y experimentos que utilizan el funcionamiento y robustez del sistema completo.
Active Vibration Control in a Rotor System by an Active Suspension with Linear Actuators
M. Arias-Montiel
2014-10-01
Full Text Available In this paper the problem of modeling, analysis and unbalance response control of a rotor system with two disks in an asymmetrical configuration is treated. The Finite Element Method (FEM is used to get the system model including the gyroscopic effects and then, the obtained model is experimentally validated. Rotordynamic analysis is carried out using the finite element model obtaining the Campbell diagram, the natural frequencies and the critical speeds of the rotor system. An asymptotic observer is designed to estimate the full state vector which is used to synthesize a Linear Quadratic Regulator (LQR to reduce the vibration amplitudes when the system passes through the first critical speed. Some numerical simulations are carried out to verify the closed-loop system behavior. The active vibration control scheme is experimentally validated using an active suspension with electromechanical linear actuators, obtaining significant reductions in the resonant peak.
Ghasemalizadeh, Omid; Sadeghi, Hossein; Ahmadian, Mohammad Taghi
2013-01-01
One of the methods to find the natural frequencies of rotating systems is the application of the transfer matrix method. In this method the rotor is modeled as several elements along the shaft which have their own mass and moment of inertia. Using these elements, the entire continuous system is discretized and the corresponding differential equation can be stated in matrix form. The bearings at the end of the shaft are modeled as equivalent spring and dampers which are applied as boundary conditions to the discretized system. In this paper the dynamics of a rotor-bearing system is analyzed, considering the gyroscopic effect. The thickness of the disk and bearings is also taken into account. Continuous model is used for shaft. Results Show that, the stiffness of the shaft and the natural frequencies of the system increase, while the amplitude of vibration decreases as a consequence of increasing the thickness of the bearing.
Constrained Balancing of Two Industrial Rotor Systems: Least Squares and Min-Max Approaches
Bin Huang
2009-01-01
Full Text Available Rotor vibrations caused by rotor mass unbalance distributions are a major source of maintenance problems in high-speed rotating machinery. Minimizing this vibration by balancing under practical constraints is quite important to industry. This paper considers balancing of two large industrial rotor systems by constrained least squares and min-max balancing methods. In current industrial practice, the weighted least squares method has been utilized to minimize rotor vibrations for many years. One of its disadvantages is that it cannot guarantee that the maximum value of vibration is below a specified value. To achieve better balancing performance, the min-max balancing method utilizing the Second Order Cone Programming (SOCP with the maximum correction weight constraint, the maximum residual response constraint as well as the weight splitting constraint has been utilized for effective balancing. The min-max balancing method can guarantee a maximum residual vibration value below an optimum value and is shown by simulation to significantly outperform the weighted least squares method.
Counteracting Rotor Imbalance in a Bearingless Motor System with Feedforward Control
Kascak, Peter Eugene; Jansen, Ralph H.; Dever, Timothy; Nagorny, Aleksandr; Loparo, Kenneth
2012-01-01
In standard motor applications, traditional mechanical bearings represent the most economical approach to rotor suspension. However, in certain high performance applications, rotor suspension without bearing contact is either required or highly beneficial. Such applications include very high speed, extreme environment, or limited maintenance access applications. This paper extends upon a novel bearingless motor concept, in which full five-axis levitation and rotation of the rotor is achieved using two motors with opposing conical air-gaps. By leaving the motors' pole-pairs unconnected, different d-axis flux in each pole-pair is created, generating a flux imbalance which creates lateral force. Note this is approach is different than that used in previous bearingless motors, which use separate windings for levitation and rotation. This paper will examine the use of feedforward control to counteract synchronous whirl caused by rotor imbalance. Experimental results will be presented showing the performance of a prototype bearingless system, which was sized for a high speed flywheel energy storage application, with and without feedforward control.
Development of a rotor alloy for advanced ultra super critical turbine power generation system
Miyashita, Shigekazu; Yamada, Masayuki; Suga, Takeo; Imai, Kiyoshi; Nemoto, Kuniyoshi; Yoshioka, Youmei [Toshiba Corporation, Yokohama (Japan)
2008-07-01
A Ni-based superalloy ''TOS1X'', for the rotor material of the 700 class advanced ultra super critical (A-USC) turbine power generation system was developed. TOS1X is an alloy that is improved in the creep rupture strength of Inconel trademark 617 maintaining both forgeability and weldability. The 7 t weight model rotor made of TOS1X was manufactured by double melt process, vacuum induction melting and electro slag remelting, and forging. During forging process, forging cracks and any other abnormalities were not detected on the ingots. The metallurgical and the mechanical properties in this rotor were investigated. Macro and micro structure observation, and some mechanical tests were conducted. According to the metallurgical structure investigation, there was no remarkable segregation in whole area and the forging effect was reached in the center part of the rotor ingot. The results of tensile test and creep rupture test proved that proof stress and tensile stress of the TOS1X are higher than those of Inconel trademark 617 and creep rupture strength of TOS1X is much superior than that of Inconel trademark 617. (orig.)
Rotordynamic Modelling and Response Characteristics of an Active Magnetic Bearing Rotor System
Free, April M.; Flowers, George T.; Trent, Victor S.
1996-01-01
Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied. These results are presented and discussed.
Modeling and control of a flexible rotor system with AMB-based sustentation.
Arredondo, I; Jugo, J; Etxebarria, V
2008-01-01
In this work the modeling and basic control design process of a rotary flexible spindle hovered by Active Magnetic Bearings (AMB) whose good capabilities for machine-tool industry extensively treated in the literature is presented. The modeling takes into account the three main behavioral characteristics of such magnetically-levitated rotor: the rigid dynamics, the flexible dynamics and the rotating unbalanced motion. Besides, the gyroscopic coupling is also studied proving that in this case, its effects are not significant and can be neglected. Using this model, a stabilizing controller based on symmetry properties is successfully designed for the system and a complete experimental analysis of its performance is carried out. Also, the predictions of the model are compared with the actual measured experimental results on a laboratory set-up based on the MBC500 Rotor Dynamics. Afterwards, a brief study about some nonlinear behavior observed in the system and its effect over the system stability at the critical speed is included.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor Blade Systems
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
The demands for high efficiency machines initiate a demand for monitoring and active control of vibrations to improve machinery performance and to prolong machinery lifetime. Applying active control to reduce vibrations in flexible bladed rotor-systems imply that several difficulties have...... of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step...... to be overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures...
Wang Liqin; Cui Li; Zheng Dezhi; Gu Le
2008-01-01
A rotor system supported by roller bearings displays very complicated nonlinear behaviors due to nonlinear Hertzian contact forces, radial clearances and bearing waviness. This paper presents nonlinear bearing forces of a roller bearing under four-dimensional loads and establishes 4-DOF dynamics equations of a rotor roller bearing system. The methods of Newmark-β and of Newton-Laphson are used to solve the nonlinear equations. The dynamics behaviors of a rigid rotor system are studied through the bifurcation, the Poincar bility caused by the quasi-periodic bifurcation, the periodic-doubling bifurcation and chaos routes as the rotational speed increases.Clearances, outer race waviness, inner race waviness, roller waviness, damping, radial forces and unbalanced forces-all these bring a significant influence to bear on the system stability. As the clearance increases, the dynamics behaviors become complicated with the number and the scale of instable regions becoming larger. The vibration frequencies induced by the roller bearing waviness and the orders of the waviness might cause severe vibrations. The system is able to eliminate non-periodic vibration by reasonable choice and optimization of the parameters.
DONG Guo-qing; CUI Ya-hui; WANG Zhong-ren; LIU Zhan-sheng; SHEN Ji-quan
2008-01-01
To study the misalignment of gear coupling, this paper analyzed the distortion of the tooth of gear coupling on the base of gear coupling's motion under parallel misalignment, and derived the specific expression of additive radial force, which produced by the rotor' torque. The motion differential equations of the large in-creased pressure wind tunnel rotor-gear coupling system were derived by the finite element method. Newmark integral method was applied to calculate the dynamic response of the system with parallel misalignment. The nu-merical results show that: under the effect of additive radial force, the static misalignment can arouse 2X fre-quency component lateral vibration; the dynamic misalignment can arouse2X,4X,6X multiple frequency compo-nents lateral vibration. The 2X frequency component is obvious. The additive radial force of the gear coupling can arouse lateral vibration with even multiple frequency components.
Control Methods Using Cross-Coupling Effects for Suppression of Rotor/Stator Rubbing System
Shang Zhiyong
2015-01-01
Full Text Available This paper investigated the influence of cross-coupling effects on the rubbing-related dynamics of rotor/stator systems, The stability analysis on the synchronous full annular rub solution of a rotor/stator system, which includes both the dynamics of the stator and the deformation on the contact surface as well as the cross-coupling terms in velocities and displacements, is carried out. It is found that some cross-coupling effects will benefit the synchronous full annular rubs and some will not. Based on the finding, a control method by generating cross-coupling damping on the stator through the active auxiliary bearing is then proposed in order to suppress the contact severity and avoid the rubbing instability. Numerical simulation shows the validity of the mehtod.
Dynamic Analysis of a Rotor-Bearing-SFD System with the Bearing Inner Race Defect
Junhong Zhang
2017-01-01
Full Text Available In this paper, the dynamic behavior of a rotor-bearing-SFD system with the inner race defect of bearing is investigated. The contact force between the rolling element and the race is calculated in Hertzian contact and elastohydrodynamic lubrication condition. The supporting force of the SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion of the rotor-bearing-SFD system are derived and solved using the fourth-order Runge-Kutta method. The dynamic behavior and the fault characteristics are analyzed with two configurations of the SFD: (1 mounted on the unfaulted bearing and (2 mounted on the faulty bearing. According to the analysis of time-frequency diagram, waterfall plot, and spectral diagram, the results show that the characteristics of inner race defects on bearing frequencies are related to the characteristic multiple frequency of the inner race defect and the fundamental frequency. The speed and defect width have different influence on the distribution and amplitude of frequency. The SFD can enhance the system stability under the bearing fault but the enhancement decreases with the increasing speed. Meanwhile, the beneficial effect of the SFD varies according to the mounted position in the rotor system.
Dynamic Analysis of a Hybrid Squeeze Film Damper Mounted Rub-Impact Rotor-Stator System
Cai-Wan Chang-Jian
2012-01-01
Full Text Available An investigation is carried out on the systematic analysis of the dynamic behavior of the hybrid squeeze-film damper (HSFD mounted a rotor-bearing system with strongly nonlinear oil-film force and nonlinear rub-impact force in the present study. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless rotating speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, bifurcation diagrams, maximum Lyapunov exponents, and fractal dimension of the rotor-bearing system. The dynamic behaviors are unlike the usual ways into chaos (1⇒2⇒4⇒8⇒16⇒32⋯⇒ chaos or periodic ⇒ quasi-periodic ⇒ chaotic, it suddenly gets in chaos from the periodic motion without any transition. The results presented in this study provide some useful insights into the design and development of a rotor-bearing system for rotating machinery that operates in highly rotating speed and highly nonlinear regimes.
Xiaoli Qiao; Guojun Hu
2017-01-01
The unbalanced vibration of the spindle rotor system in high-speed cutting processes not only seriously affects the surface quality of the machined products, but also greatly reduces the service life of the electric spindle. However, since the unbalanced vibration is often distributed on different node positions, the multinode unbalanced vibration greatly exacerbates the difficulty of vibration control. Based on the traditional influence coefficient method for controlling the vibration of a f...
System and method for smoothing a salient rotor in electrical machines
Raminosoa, Tsarafidy; Alexander, James Pellegrino; El-Refaie, Ayman Mohamed Fawzi; Torrey, David A.
2016-12-13
An electrical machine exhibiting reduced friction and windage losses is disclosed. The electrical machine includes a stator and a rotor assembly configured to rotate relative to the stator, wherein the rotor assembly comprises a rotor core including a plurality of salient rotor poles that are spaced apart from one another around an inner hub such that an interpolar gap is formed between each adjacent pair of salient rotor poles, with an opening being defined by the rotor core in each interpolar gap. Electrically non-conductive and non-magnetic inserts are positioned in the gaps formed between the salient rotor poles, with each of the inserts including a mating feature formed an axially inner edge thereof that is configured to mate with a respective opening being defined by the rotor core, so as to secure the insert to the rotor core against centrifugal force experienced during rotation of the rotor assembly.
Investigation of dynamic characteristics of a rotor system with surface coatings
Yang, Yang; Cao, Dengqing; Wang, Deyou
2017-02-01
A Jeffcott rotor system with surface coatings capable of describing the mechanical vibration resulting from unbalance and rub-impact is formulated in this article. A contact force model proposed recently to describe the impact force between the disc and casing with coatings is employed to do the dynamic analysis for the rotor system with rubbing fault. Due to the variation of penetration, the contact force model is correspondingly modified. Meanwhile, the Coulomb friction model is applied to simulate the friction characteristics. Then, the case study of rub-impact with surface coatings is simulated by the Runge-Kutta method, in which a linear interpolation method is adopted to predict the rubbing instant. Moreover, the dynamic characteristics of the rotor system with surface coatings are analyzed in terms of bifurcation plot, waveform, whirl orbit, Poincaré map and spectrum plot. And the effects of the hardness of surface coatings on the response are investigated as well. Finally, compared with the classical models, the modified contact force model is shown to be more suitable to solve the rub-impact of aero-engine with surface coatings.
Synchronization of the four identical unbalanced rotors in a vibrating system of plane motion
无
2010-01-01
A new mechanism is proposed to implement the synchronization of the four unbalanced rotors in a vibrating system, which consists of a main rigid frame (MRF) and two accessorial rigid frames (ARF). An analytical approach is developed to study the coupling dynamic characteristics of the four unbalanced rotors, which converts the problem of synchronization of the four unbalanced rotors into the existence and the stability of zero solutions for the non-dimensional differential equations of the angular velocity disturbance parameters (NDDEDP). The stability of zero solutions of the NDDEDP is decomposed into that of its generalized system and a system of the three first order differential equations for the disturbance parameters of the phase differences. The coupling dynamic characteristic of the four unbalanced rotors includes the inertia coupling, the stiffness coupling of angular velocity and the load torque coupling. The non-dimensional inertia coupling matrix is symmetric, the non dimensional matrix of the stiffness coupling of angular velocity is antisymmetric and its diagonal elements are all negative. Hence, the general system of the NDDEDP automatically satisfies the generalized Lyapunov equations when the non-dimensional inertia coupling matrix is positive definite and its elements are all positive. Using Routh-Hurwitz criterion the condition of stability of differential equations for the disturbance parameters of the phase differences is obtained. The load torque coupling makes the vibrating system have the dynamic characteristic of selecting motions and self-synchronization of the four unbalanced rotors arises from the dynamic characteristic of selecting motion of the vibrating system. When the two coefficients of coupling cosine effect of phase angles are all greater than 0 and the three indexes of synchronization are all far greater than 1, the vibrating system can implement an elliptical motion of the main rigid frame required in engineering. Numeric
Foster, John V.; Hartman, David C.
2017-01-01
The NASA Unmanned Aircraft System (UAS) Traffic Management (UTM) project is conducting research to enable civilian low-altitude airspace and UAS operations. A goal of this project is to develop probabilistic methods to quantify risk during failures and off nominal flight conditions. An important part of this effort is the reliable prediction of feasible trajectories during off-nominal events such as control failure, atmospheric upsets, or navigation anomalies that can cause large deviations from the intended flight path or extreme vehicle upsets beyond the normal flight envelope. Few examples of high-fidelity modeling and prediction of off-nominal behavior for small UAS (sUAS) vehicles exist, and modeling requirements for accurately predicting flight dynamics for out-of-envelope or failure conditions are essentially undefined. In addition, the broad range of sUAS aircraft configurations already being fielded presents a significant modeling challenge, as these vehicles are often very different from one another and are likely to possess dramatically different flight dynamics and resultant trajectories and may require different modeling approaches to capture off-nominal behavior. NASA has undertaken an extensive research effort to define sUAS flight dynamics modeling requirements and develop preliminary high fidelity six degree-of-freedom (6-DOF) simulations capable of more closely predicting off-nominal flight dynamics and trajectories. This research has included a literature review of existing sUAS modeling and simulation work as well as development of experimental testing methods to measure and model key components of propulsion, airframe and control characteristics. The ultimate objective of these efforts is to develop tools to support UTM risk analyses and for the real-time prediction of off-nominal trajectories for use in the UTM Risk Assessment Framework (URAF). This paper focuses on modeling and simulation efforts for a generic quad-rotor configuration typical
Damping by parametric excitation in a set of reduced-order cracked rotor systems
Kulesza, Zbigniew; Sawicki, Jerzy T.
2015-10-01
A common tool utilized for the stability analysis of parametrically excited linear systems, such as rotors with cracked shafts, is Floquet's method. The disadvantage is a long calculation time needed to evaluate the monodromy matrix and instability zones. An efficient alternative is the generalized Bolotin's method, where the instability zones are evaluated quickly, yet the matrices that must be calculated are of large dimensions. In the present paper, the stability analysis is conducted with both Floquet's method and the generalized Bolotin's method. However, the order of the model is reduced to two modes only and stability analyses are performed for the second-order systems obtained with various combinations of the reducing modes. Then, the results of such analyses are collected in an overall stability map. The stability map obtained in this way closely reconstructs the stability map calculated with the full-order model of the rotor, yet the calculation time needed to generate the collected map as well as the dimension of the problem are considerably reduced. The approach is demonstrated with a mathematical model of the machine with the breathing crack modeled using the rigid finite element method. The rotor is not rotating, yet the stiffness of the shaft is varied periodically to simulate the parametric excitation. An interesting indication of the developing shaft crack observed in the generated stability maps is the presence of anti-resonant zones, where the rotor vibration amplitudes quickly decay. It is anticipated that this phenomenon of increased damping at specific excitation frequencies may have potential application for shaft crack detection.
Forces exciting generation roll at rotor vibrations when rotor-to-stator rubbing
Shatokhin, V. F.
2017-07-01
The consequences of emergencies of turbosets for different application are revealed, the cause of forced shutdown and even catastrophic destructions of which many researchers consider the rotor-to-stator rubbing and development—to a greater or lesser extent—of the phenomena of the rotor generation roll over the stator. The synchronous or asynchronous generation roll is determined by the rotor precession direction, coinciding or not coinciding with the self-rotation direction of the rotor. Asynchronous generation roll is the most dangerous form of the rotor-stator contact interaction with the vibrations with rubbing. The basic equations of rotor vibrations are presented: symmetric rotor fixed on two supports and that fixed on several supports after abrupt imbalance with and without rotor coming in contact with a flexible stator. The vibration process is considered as the rotor motion in a backlash with subsequent contact with the stator, loss of contact, or development of generation roll. The latter essentially depends on the properties of the "rotor-support-stator" dynamic system. The stator stiffness characteristic is specified in "force-deformation" coordinates that make it possible to take into account damping in the supports and power loss in the stator. The diagram of elastic-damping device was presented, which makes it possible to ensure a certain level of power loss at the stator displacements. The exciting forces promoting development of self-exciting vibrations of the rotor in the form of asynchronous generation roll were compared with the exciting forces of oil film of sliding bearings and forces of aerodynamic excitation in the turbine flow path and sealings. For the rotor systems of high and medium pressure of a 300 MW capacity turboset, the simulation results of the process of development of asynchronous generation roll at the vibrations with rubbing were revealed, and the basic characteristics of development of generation roll in a span between
水轮发电机组转动部分动力学分析%Rotor-dynamic Analysis of Hydraulic Turbine Rotor System
陈德亮
2013-01-01
本文根据水轮发电机组中的密封形式及其边界条件特征，选用Muszyska密封力模型近似水轮机上冠、下环间隙流体激振力，并加载到水轮发电机组转动部分中，采用New mark数值方法对包括发电机、主轴、上导轴承、下导轴承、水轮机转轮、上冠和下环密封在内的水轮发电组转动部分-密封系统进行数值仿真，得到了水轮发电机组转动部分动力学特性，并将其与水轮发电机组实际运行数据进行对比，结果证明所建立的密封力模型符合工程实际，对水轮发电机组转动部分的设计有一定的指导意义。%Based on the seal form of hydroelectric generating unit and its boundary conditions, Muszyska model is used to approximate the fluid exciting force in gap flow between the crown and band of Francis turbine, and is loaded into the rotor system. New mark numerical method is selected to simulate rotor-seal system including generator, main shaft, upper guide bearing, lower guide bearing, turbine runner and the seals of the crown and the band of the turbine. Rotor-dynamic characteristics of the hydrogenerator rotor system is obtained and compared with the actual operation data. The result shows that the selected sealing force model can accord with engineering practice, and it has a guiding value to the design of hydrogenerator rotor system.
刘大诚; 史立伟
2014-01-01
相比于普遍使用的浮动轴承，在涡轮增压器中使用球轴承具有机械效率高和加速响应快的优势。以车用球轴承涡轮增压器为研究对象，用有限元法对轴承-转子系统进行了转子动力学特性的研究，对轴承-转子系统的临界转速进行了计算与分析，这是判断转子工作转速是否稳定和涡轮增压器工作是否可靠的重要依据；建立了增压器模型，并对比了计算结果和试验结果，证明了方法的可行性。通过整机试验表明，球轴承涡轮增压器能够满足当前车用发动机的需求，能够提高发动机的工作性能。%Turbochargers in ball bearings have much advantage than floating busing bearings,such as high mechanical efficiency and fast accelerate response.The paper studied obj ect that was ball bearing turbocharger of vehicle,researched on rotor dynamic characteristics of bearing-rotor system,and used finite element method to analyze the critical speed of bearing-rotor system which is the very important basis to j udging whether the rotor work is stable and turbocharger work is reliable. Comparing and analyzing the computing and experimental results,it proves the feasibility and accuracy of setting up model on bearing-rotor system of ball bearing turbocharger.After the test of prototype,it was proved that ball bearing turbo-charger can meet the current needs of vehicle engine and improve the working performance of the engine.
On the Flow Behavior in Rotor-Stator System with Superposed Flow
Roger Debuchy
2008-01-01
Full Text Available The flow between a rotor and a stator at high Reynolds number and small Ekman number is divided into three domains, two boundary layers adjacent to the discs separated by a central core. In the present work, a simple theoretical approach provides analytical solutions for the radial distribution of the core swirl ratio valid for a rotor-stator system with a superposed radial inflow rate. At first, the flow in the rotor boundary layer is assumed to behave as expressed by Owen and Rogers (1989 in the case of a turbulent flow on a rotating single disc. On the stator side, a necessary compensation flow rate must take place according to the conservation of mass. It is found that this compensation flow rate cannot be estimated with a good accuracy using the hypotheses of a stationary disc in a rotating fluid by Owen and Rogers (1989. Thus, two innovative weighting functions are tested, leading to new analytical laws relating the core swirl ratio K to the coefficient of flow rate Cqr introduced by Poncet et al. (2005. The adequacy between the theoretical solutions and numerous results of the literature is clearly improved and the discussion allows a better understanding of the flow behavior.
Modelling and Predictions of Isothermal Flow Inside the Closed Rotor-Stator System
Abdul Fattah Abbasi
2012-01-01
Full Text Available This paper describes the numerical predictions of isothermal closed rotor-stator flows. Steady-state finite-difference solutions are sought for two gap ratios and two rotational Reynolds number in the axisymmetric cylindrical polar coordinate frame of reference. Low Reynolds number models, low Reynolds number k-? and second moment closure models have been used to compute the necessary description of the flow inside the rotor-stator system without superpose flow. The most important dissimilarities among the computational calculations of both the turbulence models obtain at the lower radial locations, where k-? model predicted the premature transitional predictions from laminar to turbulent flow. The major feature of this computational work is the emergence of four regions of the flow i.e. source, sink and two boundary layers. Computed velocity components of both models are compared against the experimental measurements. Low Reynolds number second moment closure shows the improved level of matching with data, particularly on apex of the boundary layers and recirculating core in the middle of the rotor-stator cavity.
Instability analysis of unsymmetrical rotor-bearing systems
无
2001-01-01
This paper presents the instability analysis of unsymmetricalrotor-bearing system in accordance with the Campbell diagrams of the system, and concludes that the unstable regions stay in high speed regions with the increase of supporting stiffness and they decrease or disappear with the decrease of the inequality diametrical moments of the inertia and stiffness of shaft.
Dynamic behavior of dissymmetric rotor bearings modelled with a periodic coefficient large system
Guilhen, P. M.; Berthier, P.; Ferraris, G.; Lalanne, M.
1987-01-01
The instability and unbalance response of dissymmetric rotor-bearing systems containing periodic coefficients when modeling produces matrices with a large number of degrees of freedom are discussed. It is important to solve the equations and then predict the dynamic behavior of the system. This can be done knowing the instability areas and the unbalance response in the stable areas. One deals here with a large number of equations and a reduction of the number of degrees of freedom of the system is achieved through a pseudo modal method. This method is shown to give satisfactory results.
Development and application of a light-weight, wind-turbine rotor-based data acquisition system
Berg, D.E.; Robertson, P.J.; Ortiz, M.F. [Sandia National Labs., Albuquerque, NM (United States)
1998-04-01
Wind-energy researchers at the National Wind Technology Center (NWTC), representing Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL), are developing a new, light-weight, modular data acquisition unit capable of acquiring long-term, continuous time-series data from small and/or dynamic wind-turbine rotors. The unit utilizes commercial data acquisition hardware, spread-spectrum radio modems, and Global Positioning System receivers, and a custom-built programmable logic device. A prototype of the system is now operational, and initial field deployment is expected this summer. This paper describes the major subsystems comprising the unit, summarizes the current status of the system, and presents the current plans for near-term development of hardware and software.
Bab, Saeed; Khadem, S. E.; Shahgholi, Majid; Abbasi, Amirhassan
2017-02-01
The current paper investigates the effects of a number of smooth nonlinear energy sinks (NESs) located on the disk and bearings on the vibration attenuation of a rotor-blisk-journal bearing system under excitation of a mass eccentricity force. The blade and rotor are modeled using the Euler-Bernoulli beam theory. The nonlinear energy sinks on the bearing have a linear damping and an essentially nonlinear stiffness. The nonlinear energy sinks on the disk have a linear damping, linear stiffness, and an essentially nonlinear stiffness. It can be seen that the linear stiffness of the NESs on the disk is eliminated by the negative stiffness induced by the centrifugal force, and the collection of the NESs can be tuned to a required rotational speed of the rotor by varying the linear stiffness of the NESs. Furthermore, the remained stiffness of the NESs on the disk after elimination of their linear stiffness, would be essentially a nonlinear (nonlinearizable) one. Two nonlinear energy sinks in the vertical axes are positioned on the bearing housing and nnd NESs are located on the perimeter of the disk. The equations of motion are extracted using the extended Hamilton principle. The modal coordinates and complex transformations are employed to decrease the number of equations of motion. A genetic algorithm is used to optimize the parameters of the nonlinear energy sinks and its objective function is considered as minimizing the vibration of the rotating system within an operating speed range. In order to examine the periodic and non-periodic solutions of the system, time history, bifurcation diagram, Poincaré map, phase portrait, Lyapunov exponent, and power spectra analyses are performed. System shows periodic and quasi-periodic motions for different values of the system parameters. It is shown that the NESs on the disk and bearings have almost local effects on vibration reduction of rotating system. In addition, the optimum NESs remove the instability region from the
Zhang, Yongfang; Hei, Di; Lü, Yanjun; Wang, Quandai; Müller, Norbert
2014-03-01
Axial-grooved gas-lubricated journal bearings have been widely applied to precision instrument due to their high accuracy, low friction, low noise and high stability. The rotor system with axial-grooved gas-lubricated journal bearing support is a typical nonlinear dynamic system. The nonlinear analysis measures have to be adopted to analyze the behaviors of the axial-grooved gas-lubricated journal bearing-rotor nonlinear system as the linear analysis measures fail. The bifurcation and chaos of nonlinear rotor system with three axial-grooved gas-lubricated journal bearing support are investigated by nonlinear dynamics theory. A time-dependent mathematical model is established to describe the pressure distribution in the axial-grooved compressible gas-lubricated journal bearing. The time-dependent compressible gas-lubricated Reynolds equation is solved by the differential transformation method. The gyroscopic effect of the rotor supported by gas-lubricated journal bearing with three axial grooves is taken into consideration in the model of the system, and the dynamic equation of motion is calculated by the modified Wilson- θ-based method. To analyze the unbalanced responses of the rotor system supported by finite length gas-lubricated journal bearings, such as bifurcation and chaos, the bifurcation diagram, the orbit diagram, the Poincaré map, the time series and the frequency spectrum are employed. The numerical results reveal that the nonlinear gas film forces have a significant influence on the stability of rotor system and there are the rich nonlinear phenomena, such as the periodic, period-doubling, quasi-periodic, period-4 and chaotic motion, and so on. The proposed models and numerical results can provide a theoretical direction to the design of axial-grooved gas-lubricated journal bearing-rotor system.
Application of 3D wavelet transforms for crack detection in rotor systems
C Nagaraju; K Narayana Rao; K Mallikarjuna Rao
2009-06-01
The dynamics and diagnostics of a cracked rotor have been gaining importance in recent years. The early detection of faults like fatigue cracks in rotor shafts are very important to prevent catastrophic failure of the rotor system. Vibration monitoring during start up or shut-down is as important as during steady state operation to detect cracks especially for machines such as aircraft engines which start and stop quite frequently and run at high speeds. So, the transient data of the cracked rotor has been transformed using the wavelet transforms for crack detection. Most of the works quoted in the literature used 1D wavelets or 2D wavelets (Continuous Wavelet Transform-CWT) for crack detection. The crack detectors in the signals are both time as well as frequency dependent. So, the use of 2D wavelets is also not enough to detect the crack. In the present work a 3D wavelet (CWT) has been utilized which clearly indicates both the time and frequency features of the crack. The presence of sub-criticals in the CWT may be a best crack indicator but it is not always reliable. The addition of noise to the signal may sometimes lead to inaccurate results. So, there is a need to identify a parameter in addition to the sub-criticals. The phase angle between the two signals (cracked and un-cracked) or two transverse vibrations can be a better crack indicator because it is very less sensitive to noise disturbance. So, to extract the above phase angle a new transform has been applied called Cross Wavelet Transform (XWT). The XWT is exploited for the ﬁrst time to a rotor fault detection system in the present work. Some interesting results have been obtained using the same. The advantage of the XWT is that both, the phase angles between the transverse signals and also the amplitudes of sub-criticals are viewed in a single plot. Parametric analysis is also carried out by varying crack depth and crack position for diagnostic purposes. The inverse problem of crack identi
Stability of rotor systems: A complex modelling approach
Kliem, Wolfhard; Pommer, Christian; Stoustrup, Jakob
1998-01-01
matrices in order to describe the effect of parameters on stability. In this paper we apply the Lyapunov matrix equation in a complex setting to an equivalent system of first order and prove in this way two new stability results. We then compare the usefulness of these results with the more classical...
Development of a resonant trailing-edge flap actuation system for helicopter rotor vibration control
Kim, J.-S.; Wang, K. W.; Smith, E. C.
2007-12-01
A resonant trailing-edge flap actuation system for helicopter rotors is developed and evaluated experimentally. The concept involves deflecting each individual trailing-edge flap using a compact resonant piezoelectric actuation system. Each resonant actuation system yields high authority, while operating at a single frequency. By tailoring the natural frequencies of the actuation system (including the piezoelectric actuator and the related mechanical and electrical elements) to the required operating frequencies, one can increase the output authority. The robustness of the device can be enhanced by increasing the high authority bandwidth through electric circuitry design. Such a resonant actuation system (RAS) is analyzed for a full-scale piezoelectric induced-shear tube actuator, and bench-top testing is conducted to validate the concept. An adaptive feed-forward controller is developed to realize the electric network dynamics and adapt to phase variation. The control strategy is then implemented via a digital signal processor (DSP) system. Analysis is also performed to examine the rotor system dynamics in forward flight with piezoelectric resonant actuators, using a perturbation method to evaluate the system's time-varying characteristics. Numerical simulations reveal that the resonant actuator concept can be applied to forward flights as well as to hover conditions.
ANALYSIS ON MOTION STABILITY OF A HIGH-SPEED ROTOR-BEARING SYSTEM
Zhang Junhong; Sun Shaojun
2005-01-01
A non-linear dynamic model of one type of high-speed rotor system with gas supporting system is set up. The laws between the capacity force and the parameters of bearing, the static equilibrium position and rotating speed are studied on the basis of above model. Then, the failure rotating speed is given in the working state, and the relation between the minimum failure rotating speed and clearance of bearing is also studied. At last, the stability and failure condition are discussed in different working conditions.
Evaluation of lightning accommodation systems for wind-driven turbine rotors
Bankaitis, H
1982-03-01
Several concepts of lightning accommodation systems for wind-driven turbine rotor blades were evaluated by submitting them to simulated lightning tests. Test samples representative of epoxy-fiberglass and wood-epoxy composite structural materials were submitted to a series of high-voltage and high-current damage tests. The high-voltage tests were designed to determine the strike points and current paths through the sample and the need for, and the most proper type of, lightning accommodation. The high-current damage tests were designed to determine the capability of the potential lightning accommodation system to sustain the 200-kA lightning current without causing damage to the composite structure. The observations and data obtained in the series of tests of lightning accommodation systems clearly led to the conclusions that composite-structural-material rotor blades require a lightning accommodation system; that the concepts tested prevent internal streamering; and that keeping discharge currents on the blade surface precludes structure penetration. Induced voltage effects or any secondary effects on the integral components of the total system could not be addressed. Further studies should be carried out to encompass effects on the total system design.
Influence of unbalance levels on nonlinear dynamics of a rotor-backup rolling bearing system
Fonseca, Cesar A.; Santos, Ilmar; Weber, Hans I.
2017-01-01
Rotor drops in magnetic bearing and unbalance in rotors have been objective of study for many years. The combination of these two well-known phenomena led to an interesting chaotic response, when the rotor touches the inner race of the back-up bearing. The present work explores the nonlinear roto...
Zhao Yucheng; Sun Kun; Zhang Yahong; Xu Qingyu
2005-01-01
The dynamical behaviors of logistic map(May's model) and duffing equation are studied through fractal dimension of time series at different parameters. It is shown that the parameters of dynamical behaviors can be identified effectively by the curve of fractal dimension with parameter increments. For further verification, the relation between the fractional dimension of time series and rotational speed can be used to identify critical speed effectively by using this method to a plate Jeffoctt rotor system. The numerical and experimental result indicates that the identification of critical parameters is effective.
Design of automatic rotor blades folding system using NiTi shape memory alloy actuator
Ali, M. I. F.; Abdullah, E. J.
2016-10-01
This present paper will study the requirements for development of a new Automatic Rotor Blades Folding (ARBF) system that could possibly solve the availability, compatibility and complexity issue of upgrading a manual to a fully automatic rotor blades folding system of a helicopter. As a subject matter, the Royal Malaysian Navy Super Lynx Mk 100 was chosen as the baseline model. The aim of the study was to propose a design of SMART ARBF's Shape Memory Alloy (SMA) actuator and proof of operating concept using a developed scale down prototype model. The performance target for the full folding sequence is less than ten minutes. Further analysis on design requirements was carried out, which consisted of three main phases. Phase 1 was studying the SMA behavior on the Nickel Titanium (NiTi) SMA wire and spring (extension type). Technical values like activation requirement, contraction length, and stroke- power and stroke-temperature relationship were gathered. Phase 2 was the development of the prototype where the proposed design of stepped-retractable SMA actuator was introduced. A complete model of the SMART ARBF system that consisted of a base, a main rotor hub, four main rotor blades, four SMA actuators and also electrical wiring connections was fabricated and assembled. Phase 3 was test and analysis whereby a PINENG-PN968s-10000mAh Power Bank's 5 volts, which was reduced to 2.5 volts using LM2596 Step-Down Converter, powered and activated the NiTi spring inside each actuator. The bias spring (compression type), which functions to protract and push the blades to spread position, will compress together with the retraction of actuators and pull the blades to the folding position. Once the power was removed and SMA spring deactivated, the bias spring stiffness will extend the SMA spring and casing and push the blades back to spread position. The timing for the whole revolution was recorded. Based on the experimental analysis, the recorded timing for folding sequence is
Flight Adaptive Blade for Optimum Rotor Response (FABFORR) Project
National Aeronautics and Space Administration — While past research has demonstrated the utility and benefits to be gained with the application of advanced rotor system control concepts, none have been implemented...
Flight Adaptive Blade for Optimum Rotor Response (FABFORR) Project
National Aeronautics and Space Administration — While past research has demonstrated the utility and benefits to be gained with the application of advanced rotor system control concepts, none have been...
Analysis of Space Station Centrifuge Rotor Bearing Systems: A Case Study
Poplawski, Joseph V.; Loewenthal, Stuart H.; Oswald, Fred B.; Zaretsky, Erwin V.; Morales, Wilfredo; Street, Kenneth W., Jr.
2014-01-01
A team of NASA bearing and lubrication experts was assembled to assess the risk for the rolling-element bearings used in the International Space Station (ISS) centrifuge rotor (CR) to seize or otherwise fail to survive for the required 10-year life. The CR was designed by the Japan Aerospace Exploration Agency and their subcontractor, NEC Toshiba Space Systems, Ltd. (NTSpace). The NASA team performed a design audit for the most critical rolling-element bearing systems and reviewed the lubricant selected. There is uncertainty regarding the ability of the Braycote 601 grease (Castrol Limited) to reliably provide the 10-year continuous life required without relubrication of the system. The fatigue life of the Rotor Shaft Assembly (RSA) spring loaded face-to-face mount at a 99-percent probability of survival (L1 life) for the ball bearing set was estimated at 700 million hours and the single ball bearing (Row 3) at 58 million hours. These lives satisfy the mission requirements for fatigue. Rolling-element seizure tests on the RSA and fluid slip joint bearings were found unlikely to stop the centrifuge, which can cause damage to the ISS structure. The spin motor encoder duplex angular-contact ball bearings have a hard preload and a large number of small balls have the highest risk of failure. These bearings were not tested for seizure even though they are less tolerant to debris or internal clearance reductions.
Pan Fang
Full Text Available A new mechanism is proposed to implement synchronization of the two unbalanced rotors in a vibration system, which consists of a double vibro-body, two induction motors and spring foundations. The coupling relationship between the vibro-bodies is ascertained with the Laplace transformation method for the dynamics equation of the system obtained with the Lagrange's equation. An analytical approach, the average method of modified small parameters, is employed to study the synchronization characteristics between the two unbalanced rotors, which is converted into that of existence and the stability of zero solutions for the non-dimensional differential equations of the angular velocity disturbance parameters. By assuming the disturbance parameters that infinitely approach to zero, the synchronization condition for the two rotors is obtained. It indicated that the absolute value of the residual torque between the two motors should be equal to or less than the maximum of their coupling torques. Meanwhile, the stability criterion of synchronization is derived with the Routh-Hurwitz method, and the region of the stable phase difference is confirmed. At last, computer simulations are preformed to verify the correctness of the approximate solution of the theoretical computation for the stable phase difference between the two unbalanced rotors, and the results of theoretical computation is in accordance with that of computer simulations. To sum up, only the parameters of the vibration system satisfy the synchronization condition and the stability criterion of the synchronization, the two unbalanced rotors can implement the synchronization operation.
SMART wind turbine rotor. Design and field test
Berg, Jonathan Charles; Resor, Brian Ray; Paquette, Joshua A.; White, Jonathan Randall
2014-01-01
The Wind Energy Technologies department at Sandia National Laboratories has developed and field tested a wind turbine rotor with integrated trailing-edge flaps designed for active control of rotor aerodynamics. The SMART Rotor project was funded by the Wind and Water Power Technologies Office of the U.S. Department of Energy (DOE) and was conducted to demonstrate active rotor control and evaluate simulation tools available for active control research. This report documents the design, fabrication, and testing of the SMART Rotor. This report begins with an overview of active control research at Sandia and the objectives of this project. The SMART blade, based on the DOE / SNL 9-meter CX-100 blade design, is then documented including all modifications necessary to integrate the trailing edge flaps, sensors incorporated into the system, and the fabrication processes that were utilized. Finally the test site and test campaign are described.
Blade Deflection Measurements of a Full-Scale UH-60A Rotor System
Olson, Lawrence E.; Abrego, Anita; Barrows, Danny A.; Burner, Alpheus W.
2010-01-01
Blade deflection (BD) measurements using stereo photogrammetry have been made during the individual blade control (IBC) testing of a UH-60A 4-bladed rotor system in the 40 by 80-foot test section of the National Full-Scale Aerodynamic Complex (NFAC). Measurements were made in quadrants one and two, encompassing advance ratios from 0.15 to 0.40, thrust coefficient/solidities from 0.05 to 0.12 and rotor-system drive shaft angles from 0.0 to -9.6 deg. The experiment represents a significant step toward providing benchmark databases to be utilized by theoreticians in the development and validation of rotorcraft prediction techniques. In addition to describing the stereo measurement technique and reporting on preliminary measurements made to date, the intent of this paper is to encourage feedback from the rotorcraft community concerning continued analysis of acquired data and to solicit suggestions for improved test technique and areas of emphasis for measurements in the upcoming UH-60A Airloads test at the NFAC.
Dynamic modelling of rotor in non-inertia system%转子在非惯性系中的动力学建模
惠旭升; 蔡安江; 张小龙
2009-01-01
以Jeffcott转子为模型,对其在非惯性系中进行了动力学研究.提出在非惯性系中,对于转子应考虑非惯性力和陀螺力矩的影响,采用包括陀螺近似原理在内的一些相关理论来分析.文中从非惯性参考系中质点的运动微分方程出发,推导出转子考虑非惯性力及陀螺力矩影响条件下的盘心运动分量方程函数.在模型建立过程中,还考虑了转子的偏心、初弯和阻尼力.这对进一步在非惯性系中研究转子的动力特性有一定的裨益.%Taking Jeffcott rotor as a model, the dynamics re-search of rotor in the non-inertia system was carried out. It has been brought forward that within the non-inertia system the rotor should be analyzed by adopting some oorrelated theories that includes the gyro approximation principle and with the consideration on the influ-ences of non-inertia force and gyro moment. Proceed from the mo-tion differential equation of particle in the non-inertia reference-system this paper derived the equation function of motion component of rotor' s disk center under the condition of considering the influ-ences of the non-inertia force and the gyro moment. The eccentrici-ty, initial bending and damping force of rotor had been considered as well during the course of model establishment. There exist cer-tain benefits on further study of the rotor' s dynamic characters in the non-inertia system.
The Theoretical Research for the Rotor/Fuselage Unsteady Aerodynamic Interaction Problem
Liu Dawei
2016-07-01
Full Text Available Based on coupled unsteady panel/free-wake method, a universal analysis model was established, which provides a good prediction for the rotor/fuselage unsteady aerodynamic interaction. Considering the deficiencies of the traditional time-marching rotor free-wake algorithms, notably on stability and efficiency, the CB3D algorithm with 3rd-order accuracy is proposed. For solving the problem that part of the wake vortices may penetrate the fuselage, a “material line” rectification method with 3rd-order accuracy is proposed. An analysis for the model accuracy was then conducted to validate the accuracy of the new model, and a comparison against the available experimental data is performed. The simulated results show a good agreement with these experimental data. With the new model, several simulations are conducted for the typical rotor/fuselage aerodynamic interaction, and the results are analyzed.
Open Rotor Aeroacoustic Modelling
Envia, Edmane
2012-01-01
Owing to their inherent fuel efficiency, there is renewed interest in developing open rotor propulsion systems that are both efficient and quiet. The major contributor to the overall noise of an open rotor system is the propulsor noise, which is produced as a result of the interaction of the airstream with the counter-rotating blades. As such, robust aeroacoustic prediction methods are an essential ingredient in any approach to designing low-noise open rotor systems. To that end, an effort has been underway at NASA to assess current open rotor noise prediction tools and develop new capabilities. Under this effort, high-fidelity aerodynamic simulations of a benchmark open rotor blade set were carried out and used to make noise predictions via existing NASA open rotor noise prediction codes. The results have been compared with the aerodynamic and acoustic data that were acquired for this benchmark open rotor blade set. The emphasis of this paper is on providing a summary of recent results from a NASA Glenn effort to validate an in-house open noise prediction code called LINPROP which is based on a high-blade-count asymptotic approximation to the Ffowcs-Williams Hawkings Equation. The results suggest that while predicting the absolute levels may be difficult, the noise trends are reasonably well predicted by this approach.
System Noise Assessment of Blended-Wing-Body Aircraft With Open Rotor Propulsion
Guo, Yueping; Thomas, Russell H.
2015-01-01
An aircraft system noise study is presented for the Blended-Wing-Body (BWB) aircraft concept with three open rotor engines mounted on the upper surface of the airframe. It is shown that for such an aircraft, the cumulative Effective Perceived Noise Level (EPNL) is about 24 dB below the current aircraft noise regulations of Stage 4. While this makes the design acoustically viable in meeting the regulatory requirements, even with the consideration of more stringent noise regulations of a possible Stage 5 in the next decade or so, the design will likely meet stiff competitions from aircraft with turbofan engines. It is shown that the noise levels of the BWB design are held up by the inherently high noise levels of the open rotor engines and the limitation on the shielding benefit due to the practical design constraint on the engine location. Furthermore, it is shown that the BWB design has high levels of noise from the main landing gear, due to their exposure to high speed flow at the junction between the center body and outer wing. These are also the reasons why this baseline BWB design does not meet the NASA N+2 noise goal of 42 dB below Stage 4. To identify approaches that may further reduce noise, parametric studies are also presented, including variations in engine location, vertical tail and elevon variations, and airframe surface acoustic liner treatment effect. These have the potential to further reduce noise but they are only at the conceptual stage.
Nonlinear dynamic modeling of rotor system supported by angular contact ball bearings
Wang, Hong; Han, Qinkai; Zhou, Daning
2017-02-01
In current bearing dynamic models, the displacement coordinate relations are usually utilized to approximately obtain the contact deformations between the rolling element and raceways, and then the nonlinear restoring forces of the rolling bearing could be calculated accordingly. Although the calculation efficiency is relatively higher, the accuracy is lower as the contact deformations should be solved through iterative analysis. Thus, an improved nonlinear dynamic model is presented in this paper. Considering the preload condition, surface waviness, Hertz contact and elastohydrodynamic lubrication, load distribution analysis is solved iteratively to more accurately obtain the contact deformations and angles between the rolling balls and raceways. The bearing restoring forces are then obtained through iteratively solving the load distribution equations at every time step. Dynamic tests upon a typical rotor system supported by two angular contact ball bearings are conducted to verify the model. Through comparisons, the differences between the nonlinear dynamic model and current models are also pointed out. The effects of axial preload, rotor eccentricity and inner/outer waviness amplitudes on the dynamic response are discussed in detail.
Design Study of Propulsion and Drive Systems for the Large Civil TiltRotor (LCTR2) Rotorcraft
Robuck, Mark; Wilkerson, Joseph; Zhang, Yiyi; Snyder, Christopher A.; Vonderwell, Daniel
2013-01-01
Boeing, Rolls Royce, and NASA have worked together to complete a parametric sizing study for NASA's Large Civil Tilt Rotor (LCTR2) concept 2nd iteration. Vehicle gross weight and fuel usage were evaluated as propulsion and drive system characteristics were varied to maximize the benefit of reduced rotor tip speed during cruise conditions. The study examined different combinations of engine and gearbox variability to achieve rotor cruise tip speed reductions down to 54% of the hover tip speed. Previous NASA studies identified that a 54% rotor speed reduction in cruise minimizes vehicle gross weight and fuel burn. The LCTR2 was the study baseline for initial sizing. This study included rotor tip speed ratios (cruise to hover) of 100%, 77% and 54% at different combinations of engine RPM and gearbox speed reductions, which were analyzed to achieve the lightest overall vehicle gross weight (GW) at the chosen rotor tip speed ratio. Different engine and gearbox technology levels are applied ranging from commercial off-the-shelf (COTS) engines and gearbox technology to entry-in-service (EIS) dates of 2025 and 2035 to assess the benefits of advanced technology on vehicle gross weight and fuel burn. Interim results were previously reported1. This technical paper extends that work and summarizes the final study results including additional engine and drive system study accomplishments. New vehicle sizing data is presented for engine performance at a single operating speed with a multispeed drive system. Modeling details for LCTR2 vehicle sizing and subject engine and drive sub-systems are presented as well. This study was conducted in support of NASA's Fundamental Aeronautics Program, Subsonic Rotary Wing Project.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems
Christensen, Rene Hardam; Santos, Ilmar
2003-01-01
to be overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures...... of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step...... is reformulated using complex mode theory. Next, a linear constant gain controller for the reformulated system is designed by linear control technique. Finally, this constant gain controller is transformed to a time-periodic form by applying reverse modal transformation. The non-measurable states are estimated...
H. A. Hashim
2015-01-01
Full Text Available This paper presents a comparative study of fuzzy controller design for the twin rotor multi-input multioutput (MIMO system (TRMS considering most promising evolutionary techniques. These are gravitational search algorithm (GSA, particle swarm optimization (PSO, artificial bee colony (ABC, and differential evolution (DE. In this study, the gains of four fuzzy proportional derivative (PD controllers for TRMS have been optimized using the considered techniques. The optimization techniques are developed to identify the optimal control parameters for system stability enhancement, to cancel high nonlinearities in the model, to reduce the coupling effect, and to drive TRMS pitch and yaw angles into the desired tracking trajectory efficiently and accurately. The most effective technique in terms of system response due to different disturbances has been investigated. In this work, it is observed that GSA is the most effective technique in terms of solution quality and convergence speed.
Gaonkar, G.
1987-01-01
For flap lag stability of isolated rotors, experimental and analytical investigations were conducted in hover and forward flight on the adequacy of a linear quasisteady aerodynamics theory with dynamic flow. Forward flight effects on lag regressing mode were emphasized. A soft inplane hingeless rotor with three blades was tested at advance ratios as high as 0.55 and at shaft angles as high as 20 deg. The 1.62 m model rotor was untrimmed with an essentially unrestricted tilt of the tip path plane. In combination with lag natural frequencies, collective pitch settings and flap lag coupling parameters, the data base comprises nearly 1200 test points (damping and frequency) in forward flight and 200 test points in hover. By computerized symbolic manipulation, a linear model was developed in substall to predict stability margins with mode identification. To help explain the correlation between theory and data it also predicted substall and stall regions of the rotor disk from equilibrium values. The correlation showed both the strengths and weaknesses of the theory in substall ((angle of attack) equal to or less than 12 deg).
无
2010-01-01
In this paper,the response characteristics of dry friction backward whirl of a general rotor/stator model,which accounts for both the dynamics of the rotor and the stator as well as the friction and the deformation at the contact surfaces,are investigated.The existence boundaries and the whirl frequencies of the dry friction backward whirl are determined analytically.It is found that there are two or three existence boundaries of the dry friction backward whirl that usually form two existence regions,either standing completely separately,or overlapping each other partly,or one containing the other completely,depending upon the system parameters.The whirl frequencies in the two existence regions are quite different and may jump between the lower and the higher values with the variation of the rotating speed.The results have been found to have good correspondence in the related rotor/stator rubbing experiments.
Vibration transmission through rolling element bearings. III - Geared rotor system studies
Lim, T. C.; Singh, R.
1991-01-01
The bearing matrix formulations proposed by Lim and Singh (1990) are extended to analyze the overall dynamics of a geared rotor system which includes a spur gear pair, shafts, rolling-element bearings, a motor, a load, a casing, and flexible or rigid mounts. For this purpose, discrete vibration models are developed and used to predict vibration transmission through the bearings and to investigate the effects of the bearing, casing, and mount dynamics on the dynamic characteristics of the internal rotating system. Analytical predictions show that the theory is capable of predicting the bearing and mount moment transmissibilities in addition to the force transmissibilities. The predicted flexural vibrations of the casing plate are in good agreement with measurements conducted on an experimental set-up that consisted of a high-precision beam and pinion, and four identical rolling element bearings contained in a flexible casing mounted rigidly on a massive foundation.
NURWAHA Deogratias; WANG Xin-hou
2008-01-01
This paper presents a comparison study of two models for predicting the strength of rotor spun cotton yarns from fiber properties. The adaptive neuro-fuzzy system inference (ANFIS) and Multiple Linear Regression models are used to predict the rotor spun yarn strength. Fiber properties and yarn count are used as inputs to train the two models and the count-strength-product (CSP) was the target. The predictive performances of the two models are estimated and compared. We found that the ANFIS has a better predictive power in comparison with linear multipleregression model. The impact of each fiber property is also illustrated.
Acoustic emission technique based rubbing identification for Rotor-bearing systems
2001-01-01
Rubbing is the frequent and dangerous fault in the rotating machine, and efficient identi-fication of the rubbing is a hot research subject in the field of fault diagnosis. In this paper, a newrubbing identification method is proposed, which is based on the acoustic emission technique. Inthis method, the acoustic emission signal of the rubbing in the multi-support rotor-bearing systemis acquired by the acoustic emission sensor, and then the continuous wavelet transform is utilizedto analyze this signal. Based on the rubbing mechanism, the frequency feature of the multiple fre-quency relation in the instantaneous frequency wave is extracted as the rubbing identification fea-ture. The experimental results prove that the proposed method is efficient and feasible.
LU Yanjun; LIU Heng; YU Lie; LI Qi; ZHANG Zhiyu; JIANG Ming
2007-01-01
Based on the variational constraint approach, the variational form of Reynolds equation in hydrodynamic lubrication is revised continuously to satisfy certain con- straints in the cavitation zone of oil film field. According to the physical characteristic of oil film, an eight-node isopara- metric finite element method is used to convert the revised variational form of Reynolds equation to a discrete form of finite dimensional algebraic variational equation. By this approach, a perturbance equation can be obtained directly on the finite element equation. Consequently, nonlinear oil film forces and their Jacobian matrices are calculated simul- taneously, and compatible accuracy is obtained without increasing the computational costs. A method, which is a combination ofpredictor-corrector mechanism and Newton- Raphson method, is presented to calculate equilibrium posi- tion and critical speed corresponding to Hopf bifurcation point of bearing-rotor system, as by-product dynamic coe- fficients of bearing are obtained. The timescale, i.e., the unknown whirling period of Hopf bifurcation solution of bearing-rotor system is drawn into the iterative process using Poincaré-Newton-Floquet method. The stability of the Hopf bifurcation solution can be detected when estimating Hopf bifurcation solution and its periods. The nonlinear unbalanced Tperiodic responses of the system are obtained by using PNF method and path-following technique. The local stability and bifurcation behaviors of T periodic motions are analyzed by Floquet theory. Chaotic motions are analyzed by Lyapunov exponents. The numerical results revealed the rich and complex nonlinear behavior of the system, such as periodic, quasiperiodic, jumped solution, chaos, and coexistence of multisolution, and so on.
主动电磁轴承系统的动力学性能分析%Analysis on Dynamic Performance for Active Magnetic Bearing-Rotor System
严慧燕; 汪希平; 朱礼进; 张直明; 万金贵
2001-01-01
In the application of active magnetic bearings (AMB), one of the key problems to be solved is the safety and stability in the sense of rotor dynamics. The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings, and studies its rotor dynamics performance, including calculation of the natural frequencies with their distribution characteristics, and the critical speeds of the system. One of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magnetic bearing-rotor system by combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.
Cheney, M.C. [PS Enterprises, Inc., Glastonbury, CT (United States)
1997-12-31
The cost of energy for renewables has gained greater significance in recent years due to the drop in price in some competing energy sources, particularly natural gas. In pursuit of lower manufacturing costs for wind turbine systems, work was conducted to explore an innovative rotor designed to reduce weight and cost over conventional rotor systems. Trade-off studies were conducted to measure the influence of number of blades, stiffness, and manufacturing method on COE. The study showed that increasing number of blades at constant solidity significantly reduced rotor weight and that manufacturing the blades using pultrusion technology produced the lowest cost per pound. Under contracts with the National Renewable Energy Laboratory and the California Energy Commission, a 400 kW (33m diameter) turbine was designed employing this technology. The project included tests of an 80 kW (15.5m diameter) dynamically scaled rotor which demonstrated the viability of the design.
A new algorithm for the robust optimization of rotor-bearing systems
Lopez, R. H.; Ritto, T. G.; Sampaio, Rubens; Souza de Cursi, J. E.
2014-08-01
This article presents a new algorithm for the robust optimization of rotor-bearing systems. The goal of the optimization problem is to find the values of a set of parameters for which the natural frequencies of the system are as far away as possible from the rotational speeds of the machine. To accomplish this, the penalization proposed by Ritto, Lopez, Sampaio, and Souza de Cursi in 2011 is employed. Since the rotor-bearing system is subject to uncertainties, such a penalization is modelled as a random variable. The robust optimization is performed by minimizing the expected value and variance of the penalization, resulting in a multi-objective optimization problem (MOP). The objective function of this MOP is known to be non-convex and it is shown that its resulting Pareto front (PF) is also non-convex. Thus, a new algorithm is proposed for solving the MOP: the normal boundary intersection (NBI) is employed to discretize the PF handling its non-convexity, and a global optimization algorithm based on a restart procedure and local searches are employed to minimize the NBI subproblems tackling the non-convexity of the objective function. A numerical analysis section shows the advantage of using the proposed algorithm over the weighted-sum (WS) and NSGA-II approaches. In comparison with the WS, the proposed approach obtains a much more even and useful set of Pareto points. Compared with the NSGA-II approach, the proposed algorithm provides a better approximation of the PF requiring much lower computational cost.
LUO Kai
2005-01-01
Stability is a key problem that means whether a high rate rotor-active magnetic bearings system works reliably or not. Aiming at a bearings system described with nonlinear equations, this paper built a linear model according to the system behavior. Considering realization of the control system and behavior of a high rate rotor system (magnetic force is far smaller than input force produced by mass eccentricity) this paper proposes a design method of variable parameters PD control algorithm that can be used universally. The control system was simplified and a mass of adjusting work of control parameters was reduced. Analysis and simulation indicated that the bearings system could get a wider stable region of harmonic motion, and proved that the algorithm is robust and advanced. The control system can be realized because the winding electric currents are positive. The method is convenient for operation and can easily be used for engineering practice.
Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System
Nicoletti, Rodrigo; Santos, Ilmar
2005-01-01
In the present paper the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted...... into the model by using two different approaches: (a) linearized active oil film forces and the assumption that the hydrodynamic forces and the active hydraulic forces can be decoupled, and (b) equivalent dynamic coefficients of the active oil film and the solution of the modified Reynolds equation...... lubricated tilting-pad bearing. By applying a simple proportional controller it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility...
Integration of Shape Memory Alloys into Low-Damped Rotor-Bearing Systems
Enemark, Søren
2015-01-01
to use passive adaptive control through smart materials. Shape Memory Alloys (SMAs) are interesting candidates in that relation, because of their highly temperature sensitive stiffness and mechanical hysteresis, which can be used for damping purposes. The thesis focuses on three main aspects related...... to the feasibility of integrating SMAs into rotor-bearing systems. The first one involves modelling of the constitutive relations of the metals with emphasis on stabilized cyclic behaviour under controlled temperature conditions. Two well-established phenomenological thermo-mechanical models are employed...... and identifiability, and to call attention to the inherent uncertainties of model predictions. The second aspect concerns design and modelling of machine elements made from SMAs. Different actuation principles of SMAs are covered, and pseudoelastic elements in pre-tension are found to have the most promising...
Zhang, Rui-Qin; Qi, Fei; Hermann, Klaus; Van Hove, Michel A
2016-01-01
Torque is ubiquitous in many molecular systems, including collisions, chemical reactions, vibrations, electronic excitations and especially rotor molecules. We present a straightforward theoretical method based on forces acting on atoms and obtained from atomistic quantum mechanics calculations, to quickly and qualitatively determine whether a molecule or sub-unit thereof has a tendency to rotation and, if so, around which axis and in which sense: clockwise or counterclockwise. The method also indicates which atoms, if any, are predominant in causing the rotation. Our computational approach can in general efficiently provide insights into the rotational ability of many molecules and help to theoretically screen or modify them in advance of experiments or before analyzing their rotational behavior in more detail with more extensive computations guided by the results from the torque approach. As an example, we demonstrate the effectiveness of the approach using a specific light-driven molecular rotary motor whi...
Flow field distribution of liquid film of water lubricated bearing-rotor coupling systems
Hu, Q. L.; Hu, J. N.; Ye, X. Y.; Zhang, D. S.; Zheng, J. B.
2016-05-01
According to the desalination high-pressure pump water lubricated bearing-rotor coupling systems flow field distribution of liquid film in the starting transient process and its power transmission mechanism can lay the foundation of further exploring and judging lubrication state at the boot process. By using the computational fluid dynamics Fluent secondary development platform and calling the relevant DEFINE macro function to achieve the translation and rotation movement of the journal, we will use the dynamic grid technique to realize the automatic calculation and grid update of water lubricated bearings 3d unsteady liquid film flow field, and finally we will dispose the results of numerical simulation and get the pressure. When the eccentricity is large, film thickness was negatively correlated with the pressure, and positive with the velocity. Differential pressure was negatively correlated with velocity. When the eccentricity is small, film thickness is no significant relationship with differential pressure and velocity. Differential pressure has little difference with velocity.
刘羽峰; 宁媛
2011-01-01
采用了控制不同电机转速组合的方法,对六轴旋翼碟形飞行器进行姿态控制,使六轴旋翼碟形飞行器在不同姿态下飞行时具有较好的性能;为了实现六轴旋翼碟形飞行器的飞行控制,对飞行器的控制系统进行了初步的设计,并且给出了控制系统软件设计流程图;同时以ProtueslSIS软件为基础建立了六轴旋翼碟形飞行器控制系统的仿真模型,并进行了仿真,仿真结果显示该控制系统能够满足六轴旋翼碟形飞行器起飞、悬停及降落等控制姿态的要求.%In order to control flies state of the six-axis saucer ahaped rotorcraft,method of adjusting the speed of the different motors is proposed,so that make it good works performance for different flies state.For the purpose of relizing the flight control for the six -axis rotor saucer shaped rotorcraft,the flight control system is designed preliminarily and the software of flight control system flow chart s given.At the same time.simulation model of the six-axis rotor saucer ahaped rotor saucer shaped rotoreraft control system is created on the basis of software Protues ISIS.simulation result shows that can meet control atate requirement of taking off,hovcring and landing and so on.
Influence of unbalance levels on nonlinear dynamics of a rotor-backup rolling bearing system
Fonseca, Cesar A.; Santos, Ilmar F.; Weber, Hans I.
2017-04-01
Rotor drops in magnetic bearing and unbalance in rotors have been objective of study for many years. The combination of these two well-known phenomena led to an interesting chaotic response, when the rotor touches the inner race of the back-up bearing. The present work explores the nonlinear rotor backup bearing dynamics both theoretically and experimentally using a fully instrumented test rig, where the position of shaft, its angular velocity and the contact forces between the shaft and the backup bearing are sampled at 25 kHz. The test rig is built by a removable passive magnetic bearing, which allows for simulation of magnetic bearing failure (loss of carrying capacity and rotor fall). The rotor is studied numerically as well as experimentally. A theoretical approach is given beforehand and supplies the basis of the study. Finally the presented results are commented on the point of view of nonlinear dynamics applied to the practical use. The theoretical and numerical analyses are shown through orbit plots, phase plans, Poincaré maps, force response in time and double sided spectrum. The latter is important to characterize the condition at different levels of unbalance between forward and backward whirl. Our preliminary results indicate that for smaller amount of unbalance the rotor swings at the bottom of the bearing, the more the unbalance increases, other dynamical behavior occur and some can be extremely harmful, since the rotor can be lifted from the contact state and return, starting to impact innumerable times without reaching a steady state.
Ebert, C.; Friedmann, H.; Henkel, F.O. [Woelfel Beratende Ingenieure GmbH und Co.KG, Hoechberg (Germany); Frankenstein, B.; Schubert, L. [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren, Dresden (Germany)
2010-07-01
The authors of the contribution under consideration report on a development of a Structural-Health-Monitoring-System which is to supervise the condition of the rotor blades of wind power plants and to detect in time structural changes before total failures. It is based on a combination of measuring techniques from the areas of the led rollers in the ultrasonic range and low-frequency modal analysis. The combination of both techniques was already promisingly used with past investigations of rotor blades. By means of modal analysis, statements to the total behaviour of the structure of rotor blades are possible. Endangered and strongly stressed areas additionally are supervised by led rollers within the ultrasonic range. The authors also report on the conception and execution of a fatigue test at a material rotor blade with a length by 39.1 m.
Qiang LI; Shu-lian LIU; Xiao-hong PAN; Shui-ying ZHENG
2012-01-01
The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study.A new 3D computational fluid dynamics (CFD) analysis method is applied.Also,the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearing and rotor dynamics is considered in the analysis.Based on the structured mesh,a new approach for mesh movement is proposed to update the mesh volume when the journal moves during the fluid dynamics simulation of an oil film.Existing dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings.The movement of the journal is obtained by solving the moving equations of the rotor-bearing system with the calculated film pressure as the boundary condition of the load.The data exchange between fluid dynamics and rotor dynamics is realized by data files.Results obtained from the CFD model were consistent with previous experimental results on misalignedjournal bearings.Film pressure,oil film force,friction torque,misalignment moment and attitude angle were calculated and compared for misaligned and aligned journal bearings.The results indicate that bearing performances are greatly affected by misalignment which is caused by unbalanced excitation,and the CFD method based on the fluid-structure interaction (FSI) technique can effectively predict the transient flow field ofa misaligned journal bearing in a rotor-bearing system.
2006-10-31
Molecular Dipolar Rotors on Insulating Surfaces," Salamanca , Spain. Trends in Nanotechnology Conference. September 5-9, 2003 [86] Laura I. Clarke, Mary Beth...Horansky at the Trends in Nanotechnology Conference, Salamanca , Spain (September 5-9, 2003). [145] Michl, J. “Unusual Molecules: Artificial Surface...temperature and frequency for difluorophenylene rotor crystal. Figure JP6. Monte Carlo results for the local potential asymmetry at
A hybrid intelligent controller for a twin rotor MIMO system and its hardware implementation.
Juang, Jih-Gau; Liu, Wen-Kai; Lin, Ren-Wei
2011-10-01
This paper presents a fuzzy PID control scheme with a real-valued genetic algorithm (RGA) to a setpoint control problem. The objective of this paper is to control a twin rotor MIMO system (TRMS) to move quickly and accurately to the desired attitudes, both the pitch angle and the azimuth angle in a cross-coupled condition. A fuzzy compensator is applied to the PID controller. The proposed control structure includes four PID controllers with independent inputs in 2-DOF. In order to reduce total error and control energy, all parameters of the controller are obtained by a RGA with the system performance index as a fitness function. The system performance index utilized the integral of time multiplied by the square error criterion (ITSE) to build a suitable fitness function in the RGA. A new method for RGA to solve more than 10 parameters in the control scheme is investigated. For real-time control, Xilinx Spartan II SP200 FPGA (Field Programmable Gate Array) is employed to construct a hardware-in-the-loop system through writing VHDL on this FPGA.
Theodore, Colin R.
2010-01-01
A full-scale wind tunnel test to evaluate the effects of Individual Blade Control (IBC) on the performance, vibration, noise and loads of a UH-60A rotor was recently completed in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel [1]. A key component of this wind tunnel test was an automatic rotor trim control system that allowed the rotor trim state to be set more precisely, quickly and repeatably than was possible with the rotor operator setting the trim condition manually. The trim control system was also able to maintain the desired trim condition through changes in IBC actuation both in open- and closed-loop IBC modes, and through long-period transients in wind tunnel flow. This ability of the trim control system to automatically set and maintain a steady rotor trim enabled the effects of different IBC inputs to be compared at common trim conditions and to perform these tests quickly without requiring the rotor operator to re-trim the rotor. The trim control system described in this paper was developed specifically for use during the IBC wind tunnel test
Flowers, George T.
1995-02-01
This semiannual status report lists specific accomplishments made on the research of the influence of backup bearings and support structure dynamics on the behavior of rotors with active supports. Papers have been presented representing work done on the T-501 engine model; an experimental/simulation study of auxiliary bearing rotordynamics; and a description of a rotordynamical model for a magnetic bearing supported rotor system, including auxiliary bearing effects. A finite element model for a foil bearing has been developed. Additional studies of rotor/bearing/housing dynamics are currently being performed as are studies of the effects of sideloading on auxiliary bearing rotordynamics using the magnetic bearing supported rotor model.
Synchronous b ehavior of a rotor-p endulum system%转子耦合摆系统的同步行为理论研究∗
方潘; 侯勇俊; 张丽萍; 杜明俊; 张梦媛
2016-01-01
Rotor-pendulum systems are widely applied to aero-power plants, mining screening machineries, parallel robots, and other high-speed rotating equipment. However, the investigation for synchronous behavior (the computation for stable phase difference between the rotors) of a rotor-pendulum system has been reported very little. The synchronous behavior usually affects the performance precision and quality of a mechanical system. Based on the special background, a simplified physical model for a rotor-pendulum system is introduced. The system consists of a rigid vibrating body, a rigid pendulum rod, a horizontal spring, a torsion spring, and two unbalanced rotors. The vibrating body is elastically supported via the horizontal spring. One of unbalanced rotors in the system is directly mounted in the vibrating body, and the other is fixed at the end of the pendulum rod connected with the vibrating body by the torsion spring. In addition, the rotors are actuated with the identical induction motors. In this paper, we investigate the synchronous state of the system based on Poincaré method, which further reveals the essential mechanism of synchronization phenomenon of this system. To determine the synchronous state of the system, the following computation technologies are implemented. Firstly, the dynamic equation of the system is derived based on the Lagrange equation with considering the homonymous and reversed rotation of the two rotors, then the equation is converted into a dimensionless equation. Further, the dimensionless equation is decoupled by the Laplace method, and the approximated steady solution and coupling coeﬃcient of each degree of freedom are deduced. Afterwards, the balanced equation and the stability criterion of the system are acquired. Only should the values of physical parameters of the system satisfy the balanced equation and the stability criterion, the rotor-pendulum system can implement the synchronous operation. According to the theoretical
Paquette, J. A.
2012-03-01
Sandia National Laboratories (SNL) and Verdant Power Inc. (VPI) have partnered under a Cooperative Research and Development Agreement (CRADA) to develop a new kinetic hydropower rotor. The rotor features an improved hydrodynamic and structural design which features state-of-the-art technology developed for the wind industry. The new rotor will have higher energy capture, increased system reliability, and reduction of overall cost of energy. This project was divided into six tasks: (1) Composite Rotor Project Planning and Design Specification; (2) Baseline Fatigue Testing and Failure analysis; (3) Develop Blade/Rotor Performance Model; (4) Hydrofoil Survey and Selection; (5) FEM Structural Design; and (6) Develop Candidate Rotor Designs and Prepare Final Report.
Boeing Smart Rotor Full-scale Wind Tunnel Test Data Report
Kottapalli, Sesi; Hagerty, Brandon; Salazar, Denise
2016-01-01
A full-scale helicopter smart material actuated rotor technology (SMART) rotor test was conducted in the USAF National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel at NASA Ames. The SMART rotor system is a five-bladed MD 902 bearingless rotor with active trailing-edge flaps. The flaps are actuated using piezoelectric actuators. Rotor performance, structural loads, and acoustic data were obtained over a wide range of rotor shaft angles of attack, thrust, and airspeeds. The primary test objective was to acquire unique validation data for the high-performance computing analyses developed under the Defense Advanced Research Project Agency (DARPA) Helicopter Quieting Program (HQP). Other research objectives included quantifying the ability of the on-blade flaps to achieve vibration reduction, rotor smoothing, and performance improvements. This data set of rotor performance and structural loads can be used for analytical and experimental comparison studies with other full-scale rotor systems and for analytical validation of computer simulation models. The purpose of this final data report is to document a comprehensive, highquality data set that includes only data points where the flap was actively controlled and each of the five flaps behaved in a similar manner.
Inlet Guide Vane Wakes Including Rotor Effects
Johnston, R. T.; Fleeter, S.
2001-02-01
Fundamental experiments are described directed at the investigation of forcing functions generated by an inlet guide vane (IGV) row, including interactions with the downstream rotor, for application to turbomachine forced response design systems. The experiments are performed in a high-speed research fan facility comprised of an IGV row upstream of a rotor. IGV-rotor axial spacing is variable, with the IGV row able to be indexed circumferentially, thereby allowing measurements to be made across several IGV wakes. With an IGV relative Mach number of 0.29, measurements include the IGV wake pressure and velocity fields for three IGV-rotor axial spacings. The decay characteristics of the IGV wakes are compared to the Majjigi and Gliebe empirical correlations. After Fourier decomposition, a vortical-potential gust splitting analysis is implemented to determine the vortical and potential harmonic wake gust forcing functions both upstream and downstream of the rotor. Higher harmonics of the vortical gust component of the IGV wakes are found to decay at a uniform rate due to viscous diffusion.
Effects of tooth profile modification on dynamic responses of a high speed gear-rotor-bearing system
Hu, Zehua; Tang, Jinyuan; Zhong, Jue; Chen, Siyu; Yan, Haiyan
2016-08-01
A finite element node dynamic model of a high speed gear-rotor-bearing system considering the time-varying mesh stiffness, backlash, gyroscopic effect and transmission error excitation is developed. Different tooth profile modifications are introduced into the gear pair and corresponding time-varying mesh stiffness curves are obtained. Effects of the tooth profile modification on mesh stiffness are analyzed, and the natural frequencies and mode shapes of the gear-rotor-bearing transmission system are given. The dynamic responses with respect to a wide input speed region including dynamic factor, vibration amplitude near the bearing and dynamic transmission error are obtained by introducing the time-varying mesh stiffness in different tooth profile modification cases into the gear-rotor-bearing dynamic system. Effects of the tooth profile modification on the dynamic responses are studied in detail. The numerical simulation results show that both the short profile modification and the long profile modification can affect the mutation of the mesh stiffness when the number of engaging tooth pairs changes. A short profile modification with an appropriate modification amount can improve the dynamic property of the system in certain work condition.
Seki, K.; Shimizu, Y.; Yasui, T. [Tokai University, Tokyo (Japan)
1997-11-25
Dynamic force on blades in a large wind mill changes with rotational speed for various reasons, such as wind shear that causes vertical distribution of wind velocity or titling angle. Therefore, a 2-blade system on a teetered hub is a practical selection for the coned, down-wind type. Use of teetered axis greatly reduces bending moment in the flap direction and that at the axis of rotation. An attempt was made to understand dynamic loads by inertial force resulting from oscillation of the blade rotating on the teetered axis, and thereby to avoid them. The in-plane load can be diminished to zero when the teetered axis is coincided with the center of gravity, but generally cannot be avoided when the blade is strained significantly, except it is operated at the rated condition. The in-plane load and bending moment can be avoided, when rotational freedom is given around the y axis. Dynamic load on a down-wind rotor can be avoided by use of universal joint. 3 refs., 6 figs.
Investigation of the fluid flow in an isolated rotor-stator system with a peripheral opening
Debuchy, Roger; Abdel Nour, Fadi; Naji, Hassane; Bois, Gérard
2013-04-01
This paper deals with an experimental, theoretical and numerical study of a turbulent flow with separated boundary layers between a rotor and a stator. The system is not subjected to any superimposed radial flow. The periphery of the cavity is opened to the atmosphere so that the solid body rotation for infinite discs is not always observed. Emphasis was placed on development of an asymptotic approach and a step-by-step method to compute the radial distribution of the core swirl ratio and the static pressure on the stator side. The theory also includes the radial and axial velocities in the core region. The numerical simulation has been conducted with the commercial CFD code Fluent 6.1. The k- ωSST turbulence model is used, with the assumption of 2D-axisymmetric and steady flow. CFD validations have been performed by comparison of the numerical results with the corresponding theoretical results. Numerical and experimental results are in good agreement with analytical solutions.
Local heterogeneities in cardiac systems suppress turbulence by generating multi-armed rotors
Zhang, Zhihui; Steinbock, Oliver
2016-05-01
Ventricular fibrillation is an extremely dangerous cardiac arrhythmia that is linked to rotating waves of electric activity and chaotically moving vortex lines. These filaments can pin to insulating, cylindrical heterogeneities which swiftly become the new rotation backbone of the local wave field. For thin cylinders, the stabilized rotation is sufficiently fast to repel the free segments of the turbulent filament tangle and annihilate them at the system boundaries. The resulting global wave pattern is periodic and highly ordered. Our cardiac simulations show that also thicker cylinders can establish analogous forms of tachycardia. This process occurs through the spontaneous formation of pinned multi-armed vortices. The observed number of wave arms N depends on the cylinder radius and is associated to stability windows that for N = 2, 3 partially overlap. For N = 1, 2, we find a small gap in which the turbulence is removed but the pinned rotor shows complex temporal dynamics. The relevance of our findings to human cardiology are discussed in the context of vortex pinning to more complex-shaped anatomical features and remodeled myocardium.
Non-linear dynamics of a geared rotor-bearing system with multiple clearances
Kahraman, A.; Singh, R.
1991-02-01
Non-linear frequency response characteristics of a geared rotor-bearing system are examined in this paper. A three-degree-of-freedom dynamic model is developed which includes non-linearities associated with radial clearances in the radial rolling element bearings and backlash between a spur gear pair; linear time-invariant gear meshing stiffness is assumed. The corresponding linear system problem is also solved, and predicted natural frequencies and modes match with finite element method results. The bearing non-linear stiffness function is approximated for the sake of convenience by a simple model which is identical to that used for the gear mesh. This approximate bearing model has been verified by comparing steady state frequency spectra. Applicability of both analytical and numerical solution techniques to the multi-degree-of-freedom non-linear problem is investigated. Satisfactory agreement has been found between our theory and available experimental data. Several key issues such as non-linear modal interactions and differences between internal static transmission error excitation and external torque excitation are discussed. Additionally, parametric studies are performed to understand the effect of system parameters such as bearing stiffness to gear mesh stiffness ratio, alternating to mean force ratio and radial bearing preload to mean force ratio on the non-linear dynamic behavior. A criterion used to classify the steady state solutions is presented, and the conditions for chaotic, quasi-periodic and subharmonic steady state solutions are determined. Two typical routes to chaos observed in this geared system are also identified.
Test rig for investigations of force excited and synchrocoupling loaded rotor
Rauch, Adam
1987-10-01
The main topics of test rig based rotor investigations are: dynamic relations of a rotor bearing foundation system, shaft cracking, torsional simulation of rotor-generator hunting, flexural-torsional coupling of vibrations, and other areas of rotor dynamics including balancing, maintenance and modal analysis of a rotor. The present paper describes a general purpose rotor test rig capable of handling a great number of these areas. The test rig simulates a heavy, power-loaded rotor mounted on a flexible foundation. Five forms of excitation are provided: oscillating or impact torque, impact force, step force, bearing and foundation excitation. They can be combined if necessary. New research facilities offered by the rig are: external flexural force loading, driving torque loading by synchrocoupling with a full recovery of brake energy, bending release of rotor ends by pivoting, and multi-pulse impact force excitation. The most remarkable is the synchroaxle principle, called SAP for short, which is described in detail. Test rig features have been proved to be successful by research of shaft cracking and rotor-foundation vibrations. This presentation concerns only the general description, calculation and application aspects of the rig.
Juing-Shian Chiou
2013-01-01
Full Text Available This paper has implemented nonlinear control strategy for the single tilt tri-rotor aerial robot. Based on Newton-Euler’s laws, the linear and nonlinear mathematical models of tri-rotor UAVs are obtained. A numerical analysis using Newton-Raphson method is chosen for finding hovering equilibrium point. Back-stepping nonlinear controller design is based on constructing Lyapunov candidate function for closed-loop system. By imitating the linguistic logic of human thought, fuzzy logic controllers (FLCs are designed based on control rules and membership functions, which are much less rigid than the calculations computers generally perform. Effectiveness of the controllers design scheme is shown through nonlinear simulation model on each channel.
Fecht, Nikolaus
2010-06-15
With seven wind turbines, the Austrian wind farm ''Sternwald'' is the biggest wind farm in Upper Austria. It is the only wind farm in a forest, and all turbines are therefore equipped with automatic fire fighting equipment. The mountain range on which the wind farm is located is about 1000 m high, with strong wind and much ice and snow in the winter season. For this reason, the owner decided to instal a condition monitoring system with ice detectors. The piezoelectric sensors are mounted directly on the rotor blades as measurements on the nacelle will always be incorrect. Installation on the rotor blades, on the other hand, makes high demands on the fastenings and sensors as the velocity of the blade tips may be up to 250 km per hour. (orig.)
Robuck, Mark; Wilkerson, Joseph; Snyder, Christopher A.; Zhang, Yiyi; Maciolek, Bob
2013-01-01
In a series of study tasks conducted as a part of NASA's Fundamental Aeronautics Program, Rotary Wing Project, Boeing and Rolls-Royce explored propulsion, drive, and rotor system options for the NASA Large Civil Tilt Rotor (LCTR2) concept vehicle. The original objective of this study was to identify engine and drive system configurations to reduce rotor tip speed during cruise conditions and quantify the associated benefits. Previous NASA studies concluded that reducing rotor speed (from 650 fps hover tip speed) during cruise would reduce vehicle gross weight and fuel burn. Initially, rotor cruise speed ratios of 54% of the hover tip speed were of most interest during operation at cruise air speed of 310 ktas. Interim results were previously reported1 for cruise tip speed ratios of 100%, 77%, and 54% of the hover tip speed using engine and/or gearbox features to achieve the reduction. Technology levels from commercial off-the-shelf (COTS), through entry-in-service (EIS) dates of 2025 and 2035 were considered to assess the benefits of advanced technology on vehicle gross weight and fuel burn. This technical paper presents the final study results in terms of vehicle sizing and fuel burn as well as Operational and Support (O&S) costs. New vehicle sizing at rotor tip speed reduced to 65% of hover is presented for engine performance with an EIS 2035 fixed geometry variable speed power turbine. LCTR2 is also evaluated for missions range cases of 400, 600, 800, 1000, and 1200 nautical miles and cruise air speeds of 310, 350 and 375 ktas.
ROTOR AND SCREW TECHNOLOGICAL SYSTEMS FOR PREPARATION OF SOLUTIONS AND CONCRETE
Belokur K. A.
2016-04-01
Full Text Available We have provided technical solutions to improve performance of technological systems for the preparation of solutions and concrete based on the use of screw rotors in the form of drums with helix lines formed on the perimeter as interconnect lines of his spiral surfaces. We discuss the six varieties of devices and installations for mixing, including concrete mixers, reels which are of a complicated geometric body formed by helical surfaces with variable or constant pitch and which creates screw lines in the places of their connection. In the form of screw drums, they may be conical, concave, convex, cylindrical. The experimental test was conducted on the concrete mixer drums, which are arranged one in the other. The implementation of the mixer in the form of coaxially edited two barrels provides not only a reduction in size in length, but a significant reduction in energy consumption due to the use of heat, released during the activation process of inert heating of the concrete mix as when re-mixing and concrete mix when mixing it with water and transportation. The drums of such systems is made of flat elements with the formation of the helical lines discretely spaced around the perimeter of different pitch and with different numbers directed towards each other helical surfaces. In the process of transporting the components of concrete in the internal screw drum there is active mixture of sand, gravel and cement. Thus, there is not only the destruction of lumpy, sticky components of the raw materials, but also active uniform distribution of particles of cement, sand and gravel into a homogenous mass. The implementation of the proposed technology and equipment ensures not only reduction of the dimensions of the mixer length, but also improving the quality of finished products, as well as potential cement savings of 3-5%
Ohara, Masaki; Noguchi, Toshihiko
This paper describes a new method for a rotor position sensorless control of a surface permanent magnet synchronous motor based on a model reference adaptive system (MRAS). This method features the MRAS in a current control loop to estimate a rotor speed and position by using only current sensors. This method as well as almost all the conventional methods incorporates a mathematical model of the motor, which consists of parameters such as winding resistances, inductances, and an induced voltage constant. Hence, the important thing is to investigate how the deviation of these parameters affects the estimated rotor position. First, this paper proposes a structure of the sensorless control applied in the current control loop. Next, it proves the stability of the proposed method when motor parameters deviate from the nominal values, and derives the relationship between the estimated position and the deviation of the parameters in a steady state. Finally, some experimental results are presented to show performance and effectiveness of the proposed method.
Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System
Nicoletti, Rodrigo; Santos, Ilmar
2004-01-01
In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserte...
Active vibration control of a rotor-bearing system based on dynamic stiffness
Andrés Blanco Ortega
2010-01-01
Full Text Available En este artículo se presenta un esquema de control activo de vibraciones para atenuar las amplitudes de vibración síncrona inducidas por el desbalance en un sistema rotorchumaceras; donde una de las chumaceras puede ser desplazada automáticamente para modificar la longitud efectiva del rotor, y como consecuencia, la rigidez del rotor. El control de la rigidez dinámica se basa en un análisis de la respuesta en frecuencia, control de velocidad y en el uso de esquemas de aceleración, para evadir las amplitudes de la vibración en la resonancia mientras el sistema rotatorio pasa (acelerado o desacelerado a través de una velocidad crítica. Se utiliza identificación algebraica para estimar el desbalance en línea, mientras el rotor es llevado a la velocidad de operación deseada. Algunas simulaciones numéricas y resultados experimentales son incluidos para mostrar las propiedades de la compensación del desbalance y la robustez del esquema de control activo de vibraciones propuesto, cuando el rotor se opera a una velocidad por encima de la primera velocidad crítica.
C. Udhaya Shankar
2015-02-01
Full Text Available This study deals with the comparative analysis of performances of power system stabilizer and SVC. A 3 bus 2 generator power system network is used as a test system. Both generic PSS and multi band PSS are first analyzed. The fault analysis is carried out for the above test system with both generic and multi band PSS. It is observed that multi-band PSS resulted in better transient response for single phase faults. The multi band PSS resulted in good dynamic response due to absence of low frequency oscillations after clearing the fault. The system became unstable for three phase fault in both types of PSS. Then the SVC is connected in the above test system. The fault analysis is carried out with SVC connected at the midpoint of the above system. The simulation results show that performance of SVC for voltage and rotor angle stability is improved compared to multi-band PSS based system and also the system could regain its stability after removing three phase fault. It is also observed that SVC improves transient stability margin by increasing the critical clearing time and reducing rotor angle oscillations. The simulation is carried out using MATLAB software.
Dominguez-Nuñez, L. A.; Silva-Navarro, G.
2014-04-01
The general study and applications of Magneto-Rhelogical (MR) dampers have been spread in the lasts years but only some studies have been focusing on the vibration control problems on rotor-bearings systems. Squeeze-Film Dampers (SFD) are now commonly used to passively control the vibration response on rotor-bearing systems because they can provide flexibility, damping and extend the so-called stability thresholds in rotating machinery. More recently, SFD are combined with MR or Electro-Rheological (ER) fluids to introduce a semiactive control mechanism to modify the rotordynamic coefficients and deal with the robust performance of the overall system response for higher operating speeds. There are, however, some theoretical and technological problems that complicate their extensive use, like the relationship between the centering spring flexibility and the rheological behavior of the smart fluid to produce the SFD forces. In this work it is considered a SFD with MR fluid and a set of circular section beams in a squirrel cage arrangement in combination with latex seals as centering springs. The mathematical model analysis includes the controllable viscoelastic properties associated to the MR fluid. The characterization of the SFD is made by the determination of some coefficients associated with a modified Choi-Lee-Park polynomial model. During the analysis is considered a rotor-bearing system modeled using finite element methods. The SFD with MR fluid is connected to an experimental platform to validate and experimentally evaluate the overall system. Finally, to improve the open-loop system performance, a methodology for the use of different control schemes is proposed.
Noor Izzri Abdul Wahab
2012-01-01
Full Text Available This paper describes an index for judging the severity of transient events of power systems in simulation. The proposed transient stability index, known as the area-based COI-referred rotor angle index, is developed by considering the fact that a large-sized power system is divided into several areas according to the coherency of generators in a particular area. It can be assumed that an equivalent single large machine can represent all the generators in that area. Thus, the assessment of rotor angles for all generators can be simplified by only assessing the index of areas in a power system. The effectiveness of the proposed index in assessing the stability of power systems and its ability in pinpointing the weakest area in the power system is analyzed. Furthermore, this paper developed an emergency control scheme known as the combined UFLS and generator tripping in order to stabilize the system when unstable faults occurred in a power system. The proposed index is used to identify the generator to be tripped when the developed emergency control scheme operates. The performance of the proposed index and the combined UFLS and generator tripping scheme are evaluated on the IEEE 39-bus test system.
Shilin Chen
1994-01-01
Full Text Available An exact and direct modeling technique is proposed for modeling of rotor-bearing systems with arbitrary selected degrees-of-freedom. This technique is based on the combination of the transfer and dynamic stiffness matrices. The technique differs from the usual combination methods in that the global dynamic stiffness matrix for the system or the subsystem is obtained directly by rearranging the corresponding global transfer matrix. Therefore, the dimension of the global dynamic stiffness matrix is independent of the number of the elements or the substructures. In order to show the simplicity and efficiency of the method, two numerical examples are given.
ZHOU Shihua; SONG Guiqiu; REN Zhaohui; WEN Bangchun
2016-01-01
Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.
Zhou, Shihua; Song, Guiqiu; Ren, Zhaohui; Wen, Bangchun
2016-03-01
Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.
Feedback Control of Rotor Overspeed
Churchill, G. B.
1984-01-01
Feedback system for automatically governing helicopter rotor speed promises to lessen pilot's workload, enhance maneuverability, and protect airframe. With suitable modifications, concept applied to control speed of electrical generators, automotive engines and other machinery.
无
2000-01-01
A model for the non-linear axial vibrations of the hydrodynamic thrust bearing-rotor system in a turboexpander is described.The axial transient process of the system is investigated.The timedependent form ofthe Reynolds equation is solved by a finite difference method with successive overrelaxation scheme to obtain the hydrodynamic forces of the sector-shaped thrust bearing (SSTB).Using these forces,the equation of motion is solved by the fourth-order Runge-Kutta method and the Adams method to predict the transient behaviour of the thrust bearing-rotor system (TBRS).Also,the linearized stiffness and damping coefficients of the oil film hydrodynamic SSTB are calculated.The analyses of the axial transient response of the system under both linear and non-linear conditions are performed.The non-linearity of oil film forces can significantly contribute to the axial transient response.Conclusions obtained can be applied for evaluation of the reliability of the TBRS.
On Cup Anemometer Rotor Aerodynamics
Santiago Pindado; Sergio Avila-Sanchez; Javier Pérez
2012-01-01
The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a lin...
Dynamic Analysis of a Helicopter Rotor by Dymore Program
Doğan, Vedat; Kırca, Mesut
The dynamic behavior of hingeless and bearingless blades of a light commercial helicopter which has been under design process at ITU (İstanbul Technical University, Rotorcraft Research and Development Centre) is investigated. Since the helicopter rotor consists of several parts connected to each other by joints and hinges; rotors in general can be considered as an assembly of the rigid and elastic parts. Dynamics of rotor system in rotation is complicated due to coupling of elastic forces (bending, torsion and tension), inertial forces, control and aerodynamic forces on the rotor blades. In this study, the dynamic behavior of the rotor for a real helicopter design project is analyzed by using DYMORE. Blades are modeled as elastic beams, hub as a rigid body, torque tubes as rigid bodies, control links as rigid bodies plus springs and several joints. Geometric and material cross-sectional properties of blades (Stiffness-Matrix and Mass-Matrix) are calculated by using VABS programs on a CATIA model. Natural frequencies and natural modes of the rotating (and non-rotating) blades are obtained by using DYMORE. Fan-Plots which show the variation of the natural frequencies for different modes (Lead-Lag, Flapping, Feathering, etc.) vs. rotor RPM are presented.
Ping Zheng
2017-05-01
Full Text Available The magnetic-field-modulated brushless double-rotor machine (MFM-BDRM, composed of a stator, a modulating ring rotor, and a PM rotor, is a kind of power-split device for hybrid electric vehicles (HEVs. In this paper, a new MFM-BDRM with sinusoidal-permeance modulating ring named Sinusoidal-Permeance-Modulating-Ring Brushless Double-Rotor Machine (SPMR-BDRM is proposed to solve the problem of poor mechanical strength and large iron loss. The structure and the operating principle of the MFM-BDRM are introduced. The design principle of the sinusoidal-permeance modulating ring is analyzed and derived. The main idea of that is to minimize the harmonic permeance of air gap, thereby the harmonic magnetic fields can be restrained. There are comparisons between a MFM-BDRM with sinusoidal-permeance modulating ring and a same size MFM-BDRM with traditional modulating ring, including magnetic field distributions and electromagnetic performances. Most importantly, the iron losses are compared under six different conditions. The result indicates that the harmonic magnetic fields in the air gap are restrained; the electromagnetic torque and power factor are almost the same with same armature current; the torque ripples of the modulating ring rotor and the PM rotor are reduced; the stator loss is reduced by 13% at least and the PM loss is reduced by 20% at least compared with the same size traditional MFM-BDRM under the same operating conditions.
Application of a cost/performance measurement system on a research aircraft project
Diehl, J. J.
1978-01-01
The fundamentals of the cost/performance management system used in the procurement of two tilt rotor aircraft for a joint NASA/Army research project are discussed. The contractor's reporting system and the GPO's analyses are examined. The use of this type of reporting system is assessed. Recommendations concerning the use of like systems on future projects are included.
Blade Displacement Measurements of the Full-Scale UH-60A Airloads Rotor
Barrows, Danny A.; Burner, Alpheus W.; Abrego, Anita I.; Olson, Lawrence E.
2011-01-01
Blade displacement measurements were acquired during a wind tunnel test of the full-scale UH-60A Airloads rotor. The test was conducted in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at NASA Ames Research Center. Multi-camera photogrammetry was used to measure the blade displacements of the four-bladed rotor. These measurements encompass a range of test conditions that include advance ratios from 0.15 to unique slowed-rotor simulations as high as 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective of these measurements is to provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft computational tools. The methodology, system development, measurement techniques, and preliminary sample blade displacement measurements are presented.
Higashi, K. K.; Minges, G. P.; Price, G. D.
1982-10-01
The use of a wound rotor variable speed, constant frequency generator with small wind systems was investigated. The main initial objective was to demonstrate proof of concept under controlled conditions. The feasibility of this application was confirmed and it was shown that improved performance could be expected over a constant speed, constant frequency generator systems. The ability to maintain a constant tip speed ratio near the maximum rotor performance coefficient over a wide range of wind speeds is noted. A substantial increase in annual energy output can be expected from VSCF operation. Controlled start up and shutdown can also reduce the high transient torques and concomitant inrush currents common to induction generator systems.
Zhong-xiu FEI; Shui-guang TONG; Chao WEI
2013-01-01
Recently,the finite element method (FEM) has been commonly applied in the engineering analysis of rotor dynamics.Gyroscopic moments,rotary inertia,transverse shear deformation and gravity can be included in computational models of rotor-bearing systems.In this paper,a finite element model and its solution method are presented for the calculation of the dynamics of dual rotor systems.A typical structure with two rotor shafts is discussed and the procedure for obtaining the coupling motion equations of the subsystems is illustrated.A computer program is developed to solve critical speeds and to simulate the transient motion.The influence of gyroscopic moments on co-rotation and counter-rotation is analyzed,and the effect of the speed ratio on critical speed is studied.The dynamic characteristics under different conditions of increasing speed during start-up are demonstrated by comparison with transient nodal displacements.The presented model provides a complete foundation for further investigation of the dynamics of dual rotor systems.
Estimation of Alignment and Transverse Load in Multi-Bearing Rotor System
1997-01-01
The paper presents a method for estimation of a multi-bearing machine alignment on the basis of measured eccentricities of the shaft in machine bearings. The method uses a linear FEM model of the rotor and the non-linear models of machine bearings. In the presented example, the non-linear models of hydrodynamic bearings are used, but it is shown, that the method could be easily applied to other types of bearings. In addition to the alignment estimation, the method allows to est...
Experimental Investigation of a Shrouded Rotor Micro Air Vehicle in Hover and in Edgewise Gusts
Hrishikeshavan, Vikram
Due to the hover capability of rotary wing Micro Air Vehicles (MAVs), it is of interest to improve their aerodynamic performance, and hence hover endurance (or payload capability). In this research, a shrouded rotor configuration is studied and implemented, that has the potential to offer two key operational benefits: enhanced system thrust for a given input power, and improved structural rigidity and crashworthiness of an MAV platform. The main challenges involved in realising such a system for a lightweight craft are: design of a lightweight and stiff shroud, and increased sensitivity to external flow disturbances that can affect flight stability. These key aspects are addressed and studied in order to assess the capability of the shrouded rotor as a platform of choice for MAV applications. A fully functional shrouded rotor vehicle (disk loading 60 N/ m2) was designed and constructed with key shroud design variables derived from previous studies on micro shrouded rotors. The vehicle weighed about 280 g (244 mm rotor diameter). The shrouded rotor had a 30% increase in power loading in hover compared to an unshrouded rotor. Due to the stiff, lightweight shroud construction, a net payload benefit of 20-30 g was achieved. The different components such as the rotor, stabilizer bar, yaw control vanes and the shroud were systematically studied for system efficiency and overall aerodynamic improvements. Analysis of the data showed that the chosen shroud dimensions was close to optimum for a design payload of 250 g. Risk reduction prototypes were built to sequentially arrive at the final configuration. In order to prevent periodic oscillations in ight, a hingeless rotor was incorporated in the shroud. The vehicle was successfully ight tested in hover with a proportional-integralderivative feedback controller. A flybarless rotor was incorporated for efficiency and control moment improvements. Time domain system identification of the attitude dynamics of the flybar and
M. Hassan Tanveer
2013-01-01
Full Text Available This article presents a control approach to obtain the better stabilization in attitude and altitude of quad-rotor under different disturbance conditions. In the standard Quad-rotor rotor type UAV, controlling of attitude and altitude is one of the most critical tasks and appropriate controller for stabilization of UAV is essential and necessary. These two controls under various conditions of disturbances was a field of research stimulating for the researchers. The controller proposed is contingent on the PID feedback structure with Extended Kalman Filter (EKF. From Lyapunov Stability Theorem, it is proved that quad-rotor proposed altitude control system is asymptotic as well exponentially stability. Extended Kalman Filter (EKF is used to filter out the sensors and system noises. Finally, the simulations carried out on MATLAB and the result proved the effectiveness of proposed recommended method for stabilization of attitude and altitude of quad-rotor.
A doubly-fed induction generator-based wind generation system with quasi-sine rotor injection
Yuvarajan, S.; Fan, Lingling
Wind generating systems use doubly-fed induction generators (DFIGs) to achieve high conversion efficiency and to reduce the installation cost. The paper proposes and analyzes a simple DFIG-based wind generation system in which the excitation power is obtained from a photovoltaic (PV) panel and battery. The proposed scheme is suitable for small wind power systems for which a complex field orientation control is not justified. It can be used for stand-alone operation and also grid-tied operation. The rotor of the DFIG is applied with a quasi-sine wave instead of a sine wave. The operation and harmonic characteristics of the scheme are established using analysis, simulation, and experimentation. The details of the control circuit are given along with the experimental waveforms of voltages and currents and frequency spectra. The total harmonic distortion in the output current is found to be around 8%.
LI, M.; YU, L.
2001-05-01
The misalignment of a gear coupling in a multirotor system is an important problem; it can cause various faults. In the present work the non-linear coupled lateral torsional vibration model of rotor-bearing-gear coupling system is developed based on the engagement conditions of gear couplings. Theoretical analysis shows that the forces and moments acting on gear couplings due to the initial misalignment are from the inertia forces of the sleeve and the internal damping between the meshing teeth, and depend on the misalignment, internal damping, the rotating speed, and the structural parameters of the gear coupling. Numerical analysis of the signature of vibration reveals that the even-integer multiples of the rotating speed of lateral vibration and the odd-integer multiples of the torsional vibration occur in the misaligned system, and the integer multiples of vibration are apparent around the gear coupling.
2008-03-01
capability Framework for incorporating additional ULS systems research Motivate Research • The roadmap shows how an individual research initiative...6.2.2 Metaheuristics in Software Engineering 6.2.3 Digital Evolution 6.3.1 Design of All Levels 6.3.2 Design Spaces and Design Rules 6.3.3 Harnessing...achieving a future ULS systems capability Framework for incorporating additional ULS systems research Motivate Research • The roadmap shows how an
Pegg, R. J.; Hosier, R. N.; Balcerak, J. C.; Johnson, H. K.
1975-01-01
Full-scale tests were conducted on the Langley helicopter rotor test facility as part of a study to evaluate the effectiveness of a turbulent blade tip air mass injection system in alleviating the impulsive noise (blade slap) caused by blade-vortex interaction. Although blade-slap conditions could not be induced during these tests, qualitative results from flow visualization studies using smoke showed that the differential velocity between the jet velocity and the rotor tip speed was a primary parameter controlling the vortex modification.
Active damping of flexible rotor blade dynamics using electrorheological-fluid-based actuators
Wereley, Norman M.
1994-05-01
Advanced rotor systems including hingeless and bearingless rotors have air and ground resonance instabilities due to coalescence of low-frequency rotor modes with landing gear and fuselage modes, respectively. This coalescence is of difficulty due to the direct connection of the rotor blade in these advanced rotor systems to the rotor hub using a flexure or flexbeam. We are currently exploring the mitigation of this modal coalescence through the use of active damping techniques and electro-rheological fluid technology.
Qian Chen
2016-01-01
Full Text Available The shafting of large steam turbine generator set is composed of several rotors which are connected by couplings. The computing method of shafting with different structure under specific installation requirement is studied in this paper. Based on three-moment equation, shafting alignment mathematical model is established. The computing method of bearing elevations and loads under corresponding installation requirements, where bending moment of each coupling is zero and there exist preset sag and gap in some couplings, is proposed, respectively. Bearing elevations and loads of shafting with different structure under specific installation requirement are calculated; calculation results are compared with installation data measured on site which verifies the validity and accuracy of the proposed shafting alignment computing method. The above work provides a reliable approach to analyze shafting alignment and could guide installation on site.
Enemark, Søren; Santos, Ilmar F.
2016-01-01
Helical pseudoelastic shape memory alloy (SMA) springs are integrated into a dynamic system consisting of a rigid rotor supported by passive magnetic bearings. The aim is to determine the utility of SMAs for vibration attenuation via their mechanical hysteresis, and for adaptation of the dynamic ...
Design of plywood and paper flywheel rotors
Hagen, D. L.
Technical and economic design factors of cellulosic rotors are compared with conventional materials for stationary flywheel energy storage systems. Wood species, operation in a vacuum, assembly and costs of plywood rotors are evaluated. Wound kraft paper, twine and veneer rotors are examined. Two bulb attachments are designed. Support stiffness is shown to be constrained by the material strength, rotor configuration and speed ratio. Plywood moisture equilibrium during manufacture and assembly is critical. Disk shaping and rotor assembly are described. Potential self-centering dynamic balancing methods and equipment are described. Detailed measurements of the distribution of strengths, densities and specific energy of conventional Finnish Birch plywood and of custom made hexagonal Birch plywood are detailed. High resolution tensile tests were performed while monitoring the acoustic emissions with micoprocessor controlled data acquisition. Preliminary duration of load tests were performed on vacuum dried hexagonal birch plywood. Economics of cellulosic and conventional rotors were examined.
Pneumatic boot for helicopter rotor deicing
Blaha, B. J.; Evanich, P. L.
1981-01-01
Pneumatic deicer boots for helicopter rotor blades were tested. The tests were conducted in the 6 by 9 ft icing research tunnel on a stationary section of a UH-IH helicopter main rotor blade. The boots were effective in removing ice and in reducing aerodynamic drag due to ice.
Urquiza Beltran, Gustavo; Rios Miranda, Edmundo; Venegas Guzman, Ricardo; Alvarez Garcia, Gabriela [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1991-12-31
This article presents a supervisory system that, as its main functions, assists the operator on base of the thermal stresses, monitoring in real time the high pressure (HP) and intermediate pressure rotors (IP) of a steam turbine during the start, shut down and/or sudden load changes. The system is based on a thermal model uni-dimensional integrated to the SIMPER (Information System for the Predictive Maintenance of Rotating Equipment), tested in a 300 MW unit of Comision Federal de Electricidad (CFE). [Espanol] En este articulo se presenta un sistema supervisorio que, como funciones principales, asiste al operador con base en el monitoreo de esfuerzos termicos en tiempo real en los rotores de presion alta (PA) y presion intermedia (PI) de una turbina de vapor durante un arranque, paro y/o variaciones bruscas de carga. El sistema esta basado en un modelo termico unidimensional integrado al SIMPER (sistema informatico para el mantenimiento predictivo de equipo rotatorio), experimentado en una unidad de 300 MW de la Comision Federal de Electricidad (CFE).
Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo
2016-05-01
In this paper, self- and controlled synchronizations of three eccentric rotors (ERs) in line driven by induction motors rotating in the same direction in a vibrating system are investigated. The vibrating system is a typical underactuated mechanical-electromagnetic coupling system. The analysis and control of the vibrating system convert to the synchronization motion problem of three ERs. Firstly, the self-synchronization motion of three ERs is analyzed according to self-synchronization theory. The criterions of synchronization and stability of self-synchronous state are obtained by using a modified average perturbation method. The significant synchronization motion of three ERs with zero phase differences cannot be implemented according to self-synchronization theory through analysis and simulations. To implement the synchronization motion of three ERs with zero phase differences, an adaptive sliding mode control (ASMC) algorithm based on a modified master-slave control strategy is employed to design the controllers. The stability of the controllers is verified by using Lyapunov theorem. The performances of the controlled synchronization system are presented by simulations to demonstrate the effectiveness of controllers. Finally, the effects of reference speed and non-zero phase differences on the controlled system are discussed to show the strong robustness of the proposed controllers. Additionally, the dynamic responses of the vibrating system in different synchronous states are analyzed.
Empennage Noise Shielding Benefits for an Open Rotor Transport
Berton, Jeffrey J.
2012-01-01
NASA sets aggressive, strategic, civil aircraft performance and environmental goals and develops ambitious technology roadmaps to guide its research efforts. NASA has adopted a phased approach for community noise reduction of civil aircraft. While the goal of the near-term first phase focuses primarily on source noise reduction, the goal of the second phase relies heavily on presumed architecture changes of future aircraft. The departure from conventional airplane configurations to designs that incorporate some type of propulsion noise shielding is anticipated to provide an additional 10 cumulative EPNdB of noise reduction. One candidate propulsion system for these advanced aircraft is the open rotor engine. In some planned applications, twin open rotor propulsors are located on the aft fuselage, with the vehicle s empennage shielding some of their acoustic signature from observers on the ground. This study focuses on predicting the noise certification benefits of a notional open rotor aircraft with tail structures shielding a portion of the rotor noise. The measured noise of an open rotor test article--collected with and without an acoustic barrier wall--is the basis of the prediction. The results are used to help validate NASA s reliance on acoustic shielding to achieve the second phase of its community noise reduction goals. The noise measurements are also compared to a popular empirical diffraction correlation often used at NASA to predict acoustic shielding.
Evaluation of Manufacturability of Embedded Sensors and Controls with Canned Rotor Pump System
Kisner, Roger A [ORNL; Fugate, David L [ORNL; Melin, Alexander M [ORNL; Holcomb, David Eugene [ORNL; Wilson, Dane F [ORNL; Silva, Pamela C [ORNL; Cruz Molina, Carola [ORNL
2013-07-01
This report documents the current status of fabrication and assembly planning for the magnetic bearing, canned rotor pump being used as a demonstration platform for deeply integrating I&C into nuclear power plant components. The report identifies material choices and fabrication sequences for all of the required parts and the issues that need to be either resolved or accommodated during the manufacturing process. Down selection between material options has not yet been performed. Potential suppliers for all of the necessary materials have also been identified. The assembly evaluation begins by logically subdividing the pump into modules, which are themselves decomposed into individual parts. Potential materials and fabrication processes for each part in turn are then evaluated. The evaluation process includes assessment of the environmental compatibility requirements and the tolerances available for the selected fabrication processes. A description of the pump power/control electronics is also provided. The report also includes exploded views of the modules that show the integration of the various parts into modules that are then assembled to form the pump. Emphasis has been placed on thermal environment compatibility and the part dimensional changes during heat-up. No insurmountable fabrication or assembly challenges have been identified.
董泳; 周绪强; 毕强
2012-01-01
通过对液力变速传动装置应用于风力发电系统运动规律的分析,得到了适应变化的风轮转速、保持恒定发电机输入转速的风轮转速与液力变矩器涡轮输出转速应保持的关系。根据传动系的功率分流原理及能量平衡方程,推导了液力变矩器泵轮输入功率占风轮功率的比例以及液力变速传动装置的总体传动效率关系式。结合风力机特性进行了液力变矩器涡轮输出工作特性的分析,综合评价了影响传动效率的主要因素。针对低转速比和高转速比两种型号的液力变矩器进行了系统的匹配计算,为液力元件的选型与设计、差动轮系及定轴轮系关键结构参数的选取提供了参考。%By means of analyzing characteristics of hydrodynamic variable speed umt appneu m wind power system, relationship between wind rotor speed and turbine output speed of hydrodynamic torque converter was achieved comparable to the variable wind rotor speed to sustain constant genera- tor speed. Ratio of input power of torque converter pump to wind rotor power and overall transmis- sion efficiency of hydrodynamic variable speed drive were determined based on the power splitting fun- damentals and energy balance equation. Output working characteristics of hydrodynamic torque con- verter was analyzed combining wind rotor characteristics. Overall evaluation was done with major fac- tors of influencing the transmission efficiency. System matching computation was done in the light of lower speed ratio and higher speed ratio of two types torque converter. Model selection and design for the torque converter,determination of the key construction parameters for differential gear train and ordinary gear train, the research methods and conclusions herein are for reference.
Abd-El-Kader SAHRAOUI; Dennis M. BUEDE; Andrew P. SAGE
2008-01-01
In this paper, we propose selected research topics that are believed central to progress and growth in the application of systems engineering (SE). As a professional activity, and as an intellectual activity, systems engineering has strong links to such associated disciplines as decision analysis, operation research, project management, quality management, and systems design. When focussing on systems engineering research, we should distinguish between subjects that are of systems engineering essence and others that more closely correspond to those that are more relevant for related disciplines.
Active vibration control for flexible rotor by optimal direct-output feedback control
Nonami, Kenzou; Dirusso, Eliseo; Fleming, David P.
1989-01-01
Experimental research tests were performed to actively control the rotor vibrations of a flexible rotor mounted on flexible bearing supports. The active control method used in the tests is called optimal direct-output feedback control. This method uses four electrodynamic actuators to apply control forces directly to the bearing housings in order to achieve effective vibration control of the rotor. The force actuators are controlled by an analog controller that accepts rotor displacement as input. The controller is programmed with experimentally determined feedback coefficients; the output is a control signal to the force actuators. The tests showed that this active control method reduced the rotor resonance peaks due to unbalance from approximately 250 micrometers down to approximately 25 micrometers (essentially runout level). The tests were conducted over a speed range from 0 to 10,000 rpm; the rotor system had nine critical speeds within this speed range. The method was effective in significantly reducing the rotor vibration for all of the vibration modes and critical speeds.
罗贵火; 周海仑; 王飞; 杨喜关
2012-01-01
The dual rotor-hall bearing-stator coupling dynamic model was established for the aero-engine with dual rotor as to research object. The model concerned the coupling effect of inter-rotor bearing between the low pressure rotor and high pressure rotor, between the outer race of ball bearing and bearing housing, and between the flexible support and squeeze film damper. In the model of ball bearings, the clearance of bearing, nonlinear Hertzian contract force between balls and races and the varying compliance vibration were considered. The beat vibration response and whirl orbit of co-rotating or counter-rotating dual-rotor system were analyzed by using the model. The results show that the beat vibration response occurs obviously when two rotors operate at approximate speed, the whirl orbit of the counter-rotating dual-rotor system will be the petal shape. Finally, the results of numerical integral and the model were validated with the experiments of the dual rotor rig.%以双转子航空发动机为研究对象，建立了航空发动机双转子一滚动轴承一机匣耦合动力学模型．模型中考虑了低压转子与高压转子的中介轴承耦合作用，滚动轴承模型中考虑了滚动轴承间隙、非线性赫兹接触力以及变柔性VC（varying compliance）振动等因素．利用仿真模型，进行了同向和反向旋转双转子系统的拍振响应分析，结果表明当高低压转子的转速差较小时，双转子系统的拍振响应明显．同时研究了同转和反转双转子系统轴心轨迹响应的差异，研究表明反向旋转双转子系统的轴心轨迹会形成“花瓣”状．最后，利用双转子试验器验证了仿真结果的正确性，进一步验证本文所建模型的正确性．
On cup anemometer rotor aerodynamics.
Pindado, Santiago; Pérez, Javier; Avila-Sanchez, Sergio
2012-01-01
The influence of anemometer rotor shape parameters, such as the cups' front area or their center rotation radius on the anemometer's performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups' center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor's cup.
Lucía, A; Balmer, J; Davison, R C R; Pérez, M; Santalla, A; Smith, P M
2004-10-01
The aim of this study was to determine the effects of Rotor, a new cycle crank configuration that effectively allows the pedals to move independently throughout the duty cycle, on indices of endurance cycling performance in trained cyclists. Ten cyclists (5 Rotor users and 5 non-users; age (mean +/- SD): 22 +/- 5 y; VO(2)max: 69.5 +/- 5.1 mL. kg(-1).min(-1)) volunteered to participate in the study. On four separate days, the subjects performed four cycle-ergometer tests, i.e. two incremental tests and two 20-min tests. An imposed crank rate of 75 rev.min(-1) was used during all tests. The incremental protocol started at 112.5 W, and the power output was increased by 37.5 W every 3 min until volitional exhaustion. The 20-min tests were performed at a fixed power output equivalent to 80 % of the highest power output that the cyclists maintained for a complete 3-min period during incremental tests. Both types of tests were performed with the conventional crank system and the Rotor following a counter-balanced, cross-over design. Gas exchange parameters were measured in all the tests and blood lactate was determined at the end of each 3-min period (incremental tests) and at the end of the 20-min tests. A three factor (pedalling system used during the tests x habitual pedalling system x power output [incremental tests] or time [20-min tests]) ANOVA with repeated measures on power output (incremental tests) or time (20-min tests) was used to analyse several indices of performance, e.g. peak power output, VO(2)max, lactate threshold, onset of blood lactate accumulation, economy, delta, and gross efficiency. No differences (p > 0.05) were found between the Rotor and conventional systems for any of the aforementioned variables. It seems that the theoretical advantage brought about by the Rotor system, i.e. improved contra-lateral cooperation of both legs, would be minimized in trained cyclists. Although field studies are needed to assess the possible implications, in terms
Management Information Systems Research.
Research on management information systems is illusive in many respects. Part of the basic research problem in MIS stems from the absence of standard...definitions and the lack of a unified body of theory. Organizations continue to develop large and often very efficient information systems , but...decision making. But the transition from these results to the realization of ’satisfactory’ management information systems remains difficult indeed. The
Jieyu Chen
2007-08-01
Full Text Available Incorporating the velocity slip effect of the gas flow at the solid boundary, theperformance and dynamic response of a micro gas-bearing-rotor system are investigated inthis paper. For the characteristic length scale of the micro gas bearing, the gas flow in thebearing resides in the slip regime rather than in the continuum regime. The modifiedReynolds equations of different slip models are presented. Gas pressure distribution and loadcarrying capacity are obtained by solving the Reynolds equations with finite differentmethod (FDM. Comparing results from different models, it is found that the second orderslip model agrees reasonably well with the benchmarked solutions obtained from thelinearized Boltzmann equation. Therefore, dynamic coefficients derived from the secondorder slip model are employed to evaluate the linear dynamic stability and vibrationcharacteristics of the system. Compared with the continuum flow model, the slip effectreduces dynamic coefficients of the micro gas bearing, and the threshold speed for stableoperation is consequently raised. Also, dynamic analysis shows that the system responseschange with variation of the operating parameters including the eccentricity ratio, therotational speed, and the unbalance ratio.
Computational Analysis of Multi-Rotor Flows
Yoon, Seokkwan; Lee, Henry C.; Pulliam, Thomas H.
2016-01-01
Interactional aerodynamics of multi-rotor flows has been studied for a quadcopter representing a generic quad tilt-rotor aircraft in hover. The objective of the present study is to investigate the effects of the separation distances between rotors, and also fuselage and wings on the performance and efficiency of multirotor systems. Three-dimensional unsteady Navier-Stokes equations are solved using a spatially 5th order accurate scheme, dual-time stepping, and the Detached Eddy Simulation turbulence model. The results show that the separation distances as well as the wings have significant effects on the vertical forces of quadroror systems in hover. Understanding interactions in multi-rotor flows would help improve the design of next generation multi-rotor drones.
Dimitrios G. Giaourakis
2015-02-01
Full Text Available This paper deals with the operational behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System under power electronic converter and rotor terminals faulty conditions. More specifically, the effect of the short-circuit fault both in one IGBT of the back-to-back power electronic converter and in rotor phases on the overall system behavior has been investigated via simulation using a system of 2 MW. Finally, the consequences of these faults have been evaluated.
Stasicki, Bolesław; Boden, Fritz; Ludwikowski, Krzysztof
2017-02-01
The non-intrusive in-flight deformation measurement and the resulting local pitch of an aircraft propeller or helicopter rotor blade is a demanding task. The idea of an imaging system integrated and rotating with the air-craft propeller has already been presented at the 30th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been designed, constructed and tested in the laboratory as well as in-flight on the Cobra VUT100 of Evektor Aerotechnik, Kunovice (CZ). The major aim of the EU FP7 project AIM2 ("Advanced In-flight Measurement techniques 2" - contract No. 266107) was to ascertain the feasibility of this technique under extreme conditions - vibration and large centrifugal forces - to real flight testing. Based on the gained experience a new rotating system for the application on helicopter rotors has recently been constructed and tested on the whirl tower of Airbus Helicopters, Donauwoerth (D). In this paper the principle of the applied Image Pattern Correlation Technique (IPCT), a specialized type of Digital Image Correlation (DIC), is outlined and the construction of both rotating 3D image acquisition systems dedicated to the in-flight deformation measurement of the aircraft propeller and helicopter rotor are described. Furthermore, the results of the ground and in-flight tests of these systems will be shown and discussed. The obtained results will be helpful for manufacturers in the design of their future aircrafts.
Carnero, Antonio; Serrano, Luis E. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Nebradt, G. Jesus; Leyva, M. Luis [Comision Federal de Electricidad, Mexico, D.F. (Mexico)
2007-11-15
The turbine wheels undergo high thermal and mechanical stresses caused by the requirements of their operation. This causes a mechanical damage (fatigue) that is accumulated according to the frequency whereupon the different operation ways (cold starts, lukewarm or hot) happen. On the other hand, the greater efficiency of power stations of combined cycle with respect to conventional power stations is reflected in a greater production cost of the electrical energy, which has forced to that conventional generation units designed to operate on base load, now are used as variable load units to satisfy the demand during the peak hours. The former, rebounds in a greater frequency of operations of shut downs and hot starts of turbines, reason why the fatigue damage will be increased when changing its operating range. In Mexico turbines there are turbines that have been 15 or 20 years in operation and that do not have a thermal stresses supervisor, reason why when changing their load operation from base load to variable load it is essential to install a rotor supervisor of thermal efforts, with the purpose of limiting or reducing the thermal stresses and in this way reduce the fatigue damage to extend their useful life. The article deals over the integration of a supervisory system of thermal stresses, that from the operation parameters of the turbine, determines the temperature gradient in the labyrinth seals zone between the control passage and the first passage of the high pressure section of the rotor, the thermal and mechanical stresses and the fatigue are calculated, determining the consumption of the useful life for each operation cycle (shutdown and starting). [Spanish] Los rotores de turbina experimentan altas esfuerzos termicos y mecanicos causados por los requerimientos de su operacion. Esto causa un dano mecanico (fatiga) que se acumula de acuerdo a la frecuencia con que los diferentes modos de operacion (arranques en frio, tibio o caliente) suceden. Por otro
Liu, Shibing; Yang, Bingen
2015-08-01
Flexible multistage rotating systems that are supported or guided by long water-lubricated rubber bearings (WLRBs) have a variety of engineering applications. Vibration analysis of this type of machinery for performance and duality requires accurate modeling of WLRBs and related rotor-bearing assemblies. This work presents a new model of WLRBs, with attention given to the determination of bearing dynamic coefficients. Due to its large length-to-diameter ratio, a WLRB cannot be described by conventional pointwise bearing models with good fidelity. The bearing model proposed in this paper considers spatially distributed bearing forces. For the first time in the literature, the current study addresses the issue of mixed lubrication in the operation of WLRBs, which involves interactions of shaft vibration, elastic deformation of rubber material and fluid film pressure, and validates the WLRB model in experiments. Additionally, with the new bearing model, vibration analysis of WLRB-supported flexible multistage rotating systems is performed through use of a distributed transfer function method, which delivers accurate and closed-form analytical solutions of steady-state responses without discretization.
一种转子不平衡响应的求解方法%A Method To Calculate The Inbalance Response Of Rotor System
王宁; 郭晓书; 蹇勇
2012-01-01
It is significative to study the inbalance response of rotor system, we can use Riccati transfer matrix method which has a good value stability to calculate the inbalance response of rotor system . At last we used the function of Matlab to draw a inbalance response drawing and center movement track.%摘要：转子系统不平衡响应的研究是很有意义的，可以采用数值稳定的Riccati传递矩阵法计算转子的不平衡响应，同时利用Matlab矩阵运算和图形分析功能绘制出不平衡响应图及中心运动轨迹。
Fan Noise Source Diagnostic Test: Rotor Alone Aerodynamic Performance Results
Hughes, Christopher E.; Jeracki, Robert J.; Woodward, Richard P.; Miller, Christopher J.
2005-01-01
The aerodynamic performance of an isolated fan or rotor alone model was measured in the NASA Glenn Research Center 9- by 15- Foot Low Speed Wind Tunnel as part of the Fan Broadband Source Diagnostic Test conducted at NASA Glenn. The Source Diagnostic Test was conducted to identify the noise sources within a wind tunnel scale model of a turbofan engine and quantify their contribution to the overall system noise level. The fan was part of a 1/5th scale model representation of the bypass stage of a current technology turbofan engine. For the rotor alone testing, the fan and nacelle, including the inlet, external cowl, and fixed area fan exit nozzle, were modeled in the test hardware; the internal outlet guide vanes located behind the fan were removed. Without the outlet guide vanes, the velocity at the nozzle exit changes significantly, thereby affecting the fan performance. As part of the investigation, variations in the fan nozzle area were tested in order to match as closely as possible the rotor alone performance with the fan performance obtained with the outlet guide vanes installed. The fan operating performance was determined using fixed pressure/temperature combination rakes and the corrected weight flow. The performance results indicate that a suitable nozzle exit was achieved to be able to closely match the rotor alone and fan/outlet guide vane configuration performance on the sea level operating line. A small shift in the slope of the sea level operating line was measured, which resulted in a slightly higher rotor alone fan pressure ratio at take-off conditions, matched fan performance at cutback conditions, and a slightly lower rotor alone fan pressure ratio at approach conditions. However, the small differences in fan performance at all fan conditions were considered too small to affect the fan acoustic performance.
Design of the Active Elevon Rotor for Low Vibration
Fulton, Mark V.; Rutkowski, Michael (Technical Monitor)
2000-01-01
Helicopter fuselages vibrate more than desired, and traditional solutions have limited effectiveness and can impose an appreciable weight penalty. Alternative methods of combating high vibration, including Higher Harmonic Control (HHC) via harmonic swashplate motion and Individual Blade Control (IBC) via active pitch links, have been studied for several decades. HHC via an on-blade control surface was tested in 1977 on a full scale rotor using a secondary active swashplate and a mechanical control system. Recent smart material advances have prompted new research into the use of on-blade control concepts. Recent analytical studies have indicated that the use of on-blade control surfaces produces vibration reduction comparable to swashplate-based HHC but for less power. Furthermore, smart materials (such as piezoceramics) have been shown to provide sufficient control authority for preliminary rotor experiments. These experiments were initially performed at small scale for reduced tip speeds. More recent experiments have been conducted at or near full tip speeds, and a full-scale active rotor is under development by Boeing with Eurocopter et al. pursuing a similarly advanced full-scale implementation. The US Army Aeroflightdynamics Directorate has undertaken a new research program called the Active Elevon Rotor (AER) Focus Demo. This program includes the design, fabrication, and wind. tunnel testing of a four-bladed, 12.96 ft diameter rotor with one or two on-blade elevons per blade. The rotor, which will be Mach scaled, will use 2-5/rev elevon motion for closed-loop control and :will be tested in late 2001. The primary goal of the AER Focus Demo is the reduction of vibratory hub loads by 80% and the reduction of vibratory blade structural loads. A secondary goal is the reduction of rotor power. The third priority is the measurement and possible reduction of Blade Vortex Interaction (BVI) noise. The present study is focused on elevon effectiveness, that is, the elevon
T700 power turbine rotor multiplane/multispeed balancing demonstration
Burgess, G.; Rio, R.
1979-01-01
Research was conducted to demonstrate the ability of influence coefficient based multispeed balancing to control rotor vibration through bending criticals. Rotor dynamic analyses were conducted of the General Electric T700 power turbine rotor. The information was used to generate expected rotor behavior for optimal considerations in designing a balance rig and a balance technique. The rotor was successfully balanced 9500 rpm. Uncontrollable coupling behavior prevented observations through the 16,000 rpm service speed. The balance technique is practical and with additional refinement it can meet production standards.
Liu, Jing; Shao, Yimin
2017-06-01
Rotor bearing systems (RBSs) play a very valuable role for wind turbine gearboxes, aero-engines, high speed spindles, and other rotational machinery. An in-depth understanding of vibrations of the RBSs is very useful for condition monitoring and diagnosis applications of these machines. A new twelve-degree-of-freedom dynamic model for rigid RBSs with a localized defect (LOD) is proposed. This model can formulate the housing support stiffness, interfacial frictional moments including load dependent and load independent components, time-varying displacement excitation caused by a LOD, additional deformations at the sharp edges of the LOD, and lubricating oil film. The time-varying displacement model is determined by a half-sine function. A new method for calculating the additional deformations at the sharp edges of the LOD is analytical derived based on an elastic quarter-space method presented in the literature. The proposed dynamic model is utilized to analyze the influences of the housing support stiffness and LOD sizes on the vibration characteristics of the rigid RBS, which cannot be predicted by the previous dynamic models in the literature. The results show that the presented method can give a new dynamic modeling method for vibration formulation for a rigid RBS with and without the LOD on the races.
Coherence Effects on the Power and Tower Loads of a 7 × 2 MW Multi-Rotor Wind Turbine System
Shigeo Yoshida
2016-09-01
Full Text Available A multi-rotor system (MRS, in which multiple wind turbines are placed on one tower, is a promising concept for super-large wind turbines at over 10 MW due to the cost and weight advantages. The coherence effects on an MRS were investigated in this study. Although a wide range of coherences were measured so far, a decay constant of C = 12 is recommended in the IEC61400-1 standard. Dynamic simulations were performed for a 14-MW MRS, which consists of seven 2-MW turbines and includes wind models with three different coherences. Although the results show that a larger coherence increases the output power and the collective loads due to tower base fore-aft bending, it reduces the differential loads due to tower-base torque and tower-top nodding. The most significant case is the fatigue damage due to tower base fore-aft bending, which was more than doubled between the decay constants of C = 6 and C = 12. The present results indicate that the coherence should be defined carefully in the design of large-scale MRSs because its effect on them is not straightforward.
Hi-Q Rotor - Low Wind Speed Technology
Todd E. Mills; Judy Tatum
2010-01-11
The project objective was to optimize the performance of the Hi-Q Rotor. Early research funded by the California Energy Commission indicated the design might be advantageous over state-of-the-art turbines for collecting wind energy in low wind conditions. The Hi-Q Rotor is a new kind of rotor targeted for harvesting wind in Class 2, 3, and 4 sites, and has application in areas that are closer to cities, or 'load centers.' An advantage of the Hi-Q Rotor is that the rotor has non-conventional blade tips, producing less turbulence, and is quieter than standard wind turbine blades which is critical to the low-wind populated urban sites. Unlike state-of-the-art propeller type blades, the Hi-Q Rotor has six blades connected by end caps. In this phase of the research funded by DOE's Inventions and Innovation Program, the goal was to improve the current design by building a series of theoretical and numeric models, and composite prototypes to determine a best of class device. Development of the rotor was performed by aeronautical engineering and design firm, DARcorporation. From this investigation, an optimized design was determined and an 8-foot diameter, full-scale rotor was built and mounted using a Bergey LX-1 generator and furling system which were adapted to support the rotor. The Hi-Q Rotor was then tested side-by-side against the state-of-the-art Bergey XL-1 at the Alternative Energy Institute's Wind Test Center at West Texas State University for six weeks, and real time measurements of power generated were collected and compared. Early wind tunnel testing showed that the cut-in-speed of the Hi-Q rotor is much lower than a conventional tested HAWT enabling the Hi-Q Wind Turbine to begin collecting energy before a conventional HAWT has started spinning. Also, torque at low wind speeds for the Hi-Q Wind Turbine is higher than the tested conventional HAWT and enabled the wind turbine to generate power at lower wind speeds. Based on the data
Trifonov, N. N.; Svyatkin, F. A.; Sintsova, T. G.; Ukhanova, M. G.; Yesin, S. B.; Nikolayenkova, E. K.; Yurchenko, A. Yu.; Grigorieva, E. B.
2016-03-01
The regeneration system heaters are one of the sources of possible ingress of the water into the turbine. The water penetrates into the turbine either at the heaters overflow or with the return flow of steam generated when the water being in the heater boils up in the dynamic operation modes or at deenergization of the power-generating unit. The return flow of steam and water is dangerous to the turbine blades and can result in the rotor acceleration. The known protective devices used to prevent the overflow of the low-pressure and high-pressure heaters (LPH and HPH), of the horizontal and vertical heaters of heating-system water (HWH and VWH), as well as of the deaerators and low-pressure mixing heaters (LPMH) were considered. The main protective methods of the steam and water return flows supplied by the heaters in dynamic operation modes or at deenergization of the power-generating unit are described. Previous operating experience shows that the available protections do not fully prevent water ingress into the turbine and the rotor acceleration and, therefore, the development of measures to decrease the possibility of ingress of the water into the turbine is an actual problem. The measures allowing eliminating or reducing the water mass in the heaters are expounded; some of them were designed by the specialists of OAO Polzunov Scientific and Development Association on Research and Design of Power Equipment (NPO CKTI) and are efficiently introduced at heat power plants and nuclear power plants. The suggested technical solutions allow reducing the possibility of the water ingress into the turbine and rotor acceleration by return steam flow in the dynamic operation modes or in the case of power generating unit deenergization. Some of these solutions have been tested in experimental-industrial exploitation and can be used in industry.
花键连接转子系统稳定性研究%Stability Analysis of Spline Connected Rotor System
高腾; 荆建平; 梅庆; 陈全勇
2016-01-01
Involute spline couplings are widely used in aircrafts to transmit power from turbine end to the output components, generators or other engine accessories. This study is to obtain the instability principle of spline connected rotor systems. The spline force was described as equivalent stiffness coefficients and damping coefficients. The model of spline connected rotor system was established with finite element method. The effect of the spline force on the stability of the rotor system was obtained with eigenvalue method. In addition, the impact of the friction coefficient, torque load and external damping on the system stability were discussed. The results show that the increase of friction coefficient and torque load can decrease the stability of the rotor system. In the contrary, the external damping can increase the stability of the spline connected rotor system.%花键联轴器被广泛应用于飞机上，在涡轮端和输出组件、发电机以及发动机其他配件间传递动力。为获得花键联轴器引起的花键连接转子失稳原理，将花键力模拟成等效的刚度系数和阻尼系数，采用有限元方法建立花键连接转子模型，采用特征值方法得到花键力对花键连接转子系统稳定性影响，此外，讨论摩擦系数、负载扭矩和外阻尼对系统稳定性的影响。研究结果表明，摩擦系数和负载扭矩增加会降低系统稳定性，相反，外阻尼会增加花键连接转子系统稳定性。
Discrete analog computing with rotor-routers.
Propp, James
2010-09-01
Rotor-routing is a procedure for routing tokens through a network that can implement certain kinds of computation. These computations are inherently asynchronous (the order in which tokens are routed makes no difference) and distributed (information is spread throughout the system). It is also possible to efficiently check that a computation has been carried out correctly in less time than the computation itself required, provided one has a certificate that can itself be computed by the rotor-router network. Rotor-router networks can be viewed as both discrete analogs of continuous linear systems and deterministic analogs of stochastic processes.
Howard, Samuel
2012-01-01
A variable-speed power turbine concept is analyzed for rotordynamic feasibility in a Large Civil Tilt-Rotor (LCTR) class engine. Implementation of a variable-speed power turbine in a rotorcraft engine would enable high efficiency propulsion at the high forward velocities anticipated of large tilt-rotor vehicles. Therefore, rotordynamics is a critical issue for this engine concept. A preliminary feasibility study is presented herein to address this concern and identify if variable-speed is possible in a conceptual engine sized for the LCTR. The analysis considers critical speed placement in the operating speed envelope, stability analysis up to the maximum anticipated operating speed, and potential unbalance response amplitudes to determine that a variable-speed power turbine is likely to be challenging, but not impossible to achieve in a tilt-rotor propulsion engine.
Computational Study of Flow Interactions in Coaxial Rotors
Yoon, Seokkwan; Lee, Henry C.; Pulliam, Thomas H.
2016-01-01
Although the first idea of coaxial rotors appeared more than 150 years ago, most helicopters have used single main-rotor/tail-rotor combination. Since reactive moments of coaxial rotors are canceled by contra-rotation, no tail rotor is required to counter the torque generated by the main rotor. Unlike the single main rotor design that distributes power to both main and tail rotors, all of the power for coaxial rotors is used for vertical thrust. Thus, no power is wasted for anti-torque or directional control. The saved power helps coaxial rotors reach a higher hover ceiling than single rotor helicopters. Another advantage of coaxial rotors is that the overall rotor diameter can be reduced for a given vehicle gross weight because each rotor provides a maximum contribution to vertical thrust to overcome vehicle weight. However, increased mechanical complexity of the hub has been one of the challenges for manufacturing coaxial rotorcraft. Only the Kamov Design Bureau of Russia had been notably successful in production of coaxial helicopters until Sikorsky built X2, an experimental compound helicopter. Recent developments in unmanned aircraft systems and high-speed rotorcraft have renewed interest in the coaxial configuration. Multi-rotors are frequently used for small electric unmanned rotorcraft partly due to mechanical simplicity. The use of multiple motors provides redundancy as well as cost-efficiency. The multi-rotor concept has rarely been used until recently because of its inherent stability and control problems. However, advances in inexpensive electronic flight control systems have opened the floodgates for small drones using multirotors. Coaxial rotors have started to appear in some multi-rotor configurations. Small coaxial rotors have often been designed using a hundred year old approach that is "sketch, build, fly, and iterate." In that approach, there is no systematic way to explore trade-offs or determine logical next steps. It is neither possible to
Shape memory alloys applied to improve rotor-bearing system dynamics - an experimental investigation
2015-01-01
tor-bearing systems have critical speeds and to pass through them is an ongoing challenge in the field of mechanical engineering. The incorporation of shape memory alloys in rotating systems has an increasing importance to improve system performance and to avoid potential damaging situations when passing through critical speeds. In this work, the feasibility of applying shape memory alloys to a rotating system is experimentally investigated. Shape memory alloys can change their stiffness with...
Utilization of rotor kinetic energy storage for hybrid vehicles
Hsu, John S.
2011-05-03
A power system for a motor vehicle having an internal combustion engine, the power system comprises an electric machine (12) further comprising a first excitation source (47), a permanent magnet rotor (28) and a magnetic coupling rotor (26) spaced from the permanent magnet rotor and at least one second excitation source (43), the magnetic coupling rotor (26) also including a flywheel having an inertial mass to store kinetic energy during an initial acceleration to an operating speed; and wherein the first excitation source is electrically connected to the second excitation source for power cycling such that the flywheel rotor (26) exerts torque on the permanent magnet rotor (28) to assist braking and acceleration of the permanent magnet rotor (28) and consequently, the vehicle. An axial gap machine and a radial gap machine are disclosed and methods of the invention are also disclosed.
Design and analysis of Air flow duct for improving the thermal performance of disc brake rotor
Raja, T.; Mathiselvan, G.; Sreenivasulureddy, M.; Goldwin Xavier, X.
2017-05-01
safety in automotive engineering has been considered as a number one priority in development of new vehicle. A brake system is one of the most critical systems in the vehicle, without which the vehicle will put a passenger in an unsafe position. Temperature distribution on disc rotor brake and the performance brake of disc rotor is influenced by the air flow around the disc rotor. In this paper, the effect of air flow over the disc rotor is analyzed using the CFD software. The air flow over the disc rotor is increased by using a duct to supply more air flow over the disc rotor. The duct is designed to supply more air to the rotor surface and it can be placed in front of the vehicle for better performance. Increasing the air flow around the rotor will maximize the heat convection from the rotor surface. The rotor life and the performance can be improved.
Wang, Shuai; Wang, Yu; Zi, Yanyang; Li, Bing; He, Zhengjia
2015-10-01
A novel reduced-order modeling method is presented in this paper for dynamics analysis of rotating impeller-shaft-bearing assembly with cracked impellers. Based on three-dimensional finite element model, the complex component mode synthesis (CMS) method is employed to generate an efficient reduced-order model (ROM) for studying the effects of crack on the global vibration of the rotating assembly. First, a modeling framework for impeller-shaft-bearing systems in rotating frame is presented. Rotational effects, including Coriolis matrix and centrifugal softening, have been taken into account. Then, the governing equation of motion of the damped gyroscopic system is reduced by the complex CMS method. Finally, the obtained ROM is employed to study the effects of crack on assembly's vibration. During the steady-state response analysis, external excitations on the impeller due to rotor-stator interactions have been taken into account, which was however neglected in previous investigations on rotordynamics. Numerical results show that the lower-order eigenvalues and the unbalance response of the assembly are not sensitive to the local crack on impeller. Nevertheless, the flexible coupling between impeller and shaft becomes more complex when the air flow-induced excitations are considered. Under EO1 traveling wave excitations, a crack leads to slight changes in the assembly's response. In contrast, the effect of crack becomes significant when the assembly is excited by EO2 and higher EO excitations. Moreover, the nonlinear crack breathing effects affect the assembly's response obviously. Finally, a potential technique for detecting the crack on impeller during operation is discussed.
The effect of rotor dynamics on a flywheel stack energy storage system
Jayaraman, Chaitanya P.; Kirk, James A.; Anand, Davinder K.
1988-01-01
The paper presents a dynamic analysis of a magnetic-bearing stack system consisting of a single flywheel supported by two magnetic bearings. Real-time plots from a computer simulation are used to show the effect of dynamic coupling on the torque response, and the frequency response is used to determine the resonance frequencies of the stack system. It is found that system stability depends on the flywheel speed.
Gaonkar, G.
1986-01-01
For flap-lag stability of isolated rotors, experimental and analytical investigations are conducted in hover and forward flight on the adequacy of a linear quasisteady aerodynamics theory with dynamic inflow. Forward flight effects on lag regressing mode are emphasized. Accordingly, a soft inplane hingeless rotor with three blades is tested at advance ratios as high as 0.55 and at shaft angles as high as 20 degrees. The 1.62 m model rotor is untrimmed with an essentially unrestricted tilt of the tip path plane. In combination with lag natural frequencies, collective pitch settings and flap-lag coupling parameters, the data base comprises nearly 1200 test points (damping and frequency) in forward flight and 200 test points in hover. By computerized symbolic manipulation, a linear analytical model is developed in substall to predict stability margins with mode identificaton. To help explain the correlation between theory and data it also predicts substall and stall regions of the rotor disk from equilibrium values. The correlation shows both the strengthts and weaknesses of the theory in substall.
Maulana Arifin
2015-07-01
Full Text Available Organic Rankine Cycle (ORC is one of the most promising technology for small electric power generations. The geometry analysis and the effect of turbulence model on the radial turbo-expanders design for small ORC power generation systems were discussed in this paper. The rotor blades and performance were calculated using several working fluids such as R134a, R143a, R245fa, n-Pentane, and R123. Subsequently, a numerical study was carried out in the fluid flow area with R134a and R123 as the working fluids. Analyses were performed using Computational Fluid Dynamics (CFD ANSYS Multiphysics on two real gas models, with the k-epsilon and SST (shear stress transport turbulence models. The result shows the distribution of Mach number, pressure, velocity and temperature along the rotor blade of the radial turbo-expanders and estimation of performance at various operating conditions. The operating conditions are as follow: 250,000 grid mesh flow area, real gas model SST at steady state condition, 0.4 kg/s of mass flow rate, 15,000 rpm rotor speed, 5 bar inlet pressure, and 373K inlet temperature. By using those conditions, CFD analysis shows that the turbo-expander able to produce 6.7 kW and 5.5 kW of power when using R134a and R123, respectively.
外转子永磁同步电动机计算机辅助设计%CAD System for Permanent Magnet Synchronous Motors with External Rotors
许宁; 黄开胜; 邱小华; 覃建波; 宋湛华
2012-01-01
介绍外转子永磁同步电动机的设计方法,讨论了设计重点,提出了外转子永磁同步电动机计算极弧系数、绕组分布系数、铁心损耗等具体参数的计算方法.在此基础上开发出了基于windows的CAD系统,并给出了一个20P,16.8 kW的外转子永磁同步电动机的设计实例.%This paper introduced methods to design permanent magnet synchronous motors (PMSM ) with external rotors, and proposed methods to calculate parameters of the PMSM with external rotors, such as αi, Kdl,Pfe,etc.A computer aided design (CAD) system was developed based on Windows, with giving an example of 20 P, 16. 8 kW external rotor PMSM.
Fluid dynamic design and analysis of a highly loaded Centrifugal rotor for mini orc power systems
Vitale, S.; Pini, M.; Ghidoni, A.; Colonna di Paliano, P.
2015-01-01
Organic Rankine Cycle (ORC) power systems are a well-established technology for the conversion of thermal energy sources in the small-to-medium power range. In the last few years, efforts have been devoted to the development of mini ORC (mORC) power systems (5- 30 kWe) for waste heat recovery from t
Fluid dynamic design and analysis of a highly loaded Centrifugal rotor for mini orc power systems
Vitale, S.; Pini, M.; Ghidoni, A.; Colonna di Paliano, P.
2015-01-01
Organic Rankine Cycle (ORC) power systems are a well-established technology for the conversion of thermal energy sources in the small-to-medium power range. In the last few years, efforts have been devoted to the development of mini ORC (mORC) power systems (5- 30 kWe) for waste heat recovery from
Shape memory alloys applied to improve rotor-bearing system dynamics - an experimental investigation
Enemark, Søren; Santos, Ilmar; Savi, Marcelo A.
2015-01-01
tor-bearing systems have critical speeds and to pass through them is an ongoing challenge in the field of mechanical engineering. The incorporation of shape memory alloys in rotating systems has an increasing importance to improve system performance and to avoid potential damaging situations when...... passing through critical speeds. In this work, the feasibility of applying shape memory alloys to a rotating system is experimentally investigated. Shape memory alloys can change their stiffness with temperature variations and thus they may change system dynamics. Shape memory alloys also exhibit...... hysteretic stress-strain relations which may be utilized for damping purposes. These ideas are tested in this study on a dedicated test-rig, consisting of a rigid shaft and disc held vertically by passive magnetic bearings, where the damping is low. The bearing housings is flexibly supported by shape memory...
孙百军; 焦振宏; 丁宇汉
2011-01-01
双转永磁无刷直流电动机作为螺旋桨推进电机,广泛应用于无人水下航行器.基于双转永磁无刷直流电动机工作原理,建立电机数学模型,采用变参数PI控制算法设计控制器,给出相对位置检测的换相控制方案,在Matlab平台上,建立电机调速系统仿真模型.仿真结果表明,仿真建模准确,控制算法精确、稳定、可靠.%The dual-rotor permanent magnetic brushless direct current motor (dual-rotor PMBLDCM) which has two rotors running in opposite direction at any time is widely used in autonomous underwater vehicle as the driving motor of propeller. Based on the working principle, this paper built the mathematical model of dual-rotor PMBLDCM, designed controller adopting variable parameter PI control algorithm,gave a phase-change control scheme employing relative position detection and built the simulation model of the speed regulation system of dual-rotor PMBLDCM under Matlab platform. The simulation result proves that the simulation modeling and algorithm of controlling are accurate, stable and reliable.
房建成; 张会娟; 刘虎
2014-01-01
By the virtue of active magnetic bearing, magnetically suspended inertia actuators can make micro-vibration come true through active vibration control. However, there still exist vibrations with some frequencies in magnetically suspended inertia actuators. Firstly, the vibration mechanism of Magnet Runout is analyzed based on the analysis of rotor unbalance and Sensor Runout, then the dynamic model of the magnetically suspended rigid rotor system composing of three vibration sources is developed and divided into translational motion and torsional motion. The analysis dedicates that rotor unbalance, Magnet Runout and Sensor Runout will arise vibrations through different channels, and that the vibrations include the fundamental frequencies and their harmonics. Lastly, the requirements of active vibration control are proposed for the magnetically suspended rigid rotor system, and are useful for the future research.%磁悬浮惯性执行机构采用磁轴承支承，可通过主动控制实现极微振动，但磁悬浮惯性执行机构仍存在频谱分量丰富的振动。首先在转子动静不平衡和Sensor Runout振动机理分析的基础上，重点分析了Magnet Runout产生振动机理；然后，建立包含多振动源的系统动力学建模，并将整个动力学模型分解为平动和转动子系统，分析表明转子动静不平衡、Sensor Runout和Magnet Runout是通过不同的途径产生振动，不仅产生同频振动还包含倍频振动；最后，提出磁悬浮刚性转子系统主动振动控制的要求，为以后的主动振动控制研究奠定基础。
Friedmann, P. P.
1984-01-01
An aeroelastic model suitable for the study of aeroelastic and structural dynamic effects in multirotor vehicles simulating a hybrid heavy lift vehicle was developed and applied to the study of a number of diverse problems. The analytical model developed proved capable of modeling a number of aeroelastic problems, namely: (1) isolated blade aeroelastic stability in hover and forward flight, (2) coupled rotor/fuselage aeromechanical problem in air or ground resonance, (3) tandem rotor coupled rotor/fuselage problems, and (4) the aeromechanical stability of a multirotor vehicle model representing a hybrid heavy lift airship (HHLA). The model was used to simulate the ground resonance boundaries of a three bladed hingeless rotor model, including the effect of aerodynamic loads, and the theoretical predictions compared well with experimental results. Subsequently the model was used to study the aeromechanical stability of a vehicle representing a hybrid heavy lift airship, and potential instabilities which could occur for this type of vehicle were identified. The coupling between various blade, supporting structure and rigid body modes was identified.
Enemark, Søren; Santos, Ilmar F.
2016-01-01
In this work, the nonlinear dynamic behaviour of a vertical rigid rotor interacting with a flexible foundation by means of two passive magnetic bearings is quantified and evaluated. The quantification is based on theoretical and experimental investigation of the non-uniformity (anisotropy) of the...
Electric Drive Control with Rotor Resistance and Rotor Speed Observers Based on Fuzzy Logic
C. Ben Regaya
2014-01-01
Full Text Available Many scientific researchers have proposed the control of the induction motor without speed sensor. These methods have the disadvantage that the variation of the rotor resistance causes an error of estimating the motor speed. Thus, simultaneous estimation of the rotor resistance and the motor speed is required. In this paper, a scheme for estimating simultaneously the rotor resistance and the rotor speed of an induction motor using fuzzy logic has been developed. We present a method which is based on two adaptive observers using fuzzy logic without affecting each other and a simple algorithm in order to facilitate the determination of the optimal values of the controller gains. The control algorithm is proved by the simulation tests. The results analysis shows the characteristic robustness of the two observers of the proposed method even in the case of variation of the rotor resistance.
Aeroelastic stability of periodic systems with application to rotor blade flutter
Friedmann, P.; Silverthorn, L. J.
1974-01-01
The dynamics of a helicopter blade in forward flight are described by a system of linear differential equations with periodic coefficients. The stability of this periodic aeroelastic system is determined, using multivariable Floquet-Liapunov theory. The transition matrix at the end of the period is evaluated by: (1) direct numerical integration, and (2) a new, approximate method, which consists in approximating a periodic function by a series of step functions. The numerical accuracy and efficiency of the methods is compared, and the second method is shown to be superior by far. Results illustrating the effect of the periodic coefficients and various blade parameters are presented.
Geometrical optimization of a hingeless deployment system for an active rotor blade
Paternoster, Alexandre; Loendersloot, Richard; de Boer, Andries; Akkerman, Remko
2013-01-01
Deployment systems for the Gurney flap need to sustain large centrifugal loads and vibrations while maintaining precisely the displacement under aerodynamic loading. Designing such a mechanism relies on both the actuation technology and the link that transmits motion to the control surface. Flexible
Review of standard rotor configurations for a micro unmanned aerial system
Steele, A
2015-11-01
Full Text Available The use of unmanned aerial systems (UAS) is on the rise with an array of industries finding use for them in a variety of applications. This review hopes to assist potential drone designers in selecting the drone best suited for their application...
Attitude Control of Quad-rotor by Improving the Reliability of Multi-Sensor System
Yu, Dong Hyeon; Chong, Kil To [Chon-bok National University, Jeonju (Korea, Republic of); Park, Jong Ho [Seonam University, Namwon (Korea, Republic of); Ryu, Ji Hyoung [ETRI, Daejeon (Korea, Republic of)
2015-05-15
This paper presents the results of study for improving the reliability of quadrotor attitude control by applying a multi-sensor along with a data fusion algorithm. First, a mathematical model of the quadrotor dynamics was developed. Then, using the quadrotor mathematical model, simulations were performed using the improved reliability multi-sensor data as the inputs. From the simulation results, we designed a Gimbal-equipped quadrotor system. With the quadrotor in a hover state, we performed experiments according to the angle change of the user's specifications . We then calculated the attitude control data from the actual experimental data. Furthermore, with additional simulations, we verified the performance of the designed quadrotor attitude control system with multiple sensors.
Balch, D. T.; Lombardi, J.
1985-01-01
A model scale hover test was conducted in the Sikorsky Aircraft Model Rotor hover Facility to identify and quantify the impact of the tail rotor on the demonstrated advantages of advanced geometry tip configurations. The existence of mutual interference between hovering main rotor and a tail rotor was acknowledged in the test. The test was conducted using the Basic Model Test Rig and two scaled main rotor systems, one representing a 1/5.727 scale UH-60A BLACK HAWK and the others a 1/4.71 scale S-76. Eight alternate rotor tip configurations were tested, 3 on the BLACK HAWK rotor and 6 on the S-76 rotor. Four of these tips were then selected for testing in close proximity to an operating tail rotor (operating in both tractor and pusher modes) to determine if the performance advantages that could be obtained from the use of advanced geometry tips in a main rotor only environment would still exist in the more complex flow field involving a tail rotor. This volume contains the test run log and tabulated data.
Rotor dynamic analysis of main coolant pump
Lee, Chong Won; Seo, Jeong Hwan; Kim, Choong Hwan; Shin, Jae Chul; Wang, Lei Tian [Korea Advanced Institute of Science and Technology, Taejon (Korea)
1999-03-01
A rotor dynamic analysis program DARBS/MCP, for the main coolant pump of the integral reactor, has been developed. The dynamic analysis model of the main coolant pump includes a vertical shaft, three grooved radial journal bearings and gaps that represent the structure-fluid interaction effects between the rotor and the lubricant fluid. The electromagnetic force from the motor and the hydro-dynamic force induced by impeller are the major sources of vibration that may affect the rotor system stability. DARBS/MCP is a software that is developed to effectively analyze the dynamics of MCP rotor systems effectively by applying powerful numerical algorithms such as FEM with modal truncation and {lambda}-matrix method for harmonic analysis. Main design control parameters, that have much influence to the dynamic stability, have been found by Taguchi's sensitivity analysis method. Design suggestions to improve the stability of MCP rotor system have been documented. The dynamic bearing parameters of the journal bearings used for main coolant pump have been determined by directly solving the Reynolds equation using FDM method. Fluid-structure interaction effect that occurs at the small gaps between the rotor and the stator were modeled as equivalent seals, the electromagnetic force effect was regarded as a linear negative radial spring and the impeller was modeled as a rigid disk with hydrodynamic and static radial force. Although there exist critical speeds in the range of operational speeds for type I and II rotor systems, the amplitude of vibration appears to be less than the vibration limit set by the API standards. Further more, it has been verified that the main design parameters such as the clearance and length of journal bearings, and the static radial force of impeller should be properly adjusted, in order to the improve dynamic stability of the rotor system. (author). 39 refs., 81 figs., 17 tabs.
Management systems research study
Bruno, A. V.
1975-01-01
The development of a Monte Carlo simulation of procurement activities at the NASA Ames Research Center is described. Data cover: simulation of the procurement cycle, construction of a performance evaluation model, examination of employee development, procedures and review of evaluation criteria for divisional and individual performance evaluation. Determination of the influences and apparent impact of contract type and structure and development of a management control system for planning and controlling manpower requirements.
NONLINEAR DYNAMICS OF A CRACKED ROTOR IN A MANEUVERING AIRCRAFT
LIN Fu-sheng 林富生; MENG Guang 孟光; Eric Hahn
2004-01-01
The nonlinear dynamics of a cracked rotor system in an aircraft maneuvering with constant velocity or acceleration was investigated. The influence of the aircraft climbing angle on the cracked rotor system response is of particular interest and the results show that the climbing angle can markedly affect the parameter range for bifurcation, for quasi-periodic response and for chaotic response as well as for system stability. Aircraft acceleration is also shown to significantly affect the nonlinear behavior of the cracked rotor system, illustrating the possibility for on-line rotor crack fault diagnosis.
Preliminary design of mesoscale turbocompressor and rotordynamics tests of rotor bearing system
Hossain, Md Saddam
2011-12-01
A mesoscale turbocompressor spinning above 500,000 RPM is evolutionary technology for micro turbochargers, turbo blowers, turbo compressors, micro-gas turbines, auxiliary power units, etc for automotive, aerospace, and fuel cell industries. Objectives of this work are: (1) to evaluate different air foil bearings designed for the intended applications, and (2) to design & perform CFD analysis of a micro-compressor. CFD analysis of shrouded 3-D micro compressor was conducted using Ansys Bladegen as blade generation tool, ICEM CFD as mesh generation tool, and CFX as main solver for different design and off design cases and also for different number of blades. Comprehensive experimental facilities for testing the turbocompressor system have been also designed and proposed for future work.
Rotor-System Log-Decrement Identification Using Short-Time Fourier-Transform Filter
Qihang Li
2015-01-01
Full Text Available With the increase of the centrifugal compressor capability, such as large scale LNG and CO2 reinjection, the stability margin evaluation is crucial to assure the compressor work in the designed operating conditions in field. Improving the precision of parameter identification of stability is essential and necessary as well. Based on the time-varying characteristics of response vibration during the sine-swept process, a short-time Fourier transform (STFT filter was introduced to increase the signal-noise ratio and improve the accuracy of the estimated stability parameters. A finite element model was established to simulate the sine-swept process, and the simulated vibration signals were used to study the filtering effect and demonstrate the feasibility to identify the stability parameters by using Multiple-Input and Multiple-Output system identification method that combines the prediction error method and instrumental variable method. Simulation results show that the identification method with STFT filter improves the estimated accuracy much well and makes the curves of frequency response function clearer. Experiment was carried out on a test rig as well, which indicates the identification method is feasible in stability identification, and the results of experiment indicate that STFT filter works very well.
Quad-rotor flight path energy optimization
Kemper, Edward
Quad-Rotor unmanned areal vehicles (UAVs) have been a popular area of research and development in the last decade, especially with the advent of affordable microcontrollers like the MSP 430 and the Raspberry Pi. Path-Energy Optimization is an area that is well developed for linear systems. In this thesis, this idea of path-energy optimization is extended to the nonlinear model of the Quad-rotor UAV. The classical optimization technique is adapted to the nonlinear model that is derived for the problem at hand, coming up with a set of partial differential equations and boundary value conditions to solve these equations. Then, different techniques to implement energy optimization algorithms are tested using simulations in Python. First, a purely nonlinear approach is used. This method is shown to be computationally intensive, with no practical solution available in a reasonable amount of time. Second, heuristic techniques to minimize the energy of the flight path are tested, using Ziegler-Nichols' proportional integral derivative (PID) controller tuning technique. Finally, a brute force look-up table based PID controller is used. Simulation results of the heuristic method show that both reliable control of the system and path-energy optimization are achieved in a reasonable amount of time.
Optimum design configuration of Savonius rotor through wind tunnel experiments
Saha, U.K.; Thotla, S. [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039 (India); Maity, D. [Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039 (India)
2008-08-15
Wind tunnel tests were conducted to assess the aerodynamic performance of single-, two- and three-stage Savonius rotor systems. Both semicircular and twisted blades have been used in either case. A family of rotor systems has been manufactured with identical stage aspect ratio keeping the identical projected area of each rotor. Experiments were carried out to optimize the different parameters like number of stages, number of blades (two and three) and geometry of the blade (semicircular and twisted). A further attempt was made to investigate the performance of two-stage rotor system by inserting valves on the concave side of blade. (author)
On Cup Anemometer Rotor Aerodynamics
Santiago Pindado
2012-05-01
Full Text Available The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal, tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups’ center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor’s cup.
Valve-aided twisted Savonius rotor
Jaya Rajkumar, M.; Saha, U.K.
2006-05-15
Accessories, such as end plates, deflecting plates, shielding and guide vanes, may increase the power of a Savonius rotor, but make the system structurally complex. In such cases, the rotor can develop a relatively large torque at small rotational speeds and is cheap to build, however it harnesses only a small fraction of the incident wind energy. Another proposition for increasing specific output is to place non-return valves inside the concave side of the blades. Such methods have been studied experimentally with a twisted-blade Thus improving a Savonius rotor's energy capture. This new concept has been named as the 'Valve-Aided Twisted Savonius'rotor. Tests were conducted in a low-speed wind tunnel to evaluate performance. This mechanism is found to be independent of flow direction, and shows potential for large machines. [Author].
Gu, Zhiping
This paper extends Riccati transfer matrix method to the transient and stability analysis of large scale rotor-bearing systems with strong nonlinear elements, and proposes a mode summation-transfer matrix method, in which the field transfer matrix of a distributed mass uniform shaft segment is obtained with the aid of the idea of mode summation and Newmark beta formulation, and the Riccati transfer matrix method is adopted to stablize the boundary value problem of the nonlinear systems. In this investigation, the real nonlinearity of the strong nonlinear elements is considered, not linearized, and the advantages of the Riccati transfer matrix are retained. So, this method is especially applicable to analyze the transient response and stability of large-scale rotor-bear systems with strong nonlinear elements. One example, a single-spool rotating system with strong nonlinear elements, is given. The obtained results show that this method is superior to that of Gu and Chen (1990) in accuracy, stability, and economy.
Calculation of rotor impedance for use in design analysis of helicopter airframe vibrations
Nygren, Kip P.
1990-01-01
Excessive vibration is one of the most prevalent technical obstacles encountered in the development of new rotorcraft. The inability to predict these vibrations is primarily due to deficiencies in analysis and simulation tools. The Langley Rotorcraft Structural Dynamics Program was instituted in 1984 to meet long term industry needs in the area of rotorcraft vibration prediction. As a part of the Langley program, this research endeavors to develop an efficient means of coupling the rotor to the airframe for preliminary design analysis of helicopter airframe vibrations. The main effort was to modify the existing computer program for modeling the dynamic and aerodynamic behavior of rotorcraft called DYSCO (DYnamic System COupler) to calculate the rotor impedance. DYSCO was recently developed for the U.S. Army and has proven to be adaptable for the inclusion of new solution methods. The solution procedure developed to use DYSCO for the calculation of rotor impedance is presented. Verification of the procedure by comparison with a known solution for a simple wind turbine model is about 75 percent completed, and initial results are encouraging. After the wind turbine impedance is confirmed, the verification effort will continue by comparison to solutions of a more sophisticated rotorcraft model. Future work includes determination of the sensitivity of the rotorcraft airframe vibrations to helicopter flight conditions and rotor modeling assumptions. When completed, this research will ascertain the feasibility and efficiency of the impedance matching method of rotor-airframe coupling for use in the analysis of airframe vibrations during the preliminary rotorcraft design process.
转子磁链定向的矢量控制系统的研究%Study of Rotor Flux Oriented Vector Control System
晏永红
2011-01-01
利用计算机仿真技术simulink对直接矢量控制系统进行分析研究,仿真结果表明按转子磁链定向的矢量控制系统克服了磁链开环系统的缺点,提高了系统的动态性能,这种系统具有广泛的实用价值.%Using computer simulation simulink for direct vector control system analysis, simulation results show that the rotor flux-oriented vector control system overcomes the flux disadvantage of open-loop system, improves the system dynamic performance, this system has a wide range of practical value.
Health Research Information Tracking System
US Agency for International Development — The Health Research Information Tracking System (HRIT) is an expansion of the Child Health Research database that collects and maintains categorization, description,...
Ning Yan
2012-12-01
Full Text Available The magnetically suspended Control Moment Gyroscope (CMG has the advantages of long-life, micro-vibration and being non-lubricating, and is the ideal actuator for agile maneuver satellite attitude control. However, the stability of the rotor in magnetic bearing and the precision of the output torque of a magnetically suspended CMG are affected by the rapid maneuvers of satellites. In this paper, a dynamic model of the agile satellite including a magnetically suspended single gimbal control moment gyroscope is built and the equivalent disturbance torque effected on the rotor is obtained. The feedforward compensation control method is used to depress the disturbance on the rotor. Simulation results are given to show that the rotor displacement is obviously reduced.
Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting
Jinxiang Xi; Rhode, David L.
2006-01-01
Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in hi...
Balch, D. T.; Lombardi, J.
1985-01-01
A model scale hover test was conducted in the Sikorsky Aircraft Model rotor hover Facility to identify and quantify the impact of the tail rotor on the demonstrated advantages of advanced geometry tip configurations. The test was conducted using the Basic Model Test Rig and two scaled main rotor systems, one representing a 1/5.727 scale UH-60A BLACK HAWK and the others a 1/4.71 scale S-76. Eight alternate rotor tip configurations were tested, 3 on the BLACK HAWK rotor and 6 on the S-76 rotor. Four of these tips were then selected for testing in close proximity to an operating tail rotor (operating in both tractor and pusher modes) to determine if the performance advantages that could be obtained from the use of advanced geometry tips in a main rotor only environment would still exist in the more complex flow field involving a tail rotor. The test showed that overall the tail rotor effects on the advanced tip configurations tested are not substantially different from the effects on conventional tips.
Federal Laboratory Consortium — This test apparatus, when combined with the National Full-Scale Aerodynamics Complex, produces a thorough, full-scale test capability. The Large Rotor Test Apparatus...
Peter W. Tse
2017-02-01
Full Text Available Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL. Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.
2017-01-01
resonance (NMR) Spectral density functions Spin - spin relaxation Molecular dynamics Nuclear Overhauser effect Symmetric top rotor Spin -lattice relaxation...SYMMETRIC TOP ROTOR MODELS AND THE FLEXIBLE SYMMETRIC TOP ROTOR MODEL ECBC-TR-1428 Terry J. Henderson RESEARCH AND TECHNOLOGY DIRECTORATE...Symmetric Top Rotor Models and the Flexible Symmetric Top Rotor Model 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR
Turbulence characteristics of the B\\"{o}dewadt layer in a large shrouded rotor-stator system
Poncet, S; Randriamampianina, Anthony
2006-01-01
A three-dimensional direct numerical simulation (3D DNS) is performed to describe the turbulent flow in an enclosed rotor-stator cavity characterized by a large aspect ratio $G=(b-a)/h=18.32$ and a small radius ratio $a/b=0.15$ ($a$ and $b$ the inner and outer radii of the rotating disk and $h$ the interdisk spacing). Recent comparisons with velocity measurements have shown that, for the rotational Reynolds number $Re=\\Omega b^2/\
黄梓嫄; 韩邦成; 周银锋
2014-01-01
According to the large error problem of modal analysis of the rotor system for magnetic levitation motors, the nonlinear contact behavior between rotor components was considered. The flexible rotor system modal can be analyzed accurately based on the penalty method by optimizing the contact stiffness factor. Through the establishment of the rotor-bearing system finite element analysis model, the ten order natural frequencies and variations of the rotor system under different bearing stiffness were obtained. The simulation results are in good agreement with the test values. This article also analyzed the rotor system with the dynamic balancing ring. The accuracy of results has been proved by the critical speed tests of the experimental prototype.%针对磁悬浮电机转子系统模态分析误差较大的问题，提出考虑转子组件间的非线性接触行为，基于罚函数方法通过修正优化接触刚度因子实现对电机柔性转子系统模态的精确分析。通过建立弹性支承转子-轴承系统有限元分析模型，得到了在不同的支承刚度下转子系统前10阶固有频率的仿真值及变化规律。进行模态测试实验验证，结果表明仿真分析和测试值吻合较好，并对加动平衡环后的转子系统进行固有频率的仿真，其结果的准确性在试验样机穿越临界转速时得到了验证。
Composite rotor blades for large wind energy installations
Kussmann, A.; Molly, J.; Muser, D.
1980-01-01
The design of large wind power systems in Germany is reviewed with attention given to elaboration of the total wind energy system, aerodynamic design of the rotor blade, and wind loading effects. Particular consideration is given to the development of composite glass fiber/plastic or carbon fiber/plastic rotor blades for such installations.
Research Status and Application Prospects of Flywheel Battery Rotor Design%飞轮电池转子设计研究现状及应用展望
杨万利; 张维超
2014-01-01
作为国际能源界研究的热点之一，飞轮电池具有效率高、储能大、无污染、寿命长，维护简单、可持续工作等特点。本文介绍了飞轮电池的储能原理，阐述了当前基于不同材料飞轮转子设计研究现状，对飞轮电池与其他储能方式优缺点进行了比较并且给出了飞轮电池三个典型应用方面，指出飞轮电池有着广泛的应用前景。%As one of the research focus in the international energy sector, the flywheel energy storage battery has the advantages of high efficiency, high energy storage, pollution-well, long service life, easy maintenance, sustainable work and so on. This paper introduces the operation principle of flywheel battery, describes the current development status of the flywheel rotor design based on different materials in detail, then the flywheel battery and other energy storage are compared to point out the flywheel battery's advantages. At last three typical applications of the flywheel battery are given and noted that the flywheel battery has vast potential for future application.
Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model
Lee, Hyun-Ku; Viswamurthy, S.R.; Park, Sang Chul
2010-01-01
rotor-blade/control-system model was loosely coupled with various inflow and wake models in order to simulate both hover and forward-flight conditions. The resulting rotor blade response and pitch link loads are in good agreement with those predicted byCAMRADII. The present analysis features both model......In this paper, an accurate structural dynamic analysis was developed for a helicopter rotor system including rotor control components, which was coupled to various aerodynamic and wake models in order to predict an aeroelastic response and the loads acting on the rotor. Its blade analysis was based...... on an intrinsic formulation of moving beams implemented in the time domain. The rotor control system was modeled as a combination of rigid and elastic components. A multicomponent analysis was then developed by coupling the beam finite element model with the rotor control system model to obtain a complete rotor-blade/control...
Dynamic Analysis of Darrieus Vertical Axis Wind Turbine Rotors
Lobitz, D. W.
1981-01-01
The dynamic response characteristics of the vertical axis wind turbine (VAWT) rotor are important factors governing the safety and fatigue life of VAWT systems. The principal problems are the determination of critical rotor speeds (resonances) and the assessment of forced vibration response amplitudes. The solution to these problems is complicated by centrifugal and Coriolis effects which can have substantial influence on rotor resonant frequencies and mode shapes. The primary tools now in use for rotor analysis are described and discussed. These tools include a lumped spring mass model (VAWTDYN) and also finite-element based approaches. The accuracy and completeness of current capabilities are also discussed.
Position Sensing for Rotor in Hybrid Stepper Motor
Howard, David E. (Inventor); Alhorn, Dean C. (Inventor); Smith, Dennis A. (Inventor)
2011-01-01
A method and system are provided for sensing the position of a rotor in a hybrid stepper motor. First and second Hall sensors are positioned in a spaced-apart relationship with the first and second armatures of the rotor such that the first and second Hall sensors generate electrical outputs that are 90.degree. out of phase with one another as the rotor rotates. The electrical outputs are adjusted relative to a reference, and the amplitude of the electrical outputs is further adjusted to account for spacing differences between the rotor and each of the first and second Hall sensors.
Turbulence characteristics of the B\\"{o}dewadt layer in a large enclosed rotor-stator system
Randriamampianina, A; Randriamampianina, Anthony
2006-01-01
A three-dimensional (3D) direct numerical simulation is combined with a laboratory study to describe the turbulent flow in an enclosed annular rotor-stator cavity characterized by a large aspect ratio G=(b-a)/h=18.32 and a small radius ratio a/b=0.152, where a and b are the inner and outer radii of the rotating disk and h is the interdisk spacing. The rotation rate Omega under consideration is equivalent to the rotational Reynolds number Re=Omegab2/nu=9.5 x 104, where nu is the kinematic viscosity of the fluid. This corresponds to a value at which an experiment carried out at the laboratory has shown that the stator boundary layer is turbulent, whereas the rotor boundary layer is still laminar. Comparisons of the 3D computed solution with velocity measurements have given good agreement for the mean and turbulent fields. The results enhance evidence of weak turbulence at this Reynolds number, by comparing the turbulence properties with available data in the literature. An approximately self-similar boundary la...
Rotor Vibration Reduction via Active Hybrid Bearings
Nicoletti, Rodrigo; Santos, Ilmar
2002-01-01
The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...
Corrigan, J. C.; Cronkhite, J. D.; Dompka, R. V.; Perry, K. S.; Rogers, J. P.; Sadler, S. G.
1989-01-01
Under a research program designated Design Analysis Methods for VIBrationS (DAMVIBS), existing analytical methods are used for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM), which has been developed, extensively documented, and correlated with ground vibration test. One procedure that was used for predicting coupled rotor-fuselage vibrations using the advanced Rotorcraft Flight Simulation Program C81 and NASTRAN is summarized. Detailed descriptions of the analytical formulation of rotor dynamics equations, fuselage dynamic equations, coupling between the rotor and fuselage, and solutions to the total system of equations in C81 are included. Analytical predictions of hub shears for main rotor harmonics 2p, 4p, and 6p generated by C81 are used in conjunction with 2p OLS measured control loads and a 2p lateral tail rotor gearbox force, representing downwash impingement on the vertical fin, to excite the NASTRAN model. NASTRAN is then used to correlate with measured OLS flight test vibrations. Blade load comparisons predicted by C81 showed good agreement. In general, the fuselage vibration correlations show good agreement between anslysis and test in vibration response through 15 to 20 Hz.
田书欣; 杨喜军; 刘占军; 刘明霖; 管洪飞
2011-01-01
Low temperature hot-water floor heating system was a new room heating method. In order to improve the performance of hot-water floor heating system and speed regulating, decrease energy consumption, reduce cost and save space, pump motor should use permanent magnet synchronous motor controlled by adopting the technology of sliding mode observer for sensorless vector control. Based on the theoretical analysis of sliding mode observer for sensorless vector control, variable frequency drive system of hot-water floor heating system was designed and realized.The design process of the system was given. The simulation waveforms utilizing MATLAB/Simulink and measured waveforms on the basis of TMS320F2401 DSP were shown. The results showed that the efficiency of the whole system can reach 35％.%地板水暖是一种新型的房间采暖技术,为了提高地板水暖系统的整体性能、改善调速性能、节能降耗、降低成本和节约空间,水泵电机采用无速度传感器永磁同步电机(PMSM)矢量控制系统.在理论分析PMSM滑模观测器矢量控制原理的基础上,设计和实现了地板热水供暖的变频调速传动系统,描述了该系统的设计过程,给出了有关MATLAB/Simulink仿真波形和基于TMS320F2401控制器的实测波形,整个系统效率高达35%.
THEORY OF MUM FOR METAL SPHERICAL ROTOR WITH CONTACTLESS SUSPENSION
He Xiaoxia; Gao Zhongyu; Wang Yongliang
2004-01-01
Based on the motion equations of an unbalanced spherical rotor with contactless suspension,three methods of MUM (mass unbalance measurement) are put forward to measure the total mass unbalance,radical mass unbalance and radical mass unbalance of the rotor.Total mass unbalance is obtained when the unbalanced rotor plays as a simple pendulum in static situation.The pendulant period and pendulant midpoint indicate magnitude and direction of total mass unbalance of the rotor respectively.Analysis of the motion equations by using the averaging method yields that the rotor will do a special side oscillation when an auxiliary system makes the rotor spin about its pole axis which is orientating toward the local vertical.The radical mass unbalance can be obtained by building a proper displacement sensor to sense the amplitude of the side oscillation.Necessary analysis of the motion equations also shows that when the rotor spins at a small angular velocity and the rotary axis is perpendicular to the vertical,the pole axis of the rotor will precess slowly about the vertical by virtue of the axial mass unbalance.The axial mass unbalance can be estimated from the time history of the spin vector of the rotor.Finally,measurement precision of the three methods is compared and how the external torque affects the measurement precision for the three methods are examined.
Identification of helicopter rotor dynamic models
Molusis, J. A.; Bar-Shalom, Y.; Warmbrodt, W.
1983-01-01
A recursive, extended Kalman-filter approach is applied to the identifiction of rotor damping levels of representative helicopter dynamic systems. The general formulation of the approach is presented in the context of a typically posed stochastic estimation problem, and the method is analytically applied to determining the damping levels of a coupled rotor-body system. The identified damping covergence characteristics are studied for sensitivity to both constant-coefficient and periodic-coefficient measurement models, process-noise covariance levels, and specified initial estimates of the rotor-system damping. A second application of the method to identifying the plant model for a highly damped, isolated flapping blade with a constant-coefficient state model (hover) and a periodic-coefficient state model (forward flight) is also investigated. The parameter-identification capability is evaluated for the effect of periodicity on the plant model coefficients and the influence of different measurement noise levels.
彭建强
2013-01-01
综合国外700℃以上汽轮机高中压转子材料研究情况，结合我国高温合金材料的发展水平，给出我国700℃以上超超临界汽轮机高中压转子用材建议。%Integrated with domestic and international research situation on HP and MP rotor of more than 700℃steam turbine , and combined with the development level of high temperature alloy materials in China , the suggestion are given for the material of HP and MP rotor of more than 700℃ultra-supercritical steam turbine in China .
冯韧; 王兵; 侯黎平
2016-01-01
Based on the fact that asynchronous motors are characterized with periodic load operation, the optimal voltage of wound rotor asynchronous motors has been determined under no-load and light-load operating modes. With the load ratio a constant, the power factor under the optimal voltage is greater than that under the rated voltage. In light of the features of winding rotor asynchronous motors, a research has been conducted on the side series resistance starting and the capacity of voltage regulation and energy-saving series under series resistance speed regulation. When a resistance of 2 is connected in series with the rotor circuit, an accelerated starting of the motor has thus achieved. With the optimal voltage a constant, the electromagnetic torque remains constant before and after the series resistance has been connected with the rotor circuit. A step-down series resistance speed regulation model of wound rotor asynchronous motors has been set up to work out the relationship between the energy consumption of the rotor turn-on and rotor series resistance under a constant optimal voltage. When the load factor of the motor is in the range of 0%~50%, a certain energy-saving space could be obtained by appropriately reducing the power supply voltage, thus verifying the feasibility of the energy saving operation under the light load rotor series resistance voltage regulation of wound rotor asynchronous motors under the optimal voltage.%根据异步电动机带周期性负载运行的特点，确定了绕线式异步电动机处于空载、轻载运行状态下的最优电压，且维持负载率不变时，其在最优电压下的功率因数大于其在额定电压下的。针对绕线式异步电动机的特性，研究了其转子侧串电阻启动及串电阻调速下调压节能的运行状态，得知当转子回路中串入2电阻时，可加速电机启动，且在最优电压一定时，串电阻前后的电磁转矩恒定。通过搭建绕线式异步电动
Gupta, R.; Biswas, A.; Sharma, K.K. [Department of Mechanical Engineering, National Institute of Technology (NIT), Silchar 788 010, Assam (India)
2008-09-15
The vertical axis wind turbines are simple in construction, self-starting, inexpensive and can accept wind from any direction without orientation. A combined Savonius-Darrieus type vertical axis wind rotor has got many advantages over individual Savonius or individual Darrieus wind rotor, such as better efficiency than Savonius rotor and high starting torque than Darrieus rotor. But works on the combined Savonius-Darrieus wind rotor are very scare. In view of the above, two types of models, one simple Savonius and the other combined Savonius-Darrieus wind rotors were designed and fabricated. The Savonius rotor was a three-bucket system having provisions for overlap variations. The Savonius-Darrieus rotor was a combination of three-bucket Savonius and three-bladed Darrieus rotors with the Savonius placed on top of the Darrieus rotor. The overlap variation was made in the upper part, i.e. the Savonius rotor only. These were tested in a subsonic wind tunnel available in the department. The various parameters namely, power coefficients and torque coefficients were calculated for both overlap and without overlap conditions. From the present investigation, it is seen that with the increase of overlap, the power coefficients start decreasing. The maximum power coefficient of 51% is obtained at no overlap condition. However, while comparing the power coefficients (C{sub p}) for simple Savonius-rotor with that of the combined configuration of Savonius-Darrieus rotor, it is observed that there is a definite improvement in the power coefficient for the combined Savonius-Darrieus rotor without overlap condition. Combined rotor without overlap condition provided an efficiency of 0.51, which is higher than the efficiency of the Savonius rotor at any overlap positions under the same test conditions. (author)
Performance of meta power rotor shaft torque meter
Schmidt Paulsen, U.
2002-01-01
The present report describes the novel experimental facility in detecting shaft torque in the transmission system (main rotor shaft, exit stage of gearbox) of a wind turbine, the results and the perspectives in using this concept. The measurements arecompared with measurements, based on existing ...... strain gauges and transducers mounted on the main rotor shaft and controller....
Eigenfrequency sensitivity analysis of flexible rotors
Šašek J.
2007-10-01
Full Text Available This paper deals with sensitivity analysis of eigenfrequencies from the viewpoint of design parameters. The sensitivity analysis is applied to a rotor which consists of a shaft and a disk. The design parameters of sensitivity analysis are the disk radius and the disk width. The shaft is modeled as a 1D continuum using shaft finite elements. The disks of rotating systems are commonly modeled as rigid bodies. The presented approach to the disk modeling is based on a 3D flexible continuum discretized using hexahedral finite elements. The both components of the rotor are connected together by special proposed couplings. The whole rotor is modeled in rotating coordinate system with considering rotation influences (gyroscopic and dynamics stiffness matrices.
2011-01-01
The Brushless Direct Current （BLDC） motor is widely used in aerospace area, CNC machines and servo systems that require the high control accuracy Once the faults occur in the motor, it will cause great damage to the whole system. Mechanical faults are common in electric machines, and account for up to 50%-60% of the faults. Approximately, 80% of the mechanical faults lead to the eccentricity. So it is necessary to monitor the health condition of the motor to ensure the faults can be detected earlier and measures will be taken to imorove the reliability.
The Model of Nonstationary Rotor Magnetic Field Observer in the Induction Motor
Burkov, Alexander; Krasilnikyants, Evgenii; Smirnov, Alexander
2011-01-01
This article is devoted to the questions, associated with observer construction for monitoring the values of rotor magnetic vector magnitude and angular deflection of induction motor oriented on bidimensional convolution on temporal and spatial actual parameters. The interrelation of induction motor breakdown torque and rotor characteristic time and transportation lag is shown. The system of rotor running stream observer on the basis of gage rotor position and stator current is put forward.
Nearfield Unsteady Pressures at Cruise Mach Numbers for a Model Scale Counter-Rotation Open Rotor
Stephens, David B.
2012-01-01
An open rotor experiment was conducted at cruise Mach numbers and the unsteady pressure in the nearfield was measured. The system included extensive performance measurements, which can help provide insight into the noise generating mechanisms in the absence of flow measurements. A set of data acquired at a constant blade pitch angle but various rotor speeds was examined. The tone levels generated by the front and rear rotor were found to be nearly equal when the thrust was evenly balanced between rotors.
Dynamics of the rotor on elastic-damping supports under action of kinematic effects
Chernyshev, V.; Savin, L.; Fominova, O.
2017-08-01
The article describes the elements of the theory of dynamic analysis of rotor systems. The mathematical model of a gyroscopic rotor as an elementary object on elastic-damping supports. The results of simulation of the trajectories of the rotor under kinematic loading with amplitude commensurate with the clearance in bearing assemblies of fluid friction.
Effects of increasing tip velocity on wind turbine rotor design.
Resor, Brian Ray [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Maniaci, David Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Berg, Jonathan Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Richards, Phillip William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-05-01
A reduction in cost of energy from wind is anticipated when maximum allowable tip velocity is allowed to increase. Rotor torque decreases as tip velocity increases and rotor size and power rating are held constant. Reduction in rotor torque yields a lighter weight gearbox, a decrease in the turbine cost, and an increase in the capacity for the turbine to deliver cost competitive electricity. The high speed rotor incurs costs attributable to rotor aero-acoustics and system loads. The increased loads of high speed rotors drive the sizing and cost of other components in the system. Rotor, drivetrain, and tower designs at 80 m/s maximum tip velocity and 100 m/s maximum tip velocity are created to quantify these effects. Component costs, annualized energy production, and cost of energy are computed for each design to quantify the change in overall cost of energy resulting from the increase in turbine tip velocity. High fidelity physics based models rather than cost and scaling models are used to perform the work. Results provide a quantitative assessment of anticipated costs and benefits for high speed rotors. Finally, important lessons regarding full system optimization of wind turbines are documented.
风力机叶轮质量不平衡故障建模及仿真研究%Research on the Modeling and Simulation of Wind Turbine Rotor Imbalance Fault
杨涛; 任永; 刘霞; 黄树红; 高伟
2012-01-01
风力机叶轮质量不平衡故障对风力发电机组的安全稳定运行影响很大,传统的基于振动的故障诊断方法需要在风力机上安装大量的传感器,成本较高同时可靠性也较差.近年来,已有学者采用基于电信号的故障诊断方法对该故障进行试验研究,但未对该诊断方法进行理论上解释.在对该故障机理进行简要阐述后,在理论上推导该故障对风力机电功率造成的影响,利用Simulink建立在该故障状态下包含叶轮、传动链与发电机的风力机模型,仿真得到该故障条件下的电功率信号,频谱分析的结果显示其包含叶轮旋转的一倍频分量,且随着不平衡质量的增大而增大,与德国ISET研究所等试验研究的结果相符,仿真的结果从定量的角度表现该故障的严重程度,该方法可应用到故障诊断系统中用以确定不平衡质量的大小.%The rotor mass imbalance has a big effect on the safe and stable operation of the wind turbine generators, the traditional diagnosis technologies which are based on the vibration monitoring require a large number of sensors mounting on wind turbines, it costs a lot and the reliability is also poor. The experiment researches have been made using the diagnosis technologies based on the electrical signals in recent years, but it has not provide theory understanding for the diagnosis technologies. Based on the description of the mechanism of the fault, then in theory, derive the impact of the fault on the generator power, finally establish the simulink model under the fault which contains the rotor model, the drive train model and the generator model, and obtained the generator power signal which has detected the 1st frequency of the rotor under the fault, with the imbalance increases, the amplitude of 1st frequency increases too, it's consistent with the experiment results of the ISET, the simulation results reveal the severity of the fault qualitatively, this method
Jia, Mei-Hui; Wang, Cheng-Lin; Ren, Bin
2017-07-01
Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this problem has not been carried out. A rotor with an acceleration of 150,000 g is considered as the objective, the effects of manufacturing errors on rotor mechanical properties and dynamic characteristics are executed by the selection of the key affecting factors. Through the force balance equation of the rotor infinitesimal unit establishment, a theoretical model of stress calculation based on slice method is proposed and established, a formula for the rotor stress at any point derives. A finite element model (FEM) of rotor with holes is established with manufacturing errors. The changes of the stresses and strains of a rotor in parallelism and symmetry errors are analyzed, which verify the validity of the theoretical model. The pre-stressing modal analysis is performed based on the aforementioned static analysis. The key dynamic characteristics are analyzed. The results demonstrated that, as the parallelism and symmetry errors increase, the equivalent stresses and strains of the rotor slowly increase linearly, the highest growth rate does not exceed 4%, the maximum change rate of natural frequency is 0.1%. The rotor vibration mode is not significantly affected. The FEM construction method of the rotor with manufacturing errors can be utilized for the quantitative research on rotor characteristics, which will assist in the active control of rotor component reliability under high acceleration.
林广学; 高怀智
2011-01-01
该文给出了一种安装新型飞刀转子的高浓水力碎浆机的工作原理，并给出了多种纤维原料分解的试验效果。实验证明，这种安装了飞刀转子的新型碎浆机能够适应多种纤维原料的碎解，且碎解时间短，能效高，处理效果好。这种新型转子的研制可实现现有水力碎浆机处理能力的升级，具有较高的推广应用价值。%this article describes the working principle of high-concentration hydrapulper equipped with a new-type knife rotor as well as the test result on decomposition of various fiber materials. The test shows that this new-type hydrapulper with knife rotor can be applied to shredding various fiber materials with short time, high efficiency and good processing result. The research outcome of the new rotor can upgrade the processing capacity of existing hydrapulper, showing high value for promotion and application.
田文强; 李岩; 冯放; 张影微; 和庆斌
2013-01-01
利用数值计算和风洞试验相结合的方法对Savonius风力机的力矩特性进行了研究.首先在数值计算中选用了2种湍流模型,即单方程Splart-Allmaras湍流模型和双方程k-ε湍流模型,计算了Savonius风力机在不同攻角下的静力矩以及在不同转速下的输出力矩和输出功率,得到了风力机周围的流场,并对流场进行了分析；利用风洞试验对数值计算结果进行了验证,对比分析了不同湍流模型对Savonius风力机力矩特性和风轮周围流场的影响.%The torque performance of a Savonius rotor was researched by numerical simulation and wind tunnel test. First, 2 kinds of turbulence models were chosen in the simulation study including the Splart-Allmaras model and the k-ε model. The static and dynamic torque performances of Savonius rotor at different angles of attack were calculated, and the flow fields around the rotor were also obtained and analyzed. Furthermore, wind tunnel test was carried out to verify the computational results. The torque performance and the flow fields around the Savonius rotor based on different turbulence models were analyzed.
Hughes, S.
2011-02-01
The primary thrust of the CRADA will be to develop a new rotor design that will allow higher current flows (>4m/s), greater swept area (6-11m), and in the process, will maximize performance and energy capture.
Bergh, J
2012-06-01
Full Text Available improvements could be obtained through the design of custom end walls for the turbine. This investigation therefore covers the design of custom non-axisymmetric end wall contours for the rotor row of an annular turbine rig with unshrouded blades (the same rig...
A Brief Review on Dynamics of a Cracked Rotor
Chandan Kumar
2009-01-01
Full Text Available Fatigue crack is an important rotor fault, which can lead to catastrophic failure if undetected properly and in time. Study and Investigation of dynamics of cracked shafts are continuing since last four decades. Some review papers were also published during this period. The aim of this paper is to present a review on recent studies and investigations done on cracked rotor. It is not the intention of the authors to provide all literatures related with the cracked rotor. However, the main emphasis is to provide all the methodologies adopted by various researchers to investigate a cracked rotor. The paper incorporates a candid commentary on various methodologies. The paper further deals an extended Lagrangian formulation to investigate dynamics of cracked rotor.
The application of advanced rotor (performance) methods for design calculations
Bussel, G.J.W. van [Delft Univ. of Technology, Inst. for Wind Energy, Delft (Netherlands)
1997-08-01
The calculation of loads and performance of wind turbine rotors has been a topic for research over the last century. The principles for the calculation of loads on rotor blades with a given specific geometry, as well as the development of optimal shaped rotor blades have been published in the decades that significant aircraft development took place. Nowadays advanced computer codes are used for specific problems regarding modern aircraft, and application to wind turbine rotors has also been performed occasionally. The engineers designing rotor blades for wind turbines still use methods based upon global principles developed in the beginning of the century. The question what to expect in terms of the type of methods to be applied in a design environment for the near future is addressed here. (EG) 14 refs.
SMART wind turbine rotor. Data analysis and conclusions
Berg, Jonathan Charles; Barone, Matthew Franklin; Yoder, Nathanael C.
2014-01-01
The Wind Energy Technologies department at Sandia National Laboratories has developed and field tested a wind turbine rotor with integrated trailing-edge flaps designed for active control of the rotor aerodynamics. The SMART Rotor project was funded by the Wind and Water Power Technologies Office of the U.S. Department of Energy (DOE) and was conducted to demonstrate active rotor control and evaluate simulation tools available for active control research. This report documents the data post-processing and analysis performed to date on the field test data. Results include the control capability of the trailing edge flaps, the combined structural and aerodynamic damping observed through application of step actuation with ensemble averaging, direct observation of time delays associated with aerodynamic response, and techniques for characterizing an operating turbine with active rotor control.
APPLICATION OF MECHANIZED MATHEMATICS TO ROTOR DYNAMICS
胡超; 王岩; 王立国; 黄文虎
2002-01-01
Based on the mechanized mathematics and WU Wen-tsun elimination method,using oil film forces of short-bearing model and Muszynska's dynamic model, the dynamical behavior of rotor-bearing system and its stability of motion are investigated. As example,the concept of Wu characteristic set and Maple software, whirl parameters of short- bearing model, which is usually solved by the numerical method, are analyzed. At the same time,stability of zero solution of Jeffcott rotor whirl equation and stability of self-excited vibration are studied. The conditions of stable motion are obtained by using theory of nonlinear vibration.
Duda, Richard O.; Shortliffe, Edward H.
1983-01-01
Discusses a class of artificial intelligence computer programs (often called "expert systems" because they address problems normally thought to require human specialists for their solution) intended to serve as consultants for decision making. Also discusses accomplishments (including information systematization in medical diagnosis and…
Power Systems Advanced Research
California Institute of Technology
2007-03-31
In the 17 quarters of the project, we have accomplished the following milestones - first, construction of the three multiwavelength laser scattering machines for different light scattering study purposes; second, build up of simulation software package for simulation of field and laboratory particulates matters data; third, carried out field online test on exhaust from combustion engines with our laser scatter system. This report gives a summary of the results and achievements during the project's 16 quarters period. During the 16 quarters of this project, we constructed three multiwavelength scattering instruments for PM2.5 particulates. We build up a simulation software package that could automate the simulation of light scattering for different combinations of particulate matters. At the field test site with our partner, Alturdyne, Inc., we collected light scattering data for a small gas turbine engine. We also included the experimental data feedback function to the simulation software to match simulation with real field data. The PM scattering instruments developed in this project involve the development of some core hardware technologies, including fast gated CCD system, accurately triggered Passively Q-Switched diode pumped lasers, and multiwavelength beam combination system. To calibrate the scattering results for liquid samples, we also developed the calibration system which includes liquid PM generator and size sorting instrument, i.e. MOUDI. In this report, we give the concise summary report on each of these subsystems development results.
Study on the rotor design method for a small propeller-type wind turbine
Nishi, Yasuyuki; Yamashita, Yusuke; Inagaki, Terumi
2016-08-01
Small propeller-type wind turbines have a low Reynolds number, limiting the number of usable airfoil materials. Thus, their design method is not sufficiently established, and their performance is often low. The ultimate goal of this research is to establish high-performance design guidelines and design methods for small propeller-type wind turbines. To that end, we designed two rotors: Rotor A, based on the rotor optimum design method from the blade element momentum theory, and Rotor B, in which the chord length of the tip is extended and the chord length distribution is linearized. We examined performance characteristics and flow fields of the two rotors through wind tunnel experiments and numerical analysis. Our results revealed that the maximum output tip speed ratio of Rotor B shifted lower than that of Rotor A, but the maximum output coefficient increased by approximately 38.7%. Rotors A and B experienced a large-scale separation on the hub side, which extended to the mean in Rotor A. This difference in separation had an impact on the significant decrease in Rotor A's output compared to the design value and the increase in Rotor B's output compared to Rotor A.
Analysis of Permanent Magnets Bearings in Flywheel Rotor Designs
Prince Owusu-Ansah
2016-04-01
Full Text Available This paper discusses analysis of permanent magnet bearing in flywheel rotor designs. This work focuses on the advantages of using permanent magnets in flywheel rotor design as compared to that of the convectional mode of levitating the rotor position. The use of permanent magnet in magnetic bearing design to generate the steady state position of the magnetic field results in less variation of the force exerted on the rotor when it deviates from the nominal position than when an electrical coil is used for the same purpose. Theresults of the analysis shows that the magnetic bearing dynamics as well as its load carryingcapacity improves when the rotor is offset from its central position. The use of permanent magnet compared to current-carrying coils results in smaller overall size of magnetic bearing leading to a more compact system design resulting in improved rotordynamic performance
rotor of the SC rotating condenser
1974-01-01
The rotor of the rotating condenser was installed instead of the tuning fork as the modulating element of the radiofrequency system, when the SC accelerator underwent extensive improvements between 1973 to 1975 (see object AC-025). The SC was the first accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990.
A VORTEX MODEL OF A HELICOPTER ROTOR
Valentin BUTOESCU
2009-06-01
Full Text Available A vortex model of a helicopter rotor is presented. Each blade of the rotor has three degrees of freedom: flapping, lagging and feathering. The motions after each degree of freedom are also known for all blades. The blade is modelled as a thin vortex surface. The wakes are free fluid surfaces. A system of five equations are obtained: the first one is the integral equation of the lifting surface (rotor, the next three describe the wakes motion, and the last one relates the vortex strength on the wakes and the variation of vorticity on the rotor. A numerical solution of this system is presented. To avoid the singularities that can occur due to the complexity of vortex system, a desingularized model of the vortex core was adopted. A Mathcad worksheet containing the method has been written.The original contribution of the work. The calculation method of the motion of the wakes free vortex system, the development of the vortex cores in time and a new method to approximate the aerodynamic influence of remoted wake regions.
Research on a New Method for Screw Rotor Processing Using Abrasive Water Jet%基于磨料水射流的螺杆转子加工新方法研究
何雪明; 陈泽华; 武美萍; 张荣
2016-01-01
In the traditional machining processes of screw rotors,there were problems such as tool wear and high cutting heat.Abrasive water j et machining had some characteristics of no tool wear,low cutting heat and environmental protection.An abrasive water j et was introduced into the re-search of screw rotor processing,and a new method of abrasive water j et was proposed to improve the machining accuracy and efficiency of the rotors.The arbitrary Lagrangian-Eulerian method was applied to construct the rotor machining simulation model,the accuracy of simulation model was veri-fied by comparing the simulation results with the experimental data.Finally,through the analyses of the simulation results of multi axis machining of abrasive water j et,it is proved that the new machi-ning method of screw rotors has certain rationality.%螺杆转子传统加工过程中存在刀具磨损和过高切削热量等难题。为此，将具有无刀具磨损、切削热量低、绿色环保特点的磨料水射流加工方法引入螺杆转子加工研究之中，提出了磨料水射流多轴联动加工螺杆转子的新方法，以提高转子加工精度和效率。采用任意拉格朗日与欧拉方法构建了转子加工模拟模型，将模拟分析结果与实验数据进行比较，验证了模拟模型的正确性。最后，通过磨料对水射流多轴联动加工模拟结果的分析，证明了螺杆转子加工新方法的合理性。
Research on Spoken Dialogue Systems
Aist, Gregory; Hieronymus, James; Dowding, John; Hockey, Beth Ann; Rayner, Manny; Chatzichrisafis, Nikos; Farrell, Kim; Renders, Jean-Michel
2010-01-01
Research in the field of spoken dialogue systems has been performed with the goal of making such systems more robust and easier to use in demanding situations. The term "spoken dialogue systems" signifies unified software systems containing speech-recognition, speech-synthesis, dialogue management, and ancillary components that enable human users to communicate, using natural spoken language or nearly natural prescribed spoken language, with other software systems that provide information and/or services.
Tunyasrirut, Satean; Ngamwiwit, Jongkol [Faculty of Engineering and Research Center for Communications and Information Technology, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Kinnares, Vijit [Department of Electrical Engineering, Faculty of Engineering, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Furuya, Tadayoshi [Department of Electronics and Control Engineering, Kitakyushu National College of Technology, Kitakyushu, Fukuoka (Japan); Yamamoto, Yoshiichi [Department of Electronic Control, Kumamoto National College of Technology, 2659-2 Suya Nishigoshi-machi Kikuchi-Gun, Kumamoto Prefecture 861-1102 (Japan)
2008-05-15
This paper introduces a modified slip energy recovery drive system for speed control of a wound rotor induction motor offering improvement of drive performance, particularly line power factor and overall system efficiency. A 12-pulse line commutated thyristor converter operating in an inverter mode in conjunction with an additional IGBT shunt chopper is employed to transfer slip energy back to ac mains supply via three phase transformers. This approach offers motor speed control by varying the duty cycle of the chopper instead of changing the inverter firing angle. As a consequence, supply power factor can be improved. The servo state feedback designed by linear quadratic regulator (LQR) with observer is also included in order to keep motor speed to be constant over a certain range of operating conditions by using the estimated dc link current derived from motor speed. The advantage of this technique is absence of current transducers for current feedback control loop. The overall control system is implemented on DSP, DS1104'TMS320F240 controller board. Experimental results are illustrated in order to validate performance of the proposed system. (author)
K. Siva Kumar
2012-01-01
Full Text Available Problem statement: The Rotor reactance control by inclusion of external capacitance in the rotor circuit has been in recent research for improving the performances of Wound Rotor Induction Motor (WRIM. The rotor capacitive reactance is adjusted such that for any desired load torque the efficiency of the WRIM is maximized. The rotor external capacitance can be controlled using a dynamic capacitor in which the duty ratio is varied for emulating the capacitance value. This study presents a novel technique for tracking maximum efficiency point in the entire operating range of WRIM using Artificial Neural Network (ANN. The data for ANN training were obtained on a three phase WRIM with dynamic capacitor control and rotor short circuit at different speed and load torque values. Approach: A novel neural network model based on the back-propagation algorithm has been developed and trained in determining the maximum efficiency of the motor with no prior knowledge of the machine parameters. The input variables to the ANN are stator current (Is, Speed (N and Torque (Tm and the output variable is the duty ratio (D. Results: The target is pre-set and the accuracy of the ANN model is measured using Mean Square Error (MSE and R2 parameters. The result of R2 value of the proposed ANN model is found to be 0.99980. Conclusion: The optimal duty ratio and corresponding optimal rotor capacitance for improving the performances of the motor are predicted for low, medium and full loads by using proposed ANN model.
Rotor for a pyrolysis centrifuge reactor
2015-01-01
The present invention relates to a rotor for a pyrolysis centrifuge reactor, said rotor comprising a rotor body having a longitudinal centre axis, and at least one pivotally mounted blade being adapted to pivot around a pivot axis under rotation of the rotor body around the longitudinal centre axis....... Moreover, the present invention relates to a pyrolysis centrifuge reactor applying such a rotor....
组合式转子电机开环稳定性探讨%Research on Open-loop Stability of Combined Rotor Machine
陈学珍; 陈旭武; 刘俊
2014-01-01
The combined rotor machine is made up of a high density axially laminated magnetic reluctance seg-ment and a surface permanent magnet segment.Influences on the stability of the machine are analyzed for the different angle αbetween two-part d-axis,the conclusion has been drawn that the stable operation of the combined rotor motor can be obtained when the angle αmeets the certain conditions .And open-loop and no-load starting experiments on combined rotor motor are respectively completed when α=0,α=45°andα=90°,the experimental results show that theoretical analysis is correct ,which provides the reliable theoretical evidence for the combined rotor motor to realize the practical application .%组合式转子电机的转子由面贴式永磁段和高密度轴向叠片磁阻段组合而成。分析了2段 d轴之间的夹角α对电机稳定性的影响，得出了组合式转子电机稳定运行时α角应满足的条件，并分别对α＝0，α＝45°和α＝90°时3台组合式转子电机进行开环空载起动实验。实验结果表明该理论分析是正确的，为该组合式转子电机实用化提供了有力的理论依据。
Thermal Stress Research on 660MW Ultra Supercritical Turbine Rotor%660MW超超临界汽轮机转子热应力的研究
付忠广; 杜志锋; 王梦娇
2012-01-01
For the purpose of improving the safe and economic operation of the unit, based on the rated curve of hot state start-up, the temperature field and stress field of a 660 MW ultra supercritical steam turbine rotor were presented by software ANSYS. At the same time, the thermal stress of the steam turbine rotor was calculated based on the analytical recursion. Through comparison of two calculated results and further analysis on the influential factors of thermal stress, it shows that the impeller root of governing stage, the shaft shoulder of high pressure cylinder and the first level of intermediate pressure cylinder have larger stress concentration. Rotor structure, the heating rates, coefficient of heat transfer and operating parameters have bigger effects on the thermal stress of the rotor.%以提高机组的安全、经济运行为目的,利用大型通用有限元软件ANSYS,依据某电厂660MW超超临界机组热态启动曲线,对汽轮机转子进行温度场、应力场的计算；同时根据解析递推算法计算汽轮机转子热应力,比较分析两种计算结果,并进一步对影响这些部位热应力的因素进行研究,结果表明,汽轮机转子的调节级叶轮根部、高中压缸之间轴肩与中压第一级叶轮根部存在较大的应力集中,转子体结构、蒸汽温升率、换热系数、运行参数对转子热应力影响较大.
Resonant vibration control of three-bladed wind turbine rotors
Krenk, Steen; Svendsen, Martin Nymann; Høgsberg, Jan Becker
2012-01-01
Rotors with blades, as in wind turbines, are prone to vibrations due to the flexibility of the blades and the support. In the present paper a theory is developed for active control of a combined set of vibration modes in three-bladed rotors. The control system consists of identical collocated...... to influence of other nonresonant modes. The efficiency of the method isdemonstrated byapplication to a rotor with 42 m blades, where the sensor/actuator system is implemented in the form of an axial extensible strut near the root of each blade. The load is provided by a simple but fully threedimensional...
Zapoměl, J.; Ferfecki, P.
2016-09-01
A frequently used technological solution for minimization of undesirable effects caused by vibration of rotating machines consists in placing damping devices in the rotor supports. The application of magnetorheological squeeze film dampers enables their optimum performance to be achieved in a wide range of rotating speeds by adapting their damping effect to the current operating conditions. The damping force, which is produced by squeezing the layer of magnetorheological oil, can be controlled by changing magnetic flux passing through the lubricant. The force acting between the rotor and its frame is transmitted through the rolling element bearing, the lubricating layer and the squirrel spring. The loading of the bearing produces a time variable friction moment, energy losses, uneven rotor running, and has an influence on the rotor service life and the current fluctuation in electric circuits. The carried out research consisted in the development of a mathematical model of a magnetorheological squeeze film damper, its implementation into the computational models of rotor systems, and in performing the study on the dependence of the energy losses and variation of the friction moment on the damping force and its control. The new and computationally stable mathematical model of a magnetorheological squeeze film damper, its implementation in the computational models of rigid rotors and learning more on the energy losses generated in the rotor supports in dependence on the damping effect are the principal contributions of this paper. The results of the computational simulations prove that a suitable control of the damping force enables the energy losses to be reduced in a wide velocity range.
John G. Cowie; Edwin F. Brush, Jr.; Dale T. Peters; Stephen P. Midson; Darryl J. Van Son
2003-05-01
The objective of the study, Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency, was to support the Copper Development Association (CDA) in its effort to design, fabricate and demonstrate mold technologies designed to withstand the copper motor rotor die casting environment for an economically acceptable life. The anticipated result from the compiled data and tests were to: (1) identify materials suitable for die casting copper, (2) fabricate motor rotor molds and (3) supply copper rotor motors for testing in actual compressor systems. Compressor manufacturers can apply the results to assess the technical and economical viability of copper rotor motors.
J.D.Denton
1997-01-01
NASA rotor 37 was used as a blind test case for turbomachinery CFD by the Turbomachinery Committee of the IGTI.The rotor is a transonic compressor with a tip speed of 454 m/s(1500ft/s)and a relatively high pressure ratio of 2.1.It was tested in isolation with a circumferentially uniform inlet flow so that the flow through it should be steady apart from and effects of passage to passage geometry variation and mechanical vibration.As such it represents the simplest possible type of test for three-dimensional turbomachinery flow solvers.Howerver,the rotor still presents a real challenge to 3D viscous flow solvers because the shock wave-boudary layer interaction is strong and the effects of viscosity are dominant in determining the flow deviation and hence the pressure ration.Eleven blind solutions were submittewd and in addition a non-blind solution was used to prepare for the exercies.This paper reviews the flow in the test case and the comparisons of the CFD solutions with the test data.Lessons for both the Flow physics in transonic fans and for the application of CFD to such machines are pointed out.
张世海; 刘雄彪; 李录平; 晋风华; 梁伟
2016-01-01
The 3D model of rotor system of a domestic 600MW steam turbine has been modeled by using the Solidworks software.The analysis of dynamic characteristics of rotors and shaft system of this unit are completed by using the FEA software Algor.The results shows that the arrangement of modal frequency values of each order of the shaft system is roughly in ascending order according to the modal frequency values of each single rotor .And the distribution of the modal shape of each order of the shaft system with the trend that each modal shape matches the single rotor ’ s one,if the modal frequency value close to the signal rotor's one.The natural frequencies of the rotors and the shaft system are satisfied with the requirements that the values are far from with the operating frequency value .The work of this article offered a reference for the 3D modeling concrete bodies and the analysis of dynamic characteristics of large turbo machines .The results of this study provides theoretical basis for operation of this unit .%采用Solidworks软件对国产某600MW汽轮发电机组转子系统进行三维实体建模。运用Algor有限元软件对该机组各转子及轴系进行了动力特性分析。结果表明：该机组轴系的各阶模态频率值有按照各单转子各阶模态频率值由小到大顺序排列、各阶模态振型相对应的分布趋势；该机组的各转子及轴系的固有频率均满足远离工作频率的要求。为大型汽轮发电机组转子系统的三维实体建模及其动力特性有限元分析提供了一定的参考，研究结果为该机组的运行提供了理论依据。
ADVANCED GAS TURBINE SYSTEMS RESEARCH
Unknown
2002-04-01
The activities of the Advanced Gas Turbine Systems Research (AGTSR) program for this reporting period are described in this quarterly report. The report is divided into discussions of Membership, Administration, Technology Transfer (Workshop/Education), Research and Miscellaneous Related Activity. Items worthy of note are presented in extended bullet format following the appropriate heading.
ADVANCED GAS TURBINE SYSTEMS RESEARCH
Unknown
2002-02-01
The activities of the Advanced Gas Turbine Systems Research (AGTSR) program for this reporting period are described in this quarterly report. The report is divided into discussions of Membership, Administration, Technology Transfer (Workshop/Education), Research and Miscellaneous Related Activity. Items worthy of note are presented in extended bullet format following the appropriate heading.
Research on cloud-based remote measurement and analysis system
Gao, Zhiqiang; He, Lingsong; Su, Wei; Wang, Can; Zhang, Changfan
2015-02-01
The promising potential of cloud computing and its convergence with technologies such as cloud storage, cloud push, mobile computing allows for creation and delivery of newer type of cloud service. Combined with the thought of cloud computing, this paper presents a cloud-based remote measurement and analysis system. This system mainly consists of three parts: signal acquisition client, web server deployed on the cloud service, and remote client. This system is a special website developed using asp.net and Flex RIA technology, which solves the selective contradiction between two monitoring modes, B/S and C/S. This platform supplies customer condition monitoring and data analysis service by Internet, which was deployed on the cloud server. Signal acquisition device is responsible for data (sensor data, audio, video, etc.) collection and pushes the monitoring data to the cloud storage database regularly. Data acquisition equipment in this system is only conditioned with the function of data collection and network function such as smartphone and smart sensor. This system's scale can adjust dynamically according to the amount of applications and users, so it won't cause waste of resources. As a representative case study, we developed a prototype system based on Ali cloud service using the rotor test rig as the research object. Experimental results demonstrate that the proposed system architecture is feasible.
Rotor position sensor switches currents in brushless dc motors
1965-01-01
Reluctance switch incorporated in an induction motor is used for sensing rotor position and switching armature circuits in a brushless dc motor. This device drives the solar array system of an unmanned space satellite.
Effects of Factors on Open-End Rotor Yarn Properties
Gözde BUHARALI
2013-08-01
Full Text Available Open-end rotor spinning system, which was begun to be used commercially during late 1960s, is now used as successfully as the conventional ring spinning system. Thanks to open-end rotor yarn spinning machines are very suitable to automation and have high production speeds, use of these machines have increased permanently and today open-end rotor yarn spinning in the world has a share of about 30%. In open-end rotor spinning system yarn properties and production are effected from three main parameters. They are material, sliver preparing process and machine parameters. In this system which manufacture with very high-speed and uses a high-tech, parameters must be selected carefully to ensure best yarn quality with high performance in yarn production
Homopolar motor with dual rotors
Hsu, John S. (Oak Ridge, TN)
1998-01-01
A homopolar motor (10) has a field rotor (15) mounted on a frame (11) for rotation in a first rotational direction and for producing an electromagnetic field, and an armature rotor (17) mounted for rotation on said frame (11) within said electromagnetic field and in a second rotational direction counter to said first rotational direction of said field rotor (15). The two rotors (15, 17) are coupled through a 1:1 gearing mechanism (19), so as to travel at the same speed but in opposite directions. This doubles the output voltage and output power, as compared to a motor in which only the armature is rotated. Several embodiments are disclosed.
Homopolar motor with dual rotors
Hsu, J.S.
1998-12-01
A homopolar motor has a field rotor mounted on a frame for rotation in a first rotational direction and for producing an electromagnetic field, and an armature rotor mounted for rotation on said frame within said electromagnetic field and in a second rotational direction counter to said first rotational direction of said field rotor. The two rotors are coupled through a 1:1 gearing mechanism, so as to travel at the same speed but in opposite directions. This doubles the output voltage and output power, as compared to a motor in which only the armature is rotated. Several embodiments are disclosed. 7 figs.
Rotor/body aerodynamic interactions
Betzina, M. D.; Smith, C. A.; Shinoda, P.
1985-01-01
A wind tunnel investigation was conducted in which independent, steady state aerodynamic forces and moments were measured on a 2.24 m diam. two bladed helicopter rotor and on several different bodies. The mutual interaction effects for variations in velocity, thrust, tip-path-plane angle of attack, body angle of attack, rotor/body position, and body geometry were determined. The results show that the body longitudinal aerodynamic characteristics are significantly affected by the presence of a rotor and hub, and that the hub interference may be a major part of such interaction. The effects of the body on the rotor performance are presented.
Uğbreve;ur Dalli
2011-01-01
Full Text Available An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.
Effects of injection frequency on the rotor stall margin
无
2010-01-01
The stall margin of compressor could be improved effectively by rotor tip injection,and the periodic injection is commonly used in the research.The purpose of this work is to investigate the influence of injection frequency on the rotor stall margin.An unsteady CFD code was employed to simulate the flow field of the rotor with injections of different frequencies.Comparing the stall margin of the rotor with injections of different frequencies,it is shown that there is an optimal injection frequency,around which the rotor stability enhancement is the largest.When the injection frequency is away form the optimal frequency,the improvement in stable flow range decreases correspondingly.For the rotor in this paper,the optimal frequency was 1.5 times the frequency of tip leakage vortex(for short,TLV) fluctuation.Time-averaged loading distribution at 98.5% span indicates that the loading of the rotor near the leading edge is decreased through injection with the optimal frequency,and therefore,the stall could be delayed.
Suppression of Base Excitation of Rotors on Magnetic Bearings
2007-01-01
This paper deals with rotor systems that suffer harmonic base excitation when supported on magnetic bearings. Magnetic bearings using conventional control techniques perform poorly in such situations mainly due to their highly nonlinear characteristics. The compensation method presented here is a novel optimal control procedure with a combination of conventional, proportional, and differential feedback control. A four-degree-of-freedom model is used for the rotor system, and the bearings a...
Zawodny, Nikolas S.; Haskin, Henry H.
2017-01-01
The Low Speed Aeroacoustic Wind Tunnel (LSAWT) at NASA Langley Research Center has recently undergone a configuration change. This change incorporates an inlet nozzle extension meant to serve the dual purposes of achieving lower free-stream velocities as well as a larger core flow region. The LSAWT, part of the NASA Langley Jet Noise Laboratory, had historically been utilized to simulate realistic forward flight conditions of commercial and military aircraft engines in an anechoic environment. The facility was modified starting in 2016 in order to expand its capabilities for the aerodynamic and acoustic testing of small propeller and unmanned aircraft system (UAS) rotor configurations. This paper describes the modifications made to the facility, its current aerodynamic and acoustic capabilities, the propeller and UAS rotor-vehicle configurations to be tested, and some preliminary predictions and experimental data for isolated propeller and UAS rotor con figurations, respectively. Isolated propeller simulations have been performed spanning a range of advance ratios to identify the theoretical propeller operational limits of the LSAWT. Performance and acoustic measurements of an isolated UAS rotor in hover conditions are found to compare favorably with previously measured data in an anechoic chamber and blade element-based acoustic predictions.
The effect of solidity on the performance of H-rotor Darrieus turbine
Hassan, S. M. Rakibul; Ali, Mohammad; Islam, Md. Quamrul
2016-07-01
Utilization of wind energy has been investigated for a long period of time by different researchers in different ways. Out of which, the Horizontal Axis Wind Turbine and the Vertical Axis Wind Turbine have now advanced design, but still there is scope to improve their efficiency. The Vertical Axis Wind Turbine (VAWT) has the advantage over Horizontal Axis Wind Turbine (HAWT) for working on omnidirectional air flow without any extra control system. A modified H-rotor Darrieus type VAWT is analysed in this paper, which is a lift based wind turbine. The effect of solidity (i.e. chord length, no. of blades) on power coefficient (CP) of H-rotor for different tip speed ratios is numerically investigated. The study is conducted using time dependent RANS equations using SST k-ω model. SIMPLE scheme is used as pressure-velocity coupling and in all cases, the second order upwind discretization scheme is chosen for getting more accurate solution. In results, different parameters are compared, which depict the performance of the modified H-rotor Darrieus type VAWT. Double layered H-rotor having inner layer blades with longer chord gives higher power coefficient than those have inner layer blades with smaller chord.
赵南南; 刘卫国; 诸自强
2012-01-01
表贴式无刷直流电动机的永磁体和紧圈如果采用电导率较高的材料,在时间和空间谐波的影响下可能会产生明显的涡流损耗.利用有限元法计算了紧圈分别采用不锈钢和碳纤维两种电导率不同材料表贴式无刷直流电动机的转子涡流损耗,基于计算得到的涡流损耗利用解析集总参数热网络法对两台电机进行了热场分析,并通过实验验证了仿真结果.通过研究发现,采用碳纤维紧圈的电机转子涡流损耗明显减小,转子发热有效改善.%Due to relatively high electrical conductivity of permanent magnets and retaining sleeve of surface-ounted brushless DC machines, significant eddy current loss may be induced by both time and space magneto-motive force harmonics. In this paper, rotor eddy current losses of surface-mounted brushless DC machines with different sleeve materials, which were stainless steel and carbon fiber respectively, were calculated using finite element analysis. Thermal fields of the two machines were analyzed using analytical lumped-circuit method based on the obtained eddy current losses and the predicted temperature rises of machines were verified by experiment results. The research reveals that the rotor eddy current losses of the motor with carbon fiber sleeve were significantly reduced the rotor temperature rise is improved effectively.
邓四二; 付金辉; 王燕霜; 杨海生
2013-01-01
The dynamic model of dual-rotor coupling system which included rolling bearing dynamics and rotor dynamics was established. Fine integral method and predict-correct Adams-Bashforth-Moulton multi-step method were used to solve the nonlinear dynamic equations of dual-rotor system. Then the influences of bearing structural parameters on dynamic response of rotors were studied. The result shows: (1) the displacement of rotors can be decreased and the stability of rotors can be improved by reducing radical clearance of inter-shaft bearing, but the slide ratio of cage would increase when the radial clearance decreases, so the radial clearance should be selected properly; the slide ratio of cage would decrease and the displacement of rotors would increase when the rollers of inter-shaft bearing are reduced; (2) the displacement and stability of rotors can be optimized when the groove curvature radius coefficients of rings and radial clearance of supporting bearings are decreased, and the stability of rotor would be improved when the rolling elements of bearings are increased.%在滚动轴承动力学和转子动力学分析基础上,建立了含滚动轴承动力学与转子动力学耦合以及高、低压转子间耦合的滚动轴承-双转子系统动力学方程,采用精细积分法和预估-校正Adams-Bashforth-Moulton多步法相结合的算法,对航空发动机滚动轴承-双转子系统非线性动力学方程进行求解,并对滚动轴承结构参数与转子动态特性的关系进行了理论分析.分析结果表明:①中介轴承径向游隙较小时转子系统振动量较小且转子运行较平稳,但中介轴承保持架打滑率会有所提高,应合理选取中介轴承的径向游隙值；中介轴承滚子数量对转子运转稳定性有较大影响,减小中介轴承滚子数量可降低保持架打滑率,但转子系统的振动量会增大；②支承轴承内、外沟曲率半径系数及径向游隙较小时转子系统的振动量较
Computations of Torque-Balanced Coaxial Rotor Flows
Yoon, Seokkwan; Chan, William M.; Pulliam, Thomas H.
2017-01-01
Interactional aerodynamics has been studied for counter-rotating coaxial rotors in hover. The effects of torque balancing on the performance of coaxial-rotor systems have been investigated. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model. Computational results for an experimental model are compared to available data. The results for a coaxial quadcopter vehicle with and without torque balancing are discussed. Understanding interactions in coaxial-rotor flows would help improve the design of next-generation autonomous drones.
1980-06-01
Command. The program is being conducted at Solar Turbines International Research Laboratories with Mr. A. R. Stetson, Manager of Materials Technology, as...had to be fabricated. The titanium specimens were fabricated using the same coating/creep forming tecnique developed to produce the large scale Bell...and David P. Huey and A.R. Stetson of Solar, from Sikorsky Aircraft: John Longobardi, Program Manager , Peter Ogle, Rotor System Section Head and John
Dynamical localization of coupled relativistic kicked rotors
Rozenbaum, Efim B.; Galitski, Victor
2017-02-01
A periodically driven rotor is a prototypical model that exhibits a transition to chaos in the classical regime and dynamical localization (related to Anderson localization) in the quantum regime. In a recent work [Phys. Rev. B 94, 085120 (2016), 10.1103/PhysRevB.94.085120], A. C. Keser et al. considered a many-body generalization of coupled quantum kicked rotors, and showed that in the special integrable linear case, dynamical localization survives interactions. By analogy with many-body localization, the phenomenon was dubbed dynamical many-body localization. In the present work, we study nonintegrable models of single and coupled quantum relativistic kicked rotors (QRKRs) that bridge the gap between the conventional quadratic rotors and the integrable linear models. For a single QRKR, we supplement the recent analysis of the angular-momentum-space dynamics with a study of the spin dynamics. Our analysis of two and three coupled QRKRs along with the proved localization in the many-body linear model indicate that dynamical localization exists in few-body systems. Moreover, the relation between QRKR and linear rotor models implies that dynamical many-body localization can exist in generic, nonintegrable many-body systems. And localization can generally result from a complicated interplay between Anderson mechanism and limiting integrability, since the many-body linear model is a high-angular-momentum limit of many-body QRKRs. We also analyze the dynamics of two coupled QRKRs in the highly unusual superballistic regime and find that the resonance conditions are relaxed due to interactions. Finally, we propose experimental realizations of the QRKR model in cold atoms in optical lattices.
席文奎; 许吉敏; 张宏涛; 鲁周勋; 袁小阳
2013-01-01
The rotor system's dynamic stability of high-parameters steam turbine under the combined action of oil-film force and labyrinth seal force was researched. The improved two-control-volume bulk-flow model was used to compute the dynamic coefficients of multi-stage labyrinth seals, and the results show that the cross-stiffness of high pressure cylinder shroud seals has reached about 107N/m, which is equal or even higher than the six-pad tilting bearing's cross-stiffness, this indicate that seal is the dominant factor of system's dynamic stability. The rotor system was modeled by finite element method and then the rotor-bearing-seal dynamic model was built to calculate the influence of seal clearance and rotating speed on rotor system dynamic performance, the analysis results indicate that the logarithm decrement (δmin) of the rotor system decreased rapidly in considering of the sealing force, but the critical speed of rotor system is influenced weakly, while, the δmin is influenced by the seal clearance regionally, proper choice of seal clearance in range of 0.5 mm to 0.8 mm which is less than the design clearance (0.8mm), can optimize the leakage and stability of the system. The concept design knowledge representation and scheme optimization for coupling design was accomplished by axiomatic design (AD)theory, which takes four schemes of seal design as the case, and this indicate that the AD method is simple and effective.%针对高参数汽轮机,研究迷宫密封汽封力和轴承油膜力作用下的转子系统稳定性问题.首先基于两控制体模型对各级密封的动特性进行计算,并与6瓦可倾瓦轴承进行对比,发现高压缸围带密封的交叉刚度已达107N/m,与轴承相当或更大,表明密封相比轴承是稳定性的主导因素.然后采用有限元方法将实际转子进行模化,根据建立的转子-轴承-密封系统动力学模型,对不同密封间隙和转速下的系统动力学特性进行计算分析,表明:考虑
Reference Model 2: %22Rev 0%22 Rotor Design.
Barone, Matthew F.; Berg, Jonathan Charles; Griffith, Daniel
2011-12-01
The preliminary design for a three-bladed cross-flow rotor for a reference marine hydrokinetic turbine is presented. A rotor performance design code is described, along with modifications to the code to allow prediction of blade support strut drag as well as interference between two counter-rotating rotors. The rotor is designed to operate in a reference site corresponding to a riverine environment. Basic rotor performance and rigid-body loads calculations are performed to size the rotor elements and select the operating speed range. The preliminary design is verified with a simple finite element model that provides estimates of bending stresses during operation. A concept for joining the blades and support struts is developed and analyzed with a separate finite element analysis. Rotor mass, production costs, and annual energy capture are estimated in order to allow calculations of system cost-of-energy. Evaluation Only. Created with Aspose.Pdf.Kit. Copyright 2002-2011 Aspose Pty Ltd Evaluation Only. Created with Aspose.Pdf.Kit. Copyright 2002-2011 Aspose Pty Ltd
Flettner Rotor Concept for Marine Applications: A Systematic Study
A. De Marco
2016-01-01
Full Text Available The concept of Flettner rotor, a rotating cylinder immersed in a fluid current, with a top-mounted disk, has been analyzed by means of unsteady Reynolds averaged Navier-Stokes simulations, with the aim of creating a suitable tool for the preliminary design of the Flettner rotor as a ship’s auxiliary propulsion system. The simulation has been executed to evaluate the performance sensitivity of the Flettner rotor with respect to systematic variations of several parameters, that is, the spin ratio, the rotor aspect ratio, the effect of the end plates, and their dimensions. The Flettner rotor device has been characterized in terms of lift and drag coefficients, and these data were compared with experimental trends available in literature. A verification study has been conducted in order to evaluate the accuracy of the simulation results and the main sources of numerical uncertainty. All the simulation results were used to achieve a surrogate model of lift and drag coefficients. This model is an effective mathematical tool for the preliminary design of Flettner rotor. Finally, an example of assessment of the Flettner rotor performance as an auxiliary propulsion device on a real tanker ship is reported.
Amezquita-Sanchez, Juan P.; Valtierra-Rodriguez, Martin; Perez-Ramirez, Carlos A.; Camarena-Martinez, David; Garcia-Perez, Arturo; Romero-Troncoso, Rene J.
2017-07-01
Squirrel-cage induction motors (SCIMs) are key machines in many industrial applications. In this regard, the monitoring of their operating condition aiming at avoiding damage and reducing economical losses has become a demanding task for industry. In the literature, several techniques and methodologies to detect faults that affect the integrity and performance of SCIMs have been proposed. However, they have only been focused on analyzing either the start-up transient or the steady-state operation regimes, two common operating scenarios in real practice. In this work, a novel methodology for broken rotor bar (BRB) detection in SCIMs during both start-up and steady-state operation regimes is proposed. It consists of two main steps. In the first one, the analysis of three-axis vibration signals using fractal dimension (FD) theory is carried out. Since different FD-based algorithms can give different results, three algorithms named Katz’ FD, Higuchi’s FD, and box dimension, are tested. In the second step, a fuzzy logic system for each regime is presented for automatic diagnosis. To validate the proposal, a motor with different damage levels has been tested: one with a partially BRB, a second with one fully BRB, and the third with two BRBs. The obtained results demonstrate the proposed effectiveness.
胡茂欣; 程珩
2013-01-01
不平衡是旋转机械的主要故障之一,针对环锤式破碎机锤头磨损后产生的不平衡问题,建立转子系统三维模型,利用有限元分析软件对转子系统进行临界转速与不平衡响应分析,得到转子系统的各阶临界转速与各种不平衡状态下的响应情况,并将分析结果运用到配锤中来,为下一步进行动平衡优化研究提供了一定的依据.%Imbalance is one of the main faults of rotating machinery.In view of imbalance caused by wearing of hammer of ring hammer crusher,a 3D model of the rotor system was established.In addition,a finite element analysis sogtware was used to analyze the critical speed and imbalance response of the rotor system,and the critical speed of each order of the rotor system and response at various imbalance mode were obtained.Finally,the analysis results was applied to hammer arrangement,which offered references for further study of dynamic balance optimization.
Energy and momentum management of the Space Station using magnetically suspended composite rotors
Eisenhaure, D. B.; Oglevie, R. E.; Keckler, C. R.
1985-01-01
The research addresses the feasibility of using magnetically suspended composite rotors to jointly perform the energy and momentum management functions of an advanced manned Space Station. Recent advancements in composite materials, magnetic suspensions, and power conversion electronics have given flywheel concepts the potential to simultaneously perform these functions for large, long duration spacecraft, while offering significant weight, volume, and cost savings over conventional approaches. The Space Station flywheel concept arising out of this study consists of a composite-material rotor, a large-angle magnetic suspension (LAMS) system, an ironless armature motor/generator, and high-efficiency power conversion electronics. The LAMS design permits the application of appropriate spacecraft control torques without the use of conventional mechanical gimbals. In addition, flywheel systems have the growth potential and modularity needed to play a key role in many future system developments.
螺杆转子成形磨削砂轮的修整%Research on the Grinding Wheel Dressing Method of Screw Rotor
李志峰; 张彦坤; 王高勇; 王晓飞
2014-01-01
成形砂轮的修整质量直接影响着螺杆转子的齿形精度和表面质量。根据空间啮合原理，建立了螺杆转子磨削加工的数学模型，推导了成形砂轮与转子的接触线方程。针对转子端面齿形为离散点的情况，通过三次样条插值法、追赶法和MATLAB内置fsolve函数的衔接使用求解出了砂轮的轴向截形。介绍了CNC砂轮修整器的工作原理，根据计算结果设计了砂轮的修整方案，研究了砂轮截形与中心距的变化规律并提出了数控程序编制的简化方法。该修整方法简单可靠、精度高，适合复杂曲线廓形的加工。%The dressing quality of forming grinding wheel directly affects the tooth profile accuracy and surface quality of the screw rotor.Based on the meshing theory,the mathematical model of grinding screw rotor was established and the contact line equation between forming grinding wheel and the rotor was deduced.In view of the rotor's end-surface tooth for discrete points,the forming wheel edge shape was calculated with the bridging use of cubic spline interpolation method,chasing method and MATLAB built-in fsolve function.According to the working principle of CNC grinding wheel dresser,a scheme of the grinding wheel dressing was de-signed on the calculation results.A simplified method of CNC programming was put forward after studying the changing rules between grinding wheel's cross-sectional profile and center distance.This method is simple,reliable and high-precision,especially suitable for the complex curves.
Kang L. Wang
2012-08-01
Full Text Available The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P^{+} Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 10^{4}, a read window of about 2.5 V, and a retention time of greater than 10^{4} s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V revealed a temperature-dependent negative differential resistance (NDR associated with the device. The analysis of the device
Research on Trustworthy Distributed System
LI Yuan
2012-06-01
Full Text Available To arrive at the goal of intensifying the trustworthiness and controllability of distributed systems, the core function of secure algorithms and chips should be fully exerted. Through building the trustworthy model between distributed system and user behaviors, constructing the architecture of trustworthiness distributed systems, intensifying the survivability of services, and strengthening the manageability of distributed systems, the secure problem of distributed systems is to be radically solved. By setting up the trustworthy computing circumstance and supplying the trustworthy validation and the active protection based on identity and behavior for trustworthy distributed system, we will reach the goal of defending the unaware viruses and inbreak. This research insists that the security, controllability, manageability, and survivability should be basic properties of a trustworthy distributed system. The key ideas and techniques involved in these properties are studied, andrecent developments and progresses are surveyed. At the same time, the technical trends and challenges are briefly discussed.
无
2005-01-01
Some construct characteristics and composing material of the new Gyro's rotor are introduced. Some factors resulting in deformation of the rotor surface are analyzed. Under different loads such as the force of deflecting center, the change of temperature, the force of pressure and couple factors, the deformation of rotor is analyzed with the wavelet finite element simulation software. The vector distributing map of rotor reformation is given. The deformation resulting from the pressure force of photon is studied. Finally, the influence on Gyro's performance because of anomalous surface of rotor due to deformation of rotor is researched and the result is useful to forecast the performance of the drift of gyroscope. The disturbing moment resulting from the deformation of rotor can be compensated using the mathematic method, and provides an important reference for both design and optimization of the rotor.
Spatial Disorientation Training in the Rotor Wing Flight Simulator.
Powell-Dunford, Nicole; Bushby, Alaistair; Leland, Richard A
This study is intended to identify efficacy, evolving applications, best practices, and challenges of spatial disorientation (SD) training in flight simulators for rotor wing pilots. Queries of a UK Ministry of Defense research database and Pub Med were undertaken using the search terms 'spatial disorientation,' 'rotor wing,' and 'flight simulator.' Efficacy, evolving applications, best practices, and challenges of SD simulation for rotor wing pilots were also ascertained through discussion with subject matter experts and industrial partners. Expert opinions were solicited at the aeromedical physiologist, aeromedical psychologist, instructor pilot, aeromedical examiner, and corporate executive levels. Peer review literature search yielded 129 articles, with 5 relevant to the use of flight simulators for the spatial disorientation training of rotor wing pilots. Efficacy of such training was measured subjectively and objectively. A preponderance of anecdotal reports endorse the benefits of rotor wing simulator SD training, with a small trial substantiating performance improvement. Advancing technologies enable novel training applications. The mobile nature of flight students and concurrent anticollision technologies can make long-range assessment of SD training efficacy challenging. Costs of advanced technologies could limit the extent to which the most advanced simulators can be employed across the rotor wing community. Evidence suggests the excellent training value of rotor wing simulators for SD training. Objective data from further research, particularly with regards to evolving technologies, may justify further usage of advanced simulator platforms for SD training and research. Powell-Dunford N, Bushby A, Leland RA. Spatial disorientation training in the rotor wing flight simulator. Aerosp Med Hum Perform. 2016; 87(10):890-893.
INFORMATION SUPPORT SYSTEM OF MEDICAL SYSTEM RESEARCH
V. P. Martsenyuk
2014-12-01
Conclusions. The complex qualitative behavior of diseases models depending on parameters and controllers was observed in our investigation even without considering probabilistic nature of the majority of quantities and parameters of information models. KEY WORDS: data mining, system analysis, medical research, decision making
Controllability Analysis for Multirotor Helicopter Rotor Degradation and Failure
Du, Guang-Xun; Quan, Quan; Yang, Binxian; Cai, Kai-Yuan
2015-05-01
This paper considers the controllability analysis problem for a class of multirotor systems subject to rotor failure/wear. It is shown that classical controllability theories of linear systems are not sufficient to test the controllability of the considered multirotors. Owing to this, an easy-to-use measurement index is introduced to assess the available control authority. Based on it, a new necessary and sufficient condition for the controllability of multirotors is derived. Furthermore, a controllability test procedure is approached. The proposed controllability test method is applied to a class of hexacopters with different rotor configurations and different rotor efficiency parameters to show its effectiveness. The analysis results show that hexacopters with different rotor configurations have different fault-tolerant capabilities. It is therefore necessary to test the controllability of the multirotors before any fault-tolerant control strategies are employed.
Augmentation of power in slow-running vertical-axis wind rotors using multiple vanes
Sivasegaram, S.; Sivapalan, S.
Improving the sectional geometry of slow-runnig vertical-axis wind rotors of the Savonius type has resulted in considerable improvement in rotor performance. Further improvement in power output from a rotor of given overall dimensions demands the use of power augmenting systems. This paper presents a simple two-vane power augmentation system for rotors of the Savonius-type. The influence of important design parameters of the augmenting system and that of wind direction have been investigated and the system configuration giving maximum power augmentation has been determined. It is shown that an eighty percent increase in power output could be achieved using a pair of vanes of moderate size.
The Dynamics of Rotor with Rubbing
Jerzy T. Sawicki
1999-01-01
characteristics of rub-induced rotor response, initial conditions, as well as appropriate ranges of system parameters. Of special interest are the changes in the apparent nonlinearity of the system dynamics as rubs are induced at different rotor speeds. In particular, starting with 2nd order sub/superharmonics, which are symptomatic of quadratic nonlinearity, progressively higher order polynomial behavior is excited, i.e., cubic, giving rise to 3rd order sub/superharmonics. As the speed is transitioned between such apparent nonlinearities, chaotic like behavior is induced because of the lack of whole or rational tone tuning between the apparent system frequency and the external source noise. The cause of such behavior will be discussed in detail along with the results of several parametric studies.
张寿春
2012-01-01
In order to protect the electric actuator driven by the brushless DC motor and controller for locked rotor,avoid the controller is damaged.The method of protection of taking LPC2132 central processing unit and hardware circuit of electric current collected of the control system,at same time intelligent judgment and treatment by using the method of software.Realization of intelligent control in the state of locked rotor,protect the controller.The experiment shows that： the system has reliability and the advantages of processing locked rotor in intelligent mode.%为了防止直流无刷电机驱动的执行器因电机堵转而损坏控制器,控制系统采用以LPC2132微处理器和电流采集等电路相结合的硬件保护方法,同时采用软件进行智能判断与处理。实现了电动执行器在堵转的状态下的智能控制,保护了控制器。实验结果表明：该系统具有可靠性高及智能处理堵转等优点。
Active Magnetic Bearing Rotor Model Updating Using Resonance and MAC Error
Yuanping Xu
2015-01-01
Full Text Available Modern control techniques can improve the performance and robustness of a rotor active magnetic bearing (AMB system. Since those control methods usually rely on system models, it is important to obtain a precise rotor AMB analytical model. However, the interference fits and shrink effects of rotor AMB cause inaccuracy to the final system model. In this paper, an experiment based model updating method is proposed to improve the accuracy of the finite element (FE model used in a rotor AMB system. Modelling error is minimized by applying a numerical optimization Nelder-Mead simplex algorithm to properly adjust FE model parameters. Both the error resonance frequencies and modal assurance criterion (MAC values are minimized simultaneously to account for the rotor natural frequencies as well as for the mode shapes. Verification of the updated rotor model is performed by comparing the experimental and analytical frequency response. The close agreements demonstrate the effectiveness of the proposed model updating methodology.
Research on advanced transportation systems
Nagai, Hirokazu; Hashimoto, Ryouhei; Nosaka, Masataka; Koyari, Yukio; Yamada, Yoshio; Noda, Keiichirou; Shinohara, Suetsugu; Itou, Tetsuichi; Etou, Takao; Kaneko, Yutaka
1992-08-01
An overview of the researches on advanced space transportation systems is presented. Conceptual study is conducted on fly back boosters with expendable upper stage rocket systems assuming a launch capacity of 30 tons and returning to the launch site by the boosters, and prospect of their feasibility is obtained. Reviews are conducted on subjects as follows: (1) trial production of 10 tons sub scale engines for the purpose of acquiring hardware data and picking up technical problems for full scale 100 tons thrust engines using hydrocarbon fuels; (2) development techniques for advanced liquid propulsion systems from the aspects of development schedule, cost; (3) review of conventional technologies, and common use of component; (4) oxidant switching propulsion systems focusing on feasibility of Liquefied Air Cycle Engine (LACE) and Compressed Air Cycle Engine (CACE); (5) present status of slosh hydrogen manufacturing, storage, and handling; (6) construction of small high speed dynamometer for promoting research on mini pump development; (7) hybrid solid boosters under research all over the world as low-cost and clean propulsion systems; and (8) high performance solid propellant for upper stage and lower stage propulsion systems.
Assessment of Scaled Rotors for Wind Tunnel Experiments.
Maniaci, David Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chiu, Phillip [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-07-01
Rotor design and analysis work has been performed to support the conceptualization of a wind tunnel test focused on studying wake dynamics. This wind tunnel test would serve as part of a larger model validation campaign that is part of the Department of Energy Wind and Water Power Program’s Atmosphere to electrons (A2e) initiative. The first phase of this effort was directed towards designing a functionally scaled rotor based on the same design process and target full-scale turbine used for new rotors for the DOE/SNL SWiFT site. The second phase focused on assessing the capabilities of an already available rotor, the G1, designed and built by researchers at the Technical University of München.
Cary, Charles M.
1987-01-01
The interaction of a free vortex and a rotor was recorded photographically using oil smoke and stroboscopic illumination. The incident vortex is normal to the plane of the rotor and crosses the rotor plane. This idealized aerodynamic experiment most nearly corresponds to helicopter flight conditions in which a tip vortex from the main rotor is incident upon the tail rotor while hovering. The high speed photographs reveal important features not observed using conventional photography where the image is the time average of varying instantaneous images. Most prominent is the strong interaction between the rotor tip vortex system and the incident vortex, resulting in the roll-up of the incident vortex around the (stronger) tip vortices and the resulting rapid destabilization of the deformed incident vortex. The viscous interaction is clearly shown also. Other forms of instabilities or wave-like behavior may be apparent from further analysis of the photographs.
Imaging Systems in TLE Research
Allin, Thomas Højgaard; Neubert, Torsten; Laursen, Steen
2006-01-01
documented using the right equipment in the right way. This chapter provides an introduction to the concepts of low light imagers, and how they can be successfully applied in TLE research. As examples, we describe the 2003 and 2004 Spritewatch systems, which integrate low-light cameras with a digital...
Mohd Afaque Iqbal
2014-06-01
Full Text Available Single-phase induction motor (SPIM has very crucial role in industrial, domestic and commercial sectors. So, the efficient SPIM is a major requirement of today’s market. For efficient motors, many research methodologies and suggestions have been given by researchers in past. Various parameters like as stator/rotor slot variation, size and shape of stator/rotor slots, stator/rotor winding configuration, choice of core material etc. have significant impact on machine design. Rotor slot geometry influences the distribution of the magnetic field to a degree. Even a little difference of the magnetic field distribution can make big difference on the performance of the induction motor. The rotor slot geometry influences the skin effect and slot leakage flux in order to increase the torque and efficiency. In this paper, three types of rotor slot configurations are designed and simulated with different rotor slot configuration and rotor bars composition by changing the rotor slot configuration of base model. Aluminum and Copper are used simultaneously as rotor winding material. The rotor bar is a composite conductor which carries Aluminum as well as Copper sub-conductors running parallel in the same slot. Overall cross section area of rotor bar in each model kept same and work is carried out with difference proportion of Aluminum and Copper sub conductors. All models are investigated and simulated in FEMM and finally the simulated results are compared for optimal solution.
Bohmian quantum mechanical and classical Lyapunov exponents for kicked rotor
Zheng Yindong [Department of Physics, University of North Texas, Denton, TX 76203-1427 (United States); Kobe, Donald H. [Department of Physics, University of North Texas, Denton, TX 76203-1427 (United States)], E-mail: kobe@unt.edu
2008-04-15
Using de Broglie-Bohm approach to quantum theory, we show that the kicked rotor at quantum resonance exhibits quantum chaos for the control parameter K above a threshold. Lyapunov exponents are calculated from the method of Benettin et al. for bounded systems for both the quantum and classical kicked rotor. In the chaotic regime we find stability regions for control parameters equal to even and odd multiples of {pi}, but the quantum regions are only remnants of the classical ones.
Edgar Estupiñán P
2006-08-01
Full Text Available El presente trabajo resalta la importancia del balanceamiento de rotores como principal herramienta dentro de las tareas correctivas del mantenimiento predictivo, con el fin de que se reduzcan las vibraciones y sus efectos secundarios en las máquinas rotatorias. Se ha desarrollado un instrumento virtual para el balanceamiento dinámico de rotores, basado en un sistema de adquisición de datos (SAD. El instrumento tiene incluidos todos los cálculos necesarios para balancear rotores en un plano y en dos planos, a partir de la medición de los datos de vibración, utilizando el procedimiento de los coeficientes de influencia o utilizando un procedimiento de medición sin fase. También se ha incluido un módulo para determinar la severidad vibratoria del rotor y un módulo de análisis de vibraciones, que incluye análisis espectral y de la forma de onda. Este instrumento virtual es una herramienta útil para el balanceamiento de rotores en laboratorio así como también en la industria.This article highlights the importance of rotor balancing like the most important corrective action included in a predictive maintenance program, whose main objective is reducing the vibrations level and its secondary effect in rotary machines. A virtual instrument, based in a data acquisition system has been developed for rotor balancing. With this instrument it is possible to balance rotors in a single or two-plane, using the influence coefficient method or a no phase method. Also the instrument includes a function to determine the vibration severity and a function of vibration analysis with spectral and waveform analysis included. This virtual instrument is useful for rotor balancing in the laboratory as well as in the industry.
Brown, T. J.; Mccloud, J. L., III
1980-01-01
Weighted multiple linear regression is used to establish a transfer function matrix relationship between higher harmonic control inputs and transducer vibration outputs for a controllable twist rotor. Data used in the regression were taken from the test of a KAMAN controllable twist rotor conducted in the Ames Research Center's 40- by 80-Foot Wind Tunnel in June 1977. Optimal controls to minimize fixed system vibrational levels are calculated using linear quadratic regulatory theory with a control deflection penalty included in the performance criteria. Control sensitivity to changes in control travel, forward speed, and lift and propulsive forces is examined. It is found that the linear transfer matrix is a strong function of forward speed and a weak function of lift and propulsive force. An open-loop strategy is proposed for systems with limited control travel.
Turbine rotor disk health monitoring assessment based on sensor technology and spin tests data.
Abdul-Aziz, Ali; Woike, Mark
2013-01-01
The paper focuses on presenting data obtained from spin test experiments of a turbine engine like rotor disk and assessing their correlation to the development of a structural health monitoring and fault detection system. The data were obtained under various operating conditions such as the rotor disk being artificially induced with and without a notch and rotated at a rotational speed of up to 10,000 rpm under balanced and imbalanced state. The data collected included blade tip clearance, blade tip timing measurements, and shaft displacements. Two different sensor technologies were employed in the testing: microwave and capacitive sensors, respectively. The experimental tests were conducted at the NASA Glenn Research Center's Rotordynamics Laboratory using a high precision spin system. Disk flaw observations and related assessments from the collected data for both sensors are reported and discussed.
Research and implementation of a shaking seat system for flight simulator
Shi, Xiaolin; Yu, Youzhi; Shen, Weiqun; Song, Zishan
2006-11-01
To a helicopter the shaking seat system can simulate the vibration caused by the main rotor, tail rotor, engine, weapon firing, landing, etc. This paper focuses on the research and analysis of the shaking system of a helicopter flight simulator. The vibration model of the seat is built and the system is also developed. According to different flight states of the helicopter the vibration states of the seat are classified based on real measurement data, and the spectra of the vibration are interpolated to model the vibration of the seat. An electro-hydraulic servo system is used to drive the seat to shake along the direction that is parallel to the vertical body axis. The seat is shaken under the instructions at reference height with position close-loop control method, and the control law is PID algorithm. Running parameters of the system are configured by the software. The motional states of the shaking seat are displayed to the user through the visualization software. The main parts of the system and some key technologies of the implementation are also presented in the paper. The system can generate the special vibration environment in the helicopter flight process, and is successfully applied to the flight simulator. So the pilots' immersion feelings are increased.
Intelligent navigation system based on four-rotor micro UAV%基于微型四旋翼无人机的智能导航系统
詹镭; 贺人庆; 谢阳; 龙妍
2011-01-01
This intelligent navigation system can achieve the four-rotor UAV's autonomous flight Use ATMEGA644 as the flight controller. Use gyroscopes and three-axis acceleration sensors to detect the aircraft attitude which can be controlled by the BLDC motor driver modules. Use ARM7 to control the GPS and the electronic compass module, get the vehicle's real-time location. Use software filtering to improves the localization accuracy. A PC software is designed which can load the digital map and set the flight path. Communicate with the UAV by the wireless serial communication module to drive the UAV flight autonomous. The experiment proved that the system can achieve intelligent navigation features.%为了实现四旋翼无人机的自主飞行,设计了该智能导航控制系统.飞行控制器采用陀螺仪与三轴加速度传感器相结合的方式检测飞行器姿态,通过ATMEGA644芯片分别控制4个电机驱动模块调速来实现飞行姿态的改变.导航系统通过ARM7控制GPS模块与电子罗盘,获取飞行器的实时位置,并利用软件滤波的方式提高了定位精度.设计了上位机控制软件,可加载数字地图并且设置飞行路线,通过无线串口与无人机通讯,实现无人机的智能自主飞行.通过实验证明该系统能够实现智能导航的功能.
Control of Magnetic Bearings for Rotor Unbalance With Plug-In Time-Varying Resonators.
Kang, Christopher; Tsao, Tsu-Chin
2016-01-01
Rotor unbalance, common phenomenon of rotational systems, manifests itself as a periodic disturbance synchronized with the rotor's angular velocity. In active magnetic bearing (AMB) systems, feedback control is required to stabilize the open-loop unstable electromagnetic levitation. Further, feedback action can be added to suppress the repeatable runout but maintain closed-loop stability. In this paper, a plug-in time-varying resonator is designed by inverting cascaded notch filters. This formulation allows flexibility in designing the internal model for appropriate disturbance rejection. The plug-in structure ensures that stability can be maintained for varying rotor speeds. Experimental results of an AMB-rotor system are presented.
Dynamic analysis of squeeze film damper supported rotors using equivalent linearization
El-Shafei, A. (Cairo Univ., Giza (Egypt). Dept. of Mechanical Design and Production); Eranki, R.V. (Aluman Mill Products, Inc., Morris, IL (United States))
1994-07-01
The technique of equivalent linearization is presented in this paper as a powerful technique to perform nonlinear dynamic analysis of squeeze film damper (SFD) supported rotors using linear rotor-dynamic methods. Historically, it is customary to design SFDs for rotor-dynamic analysis by assuming circular-centered orbits, which is convenient in making the nonlinear damper coefficients time independent and thus can be used in an iterative approach to determine the rotor-dynamic characteristics. However, the general synchronous orbit is elliptic in nature due to possible asymmetry in the rotor support. This renders the nonlinear damper coefficients time dependent, which would require extensive numerical computation using numerical integration to determine the rotor dynamic characteristics. Alternatively, it is shown that the equivalent linearization, which is based on a least-squares approach, can be used to obtain time-independent damper coefficients for SFDs executing eccentric elliptic orbits, which are nonlinear in the orbit parameters. The resulting equivalent linear forces are then used in an iterative procedure to obtain the unbalance response of a rigid rotor-SFD system. Huge savings over numerical integration are reported for this simple rotor. The technique can be extended to be used in conjunction with currently available linear rotor-dynamic programs to determine the rotor-dynamic characteristics through iteration. It is expected that for multirotor multibearing systems this technique will result in even more economical computation.
Wind Turbine Rotors with Active Vibration Control
Svendsen, Martin Nymann
are assumed to be proportional to the relative inflow angle, which also gives a linear form with equivalent stiffness and damping terms. Geometric stiffness effects including the important stiffening from tensile axial stresses in equilibrium with centrifugal forces are included via an initial stress......This thesis presents a framework for structural modeling, analysis and active vibration damping of rotating wind turbine blades and rotors. A structural rotor model is developed in terms of finite beam elements in a rotating frame of reference. The element comprises a representation of general...... formulation. The element provides an accurate representation of the eigenfrequencies and whirling modes of the gyroscopic system, and identifies lightly damped edge-wise modes. By adoption of a method for active, collocated resonant vibration of multi-degree-of-freedom systems it is demonstrated...
吴侹
2016-01-01
为了更好地解决灾害环境下通信系统的快速恢复，提出了利用系留多旋翼无人机实现一定区域通信组网及中继的应急通信应用方案，提炼出多旋翼无人机系留和小型化通信基站技术等关键技术，在此基础上展望了系留多旋翼无人机在应急通信领域的发展前景。%To achieve fast recovery of communication system in disaster, the paper presented emergency communication solutions using the captive multi-rotor UAV to establish communication network and relay in certain area. The paper introduced several key technologies with captive multi-rotor UAV and small base stations, on which basis, it foresaw development prospects of captive multi-rotor UAV in the field of emergency communication.
Usage of modal synthesis method with condensation in rotor
Zeman V.
2008-11-01
Full Text Available The paper deals with mathematical modelling of vibration and modal analysis of rotors composed of a flexible shaft and several flexible disks. The shaft is modelled as a one dimensional continuum whereon flexible disks modelled as a three dimensional continuum are rigid mounted to shaft. The presented approach allows to introduce continuously distributed centrifugal and gyroscopic effects. The finite element method was used for shaft and disks discretization. The modelling of such flexible multi-body rotors with large DOF number is based on the system decomposition into subsystems and on the modal synthesis method with condensation. Lower vibration mode shapes of the mutually uncoupled and non-rotating subsystems are used for creation of the rotor condensed mathematical model. An influence of the different level of a rotor condensation model on the accuracy of calculated eigenfrequencies and eigenvectors is discussed.
Spectral Analysis of Two Coupled Diatomic Rotor Molecules
Horace T. Crogman
2014-10-01
Full Text Available In a previous article the theory of frame transformation relation between Body Oriented Angular (BOA states and Lab Weakly Coupled states (LWC was developed to investigate simple rotor–rotor interactions. By analyzing the quantum spectrum for two coupled diatomic molecules and comparing it with spectrum and probability distribution of simple models, evidence was found that, as we move from a LWC state to a strongly coupled state, a single rotor emerges in the strong limit. In the low coupling, the spectrum was quadratic which indicates the degree of floppiness in the rotor–rotor system. However in the high coupling behavior it was found that the spectrum was linear which corresponds to a rotor deep in a well.
Extension of Goldstein's circulation function for optimal rotors with hub
Okulov, V. L.; Sørensen, J. N.; Shen, W. Z.
2016-09-01
The aerodynamic interaction or interference between rotor blades and hub body is usually very complicated, but some useful simplifications can be made by considering the hub with an infinite cylinder. Various attempts to find the optimum distribution of circulation by the lifting vortex lines method have been previously proposed to describe the blade interaction with the hub modeled by the infinite cylinder. In this case, the ideal distribution of bound circulation on the rotor blades is such that the shed vortex system in the hub-area is a set of helicoidal vortex sheets moving uniformly as if rigid, exactly as in the case where there is no influence of the streamtube deformations by the central hub-body. In the present investigation, we consider a more specific problem of the rotor-hub interaction where the initial flow streamtubes and the rotor slipstream submitted strong deformations at the nose-area of the semi-infinite hub.
Aero dynamical and mechanical behaviour of the Savonius rotor
Aouachria, Z. [Batna Univ., (Algeria). Applied Energetic Physics Laboratory
2009-07-01
Although the Savonius wind turbine is not as efficient as the traditional Darrieus wind turbine, its rotor design has many advantages such as simple construction; acceptance of wind from all directions; high starting torque; operation at relatively low speed; and easy adaptation to urban sites. These advantages may outweigh its low efficiency and make it suitable for small-scale power requirements such as pumping and rural electrification. This paper presented a study of the aerodynamic behaviour of a Savonius rotor, based on blade pressure measurements. A two-dimensional analysis method was used to determine the aerodynamic strengths, which leads to the Magnus effect and the generation of the vibrations on the rotor. The study explained the vibratory behaviour of the rotor and proposed an antivibration system to protect the machine. 14 refs., 1 tab., 9 figs.
On the performance analysis of Savonius rotor with twisted blades
Saha, U.K.; Rajkumar, M. Jaya [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati-781 039 (India)
2006-09-15
The present investigation is aimed at exploring the feasibility of twisted bladed Savonius rotor for power generation. The twisted blade in a three-bladed rotor system has been tested in a low speed wind tunnel, and its performance has been compared with conventional semicircular blades (with twist angle of 0{sup o}). Performance analysis has been made on the basis of starting characteristics, static torque and rotational speed. Experimental evidence shows the potential of the twisted bladed rotor in terms of smooth running, higher efficiency and self-starting capability as compared to that of the conventional bladed rotor. Further experiments have been conducted in the same setup to optimize the twist angle. (author)
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor speed. 27.1509 Section 27.1509... Rotor speed. (a) Maximum power-off (autorotation). The maximum power-off rotor speed must be established... minimum power-off rotor speed must be established so that it is not less than 105 percent of the...
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor speed. 29.1509 Section 29.1509....1509 Rotor speed. (a) Maximum power-off (autorotation). The maximum power-off rotor speed must be... minimum power-off rotor speed must be established so that it is not less than 105 percent of the...
Performance tests on helical Savonius rotors
Kamoji, M.A.; Kedare, S.B. [Department of Energy Science and Engineering, Indian Institute of Technology, Bombay (India); Prabhu, S.V. [Department of Mechanical Engineering, Indian Institute of Technology, Bombay (India)
2009-03-15
Conventional Savonius rotors have high coefficient of static torque at certain rotor angles and a negative coefficient of static torque from 135 to 165 and from 315 to 345 in one cycle of 360 . In order to decrease this variation in static torque from 0 to 360 , a helical Savonius rotor with a twist of 90 is proposed. In this study, tests on helical Savonius rotors are conducted in an open jet wind tunnel. Coefficient of static torque, coefficient of torque and coefficient of power for each helical Savonius rotor are measured. The performance of helical rotor with shaft between the end plates and helical rotor without shaft between the end plates at different overlap ratios namely 0.0, 0.1 and 0.16 is compared. Helical Savonius rotor without shaft is also compared with the performance of the conventional Savonius rotor. The results indicate that all the helical Savonius rotors have positive coefficient of static torque at all the rotor angles. The helical rotors with shaft have lower coefficient of power than the helical rotors without shaft. Helical rotor without shaft at an overlap ratio of 0.0 and an aspect ratio of 0.88 is found to have almost the same coefficient of power when compared with the conventional Savonius rotor. Correlation for coefficient of torque and power is developed for helical Savonius rotor for a range of Reynolds numbers studied. (author)
IDENTIFICATION OF CRACKED ROTOR BY WAVELET TRANSFORM
邹剑; 陈进; 蒲亚鹏
2002-01-01
The dynamic equation of cracked rotor in rotational frame was modelled, the numerical simulation solutions of the cracked rotor and the uncracked rotor were obtained. By the wavelet transform, the time-frequency properties of the cracked rotor and the uncracked rotor were discussed, the difference of the time-frequency properties between the cracked rotor and the uncracked rotor was compared. A new detection algorithm using wavelet transform to identify crack was proposed. The experiments verify the availability and validity of the wavelet transform in identification of crack.
Rotor blade assembly having internal loading features
Soloway, Daniel David
2017-05-16
Rotor blade assemblies and wind turbines are provided. A rotor blade assembly includes a rotor blade having exterior surfaces defining a pressure side, a suction side, a leading edge and a trailing edge each extending between a tip and a root, the rotor blade defining a span and a chord, the exterior surfaces defining an interior of the rotor blade. The rotor blade assembly further includes a loading assembly, the loading assembly including a weight disposed within the interior and movable generally along the span of the rotor blade, the weight connected to a rotor blade component such that movement of the weight towards the tip causes application of a force to the rotor blade component by the weight. Centrifugal force due to rotation of the rotor blade biases the weight towards the tip.
Fuzzy control of attitude of four - rotor UAV
Zhang, Zexiang; Hu, Shengbin
2017-08-01
The four - rotor unmanned aerial vehicle (UAV) is the object of study, in this paper. In order to solve the problem of poor robustness and low control precision of the four-rotor unmanned aerial vehicle (UAV) control system, and realized the stability control problem of the four-rotor UAV attitude. First, the dynamic model of the four-rotor unmanned aerial vehicle is established. And on this basis, a fuzzy controller is designed, and used to control the channel. Then, the simulation platform is built by Matlab / Simulink simulation software, and the performance of the designed fuzzy controller is analyzed comprehensively. It is also determined whether the algorithm can control the attitude of the four rotor unmanned aerial vehicle. The simulation results fully verify the accuracy of the model, and proved fuzzy controller has better dynamic performance and robustness under appropriate parameters so that UAVs can fly stable. The algorithm can improve the anti-jamming performance and control accuracy of the system, it has a certain significance for the actual four-rotor aircraft attitude control.
Stopped-Rotor Cyclocopter for Venus Exploration
Husseyin, Sema; Warmbrodt, William G.
2016-01-01
The cyclocopter system can use two or more rotating blades to create lift, propulsion and control. This system is explored for its use in a mission to Venus. Cyclocopters are not limited to speed and altitude and can provide 360 degrees of vector thrusting which is favorable for good maneuverability. The novel aspect of this study is that no other cyclocopter configuration has been previously proposed for Venus or any (terrestrial or otherwise) exploration application where the cyclocopters rotating blades are stopped, and act as fixed wings. The design considerations for this unique planetary aerial vehicle are discussed in terms of implementing the use of a cyclorotor blade system combined with a fixed wing and stopped rotor mechanism. This proposed concept avoids many of the disadvantages of conventional-rotor stopped-rotor concepts and accounts for the high temperature, pressure and atmospheric density present on Venus while carrying out the mission objectives. The fundamental goal is to find an ideal design that implements the combined use of cyclorotors and fixed wing surfaces. These design concepts will be analyzed with the computational fluid dynamics tool RotCFD for aerodynamic assessment. Aspects of the vehicle design is 3D printed and tested in a small water tunnel or wind tunnel.
Visual Positioning Method and System for Rotor Flying Robot%旋翼飞行机器人视觉定位方法及系统
李力; 王耀南; 刘洪剑; 谭建豪; 钟杭
2016-01-01
To achieve exact positioning and control of the rotor flying robot in indoor environments, an onboard visual positioning (OVP) method based on monocular vision is designed. It can recognize landmark images by moment feature extraction and image classification, and calculate camera coordinates through EPnP method. To verify the effectiveness of the proposed onboard visual positioning method, an external visual positioning system (EPVS) based on Kinect is built, and a visual tracking algorithm for rotorcraft is designed. The experimental results suggest that the positioning deviation of the rotorcraft is within 2 mm, and the OVP method is suitable for rotorcraft positioning.%为实现旋翼飞行机器人在室内环境中的精确定位及控制，设计了基于单目视觉的机载视觉定位方法．该方法通过矩特征提取、图形分类来识别地面标记图形，进而利用EPnP方法解算摄像机坐标．为验证机载视觉定位方法的有效性，利用Kinect传感器搭建了旋翼飞行器外部定位系统，设计了针对旋翼飞行器目标的视觉跟踪算法，定位精度达2 mm．实验结果表明，机载视觉定位方法能够很好地进行飞行器定位．
基于LabVIEW的旋转机械转子振动监测系统%Vibration Monitoring System for Rotating Machine's Rotor Based on LabVIEW
王彦兵; 李慧敏; 丁彩红
2011-01-01
采用传感器和信号调理技术对旋转机械转子振动的各种信号进行采集、处理,并利用LabVIEW强大的信号处理、分析和数学运算功能对信号进行显示、分析,实现了在线转子的运转状况的监测,设计出了基于LabVIEW的旋转机械转子振动的监测系统.该系统可连续测量和监视转子振动有关的各类参量:转速、轴振、轴位移等,具有直观的显示界面、强大的信号分析以及数据存储管理功能.能及时识别旋转机械设备的异常状态,保证设备安全可靠地运行,并可以为控制设备运行于最优状态以及早期诊断设备故障提供依据.%This paper used sensor and signal conditioning technology for acquiring and processing a variety of rotor vibration signals of rotating machine.It used the LahVIEW' s powerful function of signal processing,analyais and mathematical operation to display and analyze the signal, realized monitoring the work status of online rotor,designed the vibration monitoring system for rotating machine' s rotor based on LabVIEW.This system can measure and monitor various types of rotor vibration parameters in continuously,speed,rotor vibration, axial displacement, with the intuitive display interface, powerful signal analysis ability and data 0storage management functions.It can identify the abnormal states of rotating mechanical equipment to ensure the safty and reliahility of equipment operation,provide the basis to control the equipment running at an optimal condition and diagnose the early equipment fault.
Abdul-Aziz, Ali; Baaklini, George Y.; Roth, Don J.
2004-01-01
Engine makers and aviation safety government institutions continue to have a strong interest in monitoring the health of rotating components in aircraft engines to improve safety and to lower maintenance costs. To prevent catastrophic failure (burst) of the engine, they use nondestructive evaluation (NDE) and major overhauls for periodic inspections to discover any cracks that might have formed. The lowest cost fluorescent penetrant inspection NDE technique can fail to disclose cracks that are tightly closed during rest or that are below the surface. The NDE eddy current system is more effective at detecting both crack types, but it requires careful setup and operation and only a small portion of the disk can be practically inspected. So that sensor systems can sustain normal function in a severe environment, health-monitoring systems require the sensor system to transmit a signal if a crack detected in the component is above a predetermined length (but below the length that would lead to failure) and lastly to act neutrally upon the overall performance of the engine system and not interfere with engine maintenance operations. Therefore, more reliable diagnostic tools and high-level techniques for detecting damage and monitoring the health of rotating components are very essential in maintaining engine safety and reliability and in assessing life.
Bert, C.W.; Ramunujam, G.
1981-09-01
Information to designers of flywheels is provided which will enable them to predict many aspects of the dynamic behavior of their flywheel systems when spin-tested with a quill-shaft support and driven by an air turbine. Computer programs are presented for the following dynamic analysis to obtain the results indicated: free whirling for natural frequencies versus rotational speed and the associated mode shapes; rough-type stability analysis for determining the stability limits; and forced whirling analysis for estimating the response of major components of the system to flywheel mass eccentricity and initial tilt. For the first and third kinds of analyses, two different mathematical models of the generic system are investigated. One is a seven-degree-of-freedom lumped-parameter analysis, while the other is a combined distributed- and lumped-parameter analysis. When applied to an existing flywheel system, the two models yielded numerical values for the lowest first-order forward critical speed in very close agreement with each other and with experimental results obtained in spin tests. Therefore, for the second kind of analysis, only the lumped-parameter model is implemented. Qualitative discussions as to why forced retrograde whirling is not as severe as forward whirling are also presented. The analyses are applied to the multi-material ring type flywheel systems, a constant-thickness-diskring type, and a tapered-thickness-disk type. In addition, the effects of the following flywheel design parameters on system dynamics were investigated: flywheel mass; diametral and polar mass moments of inertia; location of mass center from the lower end of the quill shaft; quill shaft length; lower turbine-bearing support stiffness; equivalent viscous damping coefficient of the external damper; flywheel dead weight; and torque applied at the turbine.
Operational research in weapon system
R. S. Varma
1958-04-01
Full Text Available "The paper is divided into three parts: (a The first part deals with what operational research is. (bThe second part gives what we mean by Weapon Systems and discusses considerations that determine the choice of a particular weapon system from a class weapon systems. (cThe third part deals with some aspects of weapon replacement policy.The effectiveness of a weapon system is defined as E=D/C where E is weapon effectiveness (a comparative figure of merit; D is total damage inflicted or prevented and C is total cost, D and C being reduced to common dimensions. During the course of investigations, criteria regarding to choice of weapon or weapons from a set of weapon systems are established through production function and military effect curves. A procedure is described which maximizes the expectation of military utility in order to select a weapon system from the class of weapon systems. This is done under the following simplifying assumptions: (a Non- decreasing utility function; (b Constant average cost for each kind of weapons; and (c Independence of the performance of each unit of weapon. Some of the difficulties which arises when any of these restrictions is relaxed are briefly mentioned. Finally, the policy of weapon replacement and the factors governing the same are described."
Design Considerations for a Stopped-Rotor Cyclocopter for Venus Exploration
Husseyin, S.; Warmbrodt, William G.
2016-01-01
This paper considers the use of a cycloidal blade system as a means of providing lift and propulsive thrust as well as combined with a stopped rotor system, to create a stopped-rotor cyclocopter vehicle, during a mission to Venus. This stopped-rotor cyclocopter will be capable of flying at all atmospheric levels of Venus as well as landing on the surface for scientific investigation. Three reference conceptual designs with different stopped-rotor cyclocopter yaw angles are tested in RotCFD as well as a model of a hovering cyclorotor for comparison with past work in the literature and innovative study for future projects.
Tests of Full-Scale Helicopter Rotors at High Advancing Tip Mach Numbers and Advance Ratios
Biggers, James C.; McCloud, John L., III; Stroub, Robert H.
2015-01-01
As a continuation of the studies of reference 1, three full-scale helicopter rotors have been tested in the Ames Research Center 40- by SO-foot wind tunnel. All three of them were two-bladed, teetering rotors. One of the rotors incorporated the NACA 0012 airfoil section over the entire length of the blade. This rotor was tested at advance ratios up to 1.05. Both of the other rotors were tapered in thickness and incorporated leading-edge camber over the outer 20 percent of the blade radius. The larger of these rotors was tested at advancing tip Mach numbers up to 1.02. Data were obtained for a wide range of lift and propulsive force, and are presented without discussion.
APPLICATION OF WAVELET TIME-FR EQUENCY ANALYSIS TO IDENTIFICATION OF CRACKED ROTOR
无
2003-01-01
Based on the simple hinge crack model and the local flexibility theorem, the corresponding dynamic equation of the cracked rotor is modelled, the numerical simulation solutions of the cracked rotor and the uncracked rotor are obtained. By the continuous wavelet time-frequency transform, the wavelet time-frequency properties of the uncracked rotor and the cracked rotor are discussed. A new detection algorithm that uses the wavelet time-frequency transform to identify the crack is proposed. The influence of the sampling frequency on the wavelet time-frequency transform is analyzed by the numerical simulation research. The valid sampling frequency is suggested. Experiments demonstrate the validity and availability of the proposed algorithm in identification of the cracked rotor for engineering practices.
Vortex shedding by a Savonius rotor
Botrini, M.; Beguier, C.; Chauvin, A.; Brun, R.
1984-05-01
A series of flow visualizations was performed to characterize the wake vortices of a Savonius rotor. The trials were undertaken in an attempt to account for discrepancies between theoretical and experimentally-derived power coefficients. The Savonius examined was two-bladed with a center offset. All tests were made in a water tunnel. Dye injection provided the visualization, and average velocities and velocity fluctuations were measured using a laser Doppler anemometer. A system of three vortices was found to be periodically shed by the rotor. Flow velocity fluctuation intensity peaked as a vortex was shed. The vortex shedding alternated from blade to blade, so that one was shed from a blade moving upstream.
夏青元; 徐锦法
2013-01-01
A tri-axial unmanned rotor aircraft consisting of three sets of coaxial rotors is designed. The control mechanism of the unmanned rotor aircraft is very much simplified. The rotors are directly driven by DC motors. The speed of each motor is the only regulating variable which could control the attitude and trajectory of the aircraft. In order to verify the design of the flight control system for the triaxial unmanned rotor aircraft, a nonlinear dynamic model of the aircraft is investigated. A computing method of the rotor aerodynamic loads is established by means of the blade element momentum theory. The effect of the rotor inflow characteristics on the rotor aerodynamic load is analyzed. The validity of the rotor aerodynamic load model for the co-axial rotor is tested by experiments. Due to the influence of nonlinearity and un-modeled dynamics, it is quite difficult to establish a very accurate mathematical model, which makes it a challenge to design a flight control system. In this paper, a rotational dynamical model inverse controller and translational dynamical model inverse controller are deduced according to the nonlinear model of the aircraft. The model inverse error is adaptively compensated with an online neural network. The command following error is regulated with a PD/PI controller. A combined maneuver flight mission task element is applied to simulation validation, which included pirouette and vertical maneuvers. A demonstration is conducted to validate the flight control system of the tri-axial unmanned rotor aircraft. Simulation results including an imitation of gust disturbance are provided. The demonstration shows clearly that the designed flight control system has adaptability and robustness, and that it can implement accurate command following control.%设计了一种操控简便的三轴式无人旋翼飞行器,由三组共轴双旋翼组成,各旋翼由直流电机直接驱动,只需调节各电机转速就能控制旋翼飞行器运动姿态
Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.; Chow, Ray [Zimitar, Inc.; Nordenholz, Thomas R. [The California Maritime Academy; Wamble, John Lee [Zimitar, Inc.
2015-05-16
The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.
Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.
2015-05-16
The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.
Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.
2015-05-16
The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.
HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME THREE: MARKET & TEAM
Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.
2015-05-16
The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.
A study of EV induction motor controller based on rotor flux oriented control
Song Jianguo; Chen Quanshi
2006-01-01
Induction motor is a multi-parameter, non-linear and strong coupling system, which requires efficient control algorithms. In this paper, rotor flux oriented control (FOC) algorithm based on voltage source inverter-fed is deduced in detail, including stator voltage compensation, closed-loop PI parameters' calculation of torque and rotor flux. FOC's Simulink model is setup to simulate torque and rotor flux's response. At last, the experimental results are shown.
Shouliang Han; Shumei Cui; Liwei Song; Ching Chuen Chan
2014-01-01
The double-rotor machine is a kind of multiple input and output electromechanical energy transducer with two electrical ports and two mechanical ports, which is an ideal transmission system for hybrid electric vehicles and has a series of advantages such as integration of power and energy, high efficiency and compaction. In this paper, a switched reluctance double-rotor machine (SRDRM) is proposed for hybrid electric vehicles, while no conductor or PM in the middle rotor. This machine not onl...
Design of composite flywheel rotor
Yue BAI; Qingjia GAO; Haiwen LI; Yihui WU; Ming XUAN
2008-01-01
A design method for a flywheel rotor com-posed of a composite rim and a metal hub is proposed by studying the connection between the rotor and the driving machine. The influence of some factors such as the rotor material, configuration, connection, and frac-ture techniques on energy density is analyzed. The results show that the ratio of the inner radius to outer radius of the rim is the key factor, and is determined by the rim material. Optimizing the hub can further efficiently improve energy density. The composite flywheel rotor is produced and its rotation stress has been tested at the speed of 20 krpm. The emulation results are consistent with testing results, which proves that the introduced design method is useful.
Regenerative life support system research
1988-01-01
Sections on modeling, experimental activities during the grant period, and topics under consideration for the future are contained. The sessions contain discussions of: four concurrent modeling approaches that were being integrated near the end of the period (knowledge-based modeling support infrastructure and data base management, object-oriented steady state simulations for three concepts, steady state mass-balance engineering tradeoff studies, and object-oriented time-step, quasidynamic simulations of generic concepts); interdisciplinary research activities, beginning with a discussion of RECON lab development and use, and followed with discussions of waste processing research, algae studies and subsystem modeling, low pressure growth testing of plants, subsystem modeling of plants, control of plant growth using lighting and CO2 supply as variables, search for and development of lunar soil simulants, preliminary design parameters for a lunar base life support system, and research considerations for food processing in space; and appendix materials, including a discussion of the CELSS Conference, detailed analytical equations for mass-balance modeling, plant modeling equations, and parametric data on existing life support systems for use in modeling.
EXPERIMENTAL INVESTIGATION OF AERODYNAMIC INTERACTION EFFECT OF ROTOR WAKE ON FUSELAGE OF HELICOPTER
无
2000-01-01
The interaction effect of rotor wake on fuselage of helicopter was investigated with experimental method. The results from experiment have proved that for the drag of fuselage the effect of rotor airflow is closely in connection with both the flight speed and the collective pitch of blades, while for the thrust and pitch moment of fuselage the collective pitch angle of blades plays more important role. A simple and effective computing method about aerodynamic interaction can be derived from the measured data. In order to implement the experiment, a fuselage model, a special sensor, the measurement and data acquisition and processing system were designed and manufactured according to the special requirements of this research project, thereby a good base was built up for carrying out experiments successfully with high quality.
Assessment Report on Innovative Rotor Blades (MAREWINT WP1,D1.3)
McGugan, Malcolm; Leble, Vladimir; Pereira, Gilmar Ferreira
the innovative concept development for wind turbine blades. This covers models and experiments with damage measurement systems embedded within the composite material/structure and numerical methods investigating the effects of leading and trailing edge flaps on modifying the aerodynamic loads on the operating......The offshore wind energy industry faces many challenges in the short to medium term if it is to meet the ambitions of the global community for sustainable energy supply in the future. Not least among these challenges is the issue of rotor blades. Innovative design for “smart” rotor blades...... with embedded sensors and actuation are being developed that will deliver an improved whole-life performance, and a structural health management based operational concept. In this report, the work of two early stage researchers within the Initial Training Network MAREWINT is presented that support...
Aeromechanics and Aeroacoustics Predictions of the Boeing-SMART Rotor Using Coupled-CFD/CSD Analyses
Bain, Jeremy; Sim, Ben W.; Sankar, Lakshmi; Brentner, Ken
2010-01-01
This paper will highlight helicopter aeromechanics and aeroacoustics prediction capabilities developed by Georgia Institute of Technology, the Pennsylvania State University, and Northern Arizona University under the Helicopter Quieting Program (HQP) sponsored by the Tactical Technology Office of the Defense Advanced Research Projects Agency (DARPA). First initiated in 2004, the goal of the HQP was to develop high fidelity, state-of-the-art computational tools for designing advanced helicopter rotors with reduced acoustic perceptibility and enhanced performance. A critical step towards achieving this objective is the development of rotorcraft prediction codes capable of assessing a wide range of helicopter configurations and operations for future rotorcraft designs. This includes novel next-generation rotor systems that incorporate innovative passive and/or active elements to meet future challenging military performance and survivability goals.
开式转子发动机计算模型及调节研究%Research on Open Rotor Engine Caculating Model and Control Schedule
屠秋野; 倪力伟; 杨祥明; 郑恒; 蒋平
2016-01-01
目前先进的开式转子发动机多采用变桨距、双排共轴对转桨作为推进部件。采用双排桨的气动计算方法，根据单排桨特性图计算对应的双排对转桨特性图，验证对转桨性能计算模型。在双轴涡轮喷气发动机计算模型的基础上，添加动力涡轮、行星差动齿轮和双排对转桨，组成开式转子发动机计算模型。采用该模型研究了开式转子发动机的调节计划，对比了等转速和等叶尖速度调节的不同，以及对开式转子发动机高度速度特性的影响，并使用美国PROOSIS模型对计算结果进行验证。结果表明：开式转子发动机模型计算精度较高，可较准确地研究不同设计参数和调节规律下发动机的总体性能，其中固定桨扇叶尖速度的调节计划在较低飞行速度下具有高推力、低油耗的优点，可以获得较好的全包线性能。%Counter-rotating coaxial propellers with variable pitch blades are mostly implemented in the current advanced open rotor engine. An aerodynamic computing method of counter rotating propellers was verified through calculating the counter-rotating propeller map using two single propeller maps. Basing on the aerodynamic and thermal model of a two-spool turbojet engine, an open rotor performance model was established by adding a power turbine, a differential planetary gearbox and a pair of counter rotating propellers. With this model, the control schedules were studied. The difference between constant propeller speed strategy and constant tip speed strategy , their influences to the altitude and velocity characteristics were compared respectively. The results were demonstrated to be accurate by using the data of PROOSIS model, and the performance of open rotor engine under various design parameters and different control schedules could be precisely studied. Results show that the constant tip speed strategy had advantage of high thrust with low fuel
Numerical Analysis of Helicopter Rotor Hovering in Close Proximity to the Ground with a Wall
Itoga, Noriaki; Iboshi, Naohiro; Horimoto, Mitsumasa; Saito, Shigeru; Tanabe, Yasutada
In rescue operations and emergency medical services, helicopters are frequently required to operate near the ground with obstacles such as buildings and sidewalls of highway. In this paper, numerical analysis of helicopter rotor hovering in close proximity to the ground with an obstacle is done by solving unsteady 3D compressible Euler equations with an overlapped grid system. The obstacle is simulated by a wall vertically set up on the ground. The parameters for numerical analysis are the rotor height and distance from the rotor-hub-center to the wall. The effects of combinations of these parameters on the flowfields around the rotor, inflow distributions on the rotor disc and behaviors of blade flapping motion are discussed. It is also clarified the cause that the helicopter rotor hovering in close proximity to the ground with a wall does not have the enough ground effect depending on the combinations of these parameters.
Correlated rotational switching in two-dimensional self-assembled molecular rotor arrays
Wasio, Natalie A.; Slough, Diana P.; Smith, Zachary C.; Ivimey, Christopher J.; Thomas, Samuel W., III; Lin, Yu-Shan; Sykes, E. Charles H.
2017-07-01
Molecular devices are capable of performing a number of functions from mechanical motion to simple computation. Their utility is somewhat limited, however, by difficulties associated with coupling them with either each other or with interfaces such as electrodes. Self-assembly of coupled molecular devices provides an option for the construction of larger entities that can more easily integrate with existing technologies. Here we demonstrate that ordered organometallic arrays can be formed spontaneously by reaction of precursor molecular rotor molecules with a metal surface. Scanning tunnelling microscopy enables individual rotors in the arrays to be switched and the resultant switches in neighbouring rotors imaged. The structure and dimensions of the ordered molecular rotor arrays dictate the correlated switching properties of the internal submolecular rotor units. Our results indicate that self-assembly of two-dimensional rotor crystals produces systems with correlated dynamics that would not have been predicted a priori.
Yang, Xiaoyan; Cui, Jianwei; Lao, Dazhong; Li, Donghai; Chen, Junhui
2016-05-01
In this paper, a composite control based on Active Disturbance Rejection Control (ADRC) and Input Shaping is presented for TRMS with two degrees of freedom (DOF). The control tasks consist of accurately tracking desired trajectories and obtaining disturbance rejection in both horizontal and vertical planes. Due to un-measurable states as well as uncertainties stemming from modeling uncertainty and unknown disturbance torques, ADRC is employed, and feed-forward Input Shaping is used to improve the dynamical response. In the proposed approach, because the coupling effects are maintained in controller derivation, there is no requirement to decouple the TRMS into horizontal and vertical subsystems, which is usually performed in the literature. Finally, the proposed method is implemented on the TRMS platform, and the results are compared with those of PID and ADRC in a similar structure. The experimental results demonstrate the effectiveness of the proposed method. The operation of the controller allows for an excellent set-point tracking behavior and disturbance rejection with system nonlinearity and complex coupling conditions.
师名林; 王德忠; 张继革
2012-01-01
The lumped parameter model of large -scale canned motor pump rotor system is established,and the critical speeds and modal shapes are calculated based on Riccati transfer matrix method. The calculated results show the critical rotary speeds can effectively avoid the operation speed,thus the critical rotary speed design of large-scale canned motor pump rotor system k sufficient in design capacity. In addition,the locations of upper and lower flywheels are the sensitive part of radical vibration of rotor system and should be monitored to avoid collision with pressure casing in operation.%建立了大型屏蔽电机泵转子系统的集总参数模型,并采用Riccati传递矩阵法对转子系统的临界转速及振型进行了计算.计算结果表明:(1)采用Riccati传递矩阵法编制的转子系统临界转速求解程序计算稳定,计算精度足够高；(2)大型屏蔽电机泵转子系统的临界转速为设计超速的1.2倍,能够有效避开工作转速,设计裕量足够；(3)在正常工作下,转子系统上、下飞轮处为振动敏感部位,应重点监测,以免和承压壳体发生碰磨.
A control strategy for stand-alone wound rotor induction machine
Forchetti, D.G.; Garcia, G.O. [Grupo de Electronica Aplicada (GEA), Universidad Nacional de Rio Cuarto, X5804 BYA Rio Cuarto (Argentina); Solsona, J.A. [Instituto de Investigaciones en Ingenieria Electrica?Alfredo Desages?, Departamento de Ingenieria Electrica y de Computadoras, Universidad Nacional del Sur, Bahia Blanca (Argentina); Valla, M.I. [Laboratorio de Electronica Industrial, Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata, 1900 La Plata (Argentina)
2007-02-15
A control strategy to regulate the frequency and voltage of a stand-alone wound rotor induction machine is presented. This strategy allows the machine to work as a generator in stand-alone systems (without grid connection) with variable rotor speed. A stator flux-oriented control is proposed using the rotor voltages as actuation variables. Two cascade control loops are used to regulate the stator flux and the rotor currents. A closed loop observer is designed to estimate the machine flux which is necessary to implement these control loops. The proposed control strategy is validated through simulations with satisfactory results. (author)
William L. Murray
2015-01-01
Full Text Available Blade row interactions in turbomachinery can lead to blade vibrations and even high cycle fatigue. Forced response conditions occur when a forcing function (such as impingement of stator wakes occurs at a frequency that matches the natural frequency of a blade. The objective of this research is to develop the data processing techniques needed to detect rotor blade vibration in a forced response condition from stationary fast-response pressure transducers to allow for detection of rotor vibration from transient data and lead to techniques for vibration monitoring in gas turbines. This paper marks the first time in the open literature that engine-order resonant response of an embedded bladed disk in a 3-stage intermediate-speed axial compressor was detected using stationary pressure transducers. Experiments were performed in a stage axial research compressor focusing on the embedded rotor of blisk construction. Fourier waterfall graphs from a laser tip timing system were used to detect the vibrations after applying signal processing methods to uncover these pressure waves associated with blade vibration. Individual blade response was investigated using cross covariance to compare blade passage pressure signatures through resonance. Both methods agree with NSMS data that provide a measure of the exact compressor speeds at which individual blades enter resonance.
开式转子叶片气动设计研究%Research on Aerodynamic Design of Open Rotor Blade
刘政良; 严明; 洪青松
2013-01-01
参考现代民航飞机设计方案要求，完成了开式转子发动机叶片的气动设计工作。在设计过程中引入可压缩流动叶片数据改进了螺旋桨片条理论，使之适用于高亚声速来流的叶片设计。采用后掠叶片，NACA16系列叶型，前缘积叠方式。数值模拟结果与设计结果相近，基本满足气动设计要求。%Aerodynamic design of open rotor blade which refers to performance of engines which used on modern civil airplane is completed. Compressible blade data is introduced to optimize strip theory in order to satisfy blade design under high subsonic free stream. Sept blade, NACA-16 series data and leading edge accumulation is used. Numerical simulation is similar to the design which basicaly satisifed the design requirements.
Structural and Phase State of Fractured Rotor of High-Pressure Steam Turbine
Smirnov, A. N.; Ababkov, N. V.; Kozlov, E. V.; Koneva, N. A.; Popova, N. A.
2016-03-01
The structural and phase state of the metal of a fractured rotor of a steam turbine is studied with the use of modern methods of physical research. The metal is shown to contain gradient structures. The cause of the failure of the rotor is established. The gradient structures are determined by the developed method of acoustic scanning.
宋辰超; 王立勇; 马超; 许宝杰; 王志
2015-01-01
Based on the 2K-H planetary gear train of the wind gearbox and the translational-rotational model, this paper establishes the model of rotor-bearing system which considered the input shaft and output shaft of the transmission system. In the model of rotor-bearing system, we take into account the gear pair clearance, time-varying meshing stiffness and phase difference, meshing damping, integrated meshing phase, the bearing stiffness, the input shaft and output shaft stiffness. The dynamic coordinate system is established, each of coordinate system has three degrees of freedom. The method of integrated mass is applied to establish the model, and the motion differential equation is solved by the Lagrange equation. In this paper, it is summarized and compared the method of establishment about planetary train mode at home and abroad in recent years and the dynamic characteristic of the planetary gear train in practical engineering of wind power is researched. On this basis, the model of rotor-bearing system of planter gear train is established based on the wind gearbox.%基于风电增速箱2K-H直齿行星轮系，在行星轮系平移-扭转振动模型的基础上，结合传动系统的输入轴和输出轴，建立了转子-轴承系统模型。模型中考虑了齿轮副间隙，时变啮合刚度及其相位差，啮合阻尼，综合啮合误差及输入轴和输出轴两端轴承的刚度，输入轴和输出轴的刚度。建立了动坐标系，每个坐标系均有3个自由度。采用集中质量法，建立此模型，并利用拉格朗日方程法解运动微分方程。文中对近几年国内外有关行星轮系模型建立的方法进行了比较和总结，对工程实际中风力发电的行星齿轮传动系特性进行了研究。以此为基础，建立了基于风电增速箱行星轮系的转子-轴承系统的模型。
Rotor-Router Aggregation on the Comb
Huss, Wilfried; Sava, Ecaterina
2011-01-01
We prove a shape theorem for rotor-router aggregation on the comb, for a specific initial rotor configuration and clockwise rotor sequence for all vertices. Furthermore, as an application of rotor-router walks, we describe the harmonic measure of the rotor-router aggregate and related shapes, which is useful in the study of other growth models on the comb. We also identify the shape for which the harmonic measure is uniform. This gives the first known example where the rotor-router cluster ha...
Research on computer systems benchmarking
Smith, Alan Jay (Principal Investigator)
1996-01-01
This grant addresses the topic of research on computer systems benchmarking and is more generally concerned with performance issues in computer systems. This report reviews work in those areas during the period of NASA support under this grant. The bulk of the work performed concerned benchmarking and analysis of CPUs, compilers, caches, and benchmark programs. The first part of this work concerned the issue of benchmark performance prediction. A new approach to benchmarking and machine characterization was reported, using a machine characterizer that measures the performance of a given system in terms of a Fortran abstract machine. Another report focused on analyzing compiler performance. The performance impact of optimization in the context of our methodology for CPU performance characterization was based on the abstract machine model. Benchmark programs are analyzed in another paper. A machine-independent model of program execution was developed to characterize both machine performance and program execution. By merging these machine and program characterizations, execution time can be estimated for arbitrary machine/program combinations. The work was continued into the domain of parallel and vector machines, including the issue of caches in vector processors and multiprocessors. All of the afore-mentioned accomplishments are more specifically summarized in this report, as well as those smaller in magnitude supported by this grant.
贾语扬; 张凯; 卢小祝; 尚晓凡; 苏东林
2016-01-01
提出一套基于四旋翼无人机平台的电磁环境监测分析系统,通过将电磁环境监测硬件集成到四旋翼无人机平台上,使用自行开发的测量管理软件和电磁干扰源定位算法,可以实现对空间电磁环境的自动测量及测量数据实时分析处理.详细介绍测量管理软件的组成和基于电磁干扰源定位算法开发的电磁环境可视化软件.实验结果表明,基于四旋翼无人机平台的电磁环境监测分析系统自动化程度高,测量精度高,且显示直观.%An electromagnetic environment (EME) monitor and analysis system based on quad-rotor UAV platform is proposed. By integrating the EME monitoring hardware into quad-rotor UAV platform and utilizing self-developed measurement management software and electromagnetic interference source localization algorithm, the automatic measurement of space electromagnetic environment and real-time analysis of measurement data can be realized. The composition of measurement management software and the EME visualization software developed on the basis of electromagnetic interference source localization algorithm are introduced in detail. The experiment results show that this electromagnetic environment monitor and analysis system based on quad-rotor UAV platform has high degree of automation, high accuracy of measurement and visual display.
贺威; 袁惠群
2011-01-01
为了揭示复杂转子系统在热启动过程中的动力特性,采用Riccati传递矩阵和Wilson-θ法相结合的方法,建立了多盘转子的动力学方程,以及热启动过程中的瞬态传递矩阵表达式.模拟计算了热启动过程中转子径向温差、线膨胀系数等参数对转子系统振动特性的影响.计算结果表明,随着转子系统径向温差的增大,其固有频率逐渐降低,特别对一阶、二阶固有频率具有较大的影响;径向温差、线膨胀系数越大,转子系统热启动过程中的瞬态响应幅值越大.因此,在对转子系统的振动研究中,不应当忽略温度的影响.%To reveal the dynamic characteristics of the complicated rotor system in the process of thermal start, the kinetic equation of the multi-disc rotor and the expression formula for the transient transfer matrix in the process of thermal start are built with the help of the combination of Riccati transfer matrix and Wilson-θ methods. The influence of the parameters, such as radial temperature difference, linear expansion coefficient and so on, on the vibration characteristic in the process of thermal start is calculated. The calculation result shows that, with the increase of radial temperature difference of the rotor system, its natural frequency decreases gradually. Especially, the first-order and second -order natural frequencies are affected more greatly. The larger the radial temperature difference and linear expansion coefficient are, the larger the amplitude of the transient response is. Therefore, the influence of temperature should not be ignored in the vibration study of the rotor system.
Research on Third Order Vibration Treatment Method of 660 MW Generator Rotors%660 MW发电机转子三阶振动处理方法研究
王广庭
2015-01-01
本文介绍了双平面不平衡影响系数算法的基本原理和发电机等柔性转子的振型分解基本方法，结合发电机三阶不平衡处理的现场实践经验，可知在低发对轮和励磁机上加重可以很好地平衡发电机的三阶不平衡。本文将双平面影响系数法应用于发电机的三阶不平衡振动处理，简化了计算模型，减少了计算量，并且成功处理了印度某厂660 MW发电机的三阶不平衡故障。%This paper introduces the basic principles of the double plane unbalance influence coeffi-cient algorithm and the basic modal decomposition method of the generator and other flexible rotor. Combined with the practical field of unbalanced generator of third order processing experience,the generator third order unbalance was balanced nicely under low on the wheel and increase on excitation system This paper presented example for a double plane influence coefficient method applied to the generator of third order imbalance vibration processing,it simplified the calculation model,reduced the calculation load and successfully dealt with third order unbalance fault of India 660 MW generator rotor.
On the impact of multi-axial stress states on trailing edge bondlines in wind turbine rotor blades
Noever Castelos, Pablo; Balzani, Claudio
2016-09-01
For a reliable design of wind turbine systems all of their components have to be designed to withstand the loads appearing in the turbine's lifetime. When performed in an integral manner this is called systems engineering, and is exceptionally important for components that have an impact on the entire wind turbine system, such as the rotor blade. Bondlines are crucial subcomponents of rotor blades, but they are not much recognized in the wind energy research community. However, a bondline failure can lead to the loss of a rotor blade, and potentially of the entire turbine, and is extraordinarily relevant to be treated with strong emphasis when designing a wind turbine. Modern wind turbine rotor blades with lengths of 80 m and more offer a degree of flexibility that has never been seen in wind energy technology before. Large deflections result in high strains in the adhesive connections, especially at the trailing edge. The latest edition of the DNV GL guideline from end of 2015 demands a three-dimensional stress analysis of bondlines, whereas before an isolated shear stress proof was sufficient. In order to quantify the lack of safety from older certification guidelines this paper studies the influence of multi-axial stress states on the ultimate and fatigue load resistance of trailing edge adhesive bonds. For this purpose, detailed finite element simulations of the IWES IWT-7.5-164 reference wind turbine blades are performed. Different yield criteria are evaluated for the prediction of failure and lifetime. The results show that the multi-axial stress state is governed by span-wise normal stresses. Those are evidently not captured in isolated shear stress proofs, yielding non-conservative estimates of lifetime and ultimate load resistance. This finding highlights the importance to include a three-dimensional stress state in the failure analysis of adhesive bonds in modern wind turbine rotor blades, and the necessity to perform a three-dimensional characterization
Selami KESLER
2009-01-01
Full Text Available The power flow of the rotor circuit is controlled by different methods in induction machines used for producing high torque in applications involved great power and constant output power with constant frequency in wind turbines. The voltage with slip frequency can be applied on rotor windings to produce controlled high torque and obtain optimal power factor and speed control. In this study, firstly, the dynamic effects of the voltage applying on rotor windings through the rings in slip-ring induction machines are researched and undesirable aspects of the method are exposed with simulations supported by experiments. Afterwards, a fuzzy logic based inverter model on rotor side is proposed with a view to improving the dynamic effects, controlling high torque producing and adjusting machine speed in instantaneous forced conditions. For the simulation model of the system in which the stator side is directly connected to the grid in steady state operation, a C/C++ algorithm is developed and the results obtained for different load conditions are discussed.
Wu Zaixin
2016-01-01
Full Text Available High-speed motorized spindle is a multi-variable, non-linear and strong coupling system. The rotor static eccentricity is inevitable because of machining or assembling error. The rotor static eccentricities have an important effect on the electromechanical coupled characteristics of the motorized spindle. In this paper, the electromechanical coupled mathematical model of the motorized spindle was set up. The mathematical model includes mechanical and electrical equation. The mechanical and electrical equation is built up by the variational principle. Furthermore, the inductance parameters without the rotor static eccentricity and the inductance parameters with rotor static eccentricity have been calculated by the winding function method and the high speed motorized spindle was simulated. The result show that the rotor static eccentricity can delay the starting process of the motorized spindle, and at steady state, the rotor circuit currents are still large because of the rotor static eccentricity.
Vibratory Loads Data from a Wind-Tunnel Test of Structurally Tailored Model Helicopter Rotors
Yeager, William T., Jr.; Hamouda, M-Nabil H.; Idol, Robert F.; Mirick, Paul H.; Singleton, Jeffrey D.; Wilbur, Matthew L.
1991-01-01
An experimental study was conducted in the Langley Transonic Dynamics Tunnel to investigate the use of a Bell Helicopter Textron (BHT) rotor structural tailoring concept, known as rotor nodalization, in conjunction with advanced blade aerodynamics as well as to evaluate rotor blade aerodynamic design methodologies. A 1/5-size, four-bladed bearingless hub, three sets of Mach-scaled model rotor blades were tested in forward flight from transition up to an advance ratio of 0.35. The data presented pertain only to the evaluation of the structural tailoring concept and consist of fixed-system and rotating system vibratory loads. These data will be useful for evaluating the effects of tailoring blade structural properties on fixed-system vibratory loads, as well as validating analyses used in the design of advanced rotor systems.
Garcia Illescas, Rafael
2001-07-01
A theoretical numerical and experimental analysis of the dynamics and vibratory stability of a rotor-bearing system with a cracked shaft is presented. A new mathematical model was built to simulate the system, incorporating all possible conditions existing in reality. The presence of a transverse crack is taken into account by considering a structural rotating stiffness variation as a time-function (angular dependent). The damping of the system includes the effect of the external fluid (steam) where the shaft is rotating and, the most significant, the viscous damping of the journal bearings due to the oil film. The present problem consists in a cracked flexible Jeffcott rotor supported on identical journal bearings, which has a mass disk and a crack at the midspan of the shaft. An innovator aspect that complicates the analysis is that the mass effect of the journal bearings is also considered. A linear stability analysis of the system is accomplished including all aspects mentioned using the Floquet Theory. Some results are compared with previous work obtained by other researchers in the field like Gasch, Meng, et cetera. The resulting parametrically excited system is analyzed using a perturbation solution. The system equations are written in terms of complex variables and an associated computer code in MATLAB has been developed by the author for numerical simulation studies. A simple rotor system is studied in order to illustrate the basic properties of rotors with cracks of real machines. The experimental results were obtained in the Vibrations and Rotor dynamics Laboratory of the SEPI ESIME IPN to complement numerical analysis. The option of including the non-linear effect of the bearings is presented. The latter is under research by Dr. Gonzalez Mancilla who has implemented this non-linear model in his program called MAQUI. Proper calculation of nonlinear coefficients impact numerical simulation results and can produce adequate or inaccurate frequency spectrum
Inayat-Hussain, Jawaid I. [School of Engineering, Monash University Malaysia, No. 2, Jalan Kolej, Bandar Sunway, 46150 Petaling Jaya, Selangor Darul Ehsan (Malaysia)]. E-mail: jawaid.inayat-hussain@eng.monash.edu.my
2007-02-15
This work reports on a numerical study undertaken to investigate the response of an imbalanced rigid rotor supported by active magnetic bearings. The mathematical model of the rotor-bearing system used in this study incorporates nonlinearity arising from the electromagnetic force-coil current-air gap relationship, and the effects of geometrical cross-coupling. The response of the rotor is observed to exhibit a rich variety of dynamical behavior including synchronous, sub-synchronous, quasi-periodic and chaotic vibrations. The transition from synchronous rotor response to chaos is via the torus breakdown route. As the rotor imbalance magnitude is increased, the synchronous rotor response undergoes a secondary Hopf bifurcation resulting in quasi-periodic vibration, which is characterized by a torus attractor. With further increase in the rotor imbalance magnitude, this attractor is seen to develop wrinkles and becomes unstable resulting in a fractal torus attractor. The fractal torus is eventually destroyed as the rotor imbalance magnitude is further increased. Quasi-periodic and frequency-locked sub-synchronous vibrations are seen to appear and disappear alternately before the emergence of chaos in the response of the rotor. The magnitude of rotor imbalance where sub-synchronous, quasi-periodic and chaotic vibrations are observed in this study, albeit being higher than the specified imbalance level for rotating machinery, may possibly occur due to a gradual degradation of the rotor balance quality during operation.
A framework for systems engineering research
Erasmus, L
2013-08-01
Full Text Available This presentation discusses a framework which is proposed to perform systems engineering research within South Africa and the necessity for hybrid research methods in systems engineering....
High Confidence Software and Systems Research Needs
Networking and Information Technology Research and Development, Executive Office of the President — This White Paper presents a survey of high confidence software and systems research needs. It has been prepared by the High Confidence Software and Systems...
Rotor/Wing Interactions in Hover
Young, Larry A.; Derby, Michael R.
2002-01-01
Hover predictions of tiltrotor aircraft are hampered by the lack of accurate and computationally efficient models for rotor/wing interactional aerodynamics. This paper summarizes the development of an approximate, potential flow solution for the rotor-on-rotor and wing-on-rotor interactions. This analysis is based on actuator disk and vortex theory and the method of images. The analysis is applicable for out-of-ground-effect predictions. The analysis is particularly suited for aircraft preliminary design studies. Flow field predictions from this simple analytical model are validated against experimental data from previous studies. The paper concludes with an analytical assessment of the influence of rotor-on-rotor and wing-on-rotor interactions. This assessment examines the effect of rotor-to-wing offset distance, wing sweep, wing span, and flaperon incidence angle on tiltrotor inflow and performance.
Extension-twist coupling optimization in composite rotor blades
Ozbay, Serkan
2005-07-01
For optimal rotor performance in a tiltrotor aircraft the difference in the inflow and the rotor speeds between the hover and cruise flight modes suggests different blade twist and chord distributions. The blade twist rates in current tiltrotor applications are defined based upon a compromise between the figure of merit in hover and propeller efficiency in airplane mode. However, when each operation mode is considered separately the optimum blade distributions are found to be considerably different. Passive blade twist control, which uses the inherent variation in centrifugal forces on a rotor blade to achieve optimum blade twist distributions in each flight mode through the use of extension-twist coupled composite rotor blades, has been considered for performance improvement of tiltrotor aircraft over the last two decades. The challenge for this concept is to achieve the desired twisting deformations in the rotor blade without altering the aeroelastic characteristics of the vehicle. A concept referred to as the sliding mass concept is proposed in this work in order to increase the twist change with rotor speed for a closed-cell composite rotor blade cross-section to practical levels for performance improvement in a tiltrotor aircraft. The concept is based on load path changes for the centrifugal forces by utilizing non-structural masses readily available on a conventional blade, such as the leading edge balancing mass. A multilevel optimization technique based on the simulated annealing method is applied to improve the performance of the XV15 tiltrotor aircraft. A cross-sectional analysis tool, VABS together with a multibody dynamics code, DYMORE are integrated into the optimization process. The optimization results revealed significant improvements in the power requirement in hover while preserving cruise efficiency. It is also shown that about 21% of the improvement is provided through the sliding mass concept pointing to the additional flexibility the concept
Rotor Dynamic Analysis of RM12 Jet Engine Rotor using ANSYS
Srikrishnanivas, Deepak
2012-01-01
Rotordynamics is a field under mechanics, mainly deals with the vibration of rotating structures. In recent days, the study about rotordynamics has gained more importance within Jet engine industries. The main reason is Jet engine consists of many rotating parts constitutes a complex dynamic system. While designing rotors of high speed turbo machineries, it is of prime importance to consider rotordynamics characteristics in to account. Considering these characteristics at the design phase may...
SU (3) realization of the rigid asymmetric rotor within the IBM
Smirnova, N.A.; Van Isacker, P. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France); Smirnov, Y.F. [Instituto de Ciencias Nucleares, UNAM (Mexico)
1999-07-01
It is shown that the spectrum of the asymmetric rotor can be realized quantum mechanically in terms of a system of interacting bosons. This is achieved in the SU(3) limit of the interacting boson model by considering higher-order interactions between the bosons. The spectrum corresponds to that of a rigid asymmetric rotor in the limit of infinite boson number. (author)
Bharadwaj, Sudarsh; Dullin, Holger R; Leung, Karen; Tong, William
2015-01-01
We present and analyse a simple model for the twisting somersault. The model is a rigid body with a rotor attached which can be switched on and off. This makes it simple enough to devise explicit analytical formulas whilst still maintaining sufficient complexity to preserve the shape-changing dynamics essential for twisting somersaults in springboard and platform diving. With `rotor on' and with `rotor off' the corresponding Euler-type equations can be solved, and the essential quantities characterising the dynamics, such as the periods and rotation numbers, can be computed in terms of complete elliptic integrals. Thus we arrive at explicit formulas for how to achieve a dive with m somersaults and n twists in a given total time. This can be thought of as a special case of a geometric phase formula due to Cabrera 2007.
Transonic Axial Splittered Rotor Tandem Stator Stage
2016-12-01
compressor rotor was designed incorporating a splitter vane between the principal blades . Historical experiments conducted by Dr. Arthur J...conventional rotor design . The stage is composed of the rotor and stator. The flow of the air passing through the rotor is turned, and the flow is required...derived results achieved the best blade geometry for design continuation. The best circumferential and axial placement for the splitter blade was
Fractional Identification of Rotor Skin Effect in Induction Machines
Jean-Claude Trigeassou
2011-07-01
Full Text Available Fractional identification of rotor skin effect in induction machines is presented in this paper. Park transformation is used to obtain a system of differential equations which allows to include the skin effect in the rotor bars of asynchronous machines. A transfer function with a fractional derivative order has been selected to represent the admittance of the bar by the help of a non integer integrator which is approximated by a J+1 dimensional modal system. The machine parameters are estimated by an output-error technique using a non linear iterative optimization algorithm. Numerical simulations and experimental results show the performance of the modal approach for modeling and identification.
Sánchez, Luciano; Couso, Inés; Palacios, Ana M.; Palacios, José L.
2013-05-01
A methodology for obtaining fuzzy rule-based models from uncertain data is proposed. The granularity of the linguistic discretization is decided with the help of a new estimation of the mutual information between ill-known random variables, and a combination of boosting and genetic algorithms is used for discovering new rules. This methodology has been applied to predict whether the coating of an helicopter rotor blade is adequate, considering the shear adhesion strength of ice to different materials. The discovered knowledge is intended to increase the level of post-processing interpretation accuracy of experimental data obtained during the evaluation of ice-phobic materials for rotorcraft applications.
Research on Dynamic Model's Building of Active Magnetic Suspension Systems
SHI Jian; YAN Guo-zheng; LI Li-chuan; WANG Kun-dong
2006-01-01
An experimental method is introduced in this paper to build the dynamics of AMSS (the active magnetic suspension system), which doesn't depend on system's physical parameters. The rotor can be reliably suspended under the unit feedback control system designed with the primary dynamic model obtained. Online identification in frequency domain is processed to give the precise model. Comparisons show that the experimental method is much closer to the precise model than the theoretic method based on magnetic circuit law. So this experimental method is a good choice to build the primary dynamic model of AMSS.
无
2008-01-01
This paper proposes an adaptive rotor current controller for doubly-fed induction generator (DFIG), which consists of a proportional (P) controller and two harmonic resonant (R) controllers implemented in the rotor rotating reference frame. The two resonant controllers are tuned at slip frequencies ωslip+ and ωslip-, respectively. As a result, the positive- and negative-sequence components of the rotor current are fully regulated by the PR controller without involving the positive- and negative-sequence decomposition, which in effect improves the fault ride-through (FRT) capability of the DFIG-based wind power generation system during the period of large transient grid voltage unbalance. Correctness of the theoretical analysis and feasibility of the proposed unbalanced control scheme are validated by simulation on a 1.5-MW DFIG wind power generation system.
Active control for performance enhancement of electrically controlled rotor
Lu Yang; Wang Chao
2015-01-01
Electrically controlled rotor (ECR) system has the potential to enhance the rotor perfor-mance by applying higher harmonic flap inputs. In order to explore the feasibility and effectiveness for ECR performance enhancement using closed-loop control method, firstly, an ECR rotor perfor-mance analysis model based on helicopter flight dynamic model is established, which can reflect the performance characteristics of ECR helicopter at high advance ratio. Based on the simulation platform, an active control method named adaptive T-matrix algorithm is adopted to explore the feasibility and effectiveness for ECR performance enhancement. The simulation results verify the effectiveness of this closed-loop control method. For the sample ECR helicopter, about 3%rotor power reduction is obtained with the optimum 2/rev flap inputs at the advance ratio of 0.34. And through analyzing the distributions of attack of angle and drag in rotor disk, the underlying physical essence of ECR power reduction is cleared. Furthermore, the influence of the key control parameters, including convergence factor and weighting matrix, on the effectiveness of closed-loop control for ECR performance enhancement is explored. Some useful results are summarized, which can be used to direct the future active control law design of ECR performance enhancement.
Power harvesting using piezomaterial in a helicopter rotor blade
Jong, de P.H.; Boer, de A.; Loendersloot, R.; Hoogt, van der P.J.M.
2010-01-01
Current power harvesting research has focused on bending beams and determining power output under a given excitation. For the European CleanSky – Green Rotor Craft project a tool is being developed which optimizes the piezoelectric material and placement thereof for power harvesting. It focuses on b
A Study on Turbo-rotor Multi-fault Diagnosis Based on a Neural Network
SUN Shou-qun; ZHAO San-xing; ZHANG Wei; CHANG Xin-long
2003-01-01
The multi-fault phenomena are common in the turbo-rotor system of a liquid rocket engine. As it has many excellent qualities, the neural network might be used to solve the problems of multi-fault diagnosis of a turbo-rotor system. First, the feature expression of a common turbo-rotor fault was studied in order to build up the standard fault pattern and satisfy the need of neural network studying and diagnosing. Then, the turbo-rotor fault identification and diagnosis problems were investigated by using a BP(back-propagation) neural network. According to the BP neural network problems, the parallel BP neural network method of multi-fault diagnosis and classification was presented and investigated. The results indicated that the parallel BP neural network method could solve the turbo-rotor multi-fault diagnosis problems.
Quad-Rotor Helicopter Autonomous Navigation Based on Vanishing Point Algorithm
Jialiang Wang
2014-01-01
Full Text Available Quad-rotor helicopter is becoming popular increasingly as they can well implement many flight missions in more challenging environments, with lower risk of damaging itself and its surroundings. They are employed in many applications, from military operations to civilian tasks. Quad-rotor helicopter autonomous navigation based on the vanishing point fast estimation (VPFE algorithm using clustering principle is implemented in this paper. For images collected by the camera of quad-rotor helicopter, the system executes the process of preprocessing of image, deleting noise interference, edge extracting using Canny operator, and extracting straight lines by randomized hough transformation (RHT method. Then system obtains the position of vanishing point and regards it as destination point and finally controls the autonomous navigation of the quad-rotor helicopter by continuous modification according to the calculated navigation error. The experimental results show that the quad-rotor helicopter can implement the destination navigation well in the indoor environment.