Energy Technology Data Exchange (ETDEWEB)
Moroz, E. [Univ. of Texas at El Paso, Dept. of Mechanical and Industrial Engineering, El Paso, TX (United States)
1997-12-31
An experimental investigation into the acoustic noise from a small (7.6 m diameter) teetered rotor wind turbine, set at various yaw angles up to 90 degrees of yaw, was conducted. The results revealed a 1/3 octave spectra which was dominated by a broad peak in the higher frequency range, at all yaw angles investigated. This prompted a theoretical investigation to reveal the mechanisms producing the dominant feature in the experimentally obtained noise spectra and resulted in the development of a wind turbine aerodynamic noise prediction coce, WTNOISE. The location near busy roads and the relatively rough terrain of the wind test site caused difficulties in obtaining useful noise spectral information below 500Hz. However, sufficiently good data was obtained above 500Hz to clearly show a dominant `hump` in the spectrum, centered between 3000 and 4000Hz. Although the local Reynolds number for the blade elements was around 500,000 and one might expect Laminar flow over a significant portion of the blade, the data did not match the noise spectra predicted when Laminar flow was assumed. Given the relatively poor surface quality of the rotor blades and the high turbulence of the test site it was therefore assumed that the boundary layer on the blade may have tripped relatively early and that the turbulent flow setting should be used. This assumption led to a much better correlation between experiment and predictions. The WTNOISE code indicated that the broad peak in the spectrum was most likely caused by trailing edge bluntness noise. Unfortunately time did not allow for modifications to the trailing edge to be investigated. (au)
Analysis of a teetered, variable-speed rotor: final report
Energy Technology Data Exchange (ETDEWEB)
Weber, T L; Wilson, R E; Walker, S N [Oregon State Univ., Corvallis, OR (USA). Dept. of Mechanical Engineering
1991-06-01
A computer model of a horizontal axis wind turbine (HOOT) with four structural degrees of freedom has been derived and verified. The four degrees of freedom include flapwise motion of the blades, teeter motion, and variable rotor speed. Options for the variable rotor speed include synchronous, induction, and constant-tip speed generator models with either start, stop, or normal operations. Verification is made by comparison with analytical solutions and mean and cyclic ESI-80 data. The Veers full-field turbulence model is used as a wind input for a synchronous and induction generator test case during normal operation. As a result of the comparison, it is concluded that the computer model can be used to predict accurately mean and cyclic loads with a turbulent wind input. 47 refs., 19 figs.
Energy Technology Data Exchange (ETDEWEB)
Swift, A.H.P.; Moroz, E.M.; Craver, W.L. [Univ. of Texas, El Paso, TX (United States). Dept. of Mechanical and Industrial Engineering
1995-09-01
A large, positive {delta}{sub 3} angle offers some advantages over the usual zero {delta}{sub 3} teeter rotor;such as reduced flapping angles, reduced inplane excitations, and reduced teeter restraint impact loading. This paper discusses these advantages and presents results from theoretical analyses, computer simulations, and atmospheric test on the University of Texas at El Paso (UTEP) test-bed turbine. Results from these simulations and tests indicate stable and controlled teeter response at high yaw angles and yaw rates at wind speeds up to 30 m/s. Results of atmospheric tests also show reasonable correlation with the code TEETER, but some discrepancies with past and present versions of the code YAWDYN.
Energy Technology Data Exchange (ETDEWEB)
Swift, A.P.; Moroz, E.M.; Craver, W.L. [Texas Univ., El Paso, TX (United States)
1995-12-31
A large, positive {delta}{sub 3} offers some advantages over the usual zero {delta}{sub 3} teeter rotor; such as reduced flapping angles, reduced inplane excitations, and reduced teeter restraint impact loading. This paper discusses these advantages and presents results from theoretical analyses, computer simulations, and atmospheric tests on the University of Texas at El Paso (UTEP) test-bed turbine. Results from these simulations and test indicate stable and controlled teeter response at high yaw angles and yaw rates at wind speeds up to 30 m/s. Results of atmospheric tests also show reasonable correlation with the code TEETER, but some discrepancies with past and present versions of the code YAWDYN. (Author)
Energy Technology Data Exchange (ETDEWEB)
Shimizu, Yukimaru; Kamada, Yasunari; Maeda, Takao [Mie Univ. (Japan)
1997-12-31
For the purpose of the improvement of reliability of the Mega-Watt wind turbine, this paper indicates the development of an original mechanism for the passive-controlled hub, which has the effects of braking and damping on aerodynamic forces. This mechanism is useful for variable speed control of the large wind turbine. The passive-controlled hub is the combination of two mechanisms. One is the passive-teetered and damping mechanism, and the other is the passive-variable-pitch mechanism. These mechanism are carried out by the combination of the teetering and feathering motions. When the wind speed exceeds the rated wind speed, the blade is passively teetered in a downwind direction and, simultaneously, a feathering mechanism, which is linked to the teetering mechanism through a connecting rods, is activated. Testing of the model horizontal axis wind turbine in a wind tunnel showed that the passive-controlled hub mechanism can suppress the over-rotational speed of the rotor. By the application of the passive-controlled hub mechanism, the maximum rotor speed is reduced to about 60%.
User`s Guide for the NREL Teetering Rotor Analysis Program (STRAP)
Energy Technology Data Exchange (ETDEWEB)
Wright, A D
1992-08-01
The following report gives the reader an overview of instructions on the proper use of the National Renewable Energy Laboratory (formerly the Solar Energy Research Institute, or SERI) teetering Rotor Analysis Program (STRAP version 2.20). STRAP is a derivative of the Force and Loads Analysis program (FLAP). It is intended as a tool for prediction of rotor and blade loads and response for only two-bladed teetering hub wind turbines. The effects of delta-3, undersling, hub mass, and wind turbulence are accounted for. The objectives of the report are to give an overview of the code and also show the methods of data input and correct code execution steps in order to model an example two-bladed teetering hub turbine. A large portion of the discussion (Sections 6.0, 7.0, and 8.0) is devoted to the subject of inputting and running the code for wind turbulence effects. The ability to include turbulent wind effects is perhaps the biggest change in the code since the release of FLAP version 2.01 in 1988. This report is intended to be a user`s guide. It does not contain a theoretical discussion on equations of motion, assumptions, underlying theory, etc. It is intended to be used in conjunction with Wright, Buhl, and Thresher (1988).
Energy Technology Data Exchange (ETDEWEB)
Wright, A.D.
1992-08-01
The following report gives the reader an overview of instructions on the proper use of the National Renewable Energy Laboratory (formerly the Solar Energy Research Institute, or SERI) teetering Rotor Analysis Program (STRAP version 2.20). STRAP is a derivative of the Force and Loads Analysis program (FLAP). It is intended as a tool for prediction of rotor and blade loads and response for only two-bladed teetering hub wind turbines. The effects of delta-3, undersling, hub mass, and wind turbulence are accounted for. The objectives of the report are to give an overview of the code and also show the methods of data input and correct code execution steps in order to model an example two-bladed teetering hub turbine. A large portion of the discussion (Sections 6.0, 7.0, and 8.0) is devoted to the subject of inputting and running the code for wind turbulence effects. The ability to include turbulent wind effects is perhaps the biggest change in the code since the release of FLAP version 2.01 in 1988. This report is intended to be a user's guide. It does not contain a theoretical discussion on equations of motion, assumptions, underlying theory, etc. It is intended to be used in conjunction with Wright, Buhl, and Thresher (1988).
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.
Cyclic Control Optimization for a Smart Rotor
DEFF Research Database (Denmark)
Bergami, Leonardo; Henriksen, Lars Christian
2012-01-01
The paper presents a method to determine cyclic control trajectories for a smart rotor undergoing periodic-deterministic load variations. The control trajectories result from a constrained optimization problem, where the cost function to minimize is given by the variation of the blade root flapwise...... bending moment within a rotor revolution. The method is applied to a rotor equipped with trailing edge flaps, and capable of individual blade pitching. Results show that the optimized cyclic control significantly alleviates the load variations from periodic disturbances; the combination of both cyclic...
Investigation of rotor control system loads
Institute of Scientific and Technical Information of China (English)
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.
Electric Drive Control with Rotor Resistance and Rotor Speed Observers Based on Fuzzy Logic
Directory of Open Access Journals (Sweden)
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.
Active control for performance enhancement of electrically controlled rotor
Institute of Scientific and Technical Information of China (English)
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.
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
Control of rotor function in light-driven molecular motors
Lubbe, Anouk S.; Ruangsupapichat, Nopporn; Caroli, Giuseppe; Feringa, Ben L.
2011-01-01
A study is presented on the control of rotary motion of an appending rotor unit in a light-driven molecular motor. Two new light driven molecular motors were synthesized that contain aryl groups connected to the stereogenic centers. The aryl groups behave as bidirectional free rotors in three of the
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.
Directory of Open Access Journals (Sweden)
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.
Complete control, direct observation and study of molecular super rotors
Korobenko, Aleksey; Milner, Valery
2013-01-01
Extremely fast rotating molecules carrying significantly more energy in their rotation than in any other degree of freedom are known as "super rotors". It has been speculated that super rotors may exhibit a number of unique and intriguing properties. Theoretical studies showed that ultrafast molecular rotation may change the character of molecular scattering from solid surfaces, alter molecular trajectories in external fields, make super rotors surprisingly stable against collisions, and lead to the formation of gas vortices. New ways of molecular cooling and selective chemical bond breaking by ultrafast spinning have been proposed. Owing to the fundamental laws of nature, bringing a large number of molecules to fast, directional and synchronous rotation is rather challenging. As a result, only indirect evidence of super rotors has been reported to date. Here we demonstrate the first controlled creation, direct observation and study of molecular super rotors. Using intense laser pulses tailored to produce an ...
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.
Resonant vibration control of three-bladed wind turbine rotors
DEFF Research Database (Denmark)
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...
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.
Wind Turbine Rotors with Active Vibration Control
DEFF Research Database (Denmark)
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...
Institute of Scientific and Technical Information of China (English)
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.
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.
Active Flap Control of the SMART Rotor for Vibration Reduction
Hall, Steven R.; Anand, R. Vaidyanathan; Straub, Friedrich K.; Lau, Benton H.
2009-01-01
Active control methodologies were applied to a full-scale active flap rotor obtained during a joint Boeing/ DARPA/NASA/Army test in the Air Force National Full-Scale Aerodynamic Complex 40- by 80-foot anechoic wind tunnel. The active flap rotor is a full-scale MD 900 helicopter main rotor with each of its five blades modified to include an on-blade piezoelectric actuator-driven flap with a span of 18% of radius, 25% of chord, and located at 83% radius. Vibration control demonstrated the potential of active flaps for effective control of vibratory loads, especially normal force loads. Active control of normal force vibratory loads using active flaps and a continuous-time higher harmonic control algorithm was very effective, reducing harmonic (1-5P) normal force vibratory loads by 95% in both cruise and approach conditions. Control of vibratory roll and pitch moments was also demonstrated, although moment control was less effective than normal force control. Finally, active control was used to precisely control blade flap position for correlation with pretest predictions of rotor aeroacoustics. Flap displacements were commanded to follow specific harmonic profiles of 2 deg or more in amplitude, and the flap deflection errors obtained were less than 0.2 deg r.m.s.
Thermoelastic steam turbine rotor control based on neural network
Rzadkowski, Romuald; Dominiczak, Krzysztof; Radulski, Wojciech; Szczepanik, R.
2015-12-01
Considered here are Nonlinear Auto-Regressive neural networks with eXogenous inputs (NARX) as a mathematical model of a steam turbine rotor for controlling steam turbine stress on-line. In order to obtain neural networks that locate critical stress and temperature points in the steam turbine during transient states, an FE rotor model was built. This model was used to train the neural networks on the basis of steam turbine transient operating data. The training included nonlinearity related to steam turbine expansion, heat exchange and rotor material properties during transients. Simultaneous neural networks are algorithms which can be implemented on PLC controllers. This allows for the application neural networks to control steam turbine stress in industrial power plants.
Smart helicopter rotors optimization and piezoelectric vibration control
Ganguli, Ranjan; Viswamurthy, Sathyamangalam Ramanarayanan
2016-01-01
Exploiting the properties of piezoelectric materials to minimize vibration in rotor-blade actuators, this book demonstrates the potential of smart helicopter rotors to achieve the smoothness of ride associated with jet-engined, fixed-wing aircraft. Vibration control is effected using the concepts of trailing-edge flaps and active-twist. The authors’ optimization-based approach shows the advantage of multiple trailing-edge flaps and algorithms for full-authority control of dual trailing-edge-flap actuators are presented. Hysteresis nonlinearity in piezoelectric stack actuators is highlighted and compensated by use of another algorithm. The idea of response surfaces provides for optimal placement of trailing-edge flaps. The concept of active twist involves the employment of piezoelectrically induced shear actuation in rotating beams. Shear is then demonstrated for a thin-walled aerofoil-section rotor blade under feedback-control vibration minimization. Active twist is shown to be significant in reducing vibra...
General model and control of an n rotor helicopter
DEFF Research Database (Denmark)
Sidea, Adriana-Gabriela; Brogaard, Rune Yding; Andersen, Nils Axel
2015-01-01
The purpose of this study was to create a dynamic, nonlinear mathematical model ofa multirotor that would be valid for different numbers of rotors. Furthermore, a set of SingleInput Single Output (SISO) controllers were implemented for attitude control. Both model andcontrollers were tested exper...
General model and control of an n rotor helicopter
Sidea, A. G.; Yding Brogaard, R.; Andersen, N. A.; Ravn, O.
2014-12-01
The purpose of this study was to create a dynamic, nonlinear mathematical model of a multirotor that would be valid for different numbers of rotors. Furthermore, a set of Single Input Single Output (SISO) controllers were implemented for attitude control. Both model and controllers were tested experimentally on a quadcopter. Using the combined model and controllers, simple system simulation and control is possible, by replacing the physical values for the individual systems.
A study of EV induction motor controller based on rotor flux oriented control
Institute of Scientific and Technical Information of China (English)
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.
Field oriented control design of inset rotor PMSM drive
Mukti, Ersalina Werda; Wijanarko, Sulistyo; Muqorobin, Anwar; Rozaqi, Latif
2017-06-01
The main challenge of PMSM implementation in the adjustable-speed drives especially in automotive industry is to attain the optimal PMSM drive performance. Vector control is proved to be the best method in controlling synchronous machine such as PMSM. This paper objective is to design a speed control system for the manufactured inset rotor PMSM, which integrates the interleaved DC-DC boost converter, inverter, and sinusoidal pulse width modulation and fed by the battery bank DC source. The proposed speed control in this paper employs FOC vector control technique with PI controller which control both converter and inverter independently. This paper investigates the effectiveness of the proposed speed control method for driving the manufactured inset rotor PMSM. To verify the effectiveness of the designed speed control system, computer simulation is conducted. The motor performances are observed in operating condition with disturbance in form of sudden change of load torque. The simulation results show that the control method is stable but the rotor speed still affected by the given disturbance.
General model and control of an n rotor helicopter
2015-01-01
The purpose of this study was to create a dynamic, nonlinear mathematical model ofa multirotor that would be valid for different numbers of rotors. Furthermore, a set of SingleInput Single Output (SISO) controllers were implemented for attitude control. Both model andcontrollers were tested experimentally on a quadcopter. Using the combined model andcontrollers, simple system simulation and control is possible, by replacing the physical valuesfor the individual systems.
Rotor-Flying Manipulator: Modeling, Analysis, and Control
Directory of Open Access Journals (Sweden)
Bin Yang
2014-01-01
Full Text Available Equipping multijoint manipulators on a mobile robot is a typical redesign scheme to make the latter be able to actively influence the surroundings and has been extensively used for many ground robots, underwater robots, and space robotic systems. However, the rotor-flying robot (RFR is difficult to be made such redesign. This is mainly because the motion of the manipulator will bring heavy coupling between itself and the RFR system, which makes the system model highly complicated and the controller design difficult. Thus, in this paper, the modeling, analysis, and control of the combined system, called rotor-flying multijoint manipulator (RF-MJM, are conducted. Firstly, the detailed dynamics model is constructed and analyzed. Subsequently, a full-state feedback linear quadratic regulator (LQR controller is designed through obtaining linearized model near steady state. Finally, simulations are conducted and the results are analyzed to show the basic control performance.
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.
Fuzzy adaptive PID control for six rotor eppo UAV
Directory of Open Access Journals (Sweden)
Yongwei LI
2017-02-01
Full Text Available Six rotor eppo drones's load change itself in the job process will reduce the aircraft flight control performance and make the resistance to environmental disturbance being poor. In order to improve the six rotor eppo unmanned aerial vehicle (UAV control performance, the UAV in the process of spraying pesticide is analyzed and the model is constructed, then the eppo UAV time-varying dynamics mathematical model is deduced, and a fuzzy adaptive PID control algorithm is proposed. Fuzzy adaptive PID algorithm has good adaptability and the parameter setting is simple, which improves the system dynamic response and steady state performance, realizing the stability of the six rotor eppo UAV flight. With measured parameters of each sensor input in to the fuzzy adaptive PID algorithm, the corresponding control quality is obtained, and the stable operation of aircraft is realized. Through using Matlab to simulate the flight system and combining the practical experiments, it shows that the dynamic performance and stability of the system is improved effetively.
Control Law Design for Twin Rotor MIMO System with Nonlinear Control Strategy
Directory of Open Access Journals (Sweden)
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.
Active Flow Control on Bidirectional Rotors for Tidal MHK Applications
Energy Technology Data Exchange (ETDEWEB)
Shiu, Henry [Research Engineer; van Dam, Cornelis P. [Professor
2013-08-22
A marine and hydrokinetic (MHK) tidal turbine extracts energy from tidal currents, providing clean, sustainable electricity generation. In general, all MHK conversion technologies are confronted with significant operational hurdles, resulting in both increased capital and operations and maintenance (O&M) costs. To counter these high costs while maintaining reliability, MHK turbine designs can be simplified. Prior study found that a tidal turbine could be cost-effectively simplified by removing blade pitch and rotor/nacelle yaw. Its rotor would run in one direction during ebb and then reverse direction when the current switched to flood. We dubbed such a turbine a bidirectional rotor tidal turbine (BRTT). The bidirectional hydrofoils of a BRTT are less efficient than conventional hydrofoils and capture less energy, but the elimination of the pitch and yaw systems were estimated to reduce levelized cost of energy by 7.8%-9.6%. In this study, we investigated two mechanisms for recapturing some of the performance shortfall of the BRTT. First, we developed a novel set of hydrofoils, designated the yy series, for BRTT application. Second, we investigated the use of active flow control via microtabs. Microtabs are small deployable/retractable tabs, typically located near the leading or trailing edge of an air/hydrofoil with height on the order of the boundary layer thickness (1% - 2% of chord). They deploy approximately perpendicularly to the foil surface and, like gurney flaps and plain flaps, globally affect the aerodynamics of the airfoil. By strategically placing microtabs and selectively deploying them based on the direction of the inflow, performance of a BRTT rotor can be improved while retaining bidirectional operation. The yy foils were computationally designed and analyzed. They exhibited better performance than the baseline bidirectional foil, the ellipse. For example, the yyb07cn-180 had 14.7% higher (l/d)max than an ellipse of equal thickness. The yyb07cn
Improved Rotor Speed Brushless DC Motor using Fuzzy Controller
Directory of Open Access Journals (Sweden)
Jafar Mostafapour
2016-03-01
Full Text Available A brushless DC (BLDC Motors have advantages over brushed, direct current (DC motors and Induction motor (IM. They have better speed verses torque characteristics, high dynamic response, high efficiency, long operating life, noiseless operation, higher speed ranges, and rugged construction. Also, torque delivered to motor size is higher, making it useful in application where space and weight are critical factors. With these advantages BLDC motors find wide spread application in automotive appliance, aerospace medical, and instrumentation and automation industries This paper can be seen as fuzzy controllers compared to PI control BLDC motor rotor speed has improved significantly and better result can be achieve.
Improved Rotor Speed Brushless DC Motor Using Fuzzy Controller
Directory of Open Access Journals (Sweden)
Jafar Mostafapour
2015-04-01
Full Text Available A brushless DC (BLDC Motors have advantages over brushed, Direct current (DC Motors and , Induction motor (IM. They have better speed verses torque characteristics, high dynamic response, high efficiency, long operating life, noiseless operation, higher speed ranges, and rugged construction. Also, torque delivered to motor size is higher, making it useful in application where space and weight are critical factors. With these advantages BLDC motors find wide spread application in automotive appliance, aerospace medical, and instrumentation and automation industries This paper can be seen as fuzzy controllers compared to PI control BLDC motor rotor speed has improved significantly and beter result can be achieve.
Rezension zu: Emily Teeter (Hg.), Before the pyramids. The origins of Egyptian civilization
Köpp-Junk, Heidi
2013-01-01
Rezension zu: Emily Teeter (Hg.), Before the Pyramids. The Origins of Egyptian Civilization. The Oriental Institute of the University of Chicago, Oriental Institute Museum Publications 33 (Chicago 2011)
Extended State Observer based control for coaxial-rotor UAV.
Rida Mokhtari, M; Choukchou Braham, Amal; Cherki, Brahim
2016-03-01
This paper considers the problem of controlling the position and the orientation of a Coaxial-Rotor Unmanned Aerial Vehicle -CRUAV- despite unknown aerodynamic efforts. A hierarchical flight controller is designed, allowing the trajectory tracking and the stabilization of the vehicle. The designed controller is build through a hierarchical approach yielding two control loops, an inner one to control the attitude and an outer one to control the translational trajectory of the rotorcraft. An Extended State Observer -ESO- is used to estimate the state and the unknown aerodynamic disturbances. The analysis further extends to the design of a control law that takes the disturbance estimation procedure into account. Numerical simulations are carried out to demonstrate the efficiency of the proposed control strategy.
A control strategy for stand-alone wound rotor induction machine
Energy Technology Data Exchange (ETDEWEB)
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)
Disturbance observer based hierarchical control of coaxial-rotor UAV.
Mokhtari, M Rida; Cherki, Brahim; Braham, Amal Choukchou
2017-03-01
This paper propose an hierarchical controller based on a new disturbance observer with finite time convergence (FTDO) to solve the path tracking of a small coaxial-rotor-typs Unmanned Aerial Vehicles (UAVs) despite of unknown aerodynamic efforts. The hierarchical control technique is used to separate the flight control problem into an inner loop that controls attitude and an outer loop that controls the thrust force acting on the vehicle. The new disturbance observer with finite time convergence is intergated to online estimate the unknown uncertainties and disturbances and to actively compensate them in finite time.The analysis further extends to the design of a control law that takes the disturbance estimation procedure into account. Numerical simulations are carried out to demonstrate the efficiency of the proposed control strategy.
Impulsive Control of the Rotor-Stator Rub Based on Phase Characteristic
Directory of Open Access Journals (Sweden)
Jieqiong Xu
2014-01-01
Full Text Available An impulsive control method is proposed to eliminate the rotor-stator rubbing based on the phase characteristic. The relation between the vibration energy and the phase difference suggests the starting point for controlling the rotor-stator rubbing by implementing impulse. When the contact between the rotor and the stator occurs, the impulse is implemented in x-direction and y-direction several times to avoid the rotor-stator rubbing. The practical feasibility of this approach is investigated by numerical simulations.
Control of Rotor-Blade Coupled Vibrations Using Shaft-Based Actuation
DEFF Research Database (Denmark)
Christensen, Rene H.; Santos, Ilmar
2006-01-01
When implementing active control into bladed rotating machines aiming at reducing blade vibrations, it can be shown that blade as well as rotor vibrations can in fact be controlled by the use of only shaft-based actuation. Thus the blades have to be deliberately mistuned. This paper investigates...... of modal controllability and observability converge toward steady levels as the degree of mistuning is increased. Finally, experimental control results are presented to prove the theoretical conclusions and to show the feasibility of controlling rotor and blade vibrations by means of shaft-based actuation...... the dynamical characteristics of a mistuned bladed rotor and shows how, why and when a bladed rotor becomes controllable and observable if properly mistuned. As part of such investigation modal controllability and observability of a tuned as well as a mistuned coupled rotor-blade system are analysed...
Initial design of a stall-controlled wind turbine rotor
Energy Technology Data Exchange (ETDEWEB)
Nygaard, T.A. [Inst. for Energiteknikk, Kjeller (Norway)
1997-08-01
A model intended for initial design of stall-controlled wind turbine rotors is described. The user specifies relative radial position of an arbitrary number of airfoil sections, referring to a data file containing lift-and drag curves. The data file is on the same format as used in the commercial blade-element code BLADES-/2/, where lift- and drag coefficients are interpolated from tables as function of Reynolds number, relative thickness and angle of attack. The user can set constraints on a selection of the following: Maximum power; Maximum thrust in operation; Maximum root bending moment in operation; Extreme root bending moment, parked rotor; Tip speed; Upper and lower bounds on optimisation variables. The optimisation variables can be selected from: Blade radius; Rotational speed; Chord and twist at an arbitrary number of radial positions. The user can chose linear chord distribution and a hyperbola-like twist distribution to ensure smooth planform and twist, or cubic spline interpolation for one or both. The aerodynamic model is based on classical strip theory with Prandtl tip loss correction, supplemented by empirical data for high induction factors. (EG)
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
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
Energy Technology Data Exchange (ETDEWEB)
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.
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.
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.
Alexander, B. X. S.
Flywheel energy storage has distinct advantages over conventional energy storage methods such as electrochemical batteries. Because the energy density of a flywheel rotor increases quadratically with its speed, the foremost goal in flywheel design is to achieve sustainable high speeds of the rotor. Many issues exist with the flywheel rotor operation at high and varying speeds. A prominent problem is synchronous rotor vibration, which can drastically limit the sustainable rotor speed. In a set of projects, the novel Active Disturbance Rejection Control (ADRC) is applied to various problems of flywheel rotor operation. These applications include rotor levitation, steady state rotation at high speeds and accelerating operation. Several models such as the lumped mass model and distributed three-mass models have been analyzed. In each of these applications, the ADRC has been extended to cope with disturbance, noise, and control effort optimization; it also has been compared to various industry-standard controllers such as PID and PD/observer, and is proven to be superior. The control performance of the PID controller and the PD/observer currently used at NASA Glenn has been improved by as much as an order of magnitude. Due to the universality of the second order system, the results obtained in the rotor vibration problem can be straightforwardly extended to other vibrational systems, particularly, the MEMS gyroscope. Potential uses of a new nonlinear controller, which inherits the ease of use of the traditional PID, are also discussed.
Identification and Reconfigurable Control of Impaired Multi-Rotor Drones
Stepanyan, Vahram; Krishnakumar, Kalmanje; Bencomo, Alfredo
2016-01-01
The paper presents an algorithm for control and safe landing of impaired multi-rotor drones when one or more motors fail simultaneously or in any sequence. It includes three main components: an identification block, a reconfigurable control block, and a decisions making block. The identification block monitors each motor load characteristics and the current drawn, based on which the failures are detected. The control block generates the required total thrust and three axis torques for the altitude, horizontal position and/or orientation control of the drone based on the time scale separation and nonlinear dynamic inversion. The horizontal displacement is controlled by modulating the roll and pitch angles. The decision making algorithm maps the total thrust and three torques into the individual motor thrusts based on the information provided by the identification block. The drone continues the mission execution as long as the number of functioning motors provide controllability of it. Otherwise, the controller is switched to the safe mode, which gives up the yaw control, commands a safe landing spot and descent rate while maintaining the horizontal attitude.
Rotor experiments in controlled conditions continued: New Mexico
Boorsma, K.; Schepers, J. G.
2016-09-01
To validate and reduce the large uncertainty associated with rotor aerodynamic and acoustic models, there is a need for detailed force, noise and surrounding flow velocity measurements on wind turbines under controlled conditions. However, high quality wind tunnel campaigns on horizontal axis wind turbine models are scarce due to the large wind tunnel size needed and consequently high associated costs. To serve this purpose an experiment using the Mexico turbine was set-up in the large low speed facility of the DNW wind tunnel. An overview of the experiments is given including a selection of results. A comparison of calculations to measurements for design conditions shows a satisfactory agreement. In summary, after years of preparation, ECN and partners have performed very successful aerodynamic experiments in the largest wind tunnel in Europe. The comprehensive high quality database that has been obtained will be used in the international Mexnext consortium to further develop wind energy aerodynamic and acoustic modeling.
Control of rotor motion in a light-driven molecular motor : Towards a molecular gearbox
Wiel, Matthijs K.J. ter; Delden, Richard A. van; Meetsma, Auke; Feringa, Bernard
2005-01-01
Controlled intramolecular movement and coupling of motor and rotor functions is exerted by this new molecular device. The rate of rotation of the rotor part of the molecule can be adjusted by alteration of the conformation of the motor part of the molecule. For all states of the motor part, differen
A soft rotor concept - design, verification and potentials
Energy Technology Data Exchange (ETDEWEB)
Rasmussen, F.; Thirstrup Petersen, J. [Risoe National Lab., Roskilde (Denmark)
1999-03-01
This paper contains results from development and testing of a two-bladed soft rotor for an existing 15 kW flexible wind turbine. The new concept is characterised as a free yawing down wind turbine with nacelle tilting flexibility and a two-bladed teetering rotor with three-point supported flexible blades with built-in structural couplings. The power and the loads are controlled by active stall and active coning. The concept has been developed by extensive application of aero-elastic predictions, numerical optimisation and stability analysis in order to obtain optimal aero-elastic response and minimal loads. The flexible blades and the principle of active coning allow the blades to deflect with the wind to such an extent that the loads are reduced to between 25 and 50% of the loads for a similar rigid rotor. All conceptual design principles have been focused on application to large MW turbines, and aero-elastic predictions for an upscale 1 MW version show that this would have approximately identical characteristisc, without being particularly optimised for the actual size. (au)
Contributions to the dynamics of helicopters with active rotor controls
Malpica, Carlos A.
This dissertation presents an aeromechanical closed loop stability and response analysis of a hingeless rotor helicopter with a Higher Harmonic Control (HHC) system for vibration reduction. The analysis includes the rigid body dynamics of the helicopter and blade flexibility. The gain matrix is assumed to be fixed and computed off-line. The discrete elements of the HHC control loop are rigorously modeled, including the presence of two different time scales in the loop. By also formulating the coupled rotor-fuselage dynamics in discrete form, the entire coupled helicopter-HHC system could be rigorously modeled as a discrete system. The effect of the periodicity of the equations of motion is rigorously taken into account by converting the system into an equivalent system with constant coefficients and identical stability properties using a time lifting technique. The most important conclusion of the present study is that the discrete elements in the HHC loop must be modeled in any HHC analysis. Not doing so is unconservative. For the helicopter configuration and HHC structure used in this study, an approximate continuous modeling of the HHC system indicates that the closed loop, coupled helicopter-HHC system remains stable for optimal feedback control configurations which the more rigorous discrete analysis shows can result in closed loop instabilities. The HHC gains must be reduced to account for the loss of gain margin brought about by the discrete elements. Other conclusions of the study are: (i) the HHC is effective in quickly reducing vibrations, at least at its design condition, although the time constants associated with the closed loop transient response indicate closed loop bandwidth to be 1 rad/sec on average, thus overlapping with FCS or pilot bandwidths, and raising the issue of potential interactions; (ii) a linearized model of helicopter dynamics is adequate for HHC design, as long as the periodicity of the system is correctly taken into account, i
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.
Active control of gust- and interference-induced vibration of tilt-rotor aircraft
Ham, Norman D.; Wereley, Norman M.; Von Ellenrieder, Karl D.
1989-01-01
An active control system to suppress the response of the blade bending modes of a tilt-rotor aircraft to axial gusts and wing/rotor interference is described. The use of blade-mounted accelerometers as sensors is shown to permit the measurement and control of tilt-rotor blade modal responses and their associated vibratory loads directly. The feedback of modal acceleration, in addition to modal rate and displacement, is demonstrated to provide a control phase lead, in comparison with feedback of modal rate and displacement only, which makes higher system gains achievable.
Directory of Open Access Journals (Sweden)
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.
Development of Motor Model of Rotor Slot Harmonics for Speed Sensorless Control of Induction Motor
Okubo, Tatsuya; Ishida, Muneaki; Doki, Shinji
This paper proposes a novel mathematical dynamic model to represent steady-state and transient-state characteristics of rotor slot harmonics of an induction motor for sensorless control. Although it is well known that the rotor slot harmonics originate from the mechanical structure of the induction motor, a mathematical model that describes the relationship between stator/rotor currents of the induction motor and the slot harmonics has not yet been proposed. Therefore, in this paper, a three-phase model of the induction motor that depicts the rotor slot harmonics is developed by taking into consideration the magnetomotive force harmonics and the change in the magnetic air gap caused by the rotor slots. Moreover, the validity of the proposed model is verified by comparing the experimental results and the calculated values.
Rotor Speed Estimation Method Used in Dynamic Control of the Induction Motor
Directory of Open Access Journals (Sweden)
CRĂCIUNAŞ Gabriela
2013-10-01
Full Text Available In this paper it is proposed an algorithm for rotor speed estimation calculated directly from the rotor flux. The flux required for speed computation is estimated using Gopinath reduced order robust adaptive observer. In order to determine the structure of the observer we started from the state equations of the induction motor using spatial vectors written in fixed coordinates towards stator and considering the rotor speed constant. Quality of speed and rotor fluxestimation was evaluated from the results obtained during different operation regimes. The proposed algorithm was then tested for its usability in the case of indirect field oriented control based on the rotor flux of the induction motor by the simulation inMATLAB/Simulink.
Design, analysis, optimization and control of rotor tip flows
Maesschalck, Cis Guy M. De
Developments in turbomachinery focus on efficiency and reliability enhancements, while reducing the production costs. In spite of the many noteworthy experimental and numerical investigations over the past decades, the turbine tip design presents numerous challenges to the engine manufacturers, and remains the primary factor defining the machine durability for the periodic removal of the turbine components during overhaul. Due to the hot gases coming from the upstream combustion chamber, the turbine blades are subjected to temperatures far above the metal creep temperature, combined with severe thermal stresses induced within the blade material. Inadequate designs cause early tip burnouts leading to considerable performance degradations, or even a catastrophic turbine failure. Moreover, the leakage spillage, nowadays often exceeding the transonic regime, generates large aerodynamic penalties which are responsible for about one third of the turbine losses. In this view, the current doctoral research exploits the potential through the modification and optimization of the blade tip shape as a means to control the tip leakage flow aerodynamics and manage the heat load distribution over the blade profile to improve the turbine efficiency and durability. Three main design strategies for unshrouded turbine blade tips were analyzed and optimized: tight running clearances, blade tip contouring and the use of complex squealer-like geometries. The altered overtip flow physics and heat transfer characteristics were simulated for tight gap sizes as low as 0.5% down to 0.1% of the blade height, occurring during engine transients and soon to be expected due to recent developments in active clearance control strategies. The potential of fully 3D contoured blade top surfaces, allowing to adapt the profile locally to the changing flow conditions throughout the camberline, is quantified. First adopting a quasi-3D approach and subsequently using a full 3D optimization. For the
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.
Dynamic modeling and nonlinear control strategy for an underactuated quad rotor rotorcraft
Institute of Scientific and Technical Information of China (English)
Ashfaq Ahmad MIAN; Dao-bo WANG
2008-01-01
In this paper, a nonlinear dynamic MIMO model of a 6-DOF underactuated quad rotor rotorcraft is derived based on Newton-Euler formalism. The derivation comprises determining equations of motion of the quad rotor in three dimensions and seeking to approximate the actuation forces through modeling of the aerodynamic coefficients and electric motor dynamics. The derived model is dynamically unstable, so a sequential nonlinear control strategy is implemented for the quad rotor. The control strategy includes exact feedback linearization technique, using the geometric methods of nonlinear control. The performance of the nonlinear control algorithm is evaluated using simulation and the results show the effectiveness of the proposed control strategy for the quad rotor rotorcraft near quasi-stationary flight.
Flow Modification over Rotor Blade with Suction Boundary Layer Control Technique
Directory of Open Access Journals (Sweden)
Navneet Kumar
2016-06-01
Full Text Available The efficiency of transonic aircraft engines depend upon the performance of compressor rotor. To increase compressor rotors performance flow separation around rotor blades must be delayed and controlled. The aim was to control the flow separation of blades using suction boundary layer control method. Rotor blade has been modelled in designing software CATIA and then a suction surface has been created on blade and then import these geometries to ANSYS-CFX 14.5 for computational analysis of flow around blades. Suction slot has been applied at the trailing edge of suction surface and Shear stress transport model has been used for computational analysis. Two different suction mass flow rates 1 kg/s and 1.5 kg/s have been used here and boundary layer separation effects have been changed and this could be readily seen that the velocity vectors have reattached, preventing the boundary layer separation at the suction surface of the blade.
Bielawa, R. L.
1982-01-01
Mathematical development is presented for the expanded capabilities of the United Technologies Research Center (UTRC) G400 Rotor Aeroelastic Analysis. This expanded analysis, G400PA, simulates the dynamics of teetered rotors, blade pendulum vibration absorbers and the higher harmonic excitations resulting from prescribed vibratory hub motions and higher harmonic blade pitch control. Formulations are also presented for calculating the rotor impedance matrix appropriate to these higher harmonic blade excitations. This impedance matrix and the associated vibratory hub loads are intended as the rotor blade characteristics elements for use in the Simplified Coupled Rotor/Fuselage Vibration Analysis (SIMVIB). Sections are included presenting updates to the development of the original G400 theory, and material appropriate to the user of the G400PA computer program. This material includes: (1) a general descriptionof the tructuring of the G400PA FORTRAN coding, (2) a detaild description of the required input data and other useful information for successfully running the program, and (3) a detailed description of the output results.
Emotional Learning Based Intelligent Controllers for Rotor Flux Oriented Control of Induction Motor
Abdollahi, Rohollah; Farhangi, Reza; Yarahmadi, Ali
2014-08-01
This paper presents design and evaluation of a novel approach based on emotional learning to improve the speed control system of rotor flux oriented control of induction motor. The controller includes a neuro-fuzzy system with speed error and its derivative as inputs. A fuzzy critic evaluates the present situation, and provides the emotional signal (stress). The controller modifies its characteristics so that the critics stress is reduced. The comparative simulation results show that the proposed controller is more robust and hence found to be a suitable replacement of the conventional PI controller for the high performance industrial drive applications.
Directory of Open Access Journals (Sweden)
Robert Porter
2016-11-01
Full Text Available This paper presents the development and implementation of a single tilting rotor multirotor helicopter. A single tilting rotor multirotor helicopter is proposed that allows for decoupled lateral acceleration and attitude states. A dynamics model of the proposed multirotor helicopter is established to enable control system development. A control system architecture and daisy chaining-based control allocation scheme is developed and implemented. The control architecture facilitates the control of decoupled lateral accelerations and attitudes. Further, a computational and experimental analysis is undertaken and offers evidence that the proposed multirotor helicopter and control system architecture enables the multirotor helicopter to achieve lateral accelerations without requiring attitude actuation.
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
Investigation of the effect of controllable dampers on limit states of rotor systems
Directory of Open Access Journals (Sweden)
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.
Parametric analyses for synthetic jet control on separation and stall over rotor airfoil
Institute of Scientific and Technical Information of China (English)
Zhao Guoqing; Zhao Qijun
2014-01-01
Numerical simulations are performed to investigate the effects of synthetic jet control on separation and stall over rotor airfoils. The preconditioned and unsteady Reynolds-averaged Navier-Stokes equations coupled with akxshear stream transport turbulence model are employed to accomplish the flowfield simulation of rotor airfoils under jet control. Additionally, a velocity boundary condition modeled by a sinusoidal function is developed to fulfill the perturba-tion effect of periodic jets. The validity of the present CFD procedure is evaluated by the simulated results of an isolated synthetic jet and the jet control case for airfoil NACA0015. Then, parametric analyses are conducted specifically for an OA213 rotor airfoil to investigate the effects of jet param-eters (forcing frequency, jet location and momentum coefficient, jet direction, and distribution of jet arrays) on the control effect of the aerodynamic characteristics of a rotor airfoil. Preliminary results indicate that the efficiency of jet control can be improved with specific frequencies (the best lift-drag ratio at F+=2.0) and jet angles (40? or 75?) when the jets are located near the separation point of the rotor airfoil. Furthermore, as a result of a suitable combination of jet arrays, the lift coefficient of the airfoil can be improved by nearly 100%, and the corresponding drag coefficient decreased by 26.5%in comparison with the single point control case.
Numerical and Experimental Modal Control of Flexible Rotor Using Electromagnetic Actuator
Directory of Open Access Journals (Sweden)
Edson Hideki Koroishi
2014-01-01
Full Text Available The present work is dedicated to active modal control applied to flexible rotors. The effectiveness of the corresponding techniques for controlling a flexible rotor is tested numerically and experimentally. Two different approaches are used to determine the appropriate controllers. The first uses the linear quadratic regulator and the second approach is the fuzzy modal control. This paper is focused on the electromagnetic actuator, which in this case is part of a hybrid bearing. Due to numerical reasons it was necessary to reduce the size of the model of the rotating system so that the design of the controllers and estimator could be performed. The role of the Kalman estimator in the present contribution is to estimate the modal states of the system and to determine the displacement of the rotor at the position of the hybrid bearing. Finally, numerical and experimental results demonstrate the success of the methodology conveyed.
Modeling and Robust Trajectory Tracking Control for a Novel Six-Rotor Unmanned Aerial Vehicle
Directory of Open Access Journals (Sweden)
Chengshun Yang
2013-01-01
Full Text Available Modeling and trajectory tracking control of a novel six-rotor unmanned aerial vehicle (UAV is concerned to solve problems such as smaller payload capacity and lack of both hardware redundancy and anticrosswind capability for quad-rotor. The mathematical modeling for the six-rotor UAV is developed on the basis of the Newton-Euler formalism, and a second-order sliding-mode disturbance observer (SOSMDO is proposed to reconstruct the disturbances of the rotational dynamics. In consideration of the under-actuated and strong coupling properties of the six-rotor UAV, a nested double loops trajectory tracking control strategy is adopted. In the outer loop, a position error PID controller is designed, of which the task is to compare the desired trajectory with real position of the six-rotor UAV and export the desired attitude angles to the inner loop. In the inner loop, a rapid-convergent nonlinear differentiator (RCND is proposed to calculate the derivatives of the virtual control signal, instead of using the analytical differentiation, to avoid “differential expansion” in the procedure of the attitude controller design. Finally, the validity and effectiveness of the proposed technique are demonstrated by the simulation results.
The Hybrid RFNN Control for a PMSM Drive Electric Scooter Using Rotor Flux Estimator
Directory of Open Access Journals (Sweden)
Chih-Hong Lin
2012-01-01
Full Text Available The hybrid recurrent fuzzy neural network (HRFNN control for permanent magnet synchronous motor (PMSM drive system using rotor flux estimator is developed to control electric scooter in this paper. First, the dynamic models of a PMSM drive system were derived in according to electric scooter. Owing to the load of electric scooter exited many uncertainties, for example, nonlinear friction force of the transmission belt, and so forth. The electric scooter with nonlinear uncertainties made the PI controller to disable speed tracking control. Moreover, in order to reduce interference of encoder and cost down, an HRFNN control system using rotor flux estimator was developed to control PMSM drive system in order to drive electric scooter. The rotor flux estimator consists of the estimation algorithm of rotor flux position and speed based on the back electromagnetic force (EMF in order to supply with HRFNN controller. The HRFNN controller consists of the supervisor control, RFNN, and compensated control with adaptive law is applied to PMSM drive system. The parameters of RFNN are trained according to different speeds in electric scooter. The electric scooter is operated to provide disturbance torque. To show the effectiveness of the proposed controller, comparative studies with PI controller are demonstrated by experimental results.
DEFF Research Database (Denmark)
Theisen, Lukas Roy Svane; Galeazzi, Roberto; Niemann, Hans Henrik
2015-01-01
Rotor-gas bearings are attracting increasing interest because of their high speed capabilities, low friction and clean operation. However, hydrostatic rotor-gas bearings show reduced damping characteristics, which makes it challenging to operate the rotating machine at and about the resonance...... directions. Hardening and softening P-lead controllers are designed based on the models experimentally identified, and salient features of both controllers are discussed. Both controllers are implemented and validated on the physical test rig. Experimental results confirm the validity of the proposed...
Control system design for flexible rotors supported by actively lubricated bearings
DEFF Research Database (Denmark)
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...
An active optimal control strategy of rotor vibrations using external forces
Zhu, W.; Castelazo, I.; Nelson, H. D.
1989-01-01
An active control strategy for lateral rotor vibrations using external forces is proposed. An extended state observer is used to reconstruct the full states and the unbalance distribution. An optimal controller which accommodates persistent unbalance excitation is derived with feedback of estimated states and unbalances. Numerical simulations were conducted for two separate four degree of freedom rotor systems. These simulations indicated that the proposed strategy can achieve almost complete vibration cancellation. This was shown to be true even when the number of external control forces was less than the system order so long as coordinate coupling was present. Both steady state and transient response at a constant speed are presented.
Control and flight test of a tilt-rotor unmanned aerial vehicle
Directory of Open Access Journals (Sweden)
Chao Chen
2017-01-01
Full Text Available Tilt-rotor unmanned aerial vehicles have attracted increasing attention due to their ability to perform vertical take-off and landing and their high-speed cruising abilities, thereby presenting broad application prospects. Considering portability and applications in tasks characterized by constrained or small scope areas, this article presents a compact tricopter configuration tilt-rotor unmanned aerial vehicle with full modes of flight from the rotor mode to the fixed-wing mode and vice versa. The unique multiple modes make the tilt-rotor unmanned aerial vehicle a multi-input multi-output, non-affine, multi-channel cross coupling, and nonlinear system. Considering these characteristics, a control allocation method is designed to make the controller adaptive to the full modes of flight. To reduce the cost, the accurate dynamic model of the tilt-rotor unmanned aerial vehicle is not obtained, so a full-mode flight strategy is designed in view of this situation. An autonomous flight test was conducted, and the results indicate the satisfactory performance of the control allocation method and flight strategy.
Effect of control activity on blade fatigue damage rate for a small horizontal axis wind turbine
Energy Technology Data Exchange (ETDEWEB)
Riddle, A.F.; Freris, L.L.; Graham, J.M.R. [Imperial College, London (United Kingdom)
1996-09-01
An experiment into the effect of control activity on blade fatigue damage rate for a 5 kW, two bladed, teetered HAWT has been performed. It has been shown that control activity influences the distribution of strain in the blade but that in a high rotor speed, high cycle fatigue regime this has little influence on damage rate. The experiment was conducted on a small test turbine by implementing variable speed stall, pitch and yaw control strategies and measuring blade flapwise strain response at root and midspan locations. A full description of the investigation is provided. (au)
Rotor Field Oriented Control with adaptive Iron Loss Compensation
DEFF Research Database (Denmark)
Rasmussen, Henrik; Vadstrup, P.; Børsting, H.
1999-01-01
It is well known from the literature that iron loses in an induction motor implies field angle estimation errors and hence detuning problems. In this paper a new method for estimating the iron loss resistor in an induction motor is presented. The method is based on a traditional dynamic model...... of the motor referenced to the rotor magnetizing current, and with the extension of an iron loss resistor added in parallel to the magnetizing inductance. The resistor estimator is based on the observation that the actual applied stator voltages deviates from the voltage estimated, when a motor is current...
Directory of Open Access Journals (Sweden)
Guowei Cai
2014-01-01
Full Text Available As to strong nonlinearity of doubly fed induction generators (DFIG and uncertainty of its model, a novel rotor current controller with nonlinearity and robustness is proposed to enhance fault ride-though (FRT capacities of grid-connected DFIG. Firstly, the model error, external disturbances, and the uncertain factors were estimated by constructing extended state observer (ESO so as to achieve linearization model, which is compensated dynamically from nonlinear model. And then rotor current controller of DFIG is designed by using terminal sliding mode variable structure control theory (TSMC. The controller has superior dynamic performance and strong robustness. The simulation results show that the proposed control approach is effective.
Directory of Open Access Journals (Sweden)
Timothy Dimond
2012-01-01
Full Text Available Most industrial rotors supported in active magnetic bearings (AMBs are operated well below the first bending critical speed. Also, they are usually controlled using proportional, integral and derivative controllers, which are set up as modally uncoupled parallel and tilt rotor axes. Gyroscopic effects create mode splitting and a speed-dependent plant. Two AMBs with four axes of control must simultaneously control and stabilize the rotor/AMB system. Various analyses have been published considering this problem for different rotor/AMB configurations. There has not been a fully dimensionless analysis of these rigid rotor AMB systems. This paper will perform this analysis with a modal PD controller in terms of translation mode and tilt mode dimensionless eigenvalues and eigenvectors. The number of independent system parameters is significantly reduced. Dimensionless PD controller gains, the ratio of rotor polar to transverse moments of inertia and a dimensionless speed ratio are used to evaluate a fully general system stability rigid rotor analysis. An objective of this work is to quantify the effects of gyroscopics on rigid rotor AMB systems. These gyroscopic forces reduce the system stability margin. The paper is also intended to help provide a common framework for communication between rotating machinery designers and controls engineers
Energy Technology Data Exchange (ETDEWEB)
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.
Field Oriented Control for Rotor Position Estimation of IPM Drives over a Wide Speed Range
Directory of Open Access Journals (Sweden)
Ekhlas Kadhum
2013-01-01
Full Text Available Field oriented control strategy of Interior Permanent Magnet IPM Synchronous Motor drives over a wide speed range applications is presented. Rotor position estimation using model reference adaptive system method for IPM Drive without using a mechanical sensor is illustrated considering the effects of cross-saturation between the d and q axes. The cross saturation between d and q axes has been calculated by finite-element analysis. The inductance measurement regards the cross saturation which is used to obtain the suitable id - characteristics in base and flux weakening regions. The simulation results show that rotor position estimation error accuracy was improved. Various dynamic conditions have been investigated
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
. The remaining two sets of actuators are applied to act directly onto the hub, working as an active radial bearing controlling the rotor lateral movement. The rig is equipped with sensors measuring blade and rotor vibrations. Actuators and sensors are connected to a digital signal processor running the control......This is the second paper in a two-part study on active rotor-blade vibration control. This part presents an experimental contribution into the work of active controller design for rotor-blade systems. The primary aim is to give an experimental validation and show the applicability...... shaft is mounted in a flexible hub, which can perform lateral movement. The blades are designed as simple Euler-Bernoulli beams with tip masses in order to increase the vibration coupling among the rigid rotors and the flexible blades motion. Different schemes of blade configurations, with and without...
Active vibration control of a rotor-bearing system based on dynamic stiffness
Directory of Open Access Journals (Sweden)
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.
DEFF Research Database (Denmark)
Cheng, Shuangyin; Luo, Derong; Huang, Shoudao;
2015-01-01
is developed and the instability of the system with unbalanced loads is analysed. Based on the analysis, a control strategy which can keep synchronism of the two rotors under varying load is implemented. In addition, a method for starting the motor reliably is proposed, which is applicable to ship or under...
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.
Active control of counter-rotating open rotor interior noise in a Dornier 728 experimental aircraft
Haase, Thomas; Unruh, Oliver; Algermissen, Stephan; Pohl, Martin
2016-08-01
The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor Blade Systems
DEFF Research Database (Denmark)
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...
STRUCTURAL SYNTHESIS OF A STABILIZING ROBUST CONTROLLER OF THE ROTOR FLUX LINKAGE
Directory of Open Access Journals (Sweden)
N. J. Khlopenko
2017-03-01
Full Text Available Purpose. The aim is to structural synthesis of robust stabilizing control of the rotor flux vector control system of induction motor. Methodology. Synthesis controller structure was carried out in two stages. The first stage constructed a mathematical model of the channel of the rotor flux with parametric uncertainty and calculated transfer function of H∞-suboptimal controller by method of the mixed sensitivity. The second stage was carried out the expansion of the transfer function of the continued fraction for the Euclidean algorithm. This fraction was used to construct the controller structural scheme. Results. Computer modeling of the transfer function of H∞-suboptimal controller. Achieved decomposition found the transfer function of the continued fraction. The flow diagram of suboptimal H∞-controller with a proportional and integrating links and a few summers. The curves of transient rotor flux linkage in packages Robust Control Toolbox and Simulink. They coincide in the steady state, but differ among themselves in the transition. Originality. We developed the method of structural synthesis of robust stabilizing controller of the flux linkage rotor, H∞-suboptimal structural scheme of which is presented in the form of simple compounds integrating and proportional elements of the same order as the controller with the strictly correct transfer function, and takes into account the parametric uncertainty of control object. The results of the simulation of transient processes in a variety of packages MATLAB applications confirms the adequacy and small sensitivity of the system to parametric perturbation. Practical value. The resulting structure of the controller makes it possible to carry out the modernization of electric control systems, in use, with minimal financial costs.
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.
Stabilization and control of quad-rotor helicopter using a smartphone device
Desai, Alok; Lee, Dah-Jye; Moore, Jason; Chang, Yung-Ping
2013-01-01
In recent years, autonomous, micro-unmanned aerial vehicles (micro-UAVs), or more specifically hovering micro- UAVs, have proven suitable for many promising applications such as unknown environment exploration and search and rescue operations. The early versions of UAVs had no on-board control capabilities, and were difficult for manual control from a ground station. Many UAVs now are equipped with on-board control systems that reduce the amount of control required from the ground-station operator. However, the limitations on payload, power consumption and control without human interference remain the biggest challenges. This paper proposes to use a smartphone as the sole computational device to stabilize and control a quad-rotor. The goal is to use the readily available sensors in a smartphone such as the GPS, the accelerometer, the rate-gyros, and the camera to support vision-related tasks such as flight stabilization, estimation of the height above ground, target tracking, obstacle detection, and surveillance. We use a quad-rotor platform that has been built in the Robotic Vision Lab at Brigham Young University for our development and experiments. An Android smartphone is connected through the USB port to an external hardware that has a microprocessor and circuitries to generate pulse-width modulation signals to control the brushless servomotors on the quad-rotor. The high-resolution camera on the smartphone is used to detect and track features to maintain a desired altitude level. The vision algorithms implemented include template matching, Harris feature detector, RANSAC similarity-constrained homography, and color segmentation. Other sensors are used to control yaw, pitch, and roll of the quad-rotor. This smartphone-based system is able to stabilize and control micro-UAVs and is ideal for micro-UAVs that have size, weight, and power limitations.
Novel controller design demonstration for vibration alleviation of helicopter rotor blades
Ulker, Fatma Demet; Nitzsche, Fred
2012-04-01
This paper presents an advanced controller design methodology for vibration alleviation of helicopter rotor sys- tems. Particularly, vibration alleviation in a forward ight regime where the rotor blades experience periodically varying aerodynamic loading was investigated. Controller synthesis was carried out under the time-periodic H2 and H∞ framework and the synthesis problem was solved based on both periodic Riccati and Linear Matrix Inequality (LMI) formulations. The closed-loop stability was analyzed using Floquet-Lyapunov theory, and the controller's performance was validated by closed-loop high-delity aeroelastic simulations. To validate the con- troller's performance an actively controlled trailing edge ap strategy was implemented. Computational cost was compared for both formulations.
DEFF Research Database (Denmark)
Salazar, Jorge Andrés González; Santos, Ilmar
2014-01-01
In this work, the feedback-controlled lubrication regime, based on a model-free designed proportional-derivative (PD) controller, is studied and experimentally tested in a flexible rotor mounted on an actively-lubricated tilting-pad journal bearing (active TPJB). With such a lubrication regime......-controlled lubrication regime featured via PD controllers. Good experimental results are obtained, and a significant improvement of the flexible rotor-bearing system dynamic performance can be experimentally demonstrated....
Institute of Scientific and Technical Information of China (English)
CAO Jun-ci; LI Wei-li
2005-01-01
In the paper, the method to optimize the rotor structure in variable frequency speed control motors is introduced. The saturation and the skin effect are considered and 2D no-load and load electromagnetic field is calculated in finite elements for a variable frequency speed control motor before and after optimization. Finally,no-load current and operation performance before and after optimization are obtained and the two results are contrasted.
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...
Coupled rotor-flexible fuselage vibration reduction using open loop higher harmonic control
Papavassiliou, I.; Friedmann, P. P.; Venkatesan, C.
1991-01-01
A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computer facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselae vibrations a new scheme called multiple higher harmonic control is required.
Low Voltage Ride-through in DFIG Wind Generators by Controlling the Rotor Current without Crowbars
Directory of Open Access Journals (Sweden)
Jaime Rodríguez Arribas
2014-01-01
Full Text Available Among all the different types of electric wind generators, those that are based on doubly fed induction generators, or DFIG technology, are the most vulnerable to grid faults such as voltage sags. This paper proposes a new control strategy for this type of wind generator, that allows these devices to withstand the effects of a voltage sag while following the new requirements imposed by grid operators. This new control strategy makes the use of complementary devices such as crowbars unnecessary, as it greatly reduces the value of currents originated by the fault. This ensures less costly designs for the rotor systems as well as a more economic sizing of the necessary power electronics. The strategy described here uses an electric generator model based on space-phasor theory that provides a direct control over the position of the rotor magnetic flux. Controlling the rotor magnetic flux has a direct influence on the rest of the electrical variables enabling the machine to evolve to a desired work point during the transient imposed by the grid disturbance. Simulation studies have been carried out, as well as test bench trials, in order to prove the viability and functionality of the proposed control strategy.
Lackner, M.A.; van Kuik, G.A.M.
2009-01-01
Modern wind turbines have been steadily increasing in size, and have now become very large, with recent models boasting rotor diameters greater than 120 m. Reducing the loads experienced by the wind turbine rotor blades is one means of lowering the cost of energy of wind turbines. Wind turbines are
Nonlinear Motion Control of a Rotary Wing Vehicle Powered by Four Rotors
Directory of Open Access Journals (Sweden)
S. Araujo–Estrada
2009-10-01
Full Text Available This paper presents a solution to the motion control problem for a rotary wing vehicle powered by four rotors. It is considered that the rotary wing vehicle performs an indoor low speed flight mission so that aerodynamic effects are not taken into account. The proposed controller is based on a combination of the well–known backstepping nonlinear control design technique and bounded controllers. It is shown that the resulting closed—loop dynamics evolves inside a set where singularities are avoided. Numerical simulations show the performance of the proposed controller.
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.
DEFF Research Database (Denmark)
Theisen, Lukas Roy Svane; Galeazzi, Roberto; Niemann, Hans Henrik;
2015-01-01
directions. Hardening and softening P-lead controllers are designed based on the models experimentally identified, and salient features of both controllers are discussed. Both controllers are implemented and validated on the physical test rig. Experimental results confirm the validity of the proposed......-Box identification for the design of stabilising controllers, capable of enabling the active lubrication of the journal. The root locus analysis shows that two different control solutions are feasible for the dampening of the first two eigenfrequencies of the rotor-gas bearing in the horizontal and vertical...
Active Vibration Control in a Rotor System by an Active Suspension with Linear Actuators
Directory of Open Access Journals (Sweden)
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.
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.
DEFF Research Database (Denmark)
Pierart Vásquez, Fabián Gonzalo
Gas journal bearings have been increasingly adopted in modern turbo-machinery due to their numerous indisputable advantages. They can operate at higher speed than most bearing designs, almost without noise or heat generation and in most cases, as in this work, the gas used is air which is cheap...... work, the control signal design is based on a theoretical model. This approach enables easy modifications of any of the numerous physical parameters in the system if needed. The theoretical model used is based on a modifed version of Reynolds equation where an extra term is added in order to include...... frequencies and damping ratios of the rotor-bearing system) is performed and finally to design controllers that allows improvement of the dynamic properties of the rotor-active gas bearings system and lets the systemto safely cross the critical speeds, using the theoretical model as a design tool. The results...
Energy Technology Data Exchange (ETDEWEB)
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.
Vibration Control of a Flexible Rotor Using Shape Memory Alloy Wires
DEFF Research Database (Denmark)
Alves, Marco Túlio Santana; Enemark, Søren; Steffen Jr, Valdar
2015-01-01
In the present contribution, a theoretical model of a test rig containing a flexible rotor is simulated considering pseudoelastic SMA (Shape Memory Alloy) wires connected to a bearing in order to dissipate energy and consequently reduce vibration. SMAs have characteristics of shape memory...... of rotor and SMA wires are coupled. The chosen constitutive model that governs the SMA behaviour is a modified version of the model by Brinson for the one-dimensional case. Both transient and steady-state tests arenumerically simulated. The first one, a run-up test, is performed only at room temperature....... In the second, the unbalancedrotor runs at the first critical speed and two cases are considered: i) room temperature; ii) time-varying temperature.The results from these evaluations show that SMA can be an interesting alternative for vibration control in rotating machinery....
Control Methods Using Cross-Coupling Effects for Suppression of Rotor/Stator Rubbing System
Directory of Open Access Journals (Sweden)
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.
Rotor Resistance Online Identification of Vector Controlled Induction Motor Based on Neural Network
Directory of Open Access Journals (Sweden)
Bo Fan
2014-01-01
Full Text Available Rotor resistance identification has been well recognized as one of the most critical factors affecting the theoretical study and applications of AC motor’s control for high performance variable frequency speed adjustment. This paper proposes a novel model for rotor resistance parameters identification based on Elman neural networks. Elman recurrent neural network is capable of performing nonlinear function approximation and possesses the ability of time-variable characteristic adaptation. Those influencing factors of specified parameter are analyzed, respectively, and various work states are covered to ensure the completeness of the training samples. Through signal preprocessing on samples and training dataset, different input parameters identifications with one network are compared and analyzed. The trained Elman neural network, applied in the identification model, is able to efficiently predict the rotor resistance in high accuracy. The simulation and experimental results show that the proposed method owns extensive adaptability and performs very well in its application to vector controlled induction motor. This identification method is able to enhance the performance of induction motor’s variable-frequency speed regulation.
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.
Directory of Open Access Journals (Sweden)
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.
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.
Saxena, Anand
The focus of this research was to demonstrate a four blade rotor trim in forward flight using integrated trailing edge flaps instead of using a swashplate controls. A compact brushless DC motor was evaluated as an on-blade actuator, with the possibility of achieving large trailing edge flap amplitudes. A control strategy to actuate the trailing edge flap at desired frequency and amplitude was developed and large trailing edge flap amplitudes from the motor (instead of rotational motion) were obtained. Once the actuator was tested on the bench-top, a lightweight mechanism was designed to incorporate the motor in the blade and actuate the trailing edge flaps. A six feet diameter, four bladed composite rotor with motor-flap system integrated into the NACA 0012 airfoil section was fabricated. Systematic testing was carried out for a range of load conditions, first in the vacuum chamber followed by hover tests. Large trailing edge flap deflections were observed during the hover testing, and a peak to peak trailing edge flap amplitude of 18 degree was achieved at 2000 rotor RPM with hover tip Mach number of 0.628. A closed loop controller was designed to demonstrate trailing edge flap mean position and the peak to peak amplitude control. Further, a soft pitch link was designed and fabricated, to replace the stiff pitch link and thereby reduce the torsional stiffness of the blade to 2/rev. This soft pitch link allowed for blade root pitch motion in response to the trailing edge flap inputs. Blade pitch response due to both steady as well as sinusoidal flap deflections were demonstrated. Finally, tests were performed in Glenn L. Martin wind tunnel using a model rotor rig to assess the performance of motor-flap system in forward flight. A swashplateless trim using brushless DC motor actuated trailing edge flaps was achieved for a rotor operating at 1200 RPM and an advance ratio of 0.28. Also, preliminary exploration was carried out to test the scalability of the motor
Cai, Guowei; Liu, Cheng; Yang, Deyou
2013-11-01
The doubly fed induction generators (DFIG) have been recognized as the dominant technology used in wind power generation systems with the rapid development of wind power. However, continuous operation of DFIG may cause a serious wind turbine generators tripping accident, due to destructive over-current in the rotor winding which is caused by the power system fault or inefficient fault ride-through (FRT) strategy. A new rotor current control scheme in the rotor-side converter (RSC) ispresented to enhance FRT capacities of grid-connected DFIG. Due to the strongly nonlinear nature of DFIG and insensitive to DFIG parameter's variations, a novel sliding mode controller was designed. The controller combines extended state observer (ESO) with sliding model variable structure control theory. The simulation is carried out to verify the effectiveness of the proposed control approach under various types of grid disturbances. It is shown that the proposed controller provides enhanced transient features than the classic proportional-integral control. The proposed control method can effectively reduce over-current in the RSC, and the transient pulse value of electromagnetic torque is too large under power grid fault.
Fuzzy-Based Hybrid Control Algorithm for the Stabilization of a Tri-Rotor UAV
Directory of Open Access Journals (Sweden)
Zain Anwar Ali
2016-05-01
Full Text Available In this paper, a new and novel mathematical fuzzy hybrid scheme is proposed for the stabilization of a tri-rotor unmanned aerial vehicle (UAV. The fuzzy hybrid scheme consists of a fuzzy logic controller, regulation pole-placement tracking (RST controller with model reference adaptive control (MRAC, in which adaptive gains of the RST controller are being fine-tuned by a fuzzy logic controller. Brushless direct current (BLDC motors are installed in the triangular frame of the tri-rotor UAV, which helps maintain control on its motion and different altitude and attitude changes, similar to rotorcrafts. MRAC-based MIT rule is proposed for system stability. Moreover, the proposed hybrid controller with nonlinear flight dynamics is shown in the presence of translational and rotational velocity components. The performance of the proposed algorithm is demonstrated via MATLAB simulations, in which the proposed fuzzy hybrid controller is compared with the existing adaptive RST controller. It shows that our proposed algorithm has better transient performance with zero steady-state error, and fast convergence towards stability.
Fuzzy-Based Hybrid Control Algorithm for the Stabilization of a Tri-Rotor UAV.
Ali, Zain Anwar; Wang, Daobo; Aamir, Muhammad
2016-05-09
In this paper, a new and novel mathematical fuzzy hybrid scheme is proposed for the stabilization of a tri-rotor unmanned aerial vehicle (UAV). The fuzzy hybrid scheme consists of a fuzzy logic controller, regulation pole-placement tracking (RST) controller with model reference adaptive control (MRAC), in which adaptive gains of the RST controller are being fine-tuned by a fuzzy logic controller. Brushless direct current (BLDC) motors are installed in the triangular frame of the tri-rotor UAV, which helps maintain control on its motion and different altitude and attitude changes, similar to rotorcrafts. MRAC-based MIT rule is proposed for system stability. Moreover, the proposed hybrid controller with nonlinear flight dynamics is shown in the presence of translational and rotational velocity components. The performance of the proposed algorithm is demonstrated via MATLAB simulations, in which the proposed fuzzy hybrid controller is compared with the existing adaptive RST controller. It shows that our proposed algorithm has better transient performance with zero steady-state error, and fast convergence towards stability.
Fuzzy-Based Hybrid Control Algorithm for the Stabilization of a Tri-Rotor UAV
Ali, Zain Anwar; Wang, Daobo; Aamir, Muhammad
2016-01-01
In this paper, a new and novel mathematical fuzzy hybrid scheme is proposed for the stabilization of a tri-rotor unmanned aerial vehicle (UAV). The fuzzy hybrid scheme consists of a fuzzy logic controller, regulation pole-placement tracking (RST) controller with model reference adaptive control (MRAC), in which adaptive gains of the RST controller are being fine-tuned by a fuzzy logic controller. Brushless direct current (BLDC) motors are installed in the triangular frame of the tri-rotor UAV, which helps maintain control on its motion and different altitude and attitude changes, similar to rotorcrafts. MRAC-based MIT rule is proposed for system stability. Moreover, the proposed hybrid controller with nonlinear flight dynamics is shown in the presence of translational and rotational velocity components. The performance of the proposed algorithm is demonstrated via MATLAB simulations, in which the proposed fuzzy hybrid controller is compared with the existing adaptive RST controller. It shows that our proposed algorithm has better transient performance with zero steady-state error, and fast convergence towards stability. PMID:27171084
Vanaken, Johannes M.
1991-01-01
The feasibility of using active controls to delay the onset of whirl-flutter on a joined-wing tilt rotor aircraft was investigated. The CAMRAD/JA code was used to obtain a set of linear differential equations which describe the motion of the joined-wing tilt-rotor aircraft. The hub motions due to wing/body motion is a standard input to CAMRAD/JA and were obtained from a structural dynamics model of a representative joined-wing tilt-rotor aircraft. The CAMRAD/JA output, consisting of the open-loop system matrices, and the airframe free vibration motion were input to a separate program which performed the closed-loop, active control calculations. An eigenvalue analysis was performed to determine the flutter stability of both open- and closed-loop systems. Sensor models, based upon the feedback of pure state variables and based upon hub-mounted sensors, providing physically measurable accelerations, were evaluated. It was shown that the onset of tilt-rotor whirl-flutter could be delayed from 240 to above 270 knots by feeding back vertical and span-wise accelerations, measured at the rotor hub, to the longitudinal cyclic pitch. Time response calculations at a 270-knot cruise condition showed an active cyclic pitch control level of 0.009 deg, which equates to a very acceptable 9 pound active-control force applied at the rotor hub.
Rotors on Active Magnetic Bearings: Modeling and Control Techniques
Tonoli, Andrea; Bonfitto, Angelo; Silvagni, Mario; Suarez, Lester D.
2012-01-01
In the last decades the deeper and more detailed understanding of rotating machinery dynamic behavior facilitated the study and the design of several devices aiming at friction reduction, vibration damping and control, rotational speed increase and mechanical design optimization. Among these devices a promising technology is represented by active magnetic actuators which found a great spread in rotordynamics and in high precision applications due to (a) the absence of all fatigue and tribolog...
Study on seal improvement and rotor thrust control of centrifugal compressor
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Fluid pressure variations due to process fluctuations or balance drum seal degradation can result in rotor thrust increasing that may jeopardize thrust bearing and compressor's reliability. Also, the leakage flow through balance drum seal can seriously affect the efficiency of compressor. A method that can improve both the efficiency and reliability of centrifugal compressor is presented. The method focused on rotor thrust control and balance drum seal upgrading. The low leakage feature of Dry-Gas-Seal(DGS), high reliability of labyrinth, and the feasibility of upgrading existing structure are taken into account at the same time to design a combined labyrinth-dry gas seal system on the balancing drum. Based on the combined seal system, a Fault Self-Recovering(FSR) system for the fault of rotor shaft displacement is introduced to assure the safety and reliability of centrifugal compressor. The modern Computational Fluid Dynamics(CFD) is used to validate this envision. The numerical result and relevant information indicate that the combined sealing system could improve the efficiency of the centrifugal compressor by about 4%.
Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension.
Sun, Boqian; Wang, Shunyue; Li, Haixia; He, Xiaoxia
2016-10-20
A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor being controlled by a torque-rebalance loop. In this paper, a decoupling compensation method is proposed and investigated experimentally based on an electrostatically suspended micromachined gyroscope. In order to eliminate the negative spring effect inherent in the gyroscope dynamics, a stiffness compensation scheme was utilized in design of the decoupled rebalance loop to ensure loop stability and increase suspension stiffness. The experimental results show an overall stiffness increase of 30.3% after compensation. A decoupling method comprised of inner- and outer-loop decoupling compensators is proposed to minimize the cross-axis coupling error. The inner-loop decoupling compensator aims to attenuate the angular position coupling. The experimental frequency response shows a position coupling attenuation by 14.36 dB at 1 Hz. Moreover, the cross-axis coupling between the two angular rate output signals can be attenuated theoretically from -56.2 dB down to -102 dB by further appending the outer-loop decoupling compensator. The proposed dual-loop decoupling compensation algorithm could be applied to other dual-axis spinning-rotor gyroscopes with various suspension solutions.
Ribeiro, Eduardo Afonso; Pereira, Jucélio Tomás; Alberto Bavastri, Carlos
2015-09-01
One of the major reasons for inserting damping into bearings is that rotating machines are often requested in critical functioning conditions having sometimes to function under dynamic instability or close to critical speeds. Hydrodynamic and magnetic bearings have usually been used for this purpose, but they present limitations regarding costs and operation, rendering the use of viscoelastic supports a feasible solution for vibration control in rotating machines. Most papers in the area use simple analytic or single degree of freedom models for the rotor as well as classic mechanical models of linear viscoelasticity for the support - like Maxwell, Kelvin-Voigt, Zenner, four-element, GHM models and even frequency independent models - but they lack the accuracy of fractional models in a large range of frequency and temperature regarding the same number of coefficients. Even in those works, the need to consider the addition of degrees of freedom to the support is evident. However, so far no paper has been published focusing on a methodology to determine the optimal constructive form for any viscoelastic support in which the rotor is discretized by finite elements associated to an accurate model for characterizing the viscoelastic material. In general, the support is meant to be a simple isolation system, and the fact the stiffness matrix is complex and frequency-temperature dependent - due to its viscoelastic properties - forces the traditional methods to require an extremely long computing time, thus rendering them too time consuming in an optimization environment. The present work presents a robust methodology based mainly on generalized equivalent parameters (GEP) - for an optimal design of viscoelastic supports for rotating machinery - aiming at minimizing the unbalance frequency response of the system using a hybrid optimization technique (genetic algorithms and Nelder-Mead method). The rotor is modeled based on the finite element method using Timoshenko's thick
Institute of Scientific and Technical Information of China (English)
EGUCHI; Hidenori; YOSHIDA; Kouichi; NISHI; Michihiro
2010-01-01
In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by using the coning blade of 20°.Besides,owing to the torsional deformation of very soft blade,the self-power control characteristic is observed in every test rotor regardless of coning angle in the range of 0°-20° under the wind speed less than 12 m/s.
DISCUSSION AND PRACTICAL ASPECTS ON CONTROL ALLOCATION FOR A MULTI-ROTOR HELICOPTER
Directory of Open Access Journals (Sweden)
G. J. J. Ducard
2012-09-01
Full Text Available This paper presents practical methods to improve the ﬂight performance of an unmanned multi-rotor helicopter by using an efﬁcient control allocation strategy. The ﬂying vehicle considered is an hexacopter. It is indeed particularly suited for long missions and for carrying a signiﬁcant payload such as all the sensors needed in the context of cartography, photogrammetry, inspection, surveillance and transportation. Moreover, a stable ﬂight is often required for precise data recording during the mission. Therefore, a high performance ﬂight control system is required to operate the UAV. However, the ﬂight performance of a multi-rotor vehicle is tightly dependent on the control allocation strategy that is used to map the virtual control vector v = [T, L, M, N ]T composed of the thrust and the torques in roll, pitch and yaw, respectively, to the propellers' speed. This paper shows that a control allocation strategy based on the classical approach of pseudo-inverse matrix only exploits a limited range of the vehicle capabilities to generate thrust and moments. Thus, in this paper, a novel approach is presented, which is based on a weighted pseudo-inverse matrix method capable of exploiting a much larger domain in v. The proposed control allocation algorithm is designed with explicit laws for fast operation and low computational load, suitable for a small microcontroller with limited ﬂoating-point operation capability.
Stability Limits of a PD Controller for a Flywheel Supported on Rigid Rotor and Magnetic Bearings
Kascak, Albert F.; Brown, Gerald V.; Jansen, Ralph H.; Dever, TImothy P.
2006-01-01
Active magnetic bearings are used to provide a long-life, low-loss suspension of a high-speed flywheel rotor. This paper describes a modeling effort used to understand the stability boundaries of the PD controller used to control the active magnetic bearings on a high speed test rig. Limits of stability are described in terms of allowable stiffness and damping values which result in stable levitation of the nonrotating rig. Small signal stability limits for the system is defined as a nongrowth in vibration amplitude of a small disturbance. A simple mass-force model was analyzed. The force resulting from the magnetic bearing was linearized to include negative displacement stiffness and a current stiffness. The current stiffness was then used in a PD controller. The phase lag of the control loop was modeled by a simple time delay. The stability limits and the associated vibration frequencies were measured and compared to the theoretical values. The results show a region on stiffness versus damping plot that have the same qualitative tendencies as experimental measurements. The resulting stability model was then extended to a flywheel system. The rotor dynamics of the flywheel was modeled using a rigid rotor supported on magnetic bearings. The equations of motion were written for the center of mass and a small angle linearization of the rotations about the center of mass. The stability limits and the associated vibration frequencies were found as a function of nondimensional magnetic bearing stiffness and damping and nondimensional parameters of flywheel speed and time delay.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems
DEFF Research Database (Denmark)
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...
Simulink(Trademark) Controller for a Reluctance Motor With a Four-Pole Rotor and 36-Tooth Stator
Morrison, Carlos R.; Provenza, Andrew J.
2017-01-01
NASA Glenn Research Center has developed a Simulink(Trademark) controller logic for driving a room temperature, 36-teeth stator, four-pole rotor reluctance motor. The Simulink logic was extracted from an existing C++ motor controller that was previously employed to achieve a rotor speed of 3000 rpm. The Simulink controller has additional logic refinements that were not available in past C++ controller, such as the per rev logic component and its frequency filter. The filter provides a more accurate reading of the rotor input signals. The controller is versatile, and with slight modifications, can be used to drive other reluctance motor types incorporating dissimilar stator rotor pole combinations. The original C++ controller was designed with the goal (after appropriate modification) of controlling a future superconducting motor. This superconducting motor will be employed as a test bed for developing other superconducting aviation propulsion motors envisioned for future turbo-electric aircrafts. The Simulink results presented in this paper were generated from simulated rotor inputs. However, in an actual application, these simulated inputs are to be replaced by actual proximity probe signals emanating from D-Space hardware inputs.
DEFF Research Database (Denmark)
Salazar, Jorge Andrés González; Santos, Ilmar
2015-01-01
The feedback-controlled lubrication regime, based on a model-free designed proportional–derivative controller, is experimentally investigated in a flexible rotor mounted on an actively-lubricated tilting-pad journal bearing. With such a lubrication regime, both the resulting pressure distribution......-controlled lubrication regime featured via proportional–derivative controllers....
Design of Robust Adaptive Unbalance Response Controllers for Rotors with Magnetic Bearings
Knospe, Carl R.; Tamer, Samir M.; Fedigan, Stephen J.
1996-01-01
Experimental results have recently demonstrated that an adaptive open loop control strategy can be highly effective in the suppression of unbalance induced vibration on rotors supported in active magnetic bearings. This algorithm, however, relies upon a predetermined gain matrix. Typically, this matrix is determined by an optimal control formulation resulting in the choice of the pseudo-inverse of the nominal influence coefficient matrix as the gain matrix. This solution may result in problems with stability and performance robustness since the estimated influence coefficient matrix is not equal to the actual influence coefficient matrix. Recently, analysis tools have been developed to examine the robustness of this control algorithm with respect to structured uncertainty. Herein, these tools are extended to produce a design procedure for determining the adaptive law's gain matrix. The resulting control algorithm has a guaranteed convergence rate and steady state performance in spite of the uncertainty in the rotor system. Several examples are presented which demonstrate the effectiveness of this approach and its advantages over the standard optimal control formulation.
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
Rotor flux magnitude and angle control strategy for doubly fed induction generators
Anaya-Lara, Olimpo; Hughes, F. Michael; Jenkins, Nicholas; Strbac, Goran
2006-09-01
A new control strategy is investigated for Doubly Fed Induction Generators (DFIGs). It exercises control over the generator terminal voltage and output power by adjusting the magnitude and angle of the rotor flux vector. It is shown that this control strategy leads to low interaction between the power and voltage control loop, better system damping and voltage recovery following faults, and it also provides enhanced frequency regulation capability compared with that achieved with existing DFIG controllers described in the open literature. The dynamic performance of the proposed DFIG control is tested for small and large disturbances using a generic network that combines wind and conventional synchronous generation. Simulation results are presented and discussed that demonstrate the capabilities of the new strategy to enhance DFIG performance and its contribution to network operation.Received: 24 August 2005; Revised: 1 December 2005; Accepted: 22 March 2006
Attitude Control of Quad Rotors QTW-UAV with Tilt Wing Mechanism
Suzuki, Satoshi; Zhijia, Ren; Horita, Yoshikazu; Nonami, Kenzo; Kimura, Gaku; Bando, Toshio; Hirabayashi, Daisuke; Furuya, Mituhiro; Yasuda, Kenta
In this paper, we propose an autonomous attitude control of a quad tilt wing-unmanned aerial vehicle (QTW-UAV). A QTW-UAV can achieve vertical takeoff and landing; further, hovering flight, which are characteristic of rotary-wing aircraft such as helicopter. And high cruising speeds, which is a characteristic of fixed-wing aircraft, can be also achieved by changing the angle of the rotors and wings by a tilt mechanism. First, we construct an attitude model of the QTW-UAV by using the identification method. We then design the attitude control system with a Kalman filter-based linear quadratic integral (LQI) control method; the experiment results show that a model-based control design is very useful for the autonomous control of a QTW-UAV.
Splettstoesser, W. R.; Lehmann, G.; van der Wall, B.
1989-09-01
Initial acoustic results are presented from a higher harmonic control (HHC) wind tunnel pilot experiment on helicopter rotor blade-vortex interaction (BVI) impulsive noise reduction, making use of the DFVLR 40-percent-scaled BO-105 research rotor in the DNW 6m by 8m closed test section. Considerable noise reduction (of several decibels) has been measured for particular HHC control settings, however, at the cost of increased vibration levels and vice versa. The apparently adverse results for noise and vibration reduction by HHC are explained. At optimum pitch control settings for BVI noise reduction, rotor simulation results demonstrate that blade loading at the outer tip region is decreased, vortex strength and blade vortex miss-distance are increased, resulting altogether in reduced BVI noise generation. At optimum pitch control settings for vibration reduction adverse effects on blade loading, vortex strength and blade vortex miss-distance are found.
Directory of Open Access Journals (Sweden)
Yuan Ren
2014-01-01
Full Text Available For magnetically suspended rigid rotors (MSRs with significant gyroscopic effects, phase lag of the control channel is the main factor influencing the system nutation stability and decoupling performance. At first, this paper proves that the phase lag of the cross channel instead of the decentralized channel is often the main factor influencing the system nutation stability at high speeds. Then a modified cross feedback control strategy based on the phase compensation of cross channel is proposed to improve the stability and decoupling performances. The common issues associated with the traditional control methods have been successfully resolved by this method. Analysis, simulation, and experimental results are presented to demonstrate the feasibility and superiority of the proposed control method.
ul Amin, Rooh; Aijun, Li; Khan, Muhammad Umer; Shamshirband, Shahaboddin; Kamsin, Amirrudin
2017-01-01
In this paper, an adaptive trajectory tracking controller based on extended normalized radial basis function network (ENRBFN) is proposed for 3-degree-of-freedom four rotor hover vehicle subjected to external disturbance i.e. wind turbulence. Mathematical model of four rotor hover system is developed using equations of motions and a new computational intelligence based technique ENRBFN is introduced to approximate the unmodeled dynamics of the hover vehicle. The adaptive controller based on the Lyapunov stability approach is designed to achieve tracking of the desired attitude angles of four rotor hover vehicle in the presence of wind turbulence. The adaptive weight update based on the Levenberg-Marquardt algorithm is used to avoid weight drift in case the system is exposed to external disturbances. The closed-loop system stability is also analyzed using Lyapunov stability theory. Simulations and experimental results are included to validate the effectiveness of the proposed control scheme.
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.
Institute of Scientific and Technical Information of China (English)
CHEN Yiguang; PAN Wei; SHEN Yonghuan; TANG Renyuan
2006-01-01
Conventional permanent magnet synchronous machine(PMSM)has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-polar is proposed. This machine has the characteristics of low stator copper loss and wide-speed operation. The half-radial-set and half-tangential-set permanent magnets(PMs)are NdFeB that has high remanent flux density and high coercive force. The tangential-set PMs are AlNiCo that has high remanent flux density and low coercive force. By applying the pulse of d-axis stator current id, the magnetized intensity and direction of AlNiCo can be controlled. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified, or is partially bypassed by AlNiCo in the rotor, so the air-gap PM-flux is weakened. The internal magnetic field distribution in two ultra magnetized situations is analyzed by finite element method. The dimension of PMs and magnetic structure are demonstrated. Especially when the q-axis magnetic resistance is larger and the q-axis inductance is smaller, the result of flux-weakening is better and the influence of armature reaction on air-gap PM-flux is weakened.
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.
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
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
Talhaoui, Hicham; Menacer, Arezki; Kessal, Abdelhalim; Kechida, Ridha
2014-09-01
This paper presents new techniques to evaluate faults in case of broken rotor bars of induction motors. Procedures are applied with closed-loop control. Electrical and mechanical variables are treated using fast Fourier transform (FFT), and discrete wavelet transform (DWT) at start-up and steady state. The wavelet transform has proven to be an excellent mathematical tool for the detection of the faults particularly broken rotor bars type. As a performance, DWT can provide a local representation of the non-stationary current signals for the healthy machine and with fault. For sensorless control, a Luenberger observer is applied; the estimation rotor speed is analyzed; the effect of the faults in the speed pulsation is compensated; a quadratic current appears and used for fault detection.
Fractional Order PID Control of Rotor Suspension by Active Magnetic Bearings
Directory of Open Access Journals (Sweden)
Parinya Anantachaisilp
2017-01-01
Full Text Available One of the key issues in control design for Active Magnetic Bearing (AMB systems is the tradeoff between the simplicity of the controller structure and the performance of the closed-loop system. To achieve this tradeoff, this paper proposes the design of a fractional order Proportional-Integral-Derivative (FOPID controller. The FOPID controller consists of only two additional parameters in comparison with a conventional PID controller. The feasibility of FOPID for AMB systems is investigated for rotor suspension in both the radial and axial directions. Tuning methods are developed based on the evolutionary algorithms for searching the optimal values of the controller parameters. The resulting FOPID controllers are then tested and compared with a conventional PID controller, as well as with some advanced controllers such as Linear Quadratic Gausian (LQG and H ∞ controllers. The comparison is made in terms of various stability and robustness specifications, as well as the dimensions of the controllers as implemented. Lastly, to validate the proposed method, experimental testing is carried out on a single-stage centrifugal compressor test rig equipped with magnetic bearings. The results show that, with a proper selection of gains and fractional orders, the performance of the resulting FOPID is similar to those of the advanced controllers.
Nonlinear coupled rotor-fuselage helicopter vibration studies with higher harmonic control
Friedmann, P. P.; Venkatesan, C.; Papavassiliou, I.
1990-01-01
This paper addresses the problem of vibration prediction and vibration reduction in helicopters by means of active control methodologies. The nonlinear equations of a coupled rotor/flexible-fuselage system have been derived using computer algebra, thus relegating this tedious task to the computer. In the solution procedure the trim state and vibratory response of the helicopter are obtained in a single pass by using a harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter in all the rotor and fuselage degrees of freedom. Using this solution procedure, the influence of the fuselage flexibility on the vibratory response is studied. In addition, it is shown that the conventional single frequency HHC is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. A new scheme called MHHC, having multiple higher harmonic pitch inputs, was used to accomplish this task of simultaneously reducing both the vibratory hub loads and fuselage vibratory response. In addition, the uniqueness of this MHHC scheme is explained in detail.
Control of LP Turbine Rotor Blade Underloading Using Stator Blade Compound Lean at Root
Institute of Scientific and Technical Information of China (English)
PiotrLampart
2000-01-01
Due to a large gradient of reaction,LP rotor blades remain underloaded at the root over some range of volumetric flow rates.An interesting design to control the flow through the root passage of the overloaded stator and underloaded moving blade row is compound lean at the root of stator blades.The paper describes results of numerical investigations from a 3D NS solver FlowER conducted for several configurations of stator blade compund lean.The computations are carried out for a wide range of volumetric flow rates.accounting for the nominal operating regime as well as low and high load.It is found that compund lean induces additional blade force.streamwise curature and redistribution of flow parameters in the stage,including pressure and mass flow rate spanwise that can improve the flow conditions in both the stator and the rotor.The obtained efficiency improvements depend greatly on the flow regime,with the highest gains in the region of low load.
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.
Gazella, Matthew R.; Takakura, Tamuto; Sutliff, Daniel L.; Bozak, Richard F.; Tester, Brian J.
2017-01-01
Over the last 15 years, over-the-rotor acoustic treatments have been evaluated by NASA with varying success. Recently, NASA has been developing the next generation of over-the-rotor acoustic treatments for fan noise reduction. The NASA Glenn Research Centers Advanced Noise Control Fan was used as a Low Technology Readiness Level test bed. A rapid prototyped in-duct array consisting of 50 microphones was employed, and used to correlate the in-duct analysis to the far-field acoustic levels and to validate an existing beam-former method. The goal of this testing was to improve the Technology Readiness Level of various over-the-rotor acoustic treatments by advancing the understanding of the physical mechanisms and projecting the far-field acoustic benefit.
Chiariotti, P.; Ciarmatori, R.; Castellini, P.; Bastari, A.; Paone, N.
2012-06-01
When designing a test bench for vibration based diagnostics of machines with external rotating parts, such as electric motors having a rotating external rotor, one may choose among single point vibrometry, rotational vibrometry or in-plane vibrometry. The paper discusses these different options, taking the assumption that the minimum number of measuring instruments is preferred when instrumenting a quality control system and provides an insight into advantages and limitations of each instrument. In particular the following issues are discussed: a) possible installation lay-outs; b) alignment problems (and possible advantages for diagnostics), c) typical signals and diagnostic features which can be observed. The research presented refers to electric motors for home appliances, but potentially has wider application fields to other rotating machines.
Control strategies of a tilt-rotor UAV for load transportation
Marcelino Mendes de Almeida Neto
2014-01-01
Nessa dissertação são apresentadas estratégias de controle para solucionar o problema de transporte de carga suspensa ao longo de uma trajetória desejada por um Veículo Aéreo Não Tripulado (VANT) na configuração Tilt-rotor. Para o presente estudo, é importante que a aeronave seja capaz de manter tanto a si mesma quanto a carga transportada estável mesmo na presença de perturbações externas, incertezas paramétricas e erros de medição. Em geral, é importante que se tenha um modelo dinâmico prec...
Directory of Open Access Journals (Sweden)
Rajen Pudur
2016-01-01
Full Text Available This paper describes the performance of electronic load controller (ELC of asynchronous generator (AG coupled to an uncontrolled Savonius turbine and variable water velocity. An AC-DC-AC converter with a dc link capacitor is employed to maintain the required frequency. The ELC which is feeding a resistive dump load is connected in parallel with the generating system and the power consumption is varied through the duty cycle of the chopper. Gate triggering of ELC is accomplished through sinusoidal pulse width modulation (SPWM by sensing the load current. A MATLAB/Simulink model of Savonius rotor, asynchronous generator, ELC, and three-phase load is presented. The proposed scheme is tested under various load conditions under varying water velocities and the performances are observed to be satisfactory.
Directory of Open Access Journals (Sweden)
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.
A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part I: Theory
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
This is the first paper in a two-part study on active rotor-blade vibration control. Blade faults are a major problem in bladed machines, such as turbines and compressors. Moreover, increasing demands for higher efficiency, lower weight and higher speed imply that blades become even more suscepti...
Directory of Open Access Journals (Sweden)
Jian Zhong Xu
2012-09-01
Full Text Available This paper presents a newly developed aero-servo-elastic platform for implementing smart rotor control and shows its effectiveness with aerodynamic loads on large-scale offshore wind turbines. The platform was built by improving the FAST/Aerodyn codes with the integration of an external deformable trailing edge flap controller in the Matlab/Simulink software. Smart rotor control was applied to an Upwind/NREL 5 MW reference wind turbine under various operating wind conditions in accordance with the IEC Normal Turbulence Model (NTM and Extreme Turbulence Model (ETM. Results showed that, irrespective of whether the NTM or ETM case was considered, aerodynamic load in terms of blade flapwise root moment and tip deflection were effectively reduced. Furthermore, the smart rotor control also positively affected generator power, pitch system and tower load. These results laying a foundation for a future migration of the “smart rotor control” concept into the design of large-scale offshore wind turbines.
Design and implementation of a fuzzy logic yaw controller
Wu, Kung C.; Swift, Andrew H.; Craver, W. Lionel, Jr.; Chang, Yi-Chieh
1993-08-01
This paper describes a fuzzy logic controller (FLC) designed and implemented to control the yaw angle of a 10 kW fixed speed teetered-rotor wind turbine presently being commissioned at the University of Texas at El Paso. The technical challenge of this project is that the wind turbine represents a highly stochastic nonlinear system. The problems associated with the wind turbine yaw control are of a similar nature as those experienced with position control of high inertia equipment like tracking antenna, gun turrets, and overhead cranes. Furthermore, the wind turbine yaw controller must be extremely cost-effective and highly reliable in order to be economically viable compared to the fossil fueled power generators.
Sumantri, Bambang; Uchiyama, Naoki; Sano, Shigenori
2016-01-01
In this paper, a new control structure for a quad-rotor helicopter that employs the least squares method is introduced. This proposed algorithm solves the overdetermined problem of the control input for the translational motion of a quad-rotor helicopter. The algorithm allows all six degrees of freedom to be considered to calculate the control input. The sliding mode controller is applied to achieve robust tracking and stabilization. A saturation function is designed around a boundary layer to reduce the chattering phenomenon that is a common problem in sliding mode control. In order to improve the tracking performance, an integral sliding surface is designed. An energy saving effect because of chattering reduction is also evaluated. First, the dynamics of the quad-rotor helicopter is derived by the Newton-Euler formulation for a rigid body. Second, a constant plus proportional reaching law is introduced to increase the reaching rate of the sliding mode controller. Global stability of the proposed control strategy is guaranteed based on the Lyapunov's stability theory. Finally, the robustness and effectiveness of the proposed control system are demonstrated experimentally under wind gusts, and are compared with a regular sliding mode controller, a proportional-differential controller, and a proportional-integral-differential controller.
Vibration reduction in helicopter rotors using an active control surface located on the blade
Millott, T. A.; Friedmann, P. P.
1992-01-01
A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.
Vibration reduction in helicopter rotors using an active control surface located on the blade
Millott, T. A.; Friedmann, P. P.
1992-01-01
A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.
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...
Institute of Scientific and Technical Information of China (English)
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.
Modeling the effects of control systems of wind turbine fatigue life
Energy Technology Data Exchange (ETDEWEB)
Pierce, K.G.; Laino, D.J. [Univ. of Utah, Salt Lake City, UT (United States)
1996-12-31
In this study we look at the effect on fatigue life of two types of control systems. First, we investigate the Micon 65, an upwind, three bladed turbine with a simple yaw control system. Results indicate that increased fatigue damage to the blade root can be attributed to continuous operation at significant yaw error allowed by the control system. Next, we model a two-bladed teetered rotor turbine using three different control systems to adjust flap deflections. The first two limit peak power output, the third limits peak power and cyclic power output over the entire range of operation. Results for simulations conducted both with and without active control are compared to determine how active control affects fatigue life. Improvement in fatigue lifetimes were seen for all control schemes, with increasing fatigue lifetime corresponding to increased flap deflection activity. 13 refs., 6 figs., 2 tabs.
Energy Technology Data Exchange (ETDEWEB)
Jayashri, R. [Department of Electrical and Electronics Engineering, Sri Venkateswara College of Engineering (Affiliated to Anna University), Pennalur, Sriperumbudur, Tamilnadu 602105 (India); Kumudini Devi, R.P. [Department of Electrical and Electronics Engineering, College of Engineering, Anna University, Chennai (India)
2009-03-15
In this paper, the dynamic performance of grid connected Wind Energy Conversion System (WECS) is analysed in terms of the newly defined concept of rotor speed stability. The WECS is considered as a fixed-speed system that is equipped with a squirrel-cage induction generator. The drive-train is represented as a two-mass model. Results show that for a particular fault simulated the voltage at the Point of Common Coupling (PCC) drops below 80% immediately after fault application and settles at a low value. The rotor speed of induction generators becomes unstable. In order to improve the low voltage ride-through of WECS under fault conditions and to damp the rotor speed oscillations of induction generator, an Unified Power Flow Controller (UPFC) is employed. The gains of this FACTS controller are tuned with a simple Genetic Algorithm (GA). It is observed that UPFC helps not only in regulating the voltage, but also in mitigating the rotor speed instability. (author)
Directory of Open Access Journals (Sweden)
Zhao Jing
2015-01-01
Full Text Available This paper proposes a strategy of a new optimal sliding-mode control for flight control system with state constraints so that the system guarantees the optimal performance index. Besides, the strategy ensures strong robustness to the internal parametric uncertainty and the external disturbances. In order to have fast transient response speed as well as good tracking accuracy, the integral of the time multiplied by the absolute displacement tracking error is introduced as the performance index. By analyzing the state constraints which are specifically the velocity tracking error constraint and the acceleration tracking error constraint, and the performance index, the parameters of sliding-mode surface and control law are obtained. Finally, the authors conduct the semi physical simulation on Qball-X4 quad-rotor helicopter, showing the effectiveness of the proposed strategy.
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.
Energy Technology Data Exchange (ETDEWEB)
Barut, Murat; Bogosyan, Seta [University of Alaska Fairbanks, Department of Electrical and Computer Engineering, Fairbanks, AK 99775 (United States); Gokasan, Metin [Istanbul Technical University, Electrical and Electronic Engineering Faculty, 34390 Istanbul (Turkey)
2007-12-15
High performance speed sensorless control of induction motors (IMs) calls for estimation and control schemes that offer solutions to parameter uncertainties as well as to difficulties involved with accurate flux/velocity estimation at very low and zero speed. In this study, a new EKF based estimation algorithm is proposed for the solution of both problems and is applied in combination with speed sensorless direct vector control (DVC). The technique is based on the consecutive execution of two EKF algorithms, by switching from one algorithm to another at every n sampling periods. The number of sampling periods, n, is determined based on the desired system performance. The switching EKF approach, thus applied, provides an accurate estimation of an increased number of parameters than would be possible with a single EKF algorithm. The simultaneous and accurate estimation of rotor, R{sub r}{sup '} and stator, R{sub s} resistances, both in the transient and steady state, is an important challenge in speed sensorless IM control and reported studies achieving satisfactory results are few, if any. With the proposed technique in this study, the sensorless estimation of R{sub r}{sup '} and R{sub s} is achieved in transient and steady state and in both high and low speed operation while also estimating the unknown load torque, velocity, flux and current components. The performance demonstrated by the simulation results at zero speed, as well as at low and high speed operation is very promising when compared with individual EKF algorithms performing either R{sub r}{sup '} or R{sub s} estimation or with the few other approaches taken in past studies, which require either signal injection and/or a change of algorithms based on the speed range. The results also motivate utilization of the technique for multiple parameter estimation in a variety of control methods. (author)
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.
Evaluation of Manufacturability of Embedded Sensors and Controls with Canned Rotor Pump System
Energy Technology Data Exchange (ETDEWEB)
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.
Gaonkar, G. H.; Subramanian, S.
1996-01-01
Since the early 1990s the Aeroflightdynamics Directorate at the Ames Research Center has been conducting tests on isolated hingeless rotors in hover and forward flight. The primary objective is to generate a database on aeroelastic stability in trimmed flight for torsionally soft rotors at realistic tip speeds. The rotor test model has four soft inplane blades of NACA 0012 airfoil section with low torsional stiffness. The collective pitch and shaft tilt are set prior to each test run, and then the rotor is trimmed in the following sense: the longitudinal and lateral cyclic pitch controls are adjusted through a swashplate to minimize the 1/rev flapping moment at the 12 percent radial station. In hover, the database comprises lag regressive-mode damping with pitch variations. In forward flight the database comprises cyclic pitch controls, root flap moment and lag regressive-mode damping with advance ratio, shaft angle and pitch variations. This report presents the predictions and their correlation with the database. A modal analysis is used, in which nonrotating modes in flap bending, lag bending and torsion are computed from the measured blade mass and stiffness distributions. The airfoil aerodynamics is represented by the ONERA dynamic stall models of lift, drag and pitching moment, and the wake dynamics is represented by a state-space wake model. The trim analysis of finding, the cyclic controls and the corresponding, periodic responses is based on periodic shooting with damped Newton iteration; the Floquet transition matrix (FTM) comes out as a byproduct. The stabillty analysis of finding the frequencies and damping levels is based on the eigenvalue-eigenvector analysis of the FTM. All the structural and aerodynamic states are included from modeling to trim analysis. A major finding is that dynamic wake dramatically improves the correlation for the lateral cyclic pitch control. Overall, the correlation is fairly good.
A Two-Bladed Teetering Hub configuration for the DTU 10 MW RWT: loads considerations
DEFF Research Database (Denmark)
Bergami, Leonardo; Aagaard Madsen, Helge; Rasmussen, Flemming
2014-01-01
, and the rotor solidity is kept constant by increasing the blade chord by 50 %. The configuration allows saving 30 % of the rotor weight and material, corresponding to one blade, but implies several complications: lower power output due to increased tip losses effects, and increased load variations. The increase...
A Two-Bladed Teetering Hub configuration for the DTU 10 MW RWT: loads considerations
DEFF Research Database (Denmark)
Bergami, Leonardo; Aagaard Madsen, Helge; Rasmussen, Flemming
, and the rotor solidity is kept constant by increasing the blade chord by 50 %. The configuration allows saving 30 % of the rotor weight and material, corresponding to one blade, but implies several complications: lower power output due to increased tip losses effects, and increased load variations. The increase...
Directory of Open Access Journals (Sweden)
Mohammad Jannati
2014-12-01
Full Text Available Nowadays, Field-Oriented Control (FOC strategies broadly used as a vector based controller for Single-Phase Induction Motors (SPIMs. This paper is focused on Direct Rotor FOC (DRFOC of SPIM. In the proposed technique, transformation matrices are applied in order to control the motor by converting the unbalanced SPIM equations to the balanced equations (in this paper the SPIM with two different stator windings is considered. Besides this control technique, a method for speed estimation of SPIM based on Extended Kalman Filter (EKF to achieve the higher performance of SPIM drive system is presented. Simulation results are provided to demonstrate the high performance of the presented techniques.
Driving and controlling molecular surface rotors with a terahertz electric field.
Neumann, Jan; Gottschalk, Kay E; Astumian, R Dean
2012-06-26
Great progress has been made in the design and synthesis of molecular motors and rotors. Loosely inspired by biomolecular machines such as kinesin and the FoF1 ATPsynthase, these molecules are hoped to provide elements for construction of more elaborate structures that can carry out tasks at the nanoscale corresponding to the tasks accomplished by elementary machines in the macroscopic world. Most of the molecular motors synthesized to date suffer from the drawback that they operate relatively slowly (less than kHz). Here we show by molecular dynamics studies of a diethyl sulfide rotor on a gold(111) surface that a high-frequency oscillating electric field normal to the surface can drive directed rotation at GHz frequencies. The maximum directed rotation rate is 10(10) rotations per second, significantly faster than the rotation of previously reported directional molecular rotors. Understanding the fundamental basis of directed motion of surface rotors is essential for the further development of efficient externally driven artificial rotors. Our results represent a step toward the design of a surface-bound molecular rotary motor with a tunable rotation frequency and direction.
Control of a Quadrotor Equipped with a Fixed-wing by Tilting Some of Four Rotors
Directory of Open Access Journals (Sweden)
Yoshikazu Nakamura
2017-03-01
Full Text Available Abstract—Unmanned aerial vehicles (UAVs are beingexpected to be used for the vegetational observation and theinformation collection of disaster sites. Especially, rotorcraftstypified by helicopters are attractive, because they are able tohover and achieve vertical take-off and landing (VTOL.However, rotorcrafts have a disadvantage that it cannot have along-distance flight, because they fly by the thrust of upwarddirection. Aircrafts with tilt rotors are developed in order toovercome such disadvantages. Such aircrafts can be hovering andtake a VTOL and also a long-distance flight by changing theangle of the rotor. In this research, it is aimed at proposing aVTOL-type UAV with a fixed-wing and four tiltable rotors andcontrolling it.
Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems
DEFF Research Database (Denmark)
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...
MICRO ROTOR ENHANCED BLOCK CIPHER DESIGNED FOR EIGHT BITS MICRO-CONTROLLERS (MREBC
Directory of Open Access Journals (Sweden)
Ahmed ElShafee
2013-09-01
Full Text Available The sensor network is a wireless network environment that consists of the many sensors of lightweight and low-power. Authentication between nodes is very vital for network reliability and the integrity ofinformation collected by these nodes. Therefore, encryption algorithm for the implementation of reliable sensor network environments is required to the applicable sensor network. This paper gives a newproposed cryptosystem (MREBC that is designed for 8 bits microcontroller systems. MREBC uses the concept of rotor enhanced block cipher which was initially proposed by the author in [NRSC 2002] on the first version of REBC. MREBC uses rotors to achieve two basic cryptographic operations; permutation,and substitution. Round key is generated using rotor too, which is used to achieve ciphertext key dependency. Rotors implemented using 8 bits successive affine transformation, which achieves memoryless,normalized ciphertext statistics, and small processing speed trend. The strength of this system is compared with the RIJNDAEL (AES cipher. MREBC cipher gives excellent results from security characteristics and statistical point of view of. communication efficiency of MREBC is compared with AESthrough measuring performance by plaintext size, and cost of operation per hop according to the network scale. Arduino microcontroller board is used to implement both MREBC, and AES in order to compare the performance of algorithms. Authors suggests to use MREBC to implement a reliable sensor network environments.
DEFF Research Database (Denmark)
Salazar, Jorge Andrés González; Santos, Ilmar
2017-01-01
This is part II of a twofold paper series dealing with the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting pad journal bearings (active TPJBs). In both papers theoretical and experimen......This is part II of a twofold paper series dealing with the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting pad journal bearings (active TPJBs). In both papers theoretical...... and experimental analyses are presented with focus on the reduction of rotor lateral vibration. This part is devoted to synthesising model-based LQG optimal controllers (LQR regulator + Kalman Filter) for the feedback-controlled lubrication and is based upon the mathematical model of the rotor-bearing system...... derived in part I. Results show further suppression of resonant vibrations when using the feedback-controlled or active lubrication, overweighting the reduction already achieved with hybrid lubrication, thus improving the whole machine dynamic performance....
DEFF Research Database (Denmark)
Bergami, Leonardo; Poulsen, Niels Kjølstad
2015-01-01
The paper proposes a smart rotor configuration where adaptive trailing edge flaps (ATEFs) are employed for active alleviation of the aerodynamic loads on the blades of the NREL 5 MW reference turbine. The flaps extend for 20% of the blade length and are controlled by a linear quadratic (LQ....... The effects of active flap control are assessed with aeroelastic simulations of the turbine in normal operation conditions, as prescribed by the International Electrotechnical Commission standard. The turbine lifetime fatigue damage equivalent loads provide a convenient summary of the results achieved...
Energy Technology Data Exchange (ETDEWEB)
Barrera, Pablo M. de la; Bossio, Guillermo R.; Garcia, Guillermo O. [Grupo de Electronica Aplicada (GEA), Facultad de Ingenieria, UNRC, Ruta Nacional 36 Km. 601, X5804BYA, Rio Cuarto (Argentina); Solsona, Jorge A. [Instituto de Investigaciones en Ingenieria Electrica ' ' Alfredo Desages' ' , Departamento de Ingenieria Electrica y de Computadoras, UNS, Av. Alem 1253 (8000) Bahia Blanca (Argentina)
2008-10-15
A rotor flux state observer considering iron loss, for an Induction Motor (IM), is proposed. The aim of this proposal is to avoid detuning caused by the IM iron loss on a field-oriented control (FOC). An adaptive scheme for the K{sub Fe}, a parameter that represents the IM iron loss, is also proposed. The main objective of this scheme is to improve the dynamic response of control by compensating the variations of iron losses due to possible variations in the stator core characteristics. Simulation results demonstrated that the observer and the adaptive scheme showed a good performance fulfilling then the objectives. (author)
Institute of Scientific and Technical Information of China (English)
Long DI; Zongli LIN
2014-01-01
Active magnetic bearings (AMBs) have found a wide range of applications in high-speed rotating machinery industry. The instability and nonlinearity of AMBs make controller designs difficult, and when AMBs are coupled with a flexible rotor, the resulting complex dynamics make the problems of stabilization and disturbance rejection, which are critical for a stable and smooth operation of the rotor AMB system, even more difficult. Proportional-integral-derivative (PID) control dominates the current AMB applications in the field. Even though PID controllers are easy to implement, there are critical performance limitations associated with them that prevent the more advanced applications of AMBs, which usually require stronger robustness and performance offered by modern control methods such as H-infinity control andμ-synthesis. However, these advanced control designs rely heavily on the relatively accurate plant models and uncertainty characterizations, which are sometimes difficult to obtain. In this paper, we explore and report on the use of the characteristic model based all-coefficient adaptive control method to stabilize a flexible rotor AMB test rig. In spite of the simple structure of such a characteristic model based all-coefficient adaptive controller, both simulation and experimental results show its strong performance.
Energy Technology Data Exchange (ETDEWEB)
Holenemser, K.H. [Washington Univ., St. Louis, MO (United States)
1995-10-01
This report surveys the analysis and tests performed at Washington University in St. Louis, Missouri, on a horizontal-axis, two-laded wind turbine with teeter hub. The introduction is a brief account of results obtained during the 5-year period ending December 1985. The wind tunnel model and the test turbine (7.6 m [25 ft.] in diameter) at Washington University`s Tyson Research Center had a 67{degree} delta-three angle of the teeter axis. The introduction explains why this configuration was selected and named the passive cycle pitch (PCP) wind turbine. Through the analysis was not limited to the PCP rotor, all tests, including those done from 1986 to 1994, wee conducted with the same teetered wind rotor. The blades are rather stiff and have only a small elastic coning angle and no precone.
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
Control method of high-speed switched reluctance motor with an asymmetric rotor magnetic circuit
Directory of Open Access Journals (Sweden)
Bogusz Piotr
2016-12-01
Full Text Available In the paper, the modified (compared to the classical asymmetric half-bridge converter for a switched reluctance machine with an asymmetric rotor magnetic circuit was analysed. An analysis for two various structures of switched reluctance motors was conducted. The rotor shaping was used to obtain required start-up torque or/and to obtain less electromagnetic torque ripple. The discussed converter gives a possibility to turn a phase off much later while reduced time of a current flows in a negative slope of inductance. The results of the research in the form of waveforms of currents, voltages and electromagnetic torque were presented. Conclusions were formulated concerning the comparison of the characteristics of SRM supplied by the classic converter and by the one supplied by the analysed converter.
Tang, Jiqiang; Xiang, Biao; Zhang, Yongbin
2014-07-01
For a magnetically suspended control moment gyroscope, stiffness and damping of magnetic bearing will influence modal frequency of a rotor. In this paper the relationship between modal frequency and stiffness and damping has been investigated. The mathematic calculation model of axial passive magnetic bearing (PMB) stiffness is developed. And PID control based on internal model control is introduced into control of radial active magnetic bearing (AMB), considering the radial coupling of axial PMB, a mathematic calculation model of stiffness and damping of radial AMB is established. According to modal analysis, the relationship between modal frequency and modal shapes is achieved. Radial vibration frequency is mainly influenced by stiffness of radial AMB; however, when stiffness increases, radial vibration will disappear and a high frequency bending modal will appear. Stiffness of axial PMB mainly affects the axial vibration mode, which will turn into high-order bending modal. Axial PMB causes bigger influence on torsion modal of the rotor. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Doorenspleet, F. [Aerpac Special Products B.V., Amelo (Netherlands); Prats, J. [Ecotecnia S. Coop, Barcelona (Spain); Hagg, F. [Stork Product Engineering B.V. Amsterdam (Netherlands)
1996-12-31
Improvement of the price/performance ratio of wind turbines is essential if wind energy is to be taken seriously in the world energy market in the coming century. The key to improvement of the price/performance ratio lies in the minimisation of loads by inexpensive means, at a simultaneous increase in annual production of the wind turbine. On basis of the NOVEM/CEC Flexhat project, this design project is a first step towards commercialisation of flexible rotor technology. The goal of the project was to redesign an existing stall-regulated wind turbine to improve the original price/performance ratio by 20%. This goal has been reached by the use of a larger, two-bladed rotor with elastomeric tester, variable speed drivetrain and fast active tip pitch control with an advanced peakshaving function. The project has been sponsored by the European Commission under contract nr. Jou2CT93-0281. (author)
Directory of Open Access Journals (Sweden)
Shahida Khatoon
2013-12-01
Full Text Available In this research a prototype experimental Quad-rotor type UAV have been assembled using low cost components easily available in the Indian market. The quad-copter is used for testing a novel autonomous flight control strategy developed using embedded system. In order to enable a mini-UAV to perform target acquisition, localization and continuous surveillance in real world environment one must develop a technology which may be a combination of aircraft engineering, control systems, and wireless communication. The major limiting factors in developing the capabilities of small low cost UAVs are connectivity, computational processing power and lack of resource integration. To overcome these limitations in this research we have tried to assemble an experimental quad-rotor prototype UAV capable of being remotely controlled in the range of 20 meter, which is specifically designed as an economical, moderately functional, small airborne platform intended to meet the requirement for fast-response to time-critical events in many small private sectors or government agencies. The experimental prototype quad-copter has been successfully implemented and tested for 15 minutes smooth flight time.
Papavassiliou, I.; Venkatesan, C.; Friedmann, P. P.
1990-01-01
A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computing facility. The details of the derivation using the MACSYMA program are described. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control (HHC) capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselage vibrations a new scheme called multiple higher harmonic control (MHHC) is required. The fundamental aspects of this scheme and its uniqueness are described in detail, providing new insight on vibration reduction in helicopters using HHC.
Energy Technology Data Exchange (ETDEWEB)
Song, Jun Beom [Dept. of Aviation Maintenance, Dongwon Institute of Science and Technology, Yangsan (Korea, Republic of); Byun, Young Seop; Jeong, Jin Seok; Kim, Jeong; Kang, Beom Soo [Dept. of Aerospace Engineering, Pusan National University, Busan (Korea, Republic of)
2016-11-15
This paper proposes a cascaded control structure and a method of practical application for attitude control of a multi-rotor Unmanned aerial vehicle (UAV). The cascade control, which has tighter control capability than a single-loop control, is rarely used in attitude control of a multi-rotor UAV due to the input-output relation, which is no longer simply a set-point to Euler angle response transfer function of a single-loop PID control, but there are multiply measured signals and interactive control loops that increase the complexity of evaluation in conventional way of design. However, it is proposed in this research a method that can optimize a cascade control with a primary and secondary loops and a PID controller for each loop. An investigation of currently available PID-tuning methods lead to selection of the Simple internal model control (SIMC) method, which is based on the Internal model control (IMC) and direct-synthesis method. Through the analysis and experiments, this research proposes a systematic procedure to implement a cascaded attitude controller, which includes the flight test, system identification and SIMC-based PID-tuning. The proposed method was validated successfully from multiple applications where the application to roll axis lead to a PID-PID cascade control, but the application to yaw axis lead to that of PID-PI.
Indian Academy of Sciences (India)
ARCHANA SHUKLA; SRIHARI KESHAVAMURTHY
2017-07-01
The present work aims to control the rotational excitations of an ac-driven planar rotor, a model for rigid diatomic molecules, by rebuilding barriers in the classical phase space. The barriers are invariant tori with irrational winding ratios which are perturbatively constructed at desired locations in the phase space. Weestablish that constructing such barriers, equivalent to additional weak fields, can efficiently suppress the chaos leading to the control of various processes. The phase space barriers are shown to be effective in controlling the quantum dynamics as well. In particular, the efficiency of the phase space barriers towards controlling dynamical tunneling in the system is explored. Our studies are relevant to understanding the role of the chaotic regions in dynamical tunneling and for molecular alignment using bichromatic fields.
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
Fan, G.W. (3-I Scientific Development Inc., Tempe, AZ (United States)); Nelson, H.D. (Texas Christian Univ., Fort Worth (United States)); Crouch, P.E.; Mignolet, M.P. (Arizona State Univ., Tempe (United States))
1993-04-01
The complex mode and balanced realization methods are used separately to obtain reduced-order models for general linear asymmetric rotor systems. The methods are outlined and then applied to a typical rotor system represented by a 52 degree-or-freedom finite element model. The accuracy of the two methods is compared for this model and the complex model method is found to be more accurate than the balanced realization method for the desired frequency bandwidth and for models of the same reduced order. However, with some limitations, it is also shown that the balanced realization method can be applied to the reduced-order complex mode model to obtain further order reduction without loss of model accuracy. A Linear-Quadratic-Regulator-based least-squares output feedback control procedure is developed for the vibration control of rotor systems. This output feedback procedure eliminates the requirement of an observer for the use of an LQ regulator, and provides the advantage that the rotor vibration can be effectively controlled by monitoring only one single location along the rotor shaft while maintaining an acceptable performance. The procedures presented are quite general and may be applied to a large class of vibration problems including rotordynamics.
Increased Power Capture by Rotor Speed–Dependent Yaw Control of Wind Turbines
DEFF Research Database (Denmark)
Kragh, Knud Abildgaard; Fleming, Paul A.; Scholbrock, Andrew K.
2013-01-01
When extracting energy from the wind using upwind, horizontal-axis wind turbines, a primary condition for ensuring maximum power yield is the ability to align the rotor axis with the dominating wind direction. Attempts have been made to improve the yaw alignment of wind turbines by applying...... and tested. Results show that, with the correction scheme in place, the yaw alignment of the case turbine is improved and the yaw error is reduced to the vicinity of zero degrees. As a result of the improved yaw alignment, an increased power capture is observed for below-rated wind speeds....
Directory of Open Access Journals (Sweden)
Roman Czyba
2013-01-01
Full Text Available The aim of this research is to examine the different control strategies for the unmanned aerial vehicles (UAV. The control task is formulated as an angular stabilization of the four rotor platform, and also as a tracking problem of chosen state variables. The PID algorithm has been considered in three structures in respect of the optimal control signal applied to the actuators. For better performance of the quadrotor in hover mode the cascade control system has been proposed. The simulation results of attitude control with different PID controller architectures are presented, and confirm the effectiveness of the proposed control structure and theoretical expectations. Moreover, the design and the practical realization of the control architecture on the experimental aerial vehicle are described. The fast prototyping method together with Matlab/Simulink software and DAQ hardware are used for both evolution and validation of control algorithms. The capacity of the attitude stabilization system is important in the development process of more advanced functionality of autonomous flying vehicles; therefore it needs to be highlighted and taken into careful consideration.
Energy Technology Data Exchange (ETDEWEB)
Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL
2015-01-01
Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.
Millott, T. A.; Friedmann, P. P.
1994-01-01
This report describes an analytical study of vibration reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The vibration reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced vibration reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the vibration reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to vibration reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.
DEFF Research Database (Denmark)
Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar
2016-01-01
The lack of damping of radial gas bearings leads to high vibration levels of a rotor supported by this type of bearing when crossing resonant areas. This is even more relevant for flexible rotors, as studied in this work. In order to reduce these high vibration levels, an active gas bearing is pr...
ROTOR UNBALANCE LOAD CONTROL OF WIND TURBINE BASED ON UNIVERSAL MODEL%基于泛模型的风轮不平衡载荷控制
Institute of Scientific and Technical Information of China (English)
王晓东; 姚兴佳
2012-01-01
针对大型变速变桨风电机组风轮的非线性特征和难以建立精确模型的问题,设计了一种基于泛模型的风轮不平衡载荷自适应控制器.根据传感器测量的叶根载荷,对3个叶片进行独立变桨控制,通过3个叶片的桨距角差异来减小风轮的不平衡载荷.在此基础上,以双馈变速变桨机组为对象,通过仿真对该控制器进行了测试,结果表明该方法用于减小风轮的不平衡载荷是可行且有效的.%With the increasing of wind turbine size and rotor diameter, the wind shear, turbulence and tower shadow more and more affect the load of large scale turbine. Dynamic unbalance load become a key in large scale wind turbine design. It is approved that the pitch control can impact on the rotor loads. Considering the difficulty to build the exact model and non-linear character of rotor, an individual controller banded on universal model was developed in to mitigate the rotor unbalance load for variable speed wind turbine. The controller adjusts the pitch angle of three blades individually based on the measurement load. The pitch angle difference could reduce the effect of wind diversification in the rotor plane. The controller was simulated based on a doubly fed variable speed wind turbine model. The simulation result verified that it is feasible and effective.
Blackwell, Mark W.; Tutty, Owen R.; Rogers, Eric; Sandberg, Richard D.
2016-01-01
The inclusion of smart devices in wind turbine rotor blades could, in conjunction with collective and individual pitch control, improve the aerodynamic performance of the rotors. This is currently an active area of research with the primary objective of reducing the fatigue loads but mitigating the effects of extreme loads is also of interest. The aerodynamic loads on a wind turbine blade contain periodic and non-periodic components and one approach is to consider the application of iterative learning control algorithms. In this paper, the control design is based on a simple, in relative terms, computational fluid dynamics model that uses non-linear wake effects to represent flow past an airfoil. A representation for the actuator dynamics is included to undertake a detailed investigation into the level of control possible and on how performance can be effectively measured.
Smart rotor modeling aero-servo-elastic modeling of a smart rotor with adaptive trailing edge flaps
Bergami, Leonardo
2014-01-01
A smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators actively reduces the variation of the aerodynamic loads it has to withstand. Smart rotors feature?promising load alleviation potential and might provide the technological breakthrough required by the next generation of large wind turbine rotors.The book presents the aero-servo-elastic model of a smart rotor with Adaptive Trailing Edge Flaps for active load alleviation and provides an insight on the rotor aerodynamic, structural and control modeling. A novel model for the unsteady aerodynam
Design of Robust AMB Controllers for Rotors Subjected to Varying and Uncertain Seal Forces
DEFF Research Database (Denmark)
Lauridsen, Jonas Skjødt; Santos, Ilmar
2017-01-01
, and experimental results. Three controllers are synthesized: I) AnH∞ controller based on nominal plant representation, II) A µ controller, designed to be robust against uncertaintiesin the dynamic seal model and III) a Linear Parameter Varying (LPV) controller, designed to provide a unifiedperformance over a large...
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.
Fine tuning of molecular rotor function in photochemical molecular switches
ter Wiel, Matthijs K. J.; Feringa, Ben L.
2009-01-01
Molecular switches are used as scaffolds for the construction of controlled molecular rotors. The internal position of the switching entity in the molecule controls the dynamic behaviour of the rotor moiety in the molecule. Six new molecular motors with o-xylyl rotor moieties were prepared on the ba
Intelligent Controller Design for Quad-Rotor Stabilization in Presence of Parameter Variations
Directory of Open Access Journals (Sweden)
Oualid Doukhi
2017-01-01
Full Text Available The paper presents the mathematical model of a quadrotor unmanned aerial vehicle (UAV and the design of robust Self-Tuning PID controller based on fuzzy logic, which offers several advantages over certain types of conventional control methods, specifically in dealing with highly nonlinear systems and parameter uncertainty. The proposed controller is applied to the inner and outer loop for heading and position trajectory tracking control to handle the external disturbances caused by the variation in the payload weight during the flight period. The results of the numerical simulation using gazebo physics engine simulator and real-time experiment using AR drone 2.0 test bed demonstrate the effectiveness of this intelligent control strategy which can improve the robustness of the whole system and achieve accurate trajectory tracking control, comparing it with the conventional proportional integral derivative (PID.
Dag A. H. Samuelsen; Olaf H. Graven
2012-01-01
Engineering students in a module on multivariable control theory are given a laboratory exercise for developing their skills in practical implementation of control systems. This is done in an effort to create a more complete module that gives the students experiences in the practical sides of implementing control systems, while still being theoretically challenging and inspiring. Presenting students with this kind of real-life challenges like sub-optimal models, limited processing time and la...
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
3D Warping Actuation Driven Dynamic Camber Control Concept for Helicopter Rotor Blades Project
National Aeronautics and Space Administration — In a rotorcraft, optimized camber change not only reduces vibratory hub loads and noise but also increases available thrust and improved flight control augmentation....
Institute of Scientific and Technical Information of China (English)
Wahyu Kunto Wibowo; Seok-Kwon Jeong
2016-01-01
This work proposes a new strategy to improve the rotor position estimation of a permanent magnet synchronous motor (PMSM) over wide speed range. Rotor position estimation of a PMSM is performed by using sliding mode observer (SMO). An adaptive observer gain was designed based on Lyapunov function and applied to solve the chattering problem caused by the discontinuous function of the SMO in the wide speed range. The cascade low-pass filter (LPF) with variable cut-off frequency was proposed to reduce the chattering problem and to attenuate the filtering capability of the SMO. In addition, the phase shift caused by the filter was counterbalanced by applying the variable phase delay compensation for the whole speed area. High accuracy estimation result of the rotor position was obtained in the experiment by applying the proposed estimation strategy.
Attitude Control of Quad-rotor by Improving the Reliability of Multi-Sensor System
Energy Technology Data Exchange (ETDEWEB)
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.
Control of quantum localization and classical diffusion in laser-kicked molecular rotors
Bitter, M.; Milner, V.
2017-01-01
We experimentally study a system of quantum kicked rotors—an ensemble of diatomic molecules exposed to a periodic sequence of ultrashort laser pulses. In the regime where the underlying classical dynamics is chaotic, we investigate the quantum phenomenon of dynamical localization by means of state-resolved coherent Raman spectroscopy. We examine the dependence of the exponentially localized angular momentum distribution and of the total rotational energy on the time period between the pulses and their amplitude. The former parameter is shown to provide control over the localization center, whereas the latter one controls the localization length. Similar control of the center and width of a nonlocalized rotational distribution is demonstrated in the limit of classical diffusion, established by adding noise to the periodic pulse sequence.
Manchala, Daniel W.; Palazzolo, Alan B.; Kascak, Albert F.; Montague, Gerald T.; Brown, Gerald V.; Lawrence, Charles; Klusman, Steve
1994-01-01
Jet Engines may experience severe vibration due to the sudden imbalance caused by blade failure. This research investigates employment of on board magnetic bearings or piezoelectric actuators to cancel these forces in flight. This operation requires identification of the source of the vibrations via an expert system, determination of the required phase angles and amplitudes for the correction forces, and application of the desired control signals to the magnetic bearings or piezo electric actuators. This paper will show the architecture of the software system, details of the control algorithm used for the sudden imbalance correction project described above, and the laboratory test results.
Manchala, Daniel W.; Palazzolo, Alan B.; Kascak, Albert F.; Montague, Gerald T.; Brown, Gerald V.; Lawrence, Charles; Klusman, Steve
1994-01-01
Jet Engines may experience severe vibration due to the sudden imbalance caused by blade failure. This research investigates employment of on board magnetic bearings or piezoelectric actuators to cancel these forces in flight. This operation requires identification of the source of the vibrations via an expert system, determination of the required phase angles and amplitudes for the correction forces, and application of the desired control signals to the magnetic bearings or piezo electric actuators. This paper will show the architecture of the software system, details of the control algorithm used for the sudden imbalance correction project described above, and the laboratory test results.
Motion control of a rotor with a cavity with a viscous fluid
Gurchenkov, A. A.; Esenkov, A. S.; Tsurkov, V. I.
2007-01-01
A formulation and solution procedure of optimal control problems for perturbed relative uniform motion of a body with a cavity filled with a viscous incompressible fluid are proposed. In this paper, the case with a cylinder is considered; however, this approach is basically true for the a cavity of
Directory of Open Access Journals (Sweden)
Dag A. H. Samuelsen
2012-12-01
Full Text Available Engineering students in a module on multivariable control theory are given a laboratory exercise for developing their skills in practical implementation of control systems. This is done in an effort to create a more complete module that gives the students experiences in the practical sides of implementing control systems, while still being theoretically challenging and inspiring. Presenting students with this kind of real-life challenges like sub-optimal models, limited processing time and large degree of uncertainty, is a challenging task, partly due to the need of adapting the level of complexity to the student or group of students doing the exercise in order to keep them engaged throughout the exercise, and in part due to the university's need to reduce expenses related to the administration, supervision, and execution of laboratory exercises. The possibility of adapting the complexity of the exercise to each student's skill level is important, both through the design of the exercise and through the students choosing between different models. The eager student might be tempted by the better performing, but more complex models, while the struggling student can find satisfaction in stabilising the aircraft using the less complex models. The laboratory setup presented uses low-cost components, giving low investment and maintenance costs.
Directory of Open Access Journals (Sweden)
Dag A. H. Samuelsen
2012-12-01
Full Text Available Engineering students in a module on multivariable control theory are given a laboratory exercise for developing their skills in practical implementation of control systems. This is done in an effort to create a more complete module that gives the students experiences in the practical sides of implementing control systems, while still being theoretically challenging and inspiring. Presenting students with this kind of real-life challenges like sub-optimal models, limited processing time and large degree of uncertainty, is a challenging task, partly due to the need of adapting the level of complexity to the student or group of students doing the exercise in order to keep them engaged throughout the exercise, and in part due to the university's need to reduce expenses related to the administration, supervision, and execution of laboratory exercises. The possibility of adapting the complexity of the exercise to each student's skill level is important, both through the design of the exercise and through the students choosing between different models. The eager student might be tempted by the better performing, but more complex models, while the struggling student can find satisfaction in stabilising the aircraft using the less complex models. The laboratory setup presented uses low-cost components, giving low investment and maintenance costs.
Shen, Yang-Wu; Ke, De-Ping; Sun, Yuan-Zhang; Daniel, Kirschen; Wang, Yi-Shen; Hu, Yuan-Chao
2015-07-01
A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator (DFIG) equipped with a superconducting magnetic energy storage (SMES) device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter (GSC) is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter (RSC) has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive (priority) and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method. Project supported by the National Natural Science Foundation of China (Grant No. 51307124) and the Major Program of the National Natural Science Foundation of China (Grant No. 51190105).
Diepeveen, N.F.B.; Jarquin Laguna, A.
2012-01-01
As alternative to geared and direct drive solutions, fluid power drive trains are being developed by several institutions around the world. The common configuration is where the wind turbine rotor is coupled to a hydraulic pump. The pump is connected through a high pressure line to a hydraulic motor
DEFF Research Database (Denmark)
Smit, Jeroen; Berghammer, Lars O.; Navalkar, Sachin;
2014-01-01
In this paper an extension of the spectrum of applicability of rotors with active aerody-namic devices is presented. Besides the classical purpose of load alleviation, a secondary objective is established: power capture optimization. As a _rst step, wind speed regions that contribute little...
DEFF Research Database (Denmark)
Smit, Jeroen; Bernhammer, Lars O.; Navalkar, Sachin T.;
2016-01-01
An extension of the spectrum of applicability of rotors with active aerodynamic devices is presented in this paper. Besides the classical purpose of load alleviation, a secondary objective is established: optimization of power capture. As a first step, wind speed regions that contribute little...
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.
Napsholm, Svein Rivli
2013-01-01
The use of drones and remote operated aircrafts has become a useful tool for the oil and mining industry, when searching for new production areas. The remote controlled aircrafts can perform some of the tasks during these operations such as deploy sensors, gather geographical data and perform area inspections. The smaller and cheaper aircrafts are a cost and time effective solution compared to using bigger helicopters and air planes. In this master thesis, it is proposed a new type of remote ...
基于anti-windup技术的四旋翼模糊PID控制%Fuzzy PID Control of Quad-Rotor Aircraft Based on Anti-windup Technology
Institute of Scientific and Technical Information of China (English)
耿玉豪; 肖文生; 崔俊国; 王鸿雁
2016-01-01
When quad-rotor aircraft is trapped in the great disturbance of wind, windup phenomenon may appear for simple PID controller, under the combined action of integration element and saturation limit element. Thus may lead to deterioration of system’s dynamic responses, and big overshoot or imbalance of quad-rotor. A dynamics simulation model is established for the quad-rotor aircraft, and the causes of windup phenomenon are analyzed. An anti-windup PID controller with fuzzy variable parameters is designed to alleviate the windup phenomenon. Contrastive analysis is made to the controller with the existing fuzzy PID controller and the anti-windup PID controller with constant parameters. The results of simulation indicate that, the fuzzy PID controller based on anti-windup technology can effectively restrain the windup phenomenon, and speed up the attitude adjustment process of quad-rotor.%四旋翼飞行器在受到风力等大扰动的情况下，单纯的PID控制受到积分环节和饱和限幅环节的共同作用，容易产生windup现象，系统动态响应变差，造成飞行器大超调甚至失调。通过建立四旋翼飞行器的动力学仿真模型，分析了windup现象产生的原因，设计了参数模糊可变的anti-windup PID控制器，用于缓解windup现象。对比分析了该控制器与现有的模糊PID控制器、参数为定值的anti-windup PID控制器的性能，仿真结果表明，基于anti-windup技术的模糊PID控制器，能够更加有效地抑制windup现象，加快飞行器的姿态调节过程。
Directory of Open Access Journals (Sweden)
Xuan Wu
2015-10-01
Full Text Available The accurate information of the initial rotor position is very critical for successful starting of the Surface-mounted Permanent Magnet Synchronous Motor (SPMSM. In order to solve the problems of low accuracy and unreliability in the conventional estimation strategy, in this paper, an improved initial rotor position estimation strategy without any position sensor for SPMSM at standstill is proposed based on rectangular pulse voltage injection. In the work, when the second series of pulse voltages were applied. By the ways of strengthening the effect of weakening or strengthening magnetic fields and increasing the difference between each current of the vector. The improved strategy enhanced reliability and raised the initial position estimation accuracy from 7.5° to 1.875°. The improved strategy does not need any additional hardware. Experimental results demonstrate the validity and usefulness of the improved strategy.
Energy Technology Data Exchange (ETDEWEB)
Sigloch, U. [ebm-papst Mulfingen GmbH und Co. KG (Germany). Projektmanagement Vertrieb Europa; Reiff, E.C. [Redaktionsbuero Stutensee (Germany)
2008-07-01
Compact drum rotor blowers with forward-curved blades are quite common in air conditioning and ventilation because of their high efficiency and compact dimensions. They are found in air conditioner boxes, in air current systems in department stores, or in fan coils in hotel rooms, wherever other types of blowers would be too big. Until recently, EC technology was not available for the blower motors so the users had do accept low efficiency and the poor control options of conventional AC drives. This has changed by now. (orig.)
Flores Colunga, Gerardo Ramon; Aguilar-Sierra, Hipolito; Lozano, Rogelio; Salazar, Sergio
2014-01-01
International audience; This work addresses the problem of fault detection and diagnosis (FDD) for a quad-rotor mini aerial vehicle (MAV). Actuator faults are considered on this paper. The basic idea behind the proposed method is to estimate the faults signals using the extended state observers theory. To estimate the faults, a polynomial observer is presented by using the available measurements and know inputs of the system. In order to investigate the observability and diagnosability proper...
Directory of Open Access Journals (Sweden)
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
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.
Institute of Scientific and Technical Information of China (English)
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.
双转式永磁无刷电动机的控制%Control of Dual-Rotor Permanent Magnet Brushless Motors
Institute of Scientific and Technical Information of China (English)
何苗
2009-01-01
Mathematical model and closed-loop speed control strategies of dual-rotor permanent magnet brushless motors were analyzed. A set of software and hardware control system was designed based on the chip of TMS320F2407, which was tested finally. The final testing data indicates that the control system can achieve preferable performance and high control precision.%在普通永磁无刷电动机基础上,分析了双转式永磁无刷电动机的数学模型及速度闭环控制策略,并在该基础上建立以TMS320F2407为核心的闭环控制软硬件系统,并进行了试验.试验结果表明该种控制系统控制性能较好,控制精度较高.
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
Energy Technology Data Exchange (ETDEWEB)
Pierce, K. [Univ. of Utah, Salt Lake City, UT (United States)
1997-12-31
A two bladed, variable speed and variable pitch wind turbine was modeled using ADAMS{reg_sign} to evaluate load reduction abilities of a variable coning configuration as compared to a teetered rotor, and also to evaluate control methods. The basic dynamic behavior of the variable coning turbine was investigated and compared to the teetered rotor under constant wind conditions as well as turbulent wind conditions. Results indicate the variable coning rotor has larger flap oscillation amplitudes and much lower root flap bending moments than the teetered rotor. Three methods of control were evaluated for turbulent wind simulations. These were a standard IPD control method, a generalized predictive control method, and a bias estimate control method. Each control method was evaluated for both the variable coning configuration and the teetered configuration. The ability of the different control methods to maintain the rotor speed near the desired set point is evaluated from the RMS error of rotor speed. The activity of the control system is evaluated from cycles per second of the blade pitch angle. All three of the methods were found to produce similar results for the variable coning rotor and the teetered rotor, as well as similar results to each other.
转子磁链定向的矢量控制系统的研究%Study of Rotor Flux Oriented Vector Control System
Institute of Scientific and Technical Information of China (English)
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.
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.
Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model
DEFF Research Database (Denmark)
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...
Directory of Open Access Journals (Sweden)
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.
Rotor dynamic analysis of main coolant pump
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
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)
SMART wind turbine rotor. Data analysis and conclusions
Energy Technology Data Exchange (ETDEWEB)
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.
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...
Energy Technology Data Exchange (ETDEWEB)
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.
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.
SMART wind turbine rotor. Design and field test
Energy Technology Data Exchange (ETDEWEB)
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.
Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine
Institute of Scientific and Technical Information of China (English)
陈虎; 潘存云; 徐海军; 邓豪; 韩晨
2014-01-01
Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratioλ, and the position of rod swing center is controlled by eccentricitye. In order to reduce the lateral force, a smaller value ofλshould be selected in the case of the structure, and the value ofe should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.
Performance of meta power rotor shaft torque meter
DEFF Research Database (Denmark)
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....
Institute of Scientific and Technical Information of China (English)
梁兵
2001-01-01
使用MATLAB/SIMULINK语言建立三相异步电机直接转矩控制仿真模型。通过对不同转子电阻在直接转矩控制下得到的电机转速和定子磁链图形的分析比较，得出了转子电阻变化对交流异步电机直接转矩控制没有影响的结论。%Simulation model is built up for direct self control of 3-phaseasynchronous motor using MATLAB/SIMULINK software. By analysis and comparison of motor rotating speed and stator magnetic flux linkage diagram under direct self control at different rotor resistance, the conclusion is shown that the rotor resistance variation will exert no influence on the direct self control for ac asynchronous motor.
Response studies of rotors and rotor blades with application to aeroelastic tailoring
Friedmann, P. P.
1982-01-01
Various tools for the aeroelastic stability and response analysis of rotor blades in hover and forward flight were developed and incorporated in a comprehensive package capable of performing aeroelastic tailoring of rotor blades in forward flight. The results indicate that substantial vibration reductions, of order 15-40%, in the vibratory hub shears can be achieved by relatively small modifications of the initial design. Furthermore the optimized blade can be up to 20% lighter than the original design. Accomplishments are reported for the following tasks: (1) finite element modeling of rotary-wing aeroelastic problems in hover and forward flight; (2) development of numerical methods for calculating the aeroelastic response and stability of rotor blades in forward fight; (3) formulation of the helicopter air resonance problem in hover with active controls; and (4) optimum design of rotor blades for vibration reduction in forward flight.
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
Institute of Scientific and Technical Information of China (English)
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
ADRC-GPC control of a quad-rotor unmanned aerial vehicle%四旋翼无人飞行器ADRC-GPC控制
Institute of Scientific and Technical Information of China (English)
陈增强; 李毅; 孙明玮; 张青; 孙青林
2016-01-01
Aiming to the attitude control system of quad⁃rotor unmanned aerial vehicles, advanced control scheme should be studied to obtain the satisfied performance. A novel active disturbance rejection generalized predictive control ( ADRC⁃GPC) is presented by combining the technique of active disturbance rejection control ( ADRC) and generalized predictive control ( GPC) . The extended state observer ( ESO) of active disturbance rejection control is employed to estimate and compensate the existing uncertainties and disturbance of the nonlinear dynamics systems, such that an integrator form can be obtained to serve as the model for GPC design. By using this scheme, the step response coefficient matrix can be derived analytically and the computational complexity can be substantially reduced. The experiment results show that the designed ADRC-GPC scheme can be applied in the real⁃time control for the attitude system of the quad⁃rotor unmanned aerial vehicle ( UAV) , it can not only meet the need of control accuracy and rapidity, but also have strong disturbance rejection ability and stability. Therefore, the proposed active disturbance rejection generalized predictive control scheme can be used to control under⁃actuated nonlinear multivariable plants effectively.%针对四旋翼无人飞行器的姿态控制系统，需要研究先进控制策略来达到满意的性能。将自抗扰控制（ ADRC）与广义预测控制（ GPC）相结合，设计一种新型自抗扰广义预测控制器（ ADRC⁃GPC），利用ADRC中的扩张状态观测器（ ESO）来估计和补偿非线性系统的模型不确定性以及外部扰动作用，将原始对象模型转化为积分器形式，然后针对积分器设计广义预测控制器。阶跃响应系数矩阵能被解析地求解出来，可有效地解决广义预测控制计算量大的问题。研究结果表明：所提出的ADRC－GPC控制方法能够对四旋翼无人飞行器姿态系统进行实时控制，
Modeling and Position Tracking Control for Six-Rotors%六旋翼飞行器建模及位置跟踪控制
Institute of Scientific and Technical Information of China (English)
王伟; 邱启明
2014-01-01
为实现六旋翼的位置跟踪与控制功能，对六旋翼飞行器的数学模型进行了分析，通过线性化得到了其简单数学模型。在简化的数学模型基础之上设计了基于PID(比例-积分-微分控制器)控制算法的姿态控制器和位置控制器，控制器仿真结果表明位置跟踪误差小于2%。飞行实验中飞行器准确追踪给定的姿态角精度大于80%，飞行器性能稳定，实现方法合理。%In order to accomplish control functions,a simple mathematical model was achieved after the model of six-rotor unmanned aerial( UAVs) vehicle was analyzed and linearnized. Attitude controller and position controller was designed based on PID ( Proportional-Integral-Derivative ) control algorithm and the simply mathematical mentioned above. The results of simulation putted on position controller showed that position error is less than two percent. The degree of accuracy on the fact that the reference input was correctly traced by UAVs is greater than eighty percent during the flight test. The performance is stable,and the implementation method is reasonable.
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.
Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo
2016-05-01
In this paper, phase and speed synchronization control of four eccentric rotors (ERs) driven by induction motors in a linear vibratory feeder with unknown time-varying load torques is studied. Firstly, the electromechanical coupling model of the linear vibratory feeder is established by associating induction motor's model with the dynamic model of the system, which is a typical under actuated model. According to the characteristics of the linear vibratory feeder, the complex control problem of the under actuated electromechanical coupling model converts to phase and speed synchronization control of four ERs. In order to keep the four ERs operating synchronously with zero phase differences, phase and speed synchronization controllers are designed by employing adaptive sliding mode control (ASMC) algorithm via a modified master-slave structure. The stability of the controllers is proved by Lyapunov stability theorem. The proposed controllers are verified by simulation via Matlab/Simulink program and compared with the conventional sliding mode control (SMC) algorithm. The results show the proposed controllers can reject the time-varying load torques effectively and four ERs can operate synchronously with zero phase differences. Moreover, the control performance is better than the conventional SMC algorithm and the chattering phenomenon is attenuated. Furthermore, the effects of reference speed and parametric perturbations are discussed to show the strong robustness of the proposed controllers. Finally, experiments on a simple vibratory test bench are operated by using the proposed controllers and without control, respectively, to validate the effectiveness of the proposed controllers further.
Diagnosis of wind turbine rotor system
DEFF Research Database (Denmark)
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....
Rotor Vibration Reduction via Active Hybrid Bearings
DEFF Research Database (Denmark)
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...
Directory of Open Access Journals (Sweden)
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.
Institute of Scientific and Technical Information of China (English)
闫晓磊; 钟志华; 张义; 孙光永
2012-01-01
To overcome the shortcoming that the calculation efficiency of the ordinary method is low in the flywheel rotor shape optimization, adopting the optimal control theory, brief analytic expressions of the optimal rotor shapes are gained directly based on analyzing the effects of rotating speed on the rotor shapes and dividing it into low, medium and high speed intervals. Through comparing the optimal shapes of the isotropic solid and hollow rotors at low, medium and high speed respectively, variations of the shapes with the rotating speed are revealed. The results indicate that at low rotating speed, the optimal shape of the flywheel rotor has a characteristic of "inner thin, outer thick" along the radial direction, at medium rotating speed, the optimal shape is "inner thick, outer thin", and at high rotating speed, it is "inner and outer thick, middle thin". At low rotating speed, the optimal shapes of the solid and hollow rotors are similar. However, at medium and high rotating speed, the hollow rotor optimal shape does not have constant stress arc as well as the one of the solid rotor. Because of containing the constant stress arc in the optimal shape, the solid rotor energy storage performance is better than the hollow one.%为克服飞轮转子形状优化时一般优化方法效率低的缺点,在分析角速度对转子形状影响的基础上,将转子角速度划分为低速、中速和高速三个阶段,采用最优控制理论,直接得到实心和空心飞轮转子的最优形状解析表达式.通过比较实心和空心转子低速、中速和高速情况下的最优形状,揭示飞轮转子最优形状随角速度变化的规律.研究结果表明,低角速度下,转子的最优形状沿半径方向“内薄外厚”;高角速度下,“内厚外薄”；中等角速度下,“两端厚中间薄”.低角速度情况下,实心和空心转子的最优形状相同;但中、高速情况下,实心转子的最优形状中包含等应力弧
Applications of Fluorogens with Rotor Structures in Solar Cells.
Ong, Kok-Haw; Liu, Bin
2017-05-29
Solar cells are devices that convert light energy into electricity. To drive greater adoption of solar cell technologies, higher cell efficiencies and reductions in manufacturing cost are necessary. Fluorogens containing rotor structures may be helpful in addressing some of these challenges due to their unique twisted structures and photophysics. In this review, we discuss the applications of rotor-containing molecules as dyes for luminescent down-shifting layers and luminescent solar concentrators, where their aggregation-induced emission properties and large Stokes shifts are highly desirable. We also discuss the applications of molecules containing rotors in third-generation solar cell technologies, namely dye-sensitized solar cells and organic photovoltaics, where the twisted 3-dimensional rotor structures are used primarily for aggregation control. Finally, we discuss perspectives on the future role of molecules containing rotor structures in solar cell technologies.
Applications of Fluorogens with Rotor Structures in Solar Cells
Directory of Open Access Journals (Sweden)
Kok-Haw Ong
2017-05-01
Full Text Available Solar cells are devices that convert light energy into electricity. To drive greater adoption of solar cell technologies, higher cell efficiencies and reductions in manufacturing cost are necessary. Fluorogens containing rotor structures may be helpful in addressing some of these challenges due to their unique twisted structures and photophysics. In this review, we discuss the applications of rotor-containing molecules as dyes for luminescent down-shifting layers and luminescent solar concentrators, where their aggregation-induced emission properties and large Stokes shifts are highly desirable. We also discuss the applications of molecules containing rotors in third-generation solar cell technologies, namely dye-sensitized solar cells and organic photovoltaics, where the twisted 3-dimensional rotor structures are used primarily for aggregation control. Finally, we discuss perspectives on the future role of molecules containing rotor structures in solar cell technologies.
Frederick, G. R.; Winemiller, J. R.; Savino, J. M.
1982-01-01
Three designs of a guyed cylindrical tower and its foundation for an intermediate size horizontal axis wind turbine generator are discussed. The primary difference in the three designs is the configuration of the rotor. Two configurations are two-blade rotors with teetering hubs - one with full span pitchable blades, the other with fixed pitch blades. The third configuration is a three-bladed rotor with a rigid hub and fixed pitch blades. In all configurations the diameter of the rotor is 38 meters and the axis of rotation is 30.4 meters above grade, and the power output is 200 kW and 400 kW. For each configuration the design is based upon for the most severe loading condition either operating wind or hurricane conditions. The diameter of the tower is selected to be 1.5 meters (since it was determined that this would provide sufficient space for access ladders within the tower) with guy rods attached at 10.7 meters above grade. Completing a design requires selecting the required thicknesses of the various cylindrical segments, the number and diameter of the guy rods, the number and size of soil anchors, and the size of the central foundation. The lower natural frequencies of vibration are determined for each design to ensure that operation near resonance does not occur. Finally, a cost estimate is prepared for each design. A preliminary design and cost estimate of a cantilever tower (cylindrical and not guyed) and its foundation is also presented for each of the three configurations.
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...
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.
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.
Institute of Scientific and Technical Information of China (English)
刘思嘉; 范瑜; 邸珺; 纪明明
2016-01-01
竖直轴上端开口的旋转装置在低速运转时，转子的陀螺效应将减弱，可能失去稳定性，从而造成碰撞、噪声和设备损坏等问题。因此其转子定位需要采用非接触式的电磁力来控制。该文提出一种新型的无轴承电机结构，该结构由4个弧形直线感应电机定子和一个公共转子组合成一个多电机系统。在直线感应电机法向力与切向力解耦的基础上，通过直线感应电机的法向力提供转子定位控制力。针对转子的力学特性，基于陀螺效应设计了转子定位控制算法，并对其进行仿真和实验。结果表明，该方案能够实现转子的定位控制。运用此研究成果，可省去无轴承感应电机的悬浮绕组，从而减少了电机的加工困难，具有较好的应用前景。%Low speed one-side-open vertical rotation devices may lose stability because of the reduction of the gyroscope effect. This instability will lead to collision, noise, and even damage. Therefore non-contact rotor orientation control methods, such as the magnetic bearing or the bearingless motor, are needed. The authors proposed a novel structure of bearingless motors. This structure consists of four arc stators and one rotor, in which four arc linear induction motors shares the same rotor. On the basis of the decoupling control of the normal and tangential forces of linear induction motors, the authors firstly designed a rotor orientation control approach aiming to the mechanical characteristics, using the normal force of the linear motor as the orientation force, and then testified this approach via simulations and experiments. The result shows that the system is capable of achieving the position control of the rotor.
Institute of Scientific and Technical Information of China (English)
石一辉; 乔颖; 闵勇; 鲁宗相; 陈惠粉
2011-01-01
Given that the ability of doubly-fed induction generator (DFIG) to sustain power grid low voltage is mostly restricted by the overcurrent capacity of the converter at rotor side, appropriate control rules to avoid serious rotor overcurrent is key to keep DFIG connected with grid safely during voltage dip and voltage recovery. In order to improve the dynamic characteristics of rotor current, decoupling control strategy based on the 5th order model is proposed. It eliminates the adverse effects for rotor current dynamics by feedforward compensation considering transient stator flux. The corresponding control parameter design method is proposed as well. Simulation results show that the proposed strategy can quickly track the rotor current reference and restrain overcurrent so as to enhance DFIG' s low voltage ride-through capability. The results also verify the validity and availability of decoupling control strategy. The proposed method can be used in the parametrical designing method of DFIG considering its dynamic characteristics.This work is supported by National Natural Science Foundation of China (No. 51077078), State Key Lab of Power System Special Funds (No. SKLD09M08) and State Grid Research Funds for Coordination of Generator and Power System.%转子侧变流器过载能力是制约双馈感应发电机(DFIG)低电压耐受能力的主要瓶颈,合理的转子电流控制策略是DFIG安全度过电压跌落与恢复期暂态过程的保障.为改善转子电流的动态特性,以DFIG的5阶模型为基础,研究了考虑定子侧磁链暂态的转子电流解耦控制模型,通过前馈补偿环节消除定子磁链暂态对转子电流动态的不利影响,提出了DFIG转子侧变流器控制参数的设计方法.仿真结果表明,提出的控制策略可使转子电流快速跟踪参考值的变化并抑制过电流,改善了DFIG对电网电压波动的耐受能力,验证了该解耦控制模型的正确性和有效性,为DFIG转子电流动态响应
Institute of Scientific and Technical Information of China (English)
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
DEFF Research Database (Denmark)
Eriksson, Robert
2014-01-01
as possible, and is based on Lyapunov theory considering the nonlinear behavior. The time optimal controller is of a bang-bang type and uses wide-area measurements as feedback signals. Nonlinear simulations are run in the Nordic32 test system implemented in PowerFactory/DIgSILENT with an interface to Matlab...
Dynamic response of a rub-impact rotor system under axial thrust
Energy Technology Data Exchange (ETDEWEB)
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.)
Institute of Scientific and Technical Information of China (English)
陆洋; 董维生; 洪亮; 冯剑波
2012-01-01
A new control algorithm based on the adaptive filter in time domain was brought forward.Based on this,the control system of electrically controlled rotor(ECR) blade pitch with double closed-loop was developed.Then,utilizing the test rig of model ECR,the pitch control experiments were performed in hover state.The experiments show that the developed control system of ECR blade pitch can work reliably through the tests.The control law based on the adaptive filter is successful in ECR collective pitch control,cyclic pitch control and collective pitch mixing with cyclic pitch control.The amplitude of the blade pitch was fitted well with the expected value,and the phase lag was about 10°~15°.The phase lag between the servo flap deflection and the response of blade pitch was about 20°~30°.Because of the structural and aerodynamic differences among different blades and servo flaps,the effect of blade pitch control will be reduced to some extent.%提出了基于自适应滤波的电控旋翼桨距控制方法，并基于此开发了双闭环电控旋翼桨距控制系统，利用模型电控旋翼试验台进行了悬停状态下的桨距控制试验.试验结果表明：所研制的双闭环电控旋翼桨距控制系统能够有效、可靠地实现襟翼操纵和桨距控制.基于自适应滤波的桨距控制律可以很好地实现电控旋翼的总距、周期变距以及总距祸合周期变距操纵;桨距响应幅值满足要求，相位滞后约在10~15之间;从襟翼偏转到桨叶变距响应的滞后约20~30，不同桨叶/襟翼自身的结构及气动特性差异，会一定程度的影响桨距控制的实际效果.
异步电机转子IGBT斩波调阻调速的准动态模型%Quasi-dynamic model of the rotor IGBT chopper controlled induction motor
Institute of Scientific and Technical Information of China (English)
沈天飞; 陈伯时; 龚幼民
2001-01-01
转子斩波调阻是异步电机一种简便有效的调速方法，本文提出了一种新型的采用IGBT作斩波管的具有吸收保护作用的斩波回路拓扑结构，并对该系统整流回路的准动态过程进行了详细研究，推导出斩波管占空比与等效电阻之间的非线性函数关系，给出了外接电阻阻值的选择方法。%Rotor chopper control is a simple and effective speed regulation method for induc tion motor. A novel IGBT chopper topology, which can both adjust rotor resistance and protect IGBT efficiently, is presented in this paper. A thorough investigation on the quasi transient state of the rotor rectifying circuit is made, and a nonlinear mapping between the equivalent resistance and the duty cycle is deduced. Furthermore, the method of determining the magnitude of the external resistor is introduced.
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...
SMART Wind Turbine Rotor: Design and Field Test
Energy Technology Data Exchange (ETDEWEB)
Berg, Jonathan C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Resor, Brian R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Paquette, Joshua A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); White, Jonathan R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-01-29
This report documents the design, fabrication, and testing of the SMART Rotor. This work established hypothetical approaches for integrating active aerodynamic devices (AADs) into the wind turbine structure and controllers.
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
Rotor for a pyrolysis centrifuge reactor
DEFF Research Database (Denmark)
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....
Bohmian quantum mechanical and classical Lyapunov exponents for kicked rotor
Energy Technology Data Exchange (ETDEWEB)
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.
Optimal control method and test for rigid rotor auto-balancing%刚性转子自动平衡寻优控制方法与实验研究
Institute of Scientific and Technical Information of China (English)
黄立权; 王维民; 苏奕儒; 李燕; 高金吉
2011-01-01
It is very important to eliminate online vibration of a rotor system in order to ensure reliable and efficient rotating machinery operation. In early period of rotor vibration control, a tentative control force is needed. The force may make the system vibration rise or drop, which depends on the relationship between the control force phase and the excitation force phase. Here, based on the rotor system dynamic analysis and controllable characteristics of electromagnetic force, the regional division of the control force phase was done. And the control model was built and some specific optimization strategy was proposed. The finite element analysis method was used to gain the system theoretic lagging angle under working speed. The phase of the control force was determined and this phase was used as the initial value of the optimal parameter to ensure the vibration amplitude being not larger than the initial fault amplitude of the rotor during control. Finally, the test table was established and the test results showed that the proposed method is effective.%在线消除转子系统的振动对保证旋转机械的可靠和高效运行是至关重要的.在转子振动控制初期,需要一个试探性的控制力,该力可能会使系统振动加剧或减小,这取决于控制力与原激振力相位之间的关系.为此该研究在转子系统动力学及电磁力可控特性分析的基础上对控制力相位进行区域划分,建立系统寻优控制模型并提出具体寻优策略;采用有限元分析的方法获取工作转速下转子系统理论滞后角,初步确定控制力相位;以此相位值作为寻优参数起始值,按照既定寻优策略实现转子自动平衡控制,并确保控制全过程转子振幅不大于初始不平衡故障振幅;最后建立实验台并对算法进行实验验证,结果表明该方法是有效的.
Institute of Scientific and Technical Information of China (English)
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.
不对称故障下双馈风力发电机转子变换器控制研究%The Control Syudy on DFIG Rotor Side Converter'Under Asymmetic Dips
Institute of Scientific and Technical Information of China (English)
宋平岗; 喻冲
2011-01-01
由于双馈感应发电机(DFIG)的传统控制策略在电网电压不对称跌落下的控制性能较差,提出了一种基于抑制转子侧负序电流的控制策略,以提高DFIG在电网电压发生不对称跌落的控制性能.在不对称跌落下,该控制策略可对DFIG的转子电流的正、负序分量同时进行控制,使用MATLAB/Simulink建立仿真模型,仿真结果表明此控制策略可改善DFIG系统在电网电压不对称跌落下的运行性能.%Because the control strategy of double fed induction generator under asymmetic drop in grid voltage very poor. Raise a control strategy of rotor-side converter based on negative sequence current, To enhance the control performance of DFIG under asymmetic fault. Based on asymmetic dips, This control strategy can control positive negative sequence of rotor current on the same time ,Use MATLAB/Simulink build simulation model, The result shows that this control strategy can improve the operating performance of DFIG under asymmetic grid voltage dips .
Institute of Scientific and Technical Information of China (English)
张广昱; 袁昌盛
2014-01-01
To solve the attitude control problem of small quad-rotor according to its complex coupling ,non-linear and serious internal/external disturbance feature ,a control scheme based on active disturbance rejection control technique is proposed .The dynamic model is established with Newton-Euler equations ,and the uncertainty , coupling and parameter perturbation are considered as total disturbance .Extended state observer is used to esti-mate and compensate the total disturbance .The non-linear state error feedback is used to restrain the compen-sate error ,and did simulation experiment of attitude control for small quad-rotor .The result of the simulation shows that the extended state observer of the active disturbance rejection control technique can estimate/com-pensate disturbance well under circumstance of parameter perturbation and disturbance .The attitude controller based on active disturbance rejection control theory shows good dynamic quality ,steady-state accuracy and strong robustness .%针对四旋翼飞行器的强耦合性、非线性、易受外界干扰等控制难点，研究利用自抗扰控制器对四旋翼飞行器进行姿态控制的技术问题。通过牛顿-欧拉方程建立四旋翼飞行器动力学模型，将不确定性、耦合及参数摄动等干扰作为“总和干扰”，利用扩张状态观测器进行估计并动态反馈补偿，再利用非线性反馈抑制补偿残差，进行四旋翼飞行器姿态控制仿真实验。结果表明：在存在模型参数摄动和外界扰动的情况下，扩张状态观测器很好地实时估计和补偿了四旋翼飞行器的总和干扰，基于自抗扰的四旋翼飞行器姿态控制系统具有较好的动态品质、稳态精度以及较强的鲁棒性。
Homopolar motor with dual rotors
Energy Technology Data Exchange (ETDEWEB)
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
Energy Technology Data Exchange (ETDEWEB)
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.
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...
Institute of Scientific and Technical Information of China (English)
董维生; 陆洋
2013-01-01
为了提高电控旋翼桨距的控制效果,提出了两种基于误差通道在线辨识的自适应滤波控制方法:缩放因子法和约束权函数法.利用桨距开环状态试验数据和最小二乘法辨识得到的控制对象数学模型,完成了两种改进方法的电控旋翼桨距控制仿真.仿真结果表明:缩放因子法在不降低自身自适应性的同时,可以有效地提高电控旋翼的总距及周期变距桨距控制精度和响应速度；约束权函数法则在有效抑制外部噪声干扰的同时提高了控制算法的稳定性.%In order to improve the control efficiency of blade pitch control of Electrically Controlled Rotor (ECR), two methods based on adaptive control method with online identification of error path, scaling factor method and constrained weight method, were proposed. According to the data collected from the open loop pitch control test and the least-squares method, mathematical model of control object was established. Then the ECR pitch control simulation work was conducted for the two proposed methods. Simulation results indicated that; 1 ) the scaling factor method can effectively increase the speed of response and improve the control accuracy of both ECR collective pitch and cyclic pitch control, and keep itself adaptive; and 2) the constrained weight method can effectively restrain the interference caused by the external noise, and can improve the stability of the whole control system at the same time.
DEFF Research Database (Denmark)
Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær
2012-01-01
on rotor blades developed by SHEN, et al is successfully used to extract airfoil data from experimental characteristics on the MEXICO (Model experiments in controlled conditions) rotor. Detailed surface pressure and particle image velocimetry (PIV) flow fields at different rotor azimuth positions...
Yaw control for active damping of structural dynamics
Energy Technology Data Exchange (ETDEWEB)
Ekelund, T. [Chalmers Univ. of Technology, Goeteborg (Sweden). Control Engineering Lab.
1996-12-01
Yaw torque control for reduction of structural dynamic loads in a two-bladed wind turbine is investigated. The models are obtained using rigid-body mechanics. Linear quadratic control theory is utilized for design and analysis. The analysis of two simple examples, where the teeter angle and the tower lateral bending motion are regarded, shows that a time-varying controller has some advantages compared with a time-invariant controller. 6 refs, 9 figs
Smart Rotor Modeling: Aero-Servo-Elastic Modeling of a Smart Rotor with Adaptive Trailing Edge Flaps
DEFF Research Database (Denmark)
Bergami, Leonardo
This book presents the formulation of an aero-servo-elastic model for a wind turbine rotor equipped with Adaptive Trailing Edge Flaps (ATEF), a smart rotor configuration. As the name suggests, an aero-servo-elastic model consists of three main components: an aerodynamic model, a structural model......, and a control model. The book first presents an engineering type of aerodynamic model that accounts for the dynamic effects of flap deflection. The aerodynamic model is implemented in a Blade Element Momentum framework, and coupled with a multi-body structural model in the aero-servoelastic simulation code HAWC...... the trailing edge flap deflection to actively reduce the fatigue loads on the structure. The performance of the smart rotor configuration and its control algorithms are finally quantified by aero-servo-elastic simulations of the smart rotor turbine operating in a standard turbulent wind field....
9th IFToMM International Conference on Rotor Dynamics
2015-01-01
This book presents the proceedings of the 9th IFToMM International Conference on Rotor Dynamics. This conference is a premier global event that brings together specialists from the university and industry sectors worldwide in order to promote the exchange of knowledge, ideas, and information on the latest developments and applied technologies in the dynamics of rotating machinery. The coverage is wide ranging, including, for example, new ideas and trends in various aspects of bearing technologies, issues in the analysis of blade dynamic behavior, condition monitoring of different rotating machines, vibration control, electromechanical and fluid-structure interactions in rotating machinery, rotor dynamics of micro, nano, and cryogenic machines, and applications of rotor dynamics in transportation engineering. Since its inception 32 years ago, the IFToMM International Conference on Rotor Dynamics has become an irreplaceable point of reference for those working in the field, and this book reflects the high qua...
Light Rotor: The 10-MW reference wind turbine
DEFF Research Database (Denmark)
Bak, Christian; Bitsche, Robert; Yde, Anders;
2012-01-01
design show a rather well performing wind turbine both in terms of power and loads, but in the further work towards the final design the challenges in the control needs to be solved and the balance between power performance and loads and between structural performance and mass will be investigated......This paper describes the design of a rotor and a wind turbine for an artificial 10-MW wind turbine carried out in the Light Rotor project. The turbine called the Light Rotor 10-MW Reference Wind Turbine (LR10-MW RWT), is designed with existing methods and techniques and serves as a reference...... like the determination of the specific power and upscaling of the turbine. The design of Iteration #2 of the LR10-MW RWT is carried out in a sequence between aerodynamic rotor design, structural design and aero-servo-elastic design. Each of these topics is described. The results from the Iteration #2...
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.
Active Magnetic Bearing Rotor Model Updating Using Resonance and MAC Error
Directory of Open Access Journals (Sweden)
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.
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
Energy Technology Data Exchange (ETDEWEB)
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)
Institute of Scientific and Technical Information of China (English)
杨倩; 崔培玲; 韩邦成; 郑世强
2012-01-01
双框架磁悬浮控制力矩陀螺(DGMSCMG)具有寿命长、综合效益好等突出优势,但航天器机动时,航天器及DGMSCMG内、外框架系统的转动均导致磁悬浮高速转子产生一定的耦合运动,影响磁悬浮转子系统的稳定性,同时使输出力矩精度下降,从而严重影响航天器姿态控制的精度.本文建立了基于DGMSCMG的航天器动力学模型,分析航天器、外框架、内框架、磁悬浮转子四者之间的动力学耦合关系.针对磁悬浮转子的非线性耦合干扰,提出一种基于复合控制的补偿方法,通过磁轴承产生相应的电磁力,对陀螺耦合力矩和惯性耦合力矩进行补偿控制.仿真结果表明,干扰补偿控制能有效抑制航天器及框架对磁悬浮转子的耦合干扰,也有效提高了磁悬浮转子系统的稳定性.%Double gimbal magnetically suspended control moment gyros (DCMSCMC) has the outstanding advantage of long life, good comprehensive benefit and so on. However, during the spacecraft attitude maneuver, the coupled motion implicated in slewing of spacecraft, inner and outer gimbals of DGMSCMG will affect the stability of magnetically suspended high-speed rotor system and decrease the accuracy of output torque. Consequently, the control accuracy of spacecraft attitude will be depressed seriously. In this paper, the dynamics model of spacecraft with DGMSCMG is set up and the cross-coupled relationship among spacecraft body, inner gimbal, outer gimbal and rotor are analyzed. Aiming at the nonlinear couplied disturbance of the magnetically suspended rotor, a compensation method based on compound control is presented, in which the corresponding electromagnetic force is produced by magnetic bearing for compensation control of rotational inertia torque and gyro torque. The simulation results indicate that the couplied disturbance of the magnetically suspended rotor caused by spacecraft, inner and outer gimbals can be effectively suppressed, and
IDENTIFICATION OF CRACKED ROTOR BY WAVELET TRANSFORM
Institute of Scientific and Technical Information of China (English)
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.
CFD simulations of the MEXICO rotor
DEFF Research Database (Denmark)
Bechmann, Andreas; Sørensen, Niels N.; Zahle, Frederik
2011-01-01
The wake behind a wind turbine model is investigated using Computational Fluid Dynamics (CFD), and results are compared with measurements. The turbine investigated is the three‐bladed test rotor (D = 4.5 m) used in the Model Experiments in Controlled Conditions (MEXICO) wind tunnel experiment....... During the MEXICO experiment, particle image velocimetry measurements of the induction upstream and downstream of the rotor were performed for different operating conditions, giving a unique dataset to verify theoretical models and CFD models. The present paper first describes the efforts in reproducing...... the experimental results using the Reynold‐Averaged Navier‐Stokes method. Second, three‐dimensional airfoil characteristics are extracted that allow simulations with simpler wake models. Copyright © 2011 John Wiley & Sons, Ltd....
Rotor blade assembly having internal loading features
Energy Technology Data Exchange (ETDEWEB)
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.
Rotor-stator contact dynamics using a non-ideal drive—Theoretical and experimental aspects
Lahriri, Said; Weber, Hans I.; Santos, Ilmar F.; Hartmann, Henning
2012-09-01
The possible contact between rotor and stator is considered a serious malfunction that may lead to catastrophic failure. Rotor rub is seen as a secondary phenomenon caused by a primary source, i.e. sudden mass unbalance, instabilities generated by aerodynamic and hydrodynamic forces in seals and bearings among others. The contact event gives rise to normal and friction forces exerted on the rotor at impact events. The friction force plays a significant role by transferring some rotational energy of the rotor to lateral motion. A mathematical model has been developed to capture this for a conventional backup annular guide setup. It is reasonable to superpose an impact condition to the rub, where the rotor spin energy can be fully transformed into rotor lateral movements. Using a nonideal drive, i.e. an electric motor without any kind of velocity feedback control, it is even possible to stop the rotor spin under rubbing conditions. All the rotational energy will be transformed in a kind of "self-excited" rotor lateral vibration with repeated impacts against the housing. This paper studies the impact motion of a rotor impacting a conventional backup annular guide for the case of dry and lubricated inner surface of the guide. For the dry surface case, the experimental and numerical analysis shows that the rotational energy is fully transformed into lateral motion and the rotor spin is stopped. Based on this study this paper proposes a new unconventional backup bearing design in order to reduce the rub related severity in friction and center the rotor at impact events. The analysis shows that the rotor at impacts is forced to the center of the backup bearing and the lateral motion is mitigated. As a result of this, the rotor spin is kept constant.
Institute of Scientific and Technical Information of China (English)
Hamidreza SHIRAZI; Jalal NAZARZADEH
2014-01-01
In a modern electrical driver, rotor field oriented control (RFOC) method has been used to achieve a good performance and an appropriate transient response. In this method, the space vector of the rotor flux comes handy by the rotor resistance value. The rotor resistance is one of the important parameters which varies according to motor speed and room temperature alteration. In this paper, a new on-line estimation method is utilized to obtain the rotor resistance by using Walsh functions domain. The Walsh functions are one of the most applicable functions in piecewise constant basis functions (PCBF) to solve dynamic equations. On the other hand, an integral operational matrix is used to simplify the process and speed of the computation algorithm. The simulations results show that the proposed method is capable of solving the dynamic equations in an electrical machine on a time interval which robustly estimates the rotor resistance in contrast with injection noises.
Design of composite flywheel rotor
Institute of Scientific and Technical Information of China (English)
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.
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...
NUMERICAL AND EXSPERIMENTAL ASPECTS OF THERMALLY INDUCED VIBRATION IN REAL ROTORS
Directory of Open Access Journals (Sweden)
Milenko B Jevtić
2011-01-01
Full Text Available Temperature fields in electric energy generators may lead to mechanical dissbalance of an already balanced rotor. The author collected information in a number of steam power plants and confirmed the existence of the problem. This paper is presents the specific case of thermal deformation of the rotor, caused by an asymmetrical temperature field in scale of rotor. On the grounds of the relevant physical aspects, we propose a mathematical model identifying fields in a turbo generator rotor and suggest the optimum control by which the unwanted effects are eliminated.
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.
Fuzzy logic estimator of rotor time constant in induction motors
Energy Technology Data Exchange (ETDEWEB)
Alminoja, J. [Tampere University of Technology (Finland). Control Engineering Laboratory; Koivo, H. [Helsinki University of Technology, Otaniemi (Finland). Control Engineering Laboratory
1997-12-31
Vector control of AC machines is a well-known and widely used technique in induction machine control. It offers an exact method for speed control of induction motors, but it is also sensitive to the changes in machine parameters. E.g. rotor time constant has a strong dependence on temperature. In this paper a fuzzy logic estimator is developed, with which the rotor time constant can be estimated when the machine has a load. It is more simple than the estimators proposed in the literature. The fuzzy estimator is tested by simulation when step-wise abrupt changes and slow drifting occurs. (orig.) 7 refs.
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
Institute of Scientific and Technical Information of China (English)
陆洋; 王超
2013-01-01
Firstly, the unsteady aerodynamic model of the airfoil with trailing-edge flap was developed. Secondly, the finite state wake model of electrically controlled rotor (ECR) based on the Peters-He generalized dynamic wake theory was developed, in which the effect of the trailing-edge flap on the rotor aerodynamic environment was considered. Combined with the relationship among the blade flapping angle, the blade pitch and the deflection angle of the trailing-edge flap, the model of calculating the aerodynamic characteristics of ECR was established finally. Then, wind tunnel tests were conducted, in which the aerodynamic force, the blade pitch, the deflection angle of the trailing-edge flap and the blade flapping angle varying with different test statuses were measured. Theoretical results basically coincided with the experimental data, which verified the correction of the theoretical model. Conclusions are drawn as follows: with the fixed rotor speed, there is a linear relationship between blade pitch response and flap control; rotor thrust decreases with the increase of flap collective control, and actual aerodynamic efficiency of the flap decreases under large collective control; in forward flight, flap collective control can cause changes of blade cyclic pitch.%首先建立了带襟翼翼型的非定常气动力模型,继而基于Peters-He广义动态尾迹理论,考虑襟翼偏转对电控旋翼叶素环境的影响,建立了电控旋翼有限状态尾迹模型；进一步基于Theodorsen理论推导出电控旋翼桨叶挥舞响应与桨叶变距和襟翼操纵量的关系,综合以上建立了电控旋翼气动特性分析模型.以改进型电控旋翼试验系统为平台进行了风洞试验,测量了不同风速、不同襟翼操纵条件下的电控旋翼气动力、桨距、襟翼偏角及旋翼挥舞角的变化情况.理论计算结果与试验数据符合情况良好,验证了所建立的分析模型的正确性,并得出以下结论:旋翼转速一定
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...
Institute of Scientific and Technical Information of China (English)
王平; 王华; 任元
2015-01-01
In order to overcome disturbance effect in stability of magnetic suspended rotor and output torque accuracy of magnetically suspended control moment gyroscope, this paper presents a disturbance rejection method of magnetic suspended rotor based on active disturbance rejection controller. The dynamics model of magnetic suspended rotor is established, decoupling model of radial four channel is obtained based on principle of ADRC, rotor radial four channel decoupling and disturbance rejection is achieved through ADRC. Through simulation, we find ADRC controller has good function of disturbance rejection, canimprove stability precision of rotor and output torque accuracy of control moment gyroscope. Therefore, this method not only improves accuracy of decoupling control, but also improves the robustness of system to external disturbances and parameter variations, and can be used in high precision strong robust control for magnetically suspended control moment gyroscope.%为了克服外部扰动影响磁悬浮转子悬浮稳定度和磁悬浮控制力矩陀螺输出力矩精度的问题,提出一种基于自抗扰控制器的磁悬浮转子扰动抑制方法.根据牛顿第二定律和陀螺技术方程建立磁轴承坐标系下磁悬浮转子系统的动力学方程,基于自抗扰解耦控制原理得到径向四通道解耦模型,设计各通道自抗扰控制器,从而实现转子系统径向四通道解耦和扰动抑制.与分散 PID加交叉反馈控制方法进行仿真对比,结果表明:自抗扰控制器具有良好的扰动抑制功能,能提高转子的稳定精度和控制力矩陀螺的输出力矩精度;因此,此方法不仅改善了解耦控制精度,而且提高了系统对外部扰动和参数变化的鲁棒性,可应用于磁悬浮控制力矩陀螺的高精度强鲁棒控制.
Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors
Yeo, Hyeonsoo; Johnson, Wayne
2013-01-01
Maximum blade loading capability of a coaxial, lift-offset rotor is investigated using a rotorcraft configuration designed in the context of short-haul, medium-size civil and military missions. The aircraft was sized for a 6600-lb payload and a range of 300 nm. The rotor planform and twist were optimized for hover and cruise performance. For the present rotor performance calculations, the collective pitch angle is progressively increased up to and through stall with the shaft angle set to zero. The effects of lift offset on rotor lift, power, controls, and blade airloads and structural loads are examined. The maximum lift capability of the coaxial rotor increases as lift offset increases and extends well beyond the McHugh lift boundary as the lift potential of the advancing blades are fully realized. A parametric study is conducted to examine the differences between the present coaxial rotor and the McHugh rotor in terms of maximum lift capabilities and to identify important design parameters that define the maximum lift capability of the rotor. The effects of lift offset on rotor blade airloads and structural loads are also investigated. Flap bending moment increases substantially as lift offset increases to carry the hub roll moment even at low collective values. The magnitude of flap bending moment is dictated by the lift-offset value (hub roll moment) but is less sensitive to collective and speed.
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.
Rotor Voltage Dynamics in the Doubly Fed Induction Generator During Grid Faults
DEFF Research Database (Denmark)
Lima, Francisco K. A.; Luna, Alvaro; Rodriguez, Pedro
2010-01-01
, something that would permit the injection of power to the grid during the fault, as the new grid codes demand. A theoretical study of the dynamical behavior of the rotor voltage is also developed, in order to show that the voltage at the rotor terminals required for the control strategy implementation...
Determination of the angle of attack on the mexico rotor using experimental data
DEFF Research Database (Denmark)
Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær
2010-01-01
characteristics from experimental data on the MEXICO (Model Experiments in controlled Conditions) rotor. Detailed surface pressure and Particle Image Velocimetry (PIV) flow field at different rotor azimuth positions were examined for determining the sectional airfoil data. It is worthwhile noting that the present...
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
SMART Wind Turbine Rotor: Data Analysis and Conclusions
Energy Technology Data Exchange (ETDEWEB)
Berg, Jonathan C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barone, Matthew F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yoder, Nathanael C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-01-29
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.
Field Balancing of Magnetically Levitated Rotors without Trial Weights
Directory of Open Access Journals (Sweden)
Jiancheng Fang
2013-11-01
Full Text Available Unbalance in magnetically levitated rotor (MLR can cause undesirable synchronous vibrations and lead to the saturation of the magnetic actuator. Dynamic balancing is an important way to solve these problems. However, the traditional balancing methods, using rotor displacement to estimate a rotor’s unbalance, requiring several trial-runs, are neither precise nor efficient. This paper presents a new balancing method for an MLR without trial weights. In this method, the rotor is forced to rotate around its geometric axis. The coil currents of magnetic bearing, rather than rotor displacement, are employed to calculate the correction masses. This method provides two benefits when the MLR’s rotation axis coincides with the geometric axis: one is that unbalanced centrifugal force/torque equals the synchronous magnetic force/torque, and the other is that the magnetic force is proportional to the control current. These make calculation of the correction masses by measuring coil current with only a single start-up precise. An unbalance compensation control (UCC method, using a general band-pass filter (GPF to make the MLR spin around its geometric axis is also discussed. Experimental results show that the novel balancing method can remove more than 92.7% of the rotor unbalance and a balancing accuracy of 0.024 g mm kg−1 is achieved.
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
Institute of Scientific and Technical Information of China (English)
陆洋; 王超; 赵鑫
2013-01-01
首先基于Peters He广义动态尾迹理论,建立了电控旋翼动态尾迹入流模型,进一步结合电控旋翼襟翼操纵与桨叶变距之间的关系、桨叶挥舞运动方程和带襟翼翼型非定常气动力模型建立了适用于飞行力学分析的电控旋翼气动力模型.在此基础上,结合机身、尾桨、尾面的气动力模型,建立了完整的电控旋翼直升机飞行动力学分析模型.以Z-11直升机为基准改造为电控旋翼直升机作为算例,计算了前飞状态下电控旋翼直升机的诱导速度分布和桨盘迎角分布,对比了电控旋翼与常规旋翼的气动特性差异；在此基础上,进一步分析了电控旋翼直升机的配平特性随前飞速度的变化规律以及与常规直升机的差异.%Firstly,a dynamic inflow model for electrically controlled rotor (ECR) is developed based on the "Peters-He" generalized dynamic wake theory,and an accurate aerodynamics model of ECR,which is suited for the analysis of ECR helicopter flight dynamics,is built combined with the relationship between flap deflection and blade pitch,the blade flapping equation and the unsteady aerodynamic model of airfoil with trailing-edge flap.Then,on this basis,an ECR helicopter flight dynamics model is established combined with the aerodynamics models of airframe,tail rotor,horizontal and vertical tail.Taking Z-11 helicopter as a numerical example,the distributions of ECR induced velocity and angles of attack variations with advance speed are calculated and compared with the baseline rotor.Furthermore,the trim characteristics of the ECR helicopter is investigated.
Institute of Scientific and Technical Information of China (English)
张青春
2011-01-01
On the basis of expounding the principle of simplified flux method with energy optimizing,a indirect rotor-position detecting control system of switched reluctance motor based on the simplified flux method with energy optimizing was designed. The current and speed double closed loop control system was adopted. The implementation schemes of the indirect position detecting of energy optimizing flux,the current closed loop control and the speed closed loop control were given. The experiment system of the indirect rotor-position detecting control system of switched reluctance motor based on the simplified flux method with energy optimizing was built. The performances of the system were tested and analyzed. The test results show that the designed system can detect the control signals. And the expected phase current waveforms were obtained by the control system. It is developed as the approach foundation for the design of excellent performance SRD control system.%在阐述能量优化简化磁链法原理的基础上,设计了一种基于能量优化简化磁链法的开关磁阻电动机间接位置检测控制系统.系统采用电流、转速双闭环控制,给出了能量优化磁链间接位置检测、电流环控制和转速环控制的实现方案,构建了基于能量优化简化磁链法的开关磁阻电机间接位置检测控制实验系统,并对系统进行了实验测试和分析.实验结果表明,所设计系统能够准确检测控制系统所需控制信号,并通过控制系统获得了期望的相电流波形,为设计性能优良的开关磁阻电动机调速驱动系统提供了研究基础.
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.
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.
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.
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
Blade tip vortex measurements on actively twisted rotor blades
Bauknecht, André; Ewers, Benjamin; Schneider, Oliver; Raffel, Markus
2017-05-01
Active rotor control concepts, such as active twist actuation, have the potential to effectively reduce the noise and vibrations of helicopter rotors. The present study focuses on the experimental investigation of active twist for the reduction of blade-vortex interaction (BVI) effects on a model rotor. Results of a large-scale smart-twisting active rotor test under hover conditions are described. This test investigated the effects of individual blade twist control on the blade tip vortices. The rotor blades were actuated with peak torsion amplitudes of up to 2° and harmonic frequencies of 1-5/rev with different phase angles. Time-resolved stereoscopic particle image velocimetry was carried out to study the effects of active twist on the strength and trajectories of the tip vortices between ψ _ {v}= 3.6° and 45.7° of vortex age. The analysis of the vortex trajectories revealed that the 1/rev active twist actuation mainly caused a vertical deflection of the blade tip and the corresponding vortex trajectories of up to 1.3% of the rotor radius R above and -1%R below the unactuated condition. An actuation with frequencies of 2 and 3/rev significantly affected the shapes of the vortex trajectories and caused negative vertical displacements of the vortices relative to the unactuated case of up to 2%R within the first 35° of wake age. The 2 and 3/rev actuation also had the most significant effects on the vortex strength and altered the initial peak swirl velocity by up to -34 and +31% relative to the unactuated value. The present aerodynamic investigation reveals a high control authority of the active twist actuation on the strength and trajectories of the trailing blade tip vortices. The magnitude of the evoked changes indicates that the active twist actuation constitutes an effective measure for the mitigation of BVI-induced noise on helicopters.
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.
Dynamic Vibration Absorber with Negative Stiffness for Rotor System
Directory of Open Access Journals (Sweden)
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.
A New Fine Damping Method for Solid ESG Rotor
Institute of Scientific and Technical Information of China (English)
LIU Chun-ning; TIAN Wei-feng; JIN Zhi-hua
2006-01-01
For the electrostatically suspended gyro(ESG) with solid rotor, because the equatorial photoelectric sensor won't sense the equatorial marking line and output the correct damping control information when the nutation angle is small, the active damping with equatorial marking line will bring considerable error. The passive damping method by applying strong DC magnetic field requires too much time. So an active damping method by longitude marking lines is proposed to fulfill the fine damping for solid ESG rotor. The shape of rotor marking lines and the principle of fine damping are introduced. The simulation results prove that this fine damping method can effectively solve the problem of damping error introduced by active damping with equatorial marking line. The estimating results for damping time indicate that the fine damping time is less than 10 percent of passive damping time.
Study of nonlinear dynamic characteristics of rotor-bearing systems
Institute of Scientific and Technical Information of China (English)
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.
Falls, Jaye
This work studies the design of trailing edge controls for swashplateless helicopter primary control, and examines the impact of those controls on the performance of the rotor. The objective is to develop a comprehensive aeroelastic analysis for swashplateless rotors in steady level flight. The two key issues to be solved for this swashplateless control concept are actuation of the trailing edge controls and evaluating the performance of the swashplateless rotor compared to conventionally controlled helicopters. Solving the first requires simultaneous minimization of trailing flap control angles and hinge moments to reduce actuation power. The second issue requires not only the accurate assessment of swashplateless rotor power, but also similar or improved performance compared to conventional rotors. The analysis consists of two major parts, the structural model and the aerodynamic model. The inertial contributions of the trailing edge flap and tab are derived and added to the system equations in the structural model. Two different aerodynamic models are used in the analysis, a quasi-steady thin airfoil theory that includes arbitrary hinge positions for the flap and the tab, and an unsteady lifting line model with airfoil table lookup based on wind tunnel test data and computational fluid dynamics simulation. The design aspect of the problem is investigated through parametric studies of the trailing edge flap and tab for a Kaman-type conceptual rotor and a UH-60A swashplateless variant. The UH-60A model is not changed except for the addition of a trailing edge flap to the rotor blade, and the reduction of pitch link stiffness to imitate a soft root spring. Study of the uncoupled blade response identifies torsional stiffness and flap hinge stiffness as important design features of the swashplateless rotor. Important trailing edge flap and tab design features including index angle, aerodynamic overhang, chord and length are identified through examination of coupled
Genetics Home Reference: Rotor syndrome
... of these proteins. Without the function of either transport protein, bilirubin is less efficiently taken up by the ... Schinkel AH. Complete OATP1B1 and OATP1B3 deficiency causes human Rotor syndrome by interrupting conjugated bilirubin reuptake into ...
Institute of Scientific and Technical Information of China (English)
刘佳琦; 梁悦; 尹航; 高晓智; 李雪玲
2015-01-01
Fuel sloshing is the unwanted attitude disturbance of rotor aircraft which represents the force of the fuel impact the tank wall. The fuel sloshing model used for rotor aircraft represents each sloshing mode as a mass-spring-damper system. Then a nonlinear dynamic model was achieved by theoretical and empirical method to determine the relationship among the voltage, the speed of the propeller and the lift force. A sliding mode controller was developed and compared with a optimized PID controller in terms of fuel sloshing disturbance. Furthermore, the hardware in the loop simulation system with two degree of freedom was given to demonstrate the validity of the algorithms. The result shows that a little input effort can achieve a better robust performance by adopting the sliding mode controller than the PID controller.%针对燃料晃荡对旋翼飞行器燃料箱壁撞击产生的姿态扰动问题,采用质量-弹簧-阻尼模型表示燃料晃荡对系统的作用,通过理论分析与实验数据;确定飞行器控制电压与螺旋桨转速及升力之间的关系,建立燃料晃荡扰动下飞行器的非线性动力学模型,提出一种滑模变结构控制的方法,有效抑制了燃料晃荡带来的扰动. 进一步搭建了二自由度半实物仿真系统验证算法的优越性与实用价值,与尽可能优化参数的PID控制算法对比,提出的滑模变结构控制方法能够在较小的能量输入下更好地抑制燃料晃荡引起的扰动问题,使系统的姿态控制具有更为理想的鲁棒性.
Estimation of Rotor Effective Wind Speed: A Comparison
DEFF Research Database (Denmark)
Soltani, Mohsen; Knudsen, Torben; Svenstrup, Mikael
2013-01-01
Modern wind turbine controllers use wind speed information to improve power production and reduce loads on the turbine components. The turbine top wind speed measurement is unfortunately imprecise and not a good representative of the rotor effective wind speed. Consequently, many different model...
RNN Based Rotor Flux and Speed Estimation of Induction Motor
Directory of Open Access Journals (Sweden)
Bambang Purwahyudi
2011-09-01
Full Text Available Speed control of induction motor can be obtained by closed loop system which require speed sensor. Speed sensor system is less effective for wide plant system, because the sensor location is too far from the main control system and measurement result is less accurate. This paper presents the development of speed sensorless field oriented control (FOC of induction motor by using the rotor flux and speed observers. The observers only required the stator voltage and current of induction motor to obtain the rotor flux and speed estimation. The observers based on recurrent neural network (RNN methods are implemented. Finally, the effectiveness of the proposed method is verified by simulation. Simulation results show that RNN observer can produce well the rotor flux and speed estimation. MSE values of the rotor flux estimation are between 0.000087 and 0.000264, whereas MSE values of the speed estimation are between 43.0552 and 156.0798. Keywords: field oriented control, induction motor, observer, and recurrent neural network.
Egolf, T. A.; Landgrebe, A. J.
1982-01-01
A user's manual is provided which includes the technical approach for the Prescribed Wake Rotor Inflow and Flow Field Prediction Analysis. The analysis is used to provide the rotor wake induced velocities at the rotor blades for use in blade airloads and response analyses and to provide induced velocities at arbitrary field points such as at a tail surface. This analysis calculates the distribution of rotor wake induced velocities based on a prescribed wake model. Section operating conditions are prescribed from blade motion and controls determined by a separate blade response analysis. The analysis represents each blade by a segmented lifting line, and the rotor wake by discrete segmented trailing vortex filaments. Blade loading and circulation distributions are calculated based on blade element strip theory including the local induced velocity predicted by the numerical integration of the Biot-Savart Law applied to the vortex wake model.
Analysis on Dynamic Performance for Active Magnetic Bearing—Rotor System
Institute of Scientific and Technical Information of China (English)
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.
Quad-Rotor Helicopter Autonomous Navigation Based on Vanishing Point Algorithm
Directory of Open Access Journals (Sweden)
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.
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.
Rotor damage detection by using piezoelectric impedance
Qin, Y.; Tao, Y.; Mao, Y. F.
2016-04-01
Rotor is a core component of rotary machinery. Once the rotor has the damage, it may lead to a major accident. Thus the quantitative rotor damage detection method based on piezoelectric impedance is studied in this paper. With the governing equation of piezoelectric transducer (PZT) in a cylindrical coordinate, the displacement along the radius direction is derived. The charge of PZT is calculated by the electric displacement. Then, by the use of the obtained displacement and charge, an analytic piezoelectric impedance model of the rotor is built. Given the circular boundary condition of a rotor, annular elements are used as the analyzed objects and spectral element method is used to set up the damage detection model. The Electro-Mechanical (E/M) coupled impedance expression of an undamaged rotor is deduced with the application of a low-cost impedance test circuit. A Taylor expansion method is used to obtain the approximate E/M coupled impedance expression for the damaged rotor. After obtaining the difference between the undamaged and damaged rotor impedance, a rotor damage detection method is proposed. This method can directly calculate the change of bending stiffness of the structural elements, it follows that the rotor damage can be effectively detected. Finally, a preset damage configuration is used for the numerical simulation. The result shows that the quantitative damage detection algorithm based on spectral element method and piezoelectric impedance proposed in this paper can identify the location and the severity of the damaged rotor accurately.
Advances in tilt rotor noise prediction
George, A. R.; Coffen, C. D.; Ringler, T. D.
The two most serious tilt rotor external noise problems, hover noise and blade-vortex interaction noise, are studied. The results of flow visualization and inflow velocity measurements document a complex, recirculating highly unsteady and turbulent flow due to the rotor-wing-body interactions characteristic of tilt rotors. The wing under the rotor is found to obstruct the inflow, causing a deficit in the inflow velocities over the inboard region of the rotor. Discrete frequency harmonic thickness and loading noise mechanisms in hover are examined by first modeling tilt rotor hover aerodynamics and then applying various noise prediction methods using the WOPWOP code. The analysis indicates that the partial ground plane created by the wing below the rotor results in a primary sound source for hover.
Institute of Scientific and Technical Information of China (English)
Han Dong
2015-01-01
To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluid-lastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev (per revolution) pitch link load is observed to be reduced by 87.6%compared with the increase of 56.3%by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.
Rotor Position Detection of Switched Reluctance Motors with a New Indirect Technique
Directory of Open Access Journals (Sweden)
Majid Asgar
2014-09-01
Full Text Available The aligned to unaligned phase inductance ratio and the number of stator and rotor poles strongly affect the resolution of indirect rotor position sensing methods for switched reluctance motor (SRM drives. This paper presents a new sensor-less rotor position detection for a three-phase single switch SR motor with regeneration capability at standstill mode.. The proposed method is based on the dependency of phase current waveform at turn off time to rotor position angle. It is shown that the combination of a motor with single switch per phase converter and a transient voltage suppressor (TVS circuit deﬁne a resonant circuit. In this method, the rotor position is achieved by inspecting of regeneration current results of applied high frequency and low level diagnostic pulses to the motor phases at the beginning step. Obtaining the rotor position of switched reluctance motors (SRMs will done by means of the overlap of rising voltage measurements. During this interval, rotor position is detected by exchanging energy between the phase and source repeatedly in one cycle of a phase current. The resulted current magnitudes are measured and compared to detect the rotor position. The prototype controller was simulated, fabricated, and tested in laboratory and experimental results of the proposed SRM drive system are presented. The new configuration enables the motor for self-starting without any other mechanism or starting device.
Directory of Open Access Journals (Sweden)
Han Dong
2015-10-01
Full Text Available To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluidlastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev (per revolution pitch link load is observed to be reduced by 87.6% compared with the increase of 56.3% by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.
Institute of Scientific and Technical Information of China (English)
郭剑东; 宋彦国
2015-01-01
It is very difficult to determine the aerodynamics and control characteristics theo-retically for tiltrotor aircraft because of multi-flight modes,complexity of aerodynamic interac-tions,and redundancy of control surfaces.Especially for the tilting flight mode,the layout of the aircraft is transformed between the helicopter mode and the fixed-wing airplane mode with the na-celle driven rotor system tilting.In order to investigate the aerodynamics and control characteris-tics,the full-span and full-envelop flight modes of a small unmanned tilt rotor are tested in wind-tunnel prior to flight.The un-powered test is mainly determining the flight characteristics with different attack angles,nacelle angles and forward speeds.The powered test is focused on the aerodynamic interactions among rotor,wing and flaperon wing,with and without wings,as well as the efficacy manipulation of the collective aileron and elevator.According to the experimental data,the full-envelop flight control characteristics for the tiltrotor is deduced,improves aircraft designing,and provides a priori knowledge for successful flight tests.%由于倾转旋翼机飞行模式多，各部件气动干扰复杂且操纵面冗余，特别是倾转过渡模式，短舱带动旋翼系统倾转，结构布局发生改变，从理论上确定气动与操纵特性难度大。为了研究倾转旋翼机的气动与操纵特性，对某小型无人倾转旋翼机展开全尺寸、全模式吹风试验，其中不带动力试验主要用于研究倾转旋翼机在不同迎角、短舱倾角、前飞速度等飞行状态下的气动特性；带动力试验主要用于研究倾转旋翼机不同飞行模式带机翼与不带机翼时，旋翼／机翼／襟副翼相互干扰作用，以及总距、副翼、升降舵的操纵功效。根据试验数据推导出小型无人倾转旋翼机全包线飞行的操纵特性方法，对进一步完善倾转旋翼机设计以及试飞试验的成功提供了参考。
基于DSP的微型直升机主动旋翼控制系统硬件设计%Hardware Design of Mini-helicopter Rotor Active Control System Based on DSP
Institute of Scientific and Technical Information of China (English)
刘宏; 罗华; 杨淑凤
2012-01-01
针对共轴双桨直升机主动旋翼控制的工作原理及其硬件设计方案进行了介绍.该系统主要由三轴加速度计ADXL345和三轴陀螺L3G4200D及TMS320F28335 DSP组成捷联惯导系统.并在捷联惯导姿态控制中增加了旋翼受力反馈环路,提高了惯导对外界扰动的响应速度.通过实验验证,该系统对于提高悬停稳定性和高度控制响应速度具有较好的效果.%The sculls coaxial helicopter active control of the working principle and hardware design solutions were introduced.The system consists of three-axis accelerometer ADXL345 three-axis gyro and L3G4200D and TMS320F28335 DSP components.And attitude control in strap down inertial navigation system（SINS） was added to rotor force feedback loop to improve the response to external disturbances.Experiments show that the system with good results to the hover stability and response speed of height control.
Unbalance and resonance elimination with active bearings on a Jeffcott Rotor
Heindel, Stefan; Becker, Fabian; Rinderknecht, Stephan
2017-02-01
In this contribution we have proven theoretically and practically that active bearings are able to eliminate both bearing forces and the resonance of a Jeffcott Rotor system. Active bearings can displace a rotor such that its center of mass always stays in the rotational center. The proposed collocated controller is able to keep this state at any rotational speed, leading to an elimination of bearing forces and resonances. We analytically demonstrated that the closed-loop system is always stable, even without knowledge of the rotor's properties. The generalization of the proposed control approach for force-free operation either using displacement or force actuators enables its use for all kinds of active bearings. Moreover, the control approach allows a real time estimation of the rotor's eccentricity. The low parameter count and the unproblematic stability behavior qualify the controller for many applications.
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.
On Cup Anemometer Rotor Aerodynamics
Directory of Open Access Journals (Sweden)
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.
A New Sensorless MRAS Based on Active Power Calculations for Rotor Position Estimation of a DFIG
Directory of Open Access Journals (Sweden)
Gil Domingos Marques
2011-01-01
Full Text Available A sensorless method for the estimation of the rotor position of the wound-rotor induction machine is described in this paper. The method is based on the MRAS methodology and consists in the comparison of two models for the evaluation of the active power transferred across the air gap: the reference model and the adaptive model. The reference model obtains the power transferred across the air gap using directly available and measured stator variables. The adaptive model obtains the same quantity in function of electromotive forces and rotor currents that are measurable on the rotor position, which is under estimation. The method does not need any information about the stator or rotor flux and can be implemented in the rotor or in the stator reference frames with a hysteresis or with a PI controller. The stability analysis gives an unstable region on the rotor current dq plane. Simulation and experimental results show that the method is appropriate for the vector control of the doubly fed induction machine under the stability region.
Rotor Embedded with Shape Memory Alloy Wires
Directory of Open Access Journals (Sweden)
K. Gupta
2000-01-01
Full Text Available In the present analysis, the fundamental natural frequency of a Jeffcott and a two-mass rotor with fibre reinforced composite shaft embedded with shape memory alloy (SMA wires is evaluated by Rayleigh's procedure. The flexibility of rotor supports is taken into account. The effect of three factors, either singly or in combination with each other, on rotor critical speed is studied. The three factors are: (i increase in Young's modulus of SMA (NITINOL wires when activated, (ii tension in wires because of phase recovery stresses, and (iii variation of support stiffness by three times because of activation of SMA in rotor supports. It is shown by numerical examples that substantial variation in rotor critical speeds can be achieved by a combination of these factors which can be effectively used to avoid resonance during rotor coast up/down.
Ivanova, Tatiana B.; Pivovarova, Elena N.
2014-02-01
In this paper we consider the control of a dynamically asymmetric balanced ball on a plane in the case of slipping at the contact point. Necessary conditions under which a control is possible are obtained. Specific algorithms of control along a given trajectory are constructed.
Rotor speed estimation for indirect stator flux oriented induction motor drive based on MRAS scheme
Directory of Open Access Journals (Sweden)
Youssef Agrebi
2007-09-01
Full Text Available In this paper, a conventional indirect stator flux oriented controlled (ISFOC induction motor drive is presented. In order to eliminate the speed sensor, an adaptation algorithm for tuning the rotor speed is proposed. Based on the model reference adaptive system (MRAS scheme, the rotor speed is tuned to obtain an exact ISFOC induction motor drive. The reference and adjustable models, developed in stationary stator reference frame, are used in the MRAS scheme to estimate induction rotor peed from measured terminal voltages and currents. The IP gains speed controller and PI gains current controller are calculated and tuned at each sampling time according to the new estimated rotor speed. The proposed algorithm has been tested by numerical simulation, showing the capability of driving active load; and stability is preserved. Experimental results obtained with a general-purpose 1-kW induction machine are presented showing the effectiveness of the proposed approach in terms of dynamic performance.
Optimization of wind turbine rotors
Energy Technology Data Exchange (ETDEWEB)
Nygaard, Tor Anders
1999-07-01
The Constrained Steepest Descent method has been applied to the optimization of wind turbine rotors through the development of a numerical model. The model consists of an optimization kernel, an aerodynamic model, a structural dynamic model of a rotating beam, and a cost model for the wind turbine. The cost of energy is minimized directly by varying the blade design, the rotational speed and the resulting design of the drive-train and tower. The aerodynamic model is a combination of a fast engineering model based on strip-theory and two and three-dimensional Euler solvers. The two-dimensional Euler solver is used for generation of pre-stall airfoil data. Comparisons with experimental data verify that the engineering model effectively approximates non-stalled flow, except at the blade tip. The three-dimensional Euler solver is in good agreement with the experimental data at the tip, and is therefore a useful supplement for corrections of the tip-loss model, and evaluation of an optimized design. The structural dynamic model evaluates stresses and deformations for the blade. It is based on constitutive relations for a slender beam that are solved with the equations of motions using a finite-difference method. The cost model evaluates the design change of the wind turbine and the resulting costs that occur when a change in blade design modifies the blade mass and the overall forces. The cost model is based on engineering design rules for the drive-train and tower. The model was applied using a Danish 600 kW wind turbine as a reference. Two rotors were optimized using traditional NACA airfoils and a new low-lift airfoil family developed specifically for wind turbine purposes. The cost of energy decreased four percent for the NACA rotor, and seven percent for the low-lift rotor. Optimizations with a high number of degrees of freedom show that a designer has considerable flexibility in choosing some primary parameters such as rated power and rotor diameter, if the rest
Rotor Position Estimation for Switched Reluctance Wind Generator Using Extreme Learning Machine
DEFF Research Database (Denmark)
Wang, Chao; Liu, Xiao; Chen, Zhe
2014-01-01
Reluctance Wind Generator (SRWG) based on Extreme Learning Machine (ELM) which could build a nonlinear mapping between flux linkage-current and rotor position. The learning data are derived from magnetization curves of the SRWG which are obtained from Finite Element Analysis (FEA) of an SRG with 8/6 stator...... wind turbines are operating. Fast and accurate rotor position estimation is essential to promote the sensorless control as well as sensor fault tolerant operation of the SRG, which may improve the reliability of the system. This paper presents a rotor position sensorless estimation scheme for Switched...
Energy from Swastika-Shaped Rotors
Directory of Open Access Journals (Sweden)
McCulloch M. E.
2015-04-01
Full Text Available It is suggested here that a swastika-shaped rotor exposed to waves will rotate in the di- rection its arms are pointing (towards the arm-tips due to a sheltering effect. A formula is derived to predict the motion obtainable from swastika rotors of different sizes given the ocean wave height and phase speed and it is suggested that the rotor could provide a new, simpler method of wave energy generation. It is also proposed that the swastika rotor could generate energy on a smaller scale from sound waves and Brownian motion, and potentially the zero point field.
Rotor thermal stress monitoring in steam turbines
Antonín, Bouberle; Jan, Jakl; Jindřich, Liška
2015-11-01
One of the issues of steam turbines diagnostics is monitoring of rotor thermal stress that arises from nonuniform temperature field. The effort of steam turbine operator is to operate steam turbine in such conditions, that rotor thermal stress doesn't exceed the specified limits. If rotor thermal stress limits are exceeded for a long time during machine operation, the rotor fatigue life is shortened and this may lead to unexpected machine failure. Thermal stress plays important role during turbine cold startup, when occur the most significant differences of temperatures through rotor cross section. The temperature field can't be measured directly in the entire rotor cross section and standardly the temperature is measured by thermocouple mounted in stator part. From this reason method for numerical solution of partial differential equation of heat propagation through rotor cross section must be combined with method for calculation of temperature on rotor surface. In the first part of this article, the application of finite volume method for calculation of rotor thermal stress is described. The second part of article deals with optimal trend generation of thermal flux, that could be used for optimal machine loading.
Aeromechanical Analysis of a Smart Helicopter Rotor in Forward Flight
Directory of Open Access Journals (Sweden)
Jacopo Serafini
2015-02-01
Full Text Available This paper deals with a smart system integrated into a helicopter blade aimed at giving an anhedral shape to the blade tip region to alleviate the blade-vortex interaction phenomenon that may cause reduced helicopter performance in terms of noise and vibrations. The blade tip morphing is obtained through the joint action of a magneto-rheological fluid (MRF device, a shape-memory alloy ribbons- based (SMA device and a set of concentrated masses properly distributed spanwise. The presence of this smart actuator (particularly the concentrated masses inside the blades modifies the aeromechanical behaviour of the rotor and may be detrimental in terms of hub vibratory loads, pitch control effectiveness and aeroelastic stability. Following a previous literature work concerning with the effectiveness of the smart actuated rotor in hovering conditions, the present paper focuses on the aeromechanical effects due to the inclusion of the smart device in a four-bladed helicopter rotor in forward flight where blade morphing is not needed. Aim of this work is to investigate on the compatibility of the smart system with the required aeromechanical performance of the rotor, highlighting the feasibility of its application on helicopters.
Method for predicting impulsive noise generated by wind turbine rotors
Viterna, L. A.
1982-01-01
Large wind turbines can generate both broad band and impulsive noises. These noises can be controlled by proper choice of rotor design parameters such as rotor location with respect to the supporting tower, tower geometry and tip speed. A method was developed to calculate the impulsive noise generated when the wind turbine blade experiences air forces that are periodic functions of the rotational frequency. This phenomenon can occur when the blades operate in the wake of the support tower and the nonuniform velocity field near the ground due to wind shear. Results from this method were compared with measured sound spectra taken at locations of one to two rotor diameters from the DOE/NASA Mod-1 wind turbine. The calculated spectra generally agreed with the measured data in both the amplitude of the predominant harmonics and the roll of rate with frequency. Measured sound pressure levels far from the Mod-1 (15 rotor diameters), however, were higher than predicted. Simultaneous measurements in the near and far field indicated that the propagation effects could enhance the sound levels by more than 10 dB above that expected by spherical dispersion. These propagation effects are believed to be due to terrain and atmospheric characteristics of the Mod-1 site.
Performance of twist-coupled blades on variable speed rotors
Energy Technology Data Exchange (ETDEWEB)
Lobitz, D.W.; Veers, P.S.; Laino, D.J.
1999-12-07
The load mitigation and energy capture characteristics of twist-coupled HAWT blades that are mounted on a variable speed rotor are investigated in this paper. These blades are designed to twist toward feather as they bend with pretwist set to achieve a desirable twist distribution at rated power. For this investigation, the ADAMS-WT software has been modified to include blade models with bending-twist coupling. Using twist-coupled and uncoupled models, the ADAMS software is exercised for steady wind environments to generate C{sub p} curves at a number of operating speeds to compare the efficiencies of the two models. The ADAMS software is also used to generate the response of a twist-coupled variable speed rotor to a spectrum of stochastic wind time series. This spectrum contains time series with two mean wind speeds at two turbulence levels. Power control is achieved by imposing a reactive torque on the low speed shaft proportional to the RPM squared with the coefficient specified so that the rotor operates at peak efficiency in the linear aerodynamic range, and by limiting the maximum RPM to take advantage of the stall controlled nature of the rotor. Fatigue calculations are done for the generated load histories using a range of material exponents that represent materials from welded steel to aluminum to composites, and results are compared with the damage computed for the rotor without twist-coupling. Results indicate that significant reductions in damage are achieved across the spectrum of applied wind loading without any degradation in power production.
Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network
Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.
2013-01-01
The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for
Maximization of induction motor torque in the zone of high speed of rotor using a genetic algorithm
2013-01-01
Is studied the problem of quality improving of the vector-controlled induction motor drives. Using genetic algorithm obtained a law forming of the rotor flux linkage that maximizes the torque of an induction motor with constraints voltage and stator current. Numerical studies have shown that the proposed law can significantly increase the motor torque in the area of high speed of rotor.
Tang, Jiqiang; Xiang, Biao; Wang, Chun'e
2015-09-01
A novel Vernier-gimballing magnetically suspended flywheel with conical magnetic bearing (conical MB) can generate great gyroscopic moment by tilting the high-speed rotor. To output the gyroscopic moment, the high-speed rotor must be suspended stably and can be tilted. But when the rotor tilts, the gap between the stator and rotor of conical MB changes nonlinearly, what will cause the magnetic force and current stiffness of this conical MB to be serious nonlinear. To solve these problems, one kind of adaptive controller based on Lyapunov stability theory is designed by regarding the current stiffness of this conical MB as uncertain parameter. The validity of this adaptive control method is verified on a Vernier-gimballing MSFW with 68 Nms angular momentum and 1.7° maximum tilting angle. All experimental results indicated that this adaptive control has better performances on controlling rotor's stable suspension than existing PID control when the rotor translates or tilts. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
Prediction of aerodynamic performance for MEXICO rotor
DEFF Research Database (Denmark)
Hong, Zedong; Yang, Hua; Xu, Haoran
2013-01-01
The aerodynamic performance of the MEXICO (Model EXperiments In Controlled cOnditions) rotor at five tunnel wind speeds is predicted by making use of BEM and CFD methods, respectively, using commercial MATLAB and CFD software. Due to the pressure differences on both sides of the blade, the tip...... the reliability of the MEXICO data. Second, the SST turbulence model can better capture the flow separation on the blade and has high aerodynamic performance prediction accuracy for a horizontal axis wind turbine in axial inflow conditions. Finally, the comparisons of the axial and tangential forces as well...... as the contrast of the angle of attack indicate that the prediction accuracy of BEM method is high when the blade is not in the stall condition. However, the airfoil characteristic becomes unstable in the stall condition, and the maximum relative error of tangential force calculated by BEM is -0.471. As a result...
Institute of Scientific and Technical Information of China (English)
欧阳金鑫; 熊小伏
2014-01-01
双馈风电机组的规模化应用使电力系统的故障暂态特性发生变化。为了保障电力系统规划设计和保护控制的顺利实施，必须充分掌握双馈感应发电机(doubly fed induction generator，DFIG)输出短路电流的特征。目前双馈感应发电机的暂态分析尚未计及变流器励磁控制的影响，使双馈风电机组短路电流还难以准确分析和计算。针对DFIG转子侧变流器励磁控制与发电机电磁过程的复杂暂态耦合，通过构建包含变流器调控过程及发电机电磁暂态的转子回路动态模型，重点分析了电网对称短路冲击作用下DFIG的暂态扰动及其传递特性，推导了计及励磁调节作用的DFIG定转子短路电流简化表达式，分析了励磁控制下DFIG短路电流的特征以及控制方式对暂态行为的影响，利用时域仿真验证了理论分析的正确性。%The large-scale application of doubly-fed wind turbines has significantly changed the fault transient characteristics of power systems. The short-circuit current contributed by doubly-fed induction generator (DFIG) should be fully understood to ensure the implementation of the planning and protection of power system. However, the impact of the converter excitation control has not been fully assessed, thus resulting in greater difficulty in the analysis and calculation of short-circuit current. This study presents a detailed analysis of short-circuit current of a DFIG, with focus on the complex coupling between the excitation control and electromagnetic process. The transient disturbances and their transitive relation in a DFIG under symmetrical short circuit are analyzed by constructing the dynamic model of rotor circuit. The expressions of rotor and stator short-circuit currents are deduced for the simplified calculation and analytical analysis. The characteristics of the short-circuit current of DFIG under the excitation control are analyzed and the impacts of
Performance tests of a Benesh wind turbine rotor and a Savonius rotor
Energy Technology Data Exchange (ETDEWEB)
Moutsoglou, A.; Yan Weng [South Dakota State Univ., Brookings, SD (United States). Dept. of Mechanical Engineering
1995-12-31
A study was conducted to compare the performance of a Benesh rotor against a Savonius rotor as a wind power generating device. Rotors of similar dimensions were tested at the exit of a 1.22 m x 0.91 wind tunnel, at two different shaft heights above the ground. In all the tests, the maximum power coefficient for the Benesh rotor was considerably greater than for the Savonius and occurred at a lower tip speed ratio. The Benesh rotor also displayed better starting characteristics throughout. Finally, the present data compared very favourably with the experimental data of Backwell et al. (Author)
Optimal Aerodynamic Design of Conventional and Coaxial Helicopter Rotors in Hover and Forward Flight
Giovanetti, Eli B.
This dissertation investigates the optimal aerodynamic performance and design of conventional and coaxial helicopters in hover and forward flight using conventional and higher harmonic blade pitch control. First, we describe a method for determining the blade geometry, azimuthal blade pitch inputs, optimal shaft angle (rotor angle of attack), and division of propulsive and lifting forces among the components that minimize the total power for a given forward flight condition. The optimal design problem is cast as a variational statement that is discretized using a vortex lattice wake to model inviscid forces, combined with two-dimensional drag polars to model profile losses. The resulting nonlinear constrained optimization problem is solved via Newton iteration. We investigate the optimal design of a compound vehicle in forward flight comprised of a coaxial rotor system, a propeller, and optionally, a fixed wing. We show that higher harmonic control substantially reduces required power, and that both rotor and propeller efficiencies play an important role in determining the optimal shaft angle, which in turn affects the optimal design of each component. Second, we present a variational approach for determining the optimal (minimum power) torque-balanced coaxial hovering rotor using Blade Element Momentum Theory including swirl. We show that the optimal hovering coaxial rotor generates only a small percentage of its total thrust on the portion of the lower rotor operating in the upper rotor's contracted wake, resulting in an optimal design with very different upper and lower rotor twist and chord distributions. We also show that the swirl component of induced velocity has a relatively small effect on rotor performance at the disk loadings typical of helicopter rotors. Third, we describe a more refined model of the wake of a hovering conventional or coaxial rotor. We approximate the rotor or coaxial rotors as actuator disks (though not necessarily uniformly loaded
Innovative multi rotor wind turbine designs
Energy Technology Data Exchange (ETDEWEB)
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)
Rotor theories by Professor Joukowsky: Momentum theories
DEFF Research Database (Denmark)
van Kuik, G. A. M.; Sørensen, Jens Nørkær; Okulov, V. L.
2015-01-01
This paper is the first of two papers on the history of rotor aerodynamics with special emphasis on the role of Joukowsky. The present one focuses on the development of the momentum theory while the second one surveys the development of vortex theory for rotors. Joukowsky has played a major role ...
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.
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.
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.
Rotors stress analysis and design
Vullo, Vincenzo
2013-01-01
Stress and strain analysis of rotors subjected to surface and body loads, as well as to thermal loads deriving from temperature variation along the radius, constitutes a classic subject of machine design. Nevertheless attention is limited to rotor profiles for which governing equations are solvable in closed form. Furthermore very few actual engineering issues may relate to structures for which stress and strain analysis in the linear elastic field and, even more, under non-linear conditions (i.e. plastic or viscoelastic conditions) produces equations to be solved in closed form. Moreover, when a product is still in its design stage, an analytical formulation with closed-form solution is of course simpler and more versatile than numerical methods, and it allows to quickly define a general configuration, which may then be fine-tuned using such numerical methods. In this view, all subjects are based on analytical-methodological approach, and some new solutions in closed form are presented. The analytical formul...
A novel method for estimating the initial rotor position of PM motors without the position sensor
Energy Technology Data Exchange (ETDEWEB)
Rostami, Alireza; Asaei, Behzad [School of Electrical and Computer Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran)
2009-08-15
Permanent magnet (PM) motors have been used widely in the industrial applications. However, a need of the position sensor is a drawback of their control system. The sensorless methods using the back-EMF (electromotive force) cannot detect the rotor position at a standstill; recently, a few methods proposed to detect the initial rotor position, but they have high estimation error which reduces starting torque of the motor. Therefore, in this paper, a novel method to detect the initial rotor position of the PM motors is proposed, first, by using a space vector model, response of the stator current space vector to the saturation of the stator core is analyzed; then a novel method based on the saturation effect is presented that estimates the initial rotor position and the maximum estimation error is less than 3.8. Simulation results confirm this method is effective and precise, and variation of the motor parameters does not affect its precision. (author)
Initial Rotor Position Estimation of Half-Wave Rectified Brushless Synchronous Motor
Abe, Takashi; Oyama, Jun; Higuchi, Tsuyoshi
This paper presents an initial rotor position estimation of Half-Wave Rectified Brushless Synchronous Motor. In the previous paper, we proposed this motor as AC servo motor, which is based on the half-wave rectified brushless excitation principle. The basic principle of this estimation technique utilizes the dependence of inductance on the rotor position. The bias frequency component of half-Wave rectified brushless excitation is used to estimate the rotor position error. The magnetic pole is discriminated by the switching condition of the diode inserted into the rotor field winding. This estimation technique is confirmed by simulation include inverter circuit, control program and motor model. Finally, the effectiveness of the proposed estimation technique has been verified by experiments.
基于气压高度计的多旋翼飞行器高度控制%Altitude Control of Multi-Rotor Type Aircraft Based on Pressure Sensor
Institute of Scientific and Technical Information of China (English)
王伟; 周勇; 王峰; 程勇; 宋昱泽; 野波健藏
2011-01-01
洪水、台风、地震等自然灾害发生时,微小型无人机可以涉足到危险区域及时精确的获取灾区的受灾信息,在必要的时候甚至能够进入到狭窄的空间内部来收集情报.一方面可以为灾后救援提供有力的帮助,同时还可以避免发生灾后次生灾害.以自行开发的6旋翼飞行嚣为控制对象,以实现飞行器的高度方向自主飞行为目的,首先介绍了飞行嚣的构造、飞行原理及嵌入式控制系统,然后针对微小型多旋翼飞行器的高度控制,提出了使用高度气压计与加速度相结合的测量手法,代替GPS传感器来测量飞行器的飞行高度.并对飞行器的高度自由度进行数学建模,运用最优控制的理论来设计控制器.针对无法观测的状态量,设计了卡尔曼滤波器采进行推测.通过实验验证了设计的控制器的稳定性与追踪性.%In case of natural disaster like earthquake, a MAV will be very effective for surveying the site and environment in dangerous area or narrow space where human cannot access safely. A six-rotor MAV is designed and taken as the platform the configuration, the flight principles and the embedded control system of the aircraft are introduced. For the altitude control of rotary-wing MAV. The pressure sensor and acceleration sensor are used to replace the GPS receiver to observe flight altitude. The mathematical model of MAV is given, and the optimal controller is designed- To the unobservable stale value, the kalman filter is designed. The experimental result shows the performance of the designed controller.
Institute of Scientific and Technical Information of China (English)
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.
Energy Technology Data Exchange (ETDEWEB)
Ramirez Solis, Jose Antonio; Munoz Quezada, Rodolfo; Franco Nava, Jose Manuel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1993-01-01
At the Instituto de Investigaciones Electricas (IIE), the experimental modal tests were initiated in order to validate the numerical models used by computer programs for the study of the rotor dynamic behavior. In order to contribute to the application of the rotor balancing methods based in the calculation of their modal forms, currently the capacity to determine these modal forms and the natural frequencies of turbogenerator rotors, is being developed, through experimental modal tests. In this paper a short description is made of the technique and the results of its application in an experimental rotor and in one of the rotors of a turbogenerator, are presented. [Espanol] En el Instituto de Investigaciones Electricas (IIE), las pruebas modales experimentales se iniciaron con la finalidad de validar los modelos numericos empleados por programas de computo para el estudio del comportamiento dinamico de rotores. Con objeto de contribuir a la aplicacion de los metodos de balanceo de rotores basados en el calculo de sus formas modales, actualmente esta desarrollandose la capacidad para determinar esas formas modales y las frecuencias naturales de rotores de turbogeneradores, a traves de las pruebas modales experimentales. En este trabajo se describe brevemente la tecnica y se presentan los resultados de su aplicacion en un rotor experimental y en uno de los tres rotores de un turbogenerador.
14 CFR 27.1461 - Equipment containing high energy rotors.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 27... Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must be able to...
14 CFR 29.1461 - Equipment containing high energy rotors.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 29... § 29.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...
14 CFR 25.1461 - Equipment containing high energy rotors.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 25... § 25.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...
Wind rotor with vertical axis. Vindrotor med vertikal axel
Energy Technology Data Exchange (ETDEWEB)
Colling, J.; Sjoenell, B.
1987-06-15
This rotor is of dual type i.e. a paddle wheel shaped rotor close to the vertical axis and a second rotor consisting of vertical blades with wing profile and attached to radial spokes which are fixed to the axis together with the paddle wheel rotor. (L.F.).
Kottapalli, Sesi; Meza, Victor
1992-01-01
A rotorcraft analysis is conducted to assess tilt-rotor stability and conversion loads for the XV-15 rotor with metal blades within its specified test envelope. A 38-DOF flutter analysis based on the code by Johnson (1988) is developed to simulate a wind-tunnel test in which the rotor torque is constant and thereby study stability. The same analytical model provides the simulated loads including hub loads, blade loads, and oscillatory pitch-link loads with attention given to the nonuniform inflow through the proprotor in the presence of the wing. Tilt-rotor stability during the cruise mode is found to be sensitive to coupling effects in the control system stiffness, and a stability problem is identified in the XV-15 Advanced Technology Blades. The present analysis demonstrates that the tilt-rotor is stable within the specified test envelope of the NASA 40 x 80-ft wind tunnel.
On the torque mechanism of Savonius rotors
Energy Technology Data Exchange (ETDEWEB)
Fujisawa, N. (Dept. of Mechanical Univ., Kiryu (Japan))
1992-07-01
The aerodynamic performance and the flow fields of Savonius rotors at various overlap ratios have been investigated by measuring the pressure distributions on the blades and by visualizing the flow fields in and around the rotors with and without rotation. Experiments have been performed on four rotors having two semicircular blades but with different overlap ratios ranging 0 to 0.5. The static torque performance is improved by increasing the overlap ratio especially on the returning blade, which is due to the pressure recovery effect by the flow through the overlap. On the other hand, the torque and the power performance of the rotating rotor reaches a maximum at an overlap of 0.15. This effect is largely created by the Coanda-like flow on the convex side of the advancing blade, which is strengthened by the flow through the overlap at this small overlap ratio. However, this phenomena is weakened as the overlap ratio is further increased, suggesting a deteriorated performance of the rotor. Observations of the flow inside the rotor indicate an increased recirculation region at such large overlap ratios, which also suggests a reduced aerodynamic efficiency for rotors with large overlap. 11 figs., 16 refs.
Tone and Broadband Noise Separation from Acoustic Data of a Scale-Model Counter-Rotating Open Rotor
Sree, David; Stephens, David B.
2014-01-01
Renewed interest in contra-rotating open rotor technology for aircraft propulsion application has prompted the development of advanced diagnostic tools for better design and improved acoustical performance. In particular, the determination of tonal and broadband components of open rotor acoustic spectra is essential for properly assessing the noise control parameters and also for validating the open rotor noise simulation codes. The technique of phase averaging has been employed to separate the tone and broadband components from a single rotor, but this method does not work for the two-shaft contra-rotating open rotor. A new signal processing technique was recently developed to process the contra-rotating open rotor acoustic data. The technique was first tested using acoustic data taken of a hobby aircraft open rotor propeller, and reported previously. The intent of the present work is to verify and validate the applicability of the new technique to a realistic one-fifth scale open rotor model which has 12 forward and 10 aft contra-rotating blades operating at realistic forward flight Mach numbers and tip speeds. The results and discussions of that study are presented in this paper.
Tone and Broadband Noise Separation from Acoustic Data of a Scale-Model Contra-Rotating Open Rotor
Sree, Dave; Stephens, David B.
2014-01-01
Renewed interest in contra-rotating open rotor technology for aircraft propulsion application has prompted the development of advanced diagnostic tools for better design and improved acoustical performance. In particular, the determination of tonal and broadband components of open rotor acoustic spectra is essential for properly assessing the noise control parameters and also for validating the open rotor noise simulation codes. The technique of phase averaging has been employed to separate the tone and broadband components from a single rotor, but this method does not work for the two-shaft contra-rotating open rotor. A new signal processing technique was recently developed to process the contra-rotating open rotor acoustic data. The technique was first tested using acoustic data taken of a hobby aircraft open rotor propeller, and reported previously. The intent of the present work is to verify and validate the applicability of the new technique to a realistic one-fifth scale open rotor model which has 12 forward and 10 aft contra-rotating blades operating at realistic forward flight Mach numbers and tip speeds. The results and discussions of that study are presented in this paper.
Simultaneous observation of wind shears and misalignments from rotor loads
Cacciola, S.; Bertelè, M.; Bottasso, C. L.
2016-09-01
A wind turbine is used in this paper as a sensor to measure the wind conditions at the rotor disk. In fact, as any anisotropy in the wind will lead to a specific signature in the machine response, by inverting a response model one may infer its generating cause, i.e. the wind. Control laws that exploit this knowledge can be used to enhance the performance of a wind turbine or a wind power plant. This idea is used in the present paper to formulate a linear implicit model that relates wind states and rotor loads. Simulations are run in both uniform and turbulent winds, using a high-fidelity aeroservoleastic wind turbine model. Results demonstrate the ability of the proposed observer in detecting the horizontal and vertical wind misalignments, as well as the vertical and horizontal shears.
A Static Burst Test for Composite Flywheel Rotors
Hartl, Stefan; Schulz, Alexander; Sima, Harald; Koch, Thomas; Kaltenbacher, Manfred
2016-06-01
High efficient and safe flywheels are an interesting technology for decentralized energy storage. To ensure all safety aspects, a static test method for a controlled initiation of a burst event for composite flywheel rotors is presented with nearly the same stress distribution as in the dynamic case, rotating with maximum speed. In addition to failure prediction using different maximum stress criteria and a safety factor, a set of tensile and compressive tests is carried out to identify the parameters of the used carbon fiber reinforced plastics (CFRP) material. The static finite element (FE) simulation results of the flywheel static burst test (FSBT) compare well to the quasistatic FE-simulation results of the flywheel rotor using inertia loads. Furthermore, it is demonstrated that the presented method is a very good controllable and observable possibility to test a high speed flywheel energy storage system (FESS) rotor in a static way. Thereby, a much more expensive and dangerous dynamic spin up test with possible uncertainties can be substituted.
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.
Multiple piece turbine rotor blade
Energy Technology Data Exchange (ETDEWEB)
Kimmel, Keith D.; Plank, William L.
2016-07-19
A spar and shell turbine rotor blade with a spar and a tip cap formed as a single piece, the spar includes a bottom end with dovetail or fir tree slots that engage with slots on a top end of a root section, and a platform includes an opening on a top surface for insertion of the spar in which a shell made from an exotic high temperature resistant material is secured between the tip cap and the platform. The spar is tapered to form thinner walls at the tip end to further reduce the weight and therefore a pulling force due to blade rotation. The spar and tip cap piece is made from a NiAL material to further reduce the weight and the pulling force.
Study on wave rotor refrigerators
Institute of Scientific and Technical Information of China (English)
Yuqiang DAI; Dapeng HU; Meixia DING
2009-01-01
As a novel generation of a rotational gas wave machine, the wave rotor refrigerator (WRR) is an unsteady flow device used for refrigeration, in whose passages pressured streams directly contact and exchange energy due to the movement of pressure waves. In this paper, the working mechanism and refrigeration principle are inves-tigated based on the one-dimensional unsteady flow theory.A basic limitation on main structural parameters and operating parameters is deduced and the wave diagram of WRR to guide designing is sketched. The main influential factors are studied through an experiment. In the DUT Gas Wave Refrigeration Studying and Development Center (GWRSDC) lab, the isentropic efficiency can now reach about 65%. The results show that the WRR is a feasible and promising technology in pressured gas refrigeration cases.
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.
The effect of blade pitch in the rotor hydrodynamics of a cross-flow turbine
Somoano, Miguel; Huera-Huarte, Francisco
2016-11-01
In this work we will show how the hydrodynamics of the rotor of a straight-bladed Cross-Flow Turbine (CFT) are affected by the Tip Speed Ratio (TSR), and the blade pitch angle imposed to the rotor. The CFT model used in experiments consists of a three-bladed (NACA-0015) vertical axis turbine with a chord (c) to rotor diameter (D) ratio of 0.16. Planar Digital Particle Image Velocimetry (DPIV) was used, with the laser sheet aiming at the mid-span of the blades, illuminating the inner part of the rotor and the near wake of the turbine. Tests were made by forcing the rotation of the turbine with a DC motor, which provided precise control of the TSR, while being towed in a still-water tank at a constant Reynolds number of 61000. A range of TSRs from 0.7 to 2.3 were covered for different blade pitches, ranging from 8° toe-in to 16° toe-out. The interaction between the blades in the rotor will be discussed by examining dimensionless phase-averaged vorticity fields in the inner part of the rotor and mean velocity fields in the near wake of the turbine. Supported by the Spanish Ministry of Economy and Competitiveness, Grant BES-2013-065366 and project DPI2015-71645-P.
Magnetostatic analysis of a rotor system supported by radial active magnetic bearings
Directory of Open Access Journals (Sweden)
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.
HARP model rotor test at the DNW. [Hughes Advanced Rotor Program
Dawson, Seth; Jordan, David; Smith, Charles; Ekins, James; Silverthorn, Lou
1989-01-01
Data from a test of a dynamically scaled model of the Hughes Advanced Rotor Program (HARP) bearingless model main rotor and 369K tail rotor are reported. The history of the HARP program and its goals are reviewed, and the main and tail rotor models are described. The test facilities and instrumentation are described, and wind tunnel test data are presented on hover, forward flight performance, and blade-vortex interaction. Performance data, acoustic data, and dynamic data from near field/far field and shear layer studies are presented.
The Savonius rotor. A construction guide. 11. ed.; Der Savonius-Rotor. Eine Bauanleitung
Energy Technology Data Exchange (ETDEWEB)
Schulz, Heinz
2009-07-01
The Savonius rotor is particularly suited for medium and low wind velocities and low capacities (up to 500 W). It can be constructed of commercial components and using simple techniques. It requires little wind to start, and the useful energy is transmitted via a shaft. In this lavishly illustrated book, the author describes the construction and operation of a robust Savonius rotor. He also shows how this rotor can be developed into a flow-through rotor for bigger plants, and he presents recommendations for appropriate machinery like pumps and slow generators.
Aerodynamics of Rotor Blades for Quadrotors
Bangura, Moses; Naldi, Roberto; Mahony, Robert
2016-01-01
In this report, we present the theory on aerodynamics of quadrotors using the well established momentum and blade element theories. From a robotics perspective, the theoretical development of the models for thrust and horizontal forces and torque (therefore power) are carried out in the body fixed frame of the quadrotor. Using momentum theory, we propose and model the existence of a horizontal force along with its associated power. Given the limitations associated with momentum theory and the inadequacy of the theory to account for the different powers represented in a proposed bond graph lead to the use of blade element theory. Using this theory, models are then developed for the different quadrotor rotor geometries and aerodynamic properties including the optimum hovering rotor used on the majority of quadrotors. Though this rotor is proven to be the most optimum rotor, we show that geometric variations are necessary for manufacturing of the blades. The geometric variations are also dictated by a desired th...
Valve-aided twisted Savonius rotor
Energy Technology Data Exchange (ETDEWEB)
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].
Edge states of periodically kicked quantum rotors
Floß, Johannes
2015-01-01
We present a quantum localization phenomenon that exists in periodically kicked 3D rotors, but is absent in the commonly studied 2D ones: edge localization. We show that under the condition of a fractional quantum resonance there are states of the kicked rotor that are strongly localized near the edge of the angular momentum space at $J=0$. These states are analogs of surface states in crystalline solids, and they significantly affect resonant excitation of molecular rotation by laser pulse trains.
Institute of Scientific and Technical Information of China (English)
蒋科坚; 祝长生
2011-01-01
为了抑制振动,提高转子旋转精度,提出一种基于振动识别的不平衡补偿控制方法.该方法无需控制对象的传递函数,通过对主动电磁轴承施加试探性补偿信号,同时检测转子位移响应中不平衡振动的幅值和相位变化,直接计算出不平衡振动的Fourier系数,产生精确的补偿电磁力,实现不平衡补偿控制.在控制性能测试的实验中,振动响应的功率谱显示转速频率的振动能量有近30 dB的下降.实验结果表明,该方法对不平衡振动的抑制效果是显著的.%For suppressing vibrations and improving the rotor's rotating precision, a novel unbalance compensation method was proposed, which does not need the transfer function of plant model. The proposed method can directly obtain the Fourier coefficients of unbalance vibration and generate the accurate magnetic force to achieve unbalance compensation by injecting a trial signal into the active magnetic bearing (AMB) and meanwhile measuring the variety in magnitude and phase of the rotor's displacement response.Finally, in an experiment for testing the algorithm's efficiency and precision, approximately 30 dB reduction in unbalance vibrations was obtained in the power spectrum of rotor vibration. The experimental results indicate that the proposed algorithm is effective for suppressing rotor unbalance vibration.
Dynamic Gust Load Analysis for Rotors
Directory of Open Access Journals (Sweden)
Yuting Dai
2016-01-01
Full Text Available Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.
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
On Stability of Open-Loop Operation without Rotor Information for Brushless DC Motors
Directory of Open Access Journals (Sweden)
Zhong Wu
2014-01-01
Full Text Available Open-loop operation mode is often used to control the Brushless DC Motors (BLDCMs without rotor position sensors when the back electromotive force (EMF is too weak due to the very low rotor velocity. The rotor position information is not necessary in this mode and the stator windings are supplied with voltages under a certain ratio of the amplitude to the frequency. However, the rotor synchronization will be destroyed once if the commutation instant is inappropriate. In order to improve the reliability of the open-loop operation mode, a dynamic equation is established to represent the synchronization error between the rotor and the stator. Thereafter, the stability of the open-loop control mode is analyzed by using Lyapunov indirect method. Theoretical analysis indicates that the open-loop control mode is asymptotically stable only when the commutation instant of the stator current lags behind the ideal one suitably. Finally, theoretical analysis is verified through the experimental results of a certain BLDCM.
A rotor for a high-rise building; Ein Rotor fuer das Hochhaus
Energy Technology Data Exchange (ETDEWEB)
Zastrow, F. [Hochschule Bremerhaven (Germany). Inst. fuer Automatisierungs- und Elektrotechnik; Okoth, G.; Boehm, K.; El Naggar, S. [Alfred-Wegener Inst. fuer Polar- und Meeresforschung, Bremerhaven (Germany)
2004-08-30
The typical characteristics of the H rotor recommend it not only for use in extreme climate zones but also for installation on buildings and in built-on terrain. It is difficult, however, to make small H rotors efficient and economical. (orig.)
A Method to Transit the Rotor-to-Stator Rubbing to Normal Motion Using the Phase Characteristic
Directory of Open Access Journals (Sweden)
Jieqiong Xu
2014-01-01
Full Text Available A method is proposed to transit the rotor-to-stator rubbing to no-rub motion through active auxiliary bearing. The key point of this technique is to express the attractive domain of no-rub motion based on the phase characteristic and to represent the desired status. The feedback actuation is applied by an active auxiliary bearing to drive the rotor approaching the desired status. After that, the control actuation is turned off. Although the desired status is still in rubbing, it is in the attractive domain of no-rub motion, and the response of the rotor is automatically attracted to no-rub motion.
Optimum blade loading for a powered rotor in descent
Institute of Scientific and Technical Information of China (English)
Ramin Modarres; David A. Peters
2016-01-01
The optimum loading for rotors has previously been found for hover, climb and wind turbine conditions;but, up to now, no one has determined the optimum rotor loading in descent. This could be an important design consideration for rotary-wing parachutes and low-speed des-cents. In this paper, the optimal loading for a powered rotor in descent is found from momentum theory based on a variational principle. This loading is compared with the optimal loading for a rotor in hover or climb and with the Betz rotor loading (which is optimum for a lightly-loaded rotor). Wake contraction for each of the various loadings is also presented.
THE DESIGN OF AXIAL PUMP ROTORS USING THE NUMERICAL METHODS
Directory of Open Access Journals (Sweden)
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.
Rotor Wake Development During the First Revolution
McAlister, Kenneth W.
2003-01-01
The wake behind a two-bladed model rotor in light climb was measured using particle image velocimetry, with particular emphasis on the development of the trailing vortex during the first revolution of the rotor. The distribution of vorticity was distinguished from the slightly elliptical swirl pattern. Peculiar dynamics within the void region may explain why the peak vorticity appeared to shift away from the center as the vortex aged, suggesting the onset of instability. The swirl and axial velocities (which reached 44 and 12 percent of the rotor-tip speed, respectively) were found to be asymmetric relative to the vortex center. In particular, the axial flow was composed of two concentrated zones moving in opposite directions. The radial distribution of the circulation rapidly increased in magnitude until reaching a point just beyond the core radius, after which the rate of growth decreased significantly. The core-radius circulation increased slightly with wake age, but the large-radius circulation appeared to remain relatively constant. The radial distributions of swirl velocity and vorticity exhibit self-similar behaviors, especially within the core. The diameter of the vortex core was initially about 10 percent of the rotor-blade chord, but more than doubled its size after one revolution of the rotor. According to vortex models that approximate the measured data, the core-radius circulation was about 79 percent of the large-radius circulation, and the large-radius circulation was about 67 percent of the maximum bound circulation on the rotor blade. On average, about 53 percent of the maximum bound circulation resides within the vortex core during the first revolution of the rotor.
Directory of Open Access Journals (Sweden)
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
Adaptive Backstepping design of an Observer for the Rotor Speed and Field of an Induction Motor
DEFF Research Database (Denmark)
Rasmussen, Henrik
2001-01-01
is de-veloped. The resulting scheme leads to a nonlinear full order observer for the rotor field. The rotor speed and the stator resis-tance are estimated by adaptive backstepping. Assuming motor parameters known the design achieves stability with guaran-teed region of attraction. The adaptive......High performance operation of speed controlled AC drives without mechanical speed/position sensors rely on the dynamic models for estimation of flux and speed. Using backstepping, which is a recursive nonlinear design method, a new approach for the design of observers for speed sensorless control...
Segmented Ultralight Pre-Aligned Rotor for Extreme-Scale Wind Turbines
Energy Technology Data Exchange (ETDEWEB)
Loth, E.; Steele, A.; Ichter, B.; Selig, M.; Moriarty, P.
2012-01-01
To alleviate the mass-scaling issues associated with conventional upwind rotors of extreme-scale turbines, a downwind rotor concept is proposed which employs fixed blade curvature based on force alignment at rated conditions. For a given peak stress constraint, the reduction in downwind cantilever loads allows reduced shell and spar thickness, and thus a reduced blade mass as compared with a conventional upwind rotor, especially as rotor sizes approach extreme-scales. To quantify this mass reduction, a Finite Element Analysis was conducted for a 10 MW rated rotor based on the NREL offshore 5 MW baseline wind turbine. The results show that this 'pre-alignment' yields a net downstream deflection of 32 deg, a downward hub-pitch angle of 6 deg, a 20% increase in blade length (to maintain the same radius as the conventional blade), and a net mass savings of about 50% through decreased shell and spar thicknesses. The pre-alignment may also allow a more straightforward and efficient segmentation of the blade since shear stresses near joints are substantially reduced. Segmenting, in turn, can dramatically reduce costs associated with fabrication, transport and assembly for extreme-scale off-shore systems. The pre-aligned geometric curvature can also help alleviate tower wake effects on the blades since blade tips (where shadow effects can be most problematic) are shifted downstream where the tower wake is weaker. In addition, the portion of the tower that is upstream of the blade tips can be faired with an externally-rotating aerodynamic shroud. Furthermore, the downwind rotor can allow a floating off-shore tri-pod platform to reduce tower weight and yaw-control requirements. A simple economic analysis of the segmented ultralight pre-aligned rotor (SUPAR) concept suggests that the overall system cost savings can be as much as 25%, indicating that more detailed (numerical and experimental) investigations are warranted.
None of the Rotor Residues of F1-ATPase Are Essential for Torque Generation
Chiwata, Ryohei; Kohori, Ayako; Kawakami, Tomonari; Shiroguchi, Katsuyuki; Furuike, Shou; Adachi, Kengo; Sutoh, Kazuo; Yoshida, Masasuke; Kinosita, Kazuhiko
2014-01-01
F1-ATPase is a powerful rotary molecular motor that can rotate an object several hundred times as large as the motor itself against the viscous friction of water. Forced reverse rotation has been shown to lead to ATP synthesis, implying that the mechanical work against the motor’s high torque can be converted into the chemical energy of ATP. The minimal composition of the motor protein is α3β3γ subunits, where the central rotor subunit γ turns inside a stator cylinder made of alternately arranged α3β3 subunits using the energy derived from ATP hydrolysis. The rotor consists of an axle, a coiled coil of the amino- and carboxyl-terminal α-helices of γ, which deeply penetrates the stator cylinder, and a globular protrusion that juts out from the stator. Previous work has shown that, for a thermophilic F1, significant portions of the axle can be truncated and the motor still rotates a submicron sized bead duplex, indicating generation of up to half the wild-type (WT) torque. Here, we inquire if any specific interactions between the stator and the rest of the rotor are needed for the generation of a sizable torque. We truncated the protruding portion of the rotor and replaced part of the remaining axle residues such that every residue of the rotor has been deleted or replaced in this or previous truncation mutants. This protrusionless construct showed an unloaded rotary speed about a quarter of the WT, and generated one-third to one-half of the WT torque. No residue-specific interactions are needed for this much performance. F1 is so designed that the basic rotor-stator interactions for torque generation and control of catalysis rely solely upon the shape and size of the rotor at very low resolution. Additional tailored interactions augment the torque to allow ATP synthesis under physiological conditions. PMID:24853745
Characteristics of wind power on Savonius rotor using a guide-box tunnel
Energy Technology Data Exchange (ETDEWEB)
Irabu, Kunio; Roy, Jitendro Nath [Faculty of Mechanical Engineering, University of the Ryukyus, Senbaru-1, Nishihara, Okinawa 903-0213 (Japan)
2007-11-15
This study investigates to improve and adjust the output power of Savonius rotor under various wind power and suggests the method of prevention the rotor from strong wind disaster. In this study, as the appropriate device to achieve the purpose of it, a guide-box tunnel is employed. The guide-box tunnel is like a rectangular box as wind passage in which a test rotor is included. The area ratio between the inlet and exit of it is variable to adjust the inlet mass flow rate or input power. At first, the experiment was conducted to find the adequate configuration which would provide the best relative performance. The present experiment, however, does not include the test to retain the guide-box tunnel from the strong wind. The experiments include the static torque test of the fixed rotor at any phase angle and the dynamic torque test at rotation of them. Consequently, it was found that the maximum rotor rotational speed was achieved in the range of the guide-box area ratio between 0.3 and 0.7 and the value of the output power coefficient of the rotor with guide-box tunnel of the area ratio 0.43 increases about 1.5 times with three blades and 1.23 times with two blades greater than that without guide-box tunnel, respectively. It seemed that the performance of Savonius rotor within the guide-box tunnel is comparable enough with other methods for augmentation and control of the output. (author)
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.
Performance investigation of the S-Rotors
Bhayo, B. A.; Al-Kayiem, H. H.; Yahaya, N. Z.
2015-12-01
This paper presents and discusses results from an experimental investigation of three models of wind S-rotors. Models 1 is modified from conventional Savonius rotor with a single stage and zero offsets zero overlaps; model 2 is three blade single stage wind rotor; and model 3 is double stage conventional Savonius rotor. The three models were designed, fabricated and characterized in terms of their coefficient of performance and dynamic torque coefficient. A special open wind simulator was designed for the test. The optimum parameters for the models were based on previous studies. The results showed that the model 1, model 2 and model 3 has the maximum power coefficient of 0.26, 0.17, and 0.21 at the correspondence tip speed ratio (TSR) of 0.42, 0.39 and 0.46, respectively. Model 1 is further optimized in terms of the aspect ratio resulting in improved power coefficient by 24%. The maximum dynamic torque coefficient of model 1, model 2 and model 3 was found as 0.81, 0.56 and 0.67 at the correspondence minimum TSR of 0.28, 0.21 and 0.17, respectively. It was noted that the all three models have high torque coefficient because the models were tested at higher applied torque on the rotors.
RESEARCH ON KNOWLEDGE-BASED CAPP SYSTEM FOR ROTOR FORGING
Institute of Scientific and Technical Information of China (English)
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.
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.
Rotor scale model tests for power conversion unit of GT-MHR
Energy Technology Data Exchange (ETDEWEB)
Baxi, C.B., E-mail: baxicb1130@hotmail.com [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Telengator, A.; Razvi, J. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)
2012-10-15
The gas turbine modular helium reactor (GT-MHR) combines a modular high-temperature gas-cooled reactor (HTGR) nuclear heat source with a closed Brayton gas-turbine cycle power conversion unit (PCU) for thermal to electric energy conversion. The PCU has a vertical orientation and is supported on electromagnetic bearings (EMB). The rotor scale model (RSM) tests are intended to directly model the control of EMB and rotor dynamic characteristics of the full-scale GT-MHR turbo-machine (TM). The objectives of the RSM tests are to: Bullet Confirm the EMB control system design for the GT-MHR turbo machine over the full-range of operation. Bullet Confirm the redundancy and on-line maintainability features that have been specified for the EMBs. Bullet Provide a benchmark for validation of analytical tools that will be used for independent analyses of the EMB subsystem design. Bullet Provide experience with the installation, operation and maintenance of EMBs supporting multiple rotors with flexible couplings. As with the full-scale TM, the RSM incorporates two rotors that are joined by a flexible coupling. Each of the rotors is supported on one axial and two radial EMBs. Additional devices, similar in concept to radial EMBs, are installed to simulate magnetic and/or mechanical forces representing those that would be seen by the exciter, generator, compressors and turbine. Overall, the lengths of the RSM rotor is about 1/3rd that of the full-scale TM, while the diameters are approximately 1/5th scale. The design and sizing of the rotor is such that the number and values of critical speeds in the RSM are the same as in the full-scale TM. The EMBs are designed such that their response to rotor dynamic forces is representative of the full-scale TM. The fabrication and assembly of the RSM was completed at the end of 2008. All start up adjustments were finished in December 2009. To-date the generator rotor has been supported in the EMBs and rotated up to 1800 rpm. Final tests are
Institute of Scientific and Technical Information of China (English)
尤明
2012-01-01
The production process and quality control practice of the wind power-used nodular cast iron rotor shaft casting with weight of 16 t.thickness up to 200 mm was introduced. In order to prevent casting defects and meet both the high fatigue strength and low temperature toughness requirement,the following measures were adopted: (1 ) Choosing appropriate chemical composition: w (C) 3.5% -3.7% 、w (Si) 2.0% -2.2% 、w (Mn) <0.3% 、w (P) <0.04% ,w (S) <0.015% 、w (RE) 0.02% -0.03%、(Mg) 0.050%~0,070%, and adding w( Ni) 0.5%~1.0% to increase low temperature toughness;(2)Using furan resin sand and high rigidity molding box for molding and core-making, and using chills to intensify casting solidification; (3)Using bottom gated and non-pressured gating system wilh fillers, and optimizing the casting method design by using the Procast simulation software! (4)Using cored wire injection process lo conduct nodularizing trealment and using pouring stream inoculation. The result of lasting inspection showed that all mechanical properties met the requirements of EN-GJS-400-18LT grade nodular iron,and the UT detection didn't find any casting defect exceeding grade 3.%介绍了质量为16 t、壁厚达200 mm的球墨铸铁风电主轴铸件的生产工艺和质量控制实践工作.为防止产生铸造缺陷和满足高疲劳强度及低温韧性要求,采取了如下措施:(1)选择化学成分为w(C)3.5％～3.7％、w(Si)2.0％～2.2％、w(Mn)＜0.3％、w(P)＜0.04％、w(S)＜0.015％、w(RE) 0.02％～0.03％、w(Mg) 0.050％～0.070％,并添加w(Ni)0.5％～1.0％,以提高低温韧性；(2)采用呋喃树脂砂和高刚度砂箱造型,并采用冷铁强化铸件凝固；(3)采用带过滤网的底注开放式浇注系统,同时借助Procast模拟软件优化铸造工艺设计；(4)采用喂线法进行球化处理,浇注时进行随流孕育处理.检查铸件的结果显示:各项力学性能均达到了EN-GJS-400-18LT材料标准的要求,而且UT探伤未发现3级以上的铸造缺陷.
STABILITY OF ROTOR-BEARING SYSTEMS
Directory of Open Access Journals (Sweden)
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.
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.
Eigenfrequency sensitivity analysis of flexible rotors
Directory of Open Access Journals (Sweden)
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.
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
On aerodynamic design of the Savonius windmill rotor
Mojola, O. O.
This paper examines under field conditions the performance characteristics of the Savonius windmill rotor. Test data were collected on the speed, torque and power of the rotor at a large number of wind speeds for each of seven values of the rotor overlap ratio. Field testing procedures are critically appraised and a unified approach is suggested. The performance data of the Savonius rotor are also fully discussed and design criteria established.
Rotor Performance Enhancement Using Slats on the Inner Part of a 10MW Rotor
DEFF Research Database (Denmark)
Gaunaa, Mac; Zahle, Frederik; Sørensen, Niels N.
2013-01-01
The present work continues the investigations of using slats on the inner parts of wind turbine rotors by using an updated version of the 2D CFD based airfoil/slat design tool earlier used by the authors in combination with the rotor design methods from [8] to design slats for 0:1 > r=R > 0......, thus allowing for a much broader design space than in the previous works where only the position, size and additional camber of the slat airfoil could be adjusted. The aerodynamic performance of a slatted rotor is for the first time evaluated using 3D CFD in this work, and the results are compared...
Rotor Performance Enhancement Using Slats on the Inner Part of a 10MW Rotor
DEFF Research Database (Denmark)
The present work continues the investigations of using slats on the inner parts of wind turbine rotors by using an updated version of the 2D CFD based airfoil/slat design tool earlier used by the authors in combination with the rotor design methods from [8] to design slats for 0:1 > r=R > 0......, thus allowing for a much broader design space than in the previous works where only the position, size and additional camber of the slat airfoil could be adjusted. The aerodynamic performance of a slatted rotor is for the first time evaluated using 3D CFD in this work, and the results are compared...
Liang, Feng; Zhou, Ming; Xu, Quanyong
2016-09-01
Semi-floating ring bearing(SFRB) is developed to control the vibration of turbocharger rotor. The outer clearance of SFRB affects the magnitude and frequency of nonlinear whirl motion, which is significant for the design of turbocharger. In order to explore the effects of outer clearance, a transient finite element analysis program for rotor and oil film bearing is built and validated by a published experimental case. The nonlinear dynamic behaviors of rotor-SFRB system are simulated. According to the simulation results, two representative subsynchronous oscillations excited by the two bearings respectively are discovered. As the outer clearance of SFRB increases from 24 μm to 60 μm, the low-frequency subsynchronous oscillation experiences three steps, including a strong start, a gradual recession and a combination with the other one. At the same time, the high-frequency subsynchronous oscillation starts to appear gradually, then strengthens, and finally combines. If gravity and unbalance are neglected, the combination will start starts from high rotor speed and extents to low rotor speed, just like a "zipper". It is found from the quantitative analysis that when the outer clearance increases, the vibration amplitude experiences large value firstly, then reduction, and suddenly increasing after combination. A useful design principle of SFRB outer clearance for minimum vibration amplitude is proposed: the outer clearance value should be chosen to keep the frequency of two subsynchronous oscillations clearly separated and their amplitudes close.
APPLICATION OF MECHANIZED MATHEMATICS TO ROTOR DYNAMICS
Institute of Scientific and Technical Information of China (English)
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.
14 CFR 23.1461 - Equipment containing high energy rotors.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 23... Equipment Miscellaneous Equipment § 23.1461 Equipment containing high energy rotors. (a) Equipment, such as Auxiliary Power Units (APU) and constant speed drive units, containing high energy rotors must...
Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network
Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.
2013-01-01
The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for understandi
14 CFR 33.92 - Rotor locking tests.
2010-01-01
... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.92 Rotor locking tests. If continued rotation is prevented by a means to lock the rotor(s), the engine must be subjected to a test that...
On the Classification of Universal Rotor-Routers
He, Xiaoyu
2011-01-01
The combinatorial theory of rotor-routers has connections with problems of statistical mechanics, graph theory, chaos theory, and computer science. A rotor-router network defines a deterministic walk on a digraph G in which a particle walks from a source vertex until it reaches one of several target vertices. Motivated by recent results due to Giacaglia et al., we study rotor-router networks in which all non-target vertices have the same type. A rotor type r is universal if every hitting sequence can be achieved by a homogeneous rotor-router network consisting entirely of rotors of type r. We give a conjecture that completely classifies universal rotor types. Then, this problem is simplified by a theorem we call the Reduction Theorem that allows us to consider only two-state rotors. A rotor-router network called the compressor, because it tends to shorten rotor periods, is introduced along with an associated algorithm that determines the universality of almost all rotors. New rotor classes, including boppy ro...
A Recurrent Rotor-Router Configuration in Z^3
A, Tulasi Ram Reddy
2010-01-01
Rotor Router models were first introduced by James Propp in 2002. A recurrent Rotor configuration is the one in which every state is visited infinitely often. In this project we investigated whether there is a recurrent Rotor configuration in Z^d (d>2).
14 CFR 29.547 - Main and tail rotor structure.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main and tail rotor structure. 29.547 Section 29.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Requirements § 29.547 Main and tail rotor structure. (a) A rotor is an assembly of rotating components, which...
Development of an aeroelastic methodology for surface morphing rotors
Cook, James R.
Helicopter performance capabilities are limited by maximum lift characteristics and vibratory loading. In high speed forward flight, dynamic stall and transonic flow greatly increase the amplitude of vibratory loads. Experiments and computational simulations alike have indicated that a variety of active rotor control devices are capable of reducing vibratory loads. For example, periodic blade twist and flap excitation have been optimized to reduce vibratory loads in various rotors. Airfoil geometry can also be modified in order to increase lift coefficient, delay stall, or weaken transonic effects. To explore the potential benefits of active controls, computational methods are being developed for aeroelastic rotor evaluation, including coupling between computational fluid dynamics (CFD) and computational structural dynamics (CSD) solvers. In many contemporary CFD/CSD coupling methods it is assumed that the airfoil is rigid to reduce the interface by single dimension. Some methods retain the conventional one-dimensional beam model while prescribing an airfoil shape to simulate active chord deformation. However, to simulate the actual response of a compliant airfoil it is necessary to include deformations that originate not only from control devices (such as piezoelectric actuators), but also inertial forces, elastic stresses, and aerodynamic pressures. An accurate representation of the physics requires an interaction with a more complete representation of loads and geometry. A CFD/CSD coupling methodology capable of communicating three-dimensional structural deformations and a distribution of aerodynamic forces over the wetted blade surface has not yet been developed. In this research an interface is created within the Fully Unstructured Navier-Stokes (FUN3D) solver that communicates aerodynamic forces on the blade surface to University of Michigan's Nonlinear Active Beam Solver (UM/NLABS -- referred to as NLABS in this thesis). Interface routines are developed for
Analysis of generator bearing vibration data for diagnosing rotor circuit malfunction in DFIGs
DEFF Research Database (Denmark)
Skrimpas, Georgios Alexandros; Sweeney, Christian W.; Jensen, Bogi Bech
2014-01-01
. In this paper generator bearing vibration signature for a DFIG under operation with one rotor phase coil open is analysed and presented. Further this failure mode is compared to rotor dynamics fault, such as rotational looseness, and the difference in signature is discussed. Vibration data from a multi......Doubly fed induction generators (DFIGs) are the most popular configuration met in the wind energy sector occu- pying approximately 65 % of the total market share. Condition monitoring of wind turbine generators is performed based on vibration data collected from accelerometers mounted on the drive...... end and non-drive end bearings, meeting the requirements of numerous turbine operators for condition based maintenance. In a DFIG the voltage applied to the rotor is controlled by a converter, where electric connection between the two is accom- plished by using slip rings. Improper connection between...
Directory of Open Access Journals (Sweden)
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
Energy Technology Data Exchange (ETDEWEB)
Breton, S.P.; Watters, C.S.; Masson, C. [Ecole de Technologie Superieure, Montreal, PQ (Canada)
2010-07-01
This presentation discussed the model rotor experiments under controlled conditions (MEXICO) project. The experiments are being conducted in the largest wind tunnel in Europe in order to determine optimal yaw and pitch angles for wind turbines as well as to test the performance of blade aerodynamic profiles and rotor instrumentation. Data obtained during the experiments are used to determine velocity component points in order to develop a greater understanding of wind turbine aerodynamics and improve calculation methods. Blade element momentum (BEM) computational fluid dynamics (CFD) and vortex wake codes are used in the program, which includes an actuator surface method embedded in a customized CFD finite element method. To date, the project has validated various models with experimental data, and mapped the induced velocities upwind and downwind from rotors. Further research is being conducted to compare experimental results with other results in the literature related to blade loading, root bending moments, and detailed flow characteristics. Charts of experimental results were included. tabs., figs.
Nonlinear dynamics of flexible rotor supported on the gas foil journal bearings
Bhore, Skylab P.; Darpe, Ashish K.
2013-09-01
Investigation on nonlinear dynamics of a flexible rotor supported on the gas foil journal bearings is attempted. A time domain orbit simulation is carried out that couples the equations of rotor motion, unsteady Reynolds equation and foil deformation. The unsteady Reynolds equation is solved using control volume formulation with power law hybrid scheme and Gauss-Seidel method. The nonlinear dynamic response is analyzed using disc center and journal center trajectories, Poincaré maps, Fast Fourier transforms and bifurcation plots. The analysis is carried out for different system parameters, namely, rotating speed, unbalance eccentricity, compliance and loss factor of gas foil bearing. The analysis reveals highly nonlinear behavior with periodic, multi-periodic and quasiperiodic motion of the disc and the journal center. The present analysis can be useful in designing and selection of suitable operating parameters of rotor bearing system.
Energy Technology Data Exchange (ETDEWEB)
Lee, Hong Kyu; Seo, Won Chan; Park, Chan [Pukyong National University, Busan (Korea, Republic of); Lee, Jong O; Son, Young Ho [KIMM, Daejeon (Korea, Republic of)
2009-10-15
An ultrasonic signal processing algorithm was developed for extracting the information of cracks generated around the keyway of a turbine rotor disk. B-scan images were obtained by using keyway specimens and an ultrasonic scan system with x-y position controller. The B-scan images were used as input images for 2-Dimensional signal processing, and the algorithm was constructed with four processing stages of pre-processing, crack candidate region detection, crack region classification and crack information extraction. It is confirmed by experiments that the developed algorithm is effective for the quantitative evaluation of cracks generated around the keyway of turbine rotor disk
Actuator line/Navier–Stokes computations for the MEXICO rotor: comparison with detailed measurements
DEFF Research Database (Denmark)
Shen, Wen Zhong; Zhu, Wei Jun; Sørensen, Jens Nørkær
2012-01-01
In the European collaborative MEXICO (Model Experiments in Controlled Conditions) project, a series of experiments was carried out on a 4.5 m diameter wind turbine rotor to validate numerical diagnostics tools. Here, some of the measured data are compared with computations of the combined actuator...... line/Navier–Stokes (AL/NS) model developed at the Technical University of Denmark. The AL/NS model was combined with a large eddy simulation technique and used to compute the flow past the MEXICO rotor in free air and in the DNW German‐Dutch wind tunnel for three commonly defined test cases at wind...
Effect of Rotor Diameter on the Thermal Stresses of a Turbine Rotor Model
Dávalos, J. O.; García, J. C.; Urquiza, G.; Castro-Gómez, L. L.; Rodríguez, J. A.; De Santiago, O.
2016-04-01
Thermal stresses in a simplified steam turbine rotor model during a cold startup are analyzed using finite element analysis (FEA). In order to validate the numerical model, an experimental array is developed in which a hollow cylinder is heated with hot air in the external surface. At the thick wall of the cylinder, temperature distribution is measured in real time, while at the same time an algorithm computes thermal stresses. Additional computational fluid dynamics (CFD) calculations are made to obtain magnitudes of velocity and pressure in order to compute convective heat transfer coefficient. The experimental results show good agreement with the FEA computations. To evaluate the effect of rotor diameter size, FEA computations with variation in external and internal diameters are performed. Results show that thermal stresses are proportional to rotor diameter size. Also, zones of higher stress concentration are found in the external and internal surfaces of the rotor.
Dynamics of fluidic devices with applications to rotor pitch links
Scarborough, Lloyd H., III
impedance. At low frequency, the pitch link must have high impedance to pass through the pilot's collective and cyclic commands to control the aircraft. At higher frequencies, however, the pitch-link impedance can be tuned to change the blade pitching response to higher harmonic loads. Active blade control to produce higher harmonic pitch motions has been shown to reduce hub loads and increase rotor efficiency. This work investigates whether fluidic pitch links can passively provide these benefits. An analytical model of a fluidic pitch link is derived and incorporated into a rotor aeroelastic simulation for a rotor similar to that of the UH-60. Eighty-one simulations with varied fluidic pitch link parameters demonstrate that their impedance can be tailored to reduce rotor power and all six hub forces and moments. While no impedance was found that simultaneously reduced all components, the results include cases with reductions in the lateral 4/rev hub force of up to 91% and 4/rev hub pitching moment of up to 67%, and main rotor power of up to 5%.
Design and Analysis of Delta Wing Tilt Rotor UAV
Directory of Open Access Journals (Sweden)
S.Ravikanth
2015-07-01
Full Text Available A tilt rotor is an aircraft of a special kind, which possesses the characteristics of a helicopter and a fixed-wing airplane. However, there are a great number of important technical problems waiting for settlements. Of them, the flight control system might be a critical one. A tiltrotor aircraft comprising a pair of contra-rotating co-axial tiltable rotors on the longitudinal center line of the aircraft. The rotors may be tiltable sequentially and independently. They may be moveable between a lift position and a flight position in front of or behind the fuselage.In this paper we present a project aimed for the designing of a small scale Unmanned Aerial Vehicle (UAV with Tiltrotor configuration (that uses two rotating rotors. he current paper describes the adopted design methodology, the mathematical and computational models created to represent the UAV, the physical components that constitute the UAV, and the results obtained so far. An unmanned aerial vehicle (UAV, also known as a remotely piloted aircraft (RPA or unmanned aircraft, is a machine which functions either by the remote control of a navigator or pilot or autonomously. A UAV is defined as a powered, aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry payload.India‘s requirement of these unmanned aerial vehicles (UAV has become prior need for fighting in the northeast, against threat of terrorism, tension along the Pakistan border and its emerging role as a regional naval power and subsequent need for surveillance. The military wants to acquire at least 1,500 unmanned systems in the next 3-4 years, ranging from man-portable drones to high-altitude, long-endurance (HALE vehicles.Indian military is using Israeli-built UAVs such as the Heron, Searcher Mk II and Harop from Israel Aerospace Industries (IAI. Till date India has mostly deployed
Nonlinear Vibration of Rotor Rubbing Stator Caused by Initial Perturbation
Institute of Scientific and Technical Information of China (English)
张小章; 隆锦胜; 李正光
2001-01-01
The vibration of a rotor rubbing a stator caused by an initial perturbation was studied analytically.The analytical model consists of a simple disc shaft rotor and a fixed stator. The perturbation is aninstantaneous change of the radial velocity when the rotor is operating in its normal steady state. The analysisshowed that the rotor may continue rubbing the stator for small clearance, even if the initial perturbation nolonger exists. For the interest of engineering applications, we investigated various rotating speeds,perturbation amplitudes and clearances between the rotor and the stator. Various friction coefficients on thecontact surface were also considered. The graphical results can be used for the design of rotating machines.``
Time Frequency Features of Rotor Systems with Slowly Varying Mass
Directory of Open Access Journals (Sweden)
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.
Equivalence Between Squirrel Cage and Sheet Rotor Induction Motor
Dwivedi, Ankita; Singh, S. K.; Srivastava, R. K.
2016-06-01
Due to topological changes in dual stator induction motor and high cost of its fabrication, it is convenient to replace the squirrel cage rotor with a composite sheet rotor. For an experimental machine, the inner and outer stator stampings are normally available whereas the procurement of rotor stampings is quite cumbersome and is not always cost effective. In this paper, the equivalence between sheet/solid rotor induction motor and squirrel cage induction motor has been investigated using layer theory of electrical machines, so as to enable one to utilize sheet/solid rotor in dual port experimental machines.
Numerical evaluation of tandem rotor for highly loaded transonic fan
Institute of Scientific and Technical Information of China (English)
ZHAO Bin; LIU Bao-jie
2011-01-01
Transonic tandem rotor was designed for highly loaded fan at a corrected tip speed of 381 m/s and another conventional rotor was designed as a baseline to evaluate the loading superiority of tandem rotor with three-dimensional (3-D) numerical simulation. The aft blade solidity and its impact on total loading level were studied in depth. The result indicates that tandem rotor has potential to achieve higher loading level and attain favorable aerodynamic performance in a wide range of loading coefficient 0. 55 ～ 0.68, comparing with the conventional rotor which produced a total pressure ratio of 2.0 and loading coefficient of 0. 42.
On the flow field around a Savonius rotor
Bergeles, G.; Athanassiadis, N.
A model of a two-bucket Savonius rotor windmill was constructed and tested in a wind tunnel. The flow field around the rotor was examined visually and also quantitatively with the use of a hot wire. The flow visualization revealed an upstream influence on the flow field up to 3 rotor diameters away and a strong downwash downstream. Hot wire measurements showed a large velocity deficit behind the rotor and a quick velocity recovery downstream due to strong mixing; the latter was associated with high levels of turbulence. Energy spectra revealed that all turbulence was concentrated in a single harmonic corresponding to twice the rotational speed of the rotor.
Rotor Design for Diffuser Augmented Wind Turbines
Directory of Open Access Journals (Sweden)
Søren Hjort
2015-09-01
Full Text Available Diffuser augmented wind turbines (DAWTs can increase mass flow through the rotor substantially, but have often failed to fulfill expectations. We address high-performance diffusers, and investigate the design requirements for a DAWT rotor to efficiently convert the available energy to shaft energy. Several factors can induce wake stall scenarios causing significant energy loss. The causality between these stall mechanisms and earlier DAWT failures is discussed. First, a swirled actuator disk CFD code is validated through comparison with results from a far wake swirl corrected blade-element momentum (BEM model, and horizontal-axis wind turbine (HAWT reference results. Then, power efficiency versus thrust is computed with the swirled actuator disk (AD code for low and high values of tip-speed ratios (TSR, for different centerbodies, and for different spanwise rotor thrust loading distributions. Three different configurations are studied: The bare propeller HAWT, the classical DAWT, and the high-performance multi-element DAWT. In total nearly 400 high-resolution AD runs are generated. These results are presented and discussed. It is concluded that dedicated DAWT rotors can successfully convert the available energy to shaft energy, provided the identified design requirements for swirl and axial loading distributions are satisfied.
14 CFR 33.34 - Turbocharger rotors.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbocharger rotors. 33.34 Section 33.34 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34...
Flywheel system using wire-wound rotor
Energy Technology Data Exchange (ETDEWEB)
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
Directory of Open Access Journals (Sweden)
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.
Development of the optimum rotor theories
DEFF Research Database (Denmark)
Okulov, Valery; Sørensen, Jens Nørkær; van Kuik, Gijs A.M.
The purpose of this study is the examination of optimum rotor theories with ideal load distributions along the blades, to analyze some of the underlying ideas and concepts, as well as to illuminate them. The book gives the historical background of the issue and presents the analysis of the proble...
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
Directory of Open Access Journals (Sweden)
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.
Wind rotors and birds; Windraeder: neue Vogelperspektiven
Energy Technology Data Exchange (ETDEWEB)
Loenker, O.; Jensen, D.
2005-01-01
Although most birds are not shy of wind rotors, authorities tend to use environmental protection arguments in their attempt to prevent wind power projects. Planners should be careful to establish ecological expert opinions for envisaged sites at an early stage. (orig.)
MODIFIED SAVONIUS ROTOR FOR DOMESTIC POWER PRODUCTION
Directory of Open Access Journals (Sweden)
VINAY P V
2012-07-01
Full Text Available Conventional fuels which are fast depleting, have ever fluctuating price and polluting characteristic of theirs is pushing mankind towards energies which are renewable and green. Wind being one of the renewable energies among solar, geothermal, biomass, ocean and others is being more patronized in places where wind is copious by governmental and with private partnership to generate electricity. Vertical axis rotor was selected over the horizontal ones due to its simplicity and reliability. At a selected location a prototype was built and installed. The design and development process and the need of the new type of machine will be described in this paper. This paper produces an investigational exploration of a vertical axis rotor (Savonius rotor wind turbine adapted for household/domestic electricity generation. The model machine collects wind energy and generates a 12 volt output which is used to charge one heavy duty battery. As a result, the home is served simultaneously by the wind turbine and the utility. The wind turbine responds well to low wind velocities and also various materials for vanes, various transmission mechanisms were also tried to evaluate the performance of the rotor.
DEFF Research Database (Denmark)
Yang, Hua; Shen, Wen Zhong; Xu, Haoran
2013-01-01
some models before they can be used in a BEM code. In this article, the airfoil data for the MEXICO (Model EXperiments in Controlled cOnditions) rotor are extracted from CFD (Computational Fluid Dynamics) results. The azimuthally averaged velocity is used as the sectional velocity to define the angle...
Dynamic Thermal Analysis of DFIG Rotor-side Converter during Balanced Grid Fault
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede
2014-01-01
and the rotor voltage during the balanced grid fault is firstly addressed. By using the traditional demagnetizing control, the damping of the stator flux and the safety operation area are theoretically evaluated with various amounts of demagnetizing current. It is observed that the higher demagnetizing current...
An Examination of a Pumping Rotor Blade Design for Brownout Mitigation
2015-05-18
negative thrust effect was mathe - 70 matically removed, all pumping blade designs were found to exhibit similar perfor- mance characteristics. 2. When the...Pneumodynamic Characteristics of a Circulation Control Rotor Model,” 2nd Decennial Specialist ’ Meeting on Ro- torcraft Dynamics, NASA Ames Research
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
Institute of Scientific and Technical Information of China (English)
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.
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.
Rotor for a line start permanent magnet machine
Energy Technology Data Exchange (ETDEWEB)
Melfi, Mike; Schiferl, Rich; Umans, Stephen
2017-07-11
A rotor comprises laminations with a plurality of rotor bar slots with an asymmetric arrangement about the rotor. The laminations also have magnet slots equiangularly spaced about the rotor. The magnet slots extend near to the rotor outer diameter and have permanent magnets disposed in the magnet slots creating magnetic poles. The magnet slots may be formed longer than the permanent magnets disposed in the magnets slots and define one or more magnet slot apertures. The permanent magnets define a number of poles and a pole pitch. The rotor bar slots are spaced from adjacent magnet slots by a distance that is at least 4% of the pole pitch. Conductive material is disposed in the rotor bar slots, and in some embodiments, may be disposed in the magnet slot apertures.
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.
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.
Directory of Open Access Journals (Sweden)
Olfa B.H.B. Kechiche
2011-01-01
Full Text Available Problem statement: This study investigates a novel optimized scheme of a High Frequency Signal Injection (HFSI based sensorless technique in order to carry out a precise and robust rotor position error estimation of a Permanent Magnet Synchronous Motor (PMSM drive designed for washing machines. The study is carried out for standstill condition, where precise position information is required for this application. Approach: In order to get rotor position error information, a PMSM high frequency model is considered in the estimated rotor reference frame (d,q. Then, the impact of the HFSI technique parameters choice on the PMSM rotor position estimation performance is studied and experimentally tested, under various injection conditions. Results: The experimental results show that the amplitude of the high frequency current, resulting from injection, is not significant to carry out high performance rotor position estimation. In order to improve rotor position estimation performance and robustness, a modified demodulation of the high frequency current resulting from injection is proposed by using a high pass filter amplifier applied to PMSM measured currents. The novel proposed rotor position error extraction scheme is implemented on a dsPIC30F6010A and is experimentally validated on a 1kW washing salient pole PMSM. Conclusion: This study presents an improved high frequency voltage injection based sensorless control for Permanent Magnet Synchronous Motor (PMSM designed for washing machines. The optimal parameters choice of the HFSI technique and the use of a high pass filter amplifier have allowed to take the most of the high frequency injected signal for extracting the rotor position error at standstill, compared to a conventional scheme.
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.
Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction
Shin, SangJoon; Cesnik, Carlos E. S.
2001-01-01
Active integral twist control for vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight conditions: frequency domain analysis for hover, and time domain analysis for forward flight. Both stem from the same three-dimensional electroelastic beam formulation with geometrical-exactness, and axe coupled with a finite-state dynamic inflow aerodynamics model. A prototype Active Twist Rotor blade was designed with this framework using Active Fiber Composites as the actuator. The ATR prototype blade was successfully tested under non-rotating conditions. Hover testing was conducted to evaluate structural integrity and dynamic response. In both conditions, a very good correlation was obtained against the analysis. Finally, a four-bladed ATR system is built and tested to demonstrate its concept in forward flight. This experiment was conducted at NASA Langley Tansonic Dynamics Tunnel and represents the first-of-a-kind Mach-scaled fully-active-twist rotor system to undergo forward flight test. In parallel, the impact upon the fixed- and rotating-system loads is estimated by the analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well. It was also shown, both experimentally and numerically, that the ATR blade design has the potential for hub vibratory load reduction of up to 90% using individual blade control actuation. Using the numerical framework, system identification is performed to estimate the harmonic transfer functions. The linear time-periodic system can be represented by a linear time-invariant system under the three modes of blade actuation: collective, longitudinal cyclic, and lateral cyclic. A vibration
[Treatment of organic waste gas by adsorption rotor].
Zhu, Run-Ye; Zheng, Liang-Wei; Mao, Yu-Bo; Wang, Jia-De
2013-12-01
The adsorption rotor is applicable to treating organic waste gases with low concentration and high air volume. The performance of adsorption rotor for purifying organic waste gases was investigated in this paper. Toluene was selected as the simulative gaseous pollutant and the adsorption rotor was packed with honeycomb modified 13X molecular sieves (M-13X). Experimental results of the fixed adsorption and the rotor adsorption were analyzed and compared. The results indicated that some information on the fixed adsorption was useful for the rotor adsorption. Integrating the characteristics of the adsorbents, waste gases and the structures of the rotor adsorption, the formulas on optimal rotor speed and cycle removal efficiency of the adsorption rotor were deduced, based on the mass and heat balances of the adsorbing process. The numerical results were in good agreement with the experimental data, which meant that the formulas on optimal rotor speed and cycle removal efficiency could be effectively applied in design and operation of the adsorption rotor.
Vorotnikov, V. I.; Martyshenko, Yu. G.
2013-09-01
The nonlinear game problem of the three-axis reorientation of an asymmetric solid body with three flywheels (rotors) has been solved. Acceptable levels of uncontrollable noise depending on given constraints of control moments have been estimated.
Directory of Open Access Journals (Sweden)
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.
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.
Rotor-rotor interaction for counter-rotating fans. Part 1: Three-dimensional flowfield measurements
Shin, Hyoun-Woo; Whitfield, Charlotte E.; Wisler, David C.
1994-11-01
The rotor wake/vortex flowfield generated in a scale model simulator of General Electric's counter-rotating unducted fan (UDF) engine was investigated using three-dimensional hot-wire anemometry. The purpose was to obtain a set of benchmark experimental aerodynamic data defining the rotor wake and vortex structure, particularly in the tip region, and to relate this observed flow structure to its acoustic signature. The tests were conducted in a large, freejet anechoic chamber. Measurements of the three components of velocity were made at axial stations upstream and downstream of each rotor for conditions that simulate takeoff, cutback, and approach power. Two different forward blade designs were evaluated. The tip vortices, the axial velocity defect in the vortex core, and differences in the interaction of the wakes and vortices generated by the forward and aft rotor are used to explain differences in noise generated by the two different rotor designs. Part 1 presents the three-dimensional flowfield measurements. Part 2 (aeroacoustic prediction and analysis), which will be presented later, will give an acoustic prediction using the measured data.
Aerodynamic design of the National Rotor Testbed.
Energy Technology Data Exchange (ETDEWEB)
Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-10-01
A new wind turbine blade has been designed for the National Rotor Testbed (NRT) project and for future experiments at the Scaled Wind Farm Technology (SWiFT) facility with a specific focus on scaled wakes. This report shows the aerodynamic design of new blades that can produce a wake that has similitude to utility scale blades despite the difference in size and location in the atmospheric boundary layer. Dimensionless quantities circulation, induction, thrust coefficient, and tip-speed-ratio were kept equal between rotor scales in region 2 of operation. The new NRT design matched the aerodynamic quantities of the most common wind turbine in the United States, the GE 1.5sle turbine with 37c model blades. The NRT blade design is presented along with its performance subject to the winds at SWiFT. The design requirements determined by the SWiFT experimental test campaign are shown to be met.
The Dynamics of Rotor with Rubbing
Directory of Open Access Journals (Sweden)
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.
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.
Simulation of flow around rotating Savonius rotors
Ishimatsu, Katsuya; Shinohara, Toshio
1993-09-01
Flow around Savonius rotors was simulated by solving 2-D (two-dimensional) Navier-Stokes equations. The equations were discretized by finite volume method for space and fractional step method for time. Convection terms were specially discretized by an upwinding scheme for unstructured grid. Only rotating rotors were simulated in this report. The values of parameters were as follows: Reynolds number, 10(exp 5); overlap ratio, zero and 0.16; and tip speed ratio, 0.25 to 1.75. Results showed good agreement with experimental data for the following points: optimum tip speed ratio is 0.75 to 1.0; overlapping is effective to increase power coefficient. Moreover, simulated flow fields showed that vortex shedding occur at not only tips of bucket but back of bucket and the shed vortex decrease torque.
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.
Balancing of Rigid and Flexible Rotors
1986-01-01
converters Turbine wheels Turbinas (steam, gas , hydraulic), high speed > 10,000 rpm Turbines (steam, gas , hydraulic), medium speed 1000-10,000 rpm...MOUNTED ON CASINGD AI GA - + SIGNALS PROCESSED BY TRACKING FILTERS AND TIME-AVERAGED TO IDENTIFY PRINCIPAL FREQUENCY COMPONENTS Fig. 1.10, Noncontactlng...balanrcng of gas -turbine engines; by Little [121, whose thesis on flexible-rotor balancing contains selected refer- ences on this subject; and by Kendig
Dark rotors in the late universe.
Mayer, Frederick J
2015-11-01
The tresino phase-transition that took place about 300 years after the big-bang, converted most baryons into almost equal numbers of protons and tresinos. Many of these become oppositely-charged rotating pairs or "rotors". This paper examines the formation, evolution, disposition and observations of the protons and tresinos from the phase-transition to the present era. The solar corona is further examined within the same tresino phase-transition picture.
Nixon, Mark W.
1993-01-01
There is a potential for improving the performance and aeroelastic stability of tiltrotors through the use of elastically-coupled composite rotor blades. To study the characteristics of tiltrotors with these types of rotor blades it is necessary to formulate a new analysis which has the capabilities of modeling both a tiltrotor configuration and an anisotropic rotor blade. Background for these formulations is established in two preliminary investigations. In the first, the influence of several system design parameters on tiltrotor aeroelastic stability is examined for the high-speed axial flight mode using a newly-developed rigid-blade analysis with an elastic wing finite element model. The second preliminary investigation addresses the accuracy of using a one-dimensional beam analysis to predict frequencies of elastically-coupled highly-twisted rotor blades. Important aspects of the new aeroelastic formulations are the inclusion of a large steady pylon angle which controls tilt of the rotor system with respect to the airflow, the inclusion of elastic pitch-lag coupling terms related to rotor precone, the inclusion of hub-related degrees of freedom which enable modeling of a gimballed rotor system and engine drive-train dynamics, and additional elastic coupling terms which enable modeling of the anisotropic features for both the rotor blades and the tiltrotor wing. Accuracy of the new tiltrotor analysis is demonstrated by a comparison of the results produced for a baseline case with analytical and experimental results reported in the open literature. Two investigations of elastically tailored blades on a baseline tiltrotor are then conducted. One investigation shows that elastic bending-twist coupling of the rotor blade is a very effective means for increasing the flutter velocity of a tiltrotor, and the magnitude of coupling required does not have an adverse effect on performance or blade loads. The second investigation shows that passive blade twist control via
Turbine flowmeter for liquid helium with the rotor magnetically levitated
Rivetti, A.; Martini, G.; Goria, R.; Lorefice, S.
A turbine flowmeter with no mechanical contact between rotor and body is described, to be used as a reference standard in our liquid helium flow rate calibration facility. The absence of contact, zeroing the bearings friction factor, ensures a good measurement repeatability, even at very low liquid helium flow rate values. The rotor is magnetically suspended by the Meissner effect: at liquid helium temperatures two magnetic fields generate sustaining forces against the surface of the two rotor ends, which are made of niobium. Due to the repulsive nature of the acting forces, the rotor equilibrium is intrinsically stable and no external electronics are required for its levitation. A particular configuration of the superconducting windings and of the rotor ends allow the rotor to levitate and hold good axial and radial stability. A detailed description of the solutions adopted for the realization of the prototype and the operation conditions are reported. The first results, made with the absolute liquid helium calibration facility, are shown.
Performance of Savonius Rotor for Environmentally Friendly Hydraulic Turbine
Nakajima, Miyoshi; Iio, Shouichiro; Ikeda, Toshihiko
The aim of this investigation was to develop an environmentally friendly nano-hydraulic turbine. A model of a two-bucket Savonius type hydraulic turbine was constructed and tested in a water tunnel to arrive at an optimum installation condition. Effects of two installation parameters, namely a distance between a rotor and a bottom wall of the tunnel, a rotation direction of the rotor, on the power performance were studied. A flow field around the rotor was examined visually to clarify influences of installation conditions on the flow field. The flow visualization showed differences of flow pattern around the rotor by the change of these parameters. From this study it was found that the power performances of Savonius hydraulic turbine were changed with the distance between the rotor and the bottom wall of the tunnel and with a rotation direction of the rotor.
An experimental study on improvement of Savonius rotor performance
Directory of Open Access Journals (Sweden)
N.H. Mahmoud
2012-03-01
In this work different geometries of Savonius wind turbine are experimentally studied in order to determine the most effective operation parameters. It was found that, the two blades rotor is more efficient than three and four ones. The rotor with end plates gives higher efficiency than those of without end plates. Double stage rotors have higher performance compared to single stage rotors. The rotors without overlap ratio (β are better in operation than those with overlap. The results show also that the power coefficient increases with rising the aspect ratio (α. The conclusions from the measurements of the static torque for each rotor at different wind speeds verify the above summarized results of this work.
Energy Technology Data Exchange (ETDEWEB)
Kim, Yeonhee; Kang, Moses; Muljadi, Eduard; Park, Jung-Wook; Kang, Yong Cheol
2017-07-01
This paper proposes a power-smoothing scheme for a variable-speed wind turbine generator (WTG) that can smooth out the WTG's fluctuating power caused by varying wind speeds, and thereby keep the system frequency within a narrow range. The proposed scheme employs an additional loop based on the system frequency deviation that operates in conjunction with the maximum power point tracking (MPPT) control loop. Unlike the conventional, fixed-gain scheme, its control gain is modified with the rotor speed. In the proposed scheme, the control gain is determined by considering the ratio of the output of the additional loop to that of the MPPT loop. To improve the contribution of the scheme toward maintaining the frequency while ensuring the stable operation of WTGs, in the low rotor speed region, the ratio is set to be proportional to the rotor speed; in the high rotor speed region, the ratio remains constant. The performance of the proposed scheme is investigated under varying wind conditions for the IEEE 14-bus system. The simulation results demonstrate that the scheme successfully operates regardless of the output power fluctuation of a WTG by adjusting the gain with the rotor speed, and thereby improves the frequency-regulating capability of a WTG.
Abrasion Resistance Comparison between Rotor and Ring Spun Yarn
Institute of Scientific and Technical Information of China (English)
YANG Jian-ping; YU Chong-wen
2002-01-01
On the base of literature review and the analysis of yarn properties, yarn structure and some other facts, the abrasion resistance of both rotor spun yarn and ring spun yarns are discussed. The results show that with the same raw material and twist, the rotor spun yarn has lower abrasion resistance than that of ring spun yarn, because of the higher twist employed, the abrasion resistance of rotor spun yarn is higher than that of ring spun yarn.
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...
Theoretical study on the flow about Savonius rotor
Ogawa, T.
1984-03-01
A method for the two-dimensional analysis of the separated flow about Savonius rotors is presented. Calculations are performed by combining the singularity method and the discrete vortex method. The method is applied to the simulation of flows about a stationary rotor and a rotating rotor. Moreover, torque and power coefficients are computed and compared with the experimental results presented by Sheldahl et al. Theoretical and experimental results agree well qualitatively.
Numerical modeling of a rotor misalignment; Modelado numerico del desalineamiento de un rotor
Energy Technology Data Exchange (ETDEWEB)
Leon Pina, Roberto
2009-12-15
In the turbo-machinery area after an unbalancing, the misalignment is the fault that most frequently appears, and this one has been little studied compared to the unbalance. The misalignment appears when the geometric centers of two shafts and/or bearings do not coincide, these differences take place by different factors such as: incorrect installation of the bearings or rotors, thermal effects, or rotor weight, to mention some of them. The of the misalignment diagnosis continues being an area little studied, since the effects it generates are complex and include diverse physical processes reason why it presents/displays similar symptoms to those of other faults; thus, one of the methods that are used to diagnose this fault, is based on analyzing the vibration phantoms but this works only under particular conditions. In order to reproduce the dynamic behavior of a misaligned rotor, in the present work non-linear simplified models of the supports are used, whose objective is to contribute to facilitate future studies of the flow-dynamic behavior of the bearing, helping to identify the type and magnitude of the existing non-linearity in the supports and leaning in the analysis of the vibratory behavior of misaligned rotors observed in the field. [Spanish] En el area de turbomaquinaria despues del desbalance, el desalineamiento es la falla que se presenta con mayor frecuencia, y esta se ha estudiado poco comparada con el desbalance. El desalineamiento se presenta cuando los centros geometricos de dos flechas y/o chumaceras no coinciden, estas diferencias se producen por diferentes factores como: instalacion incorrecta de las chumaceras o rotores, efectos termicos, o el peso del rotor, por mencionar algunos. El diagnostico del desalineamiento sigue siendo una area poco estudiada, ya que los efectos que genera son complejos y abarcan diversos procesos fisicos por lo que presenta sintomas similares a los de otras fallas; asi, uno de los metodos que se utilizan para
Equations of motion for a rotor blade, including gravity, pitch action and rotor speed variations
DEFF Research Database (Denmark)
Kallesøe, Bjarne Skovmose
2007-01-01
This paper extends Hodges-Dowell's partial differential equations of blade motion, by including the effects from gravity, pitch action and varying rotor speed. New equations describing the pitch action and rotor speeds are also derived. The physical interpretation of the individual terms...... in the equations is discussed. The partial differential equations of motion are approximated by ordinary differential equations of motion using an assumed mode method. The ordinary differential equations are used to simulate a sudden pitch change of a rotating blade. This work is a part of a project on pitch blade...
Experimental study on the aerodynamic performance of a Savonius rotor
Energy Technology Data Exchange (ETDEWEB)
Fujisawa, Nobuyuki; Gotoh, Futoshi (Gunma Univ., Kiryu (Japan). Dept. of Mechanical Engineering)
1994-08-01
The aerodynamic performance of a Savonius rotor has been studied by measuring the pressure distributions on the blade surfaces at various rotor angles and tip-speed ratios. It is found that the pressure distributions on the rotating rotor differ remarkably from those on the still rotor especially on the convex side of the advancing blade, where a low pressure region is formed by the moving wall effect of the blade. The torque and power performances, evaluated by integrating the pressure, are in close agreement with those by the direct torque measurement. The drag and side force performance is also studied.
Open Rotor Noise Shielding by Blended-Wing-Body Aircraft
Guo, Yueping; Czech, Michael J.; Thomas, Russell H.
2015-01-01
This paper presents an analysis of open rotor noise shielding by Blended Wing Body (BWB) aircraft by using model scale test data acquired in the Boeing Low Speed Aeroacoustic Facility (LSAF) with a legacy F7/A7 rotor model and a simplified BWB platform. The objective of the analysis is the understanding of the shielding features of the BWB and the method of application of the shielding data for noise studies of BWB aircraft with open rotor propulsion. By studying the directivity patterns of individual tones, it is shown that though the tonal energy distribution and the spectral content of the wind tunnel test model, and thus its total noise, may differ from those of more advanced rotor designs, the individual tones follow directivity patterns that characterize far field radiations of modern open rotors, ensuring the validity of the use of this shielding data. Thus, open rotor tonal noise shielding should be categorized into front rotor tones, aft rotor tones and interaction tones, not only because of the different directivities of the three groups of tones, but also due to the differences in their source locations and coherence features, which make the respective shielding characteristics of the three groups of tones distinctly different from each other. To reveal the parametric trends of the BWB shielding effects, results are presented with variations in frequency, far field emission angle, rotor operational condition, engine installation geometry, and local airframe features. These results prepare the way for the development of parametric models for the shielding effects in prediction tools.
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.
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.
THEORY OF MUM FOR METAL SPHERICAL ROTOR WITH CONTACTLESS SUSPENSION
Institute of Scientific and Technical Information of China (English)
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.
Numerical Analysis of Nonlinear Rotor-bearing-seal System
Institute of Scientific and Technical Information of China (English)
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.
Stability of Rotor Systems: A Complex Modelling Approach
DEFF Research Database (Denmark)
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...
Mechanical coupling for a rotor shaft assembly of dissimilar materials
Shi, Jun; Bombara, David; Green, Kevin E.; Bird, Connic; Holowczak, John
2009-05-05
A mechanical coupling for coupling a ceramic disc member to a metallic shaft includes a first wedge clamp and a second wedge clamp. A fastener engages a threaded end of a tie-bolt to sandwich the ceramic disc between the wedge clamps. An axial spring is positioned between the fastener and the second wedge clamp to apply an axial preload along the longitudinal axis. Another coupling utilizes a rotor shaft end of a metallic rotor shaft as one wedge clamp. Still another coupling includes a solid ceramic rotor disc with a multiple of tie-bolts radially displaced from the longitudinal axis to exert the preload on the solid ceramic rotor disc.
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.
NONLINEAR DYNAMICS OF A CRACKED ROTOR IN A MANEUVERING AIRCRAFT
Institute of Scientific and Technical Information of China (English)
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.
Coupled Thermal Field of the Rotor of Liquid Floated Gyroscope
Directory of Open Access Journals (Sweden)
Wang Zhengjun
2015-01-01
Full Text Available Inertial navigation devices include star sensor, GPS, and gyroscope. Optical fiber and laser gyroscopes provide high accuracy, and their manufacturing costs are also high. Magnetic suspension rotor gyroscope improves the accuracy and reduces the production cost of the device because of the influence of thermodynamic coupling. Therefore, the precision of the gyroscope is reduced and drift rate is increased. In this study, the rotor of liquid floated gyroscope, particularly the dished rotor gyroscope, was placed under a thermal field, which improved the measurement accuracy of the gyroscope. A dynamic theory of the rotor of liquid floated gyroscope was proposed, and the thermal field of the rotor was simulated. The maximum stress was in x, 1.4; y, 8.43; min 97.23; and max 154.34. This stress occurred at the border of the dished rotor at a high-speed rotation. The secondary flow reached 5549 r/min, and the generated heat increased. Meanwhile, the high-speed rotation of the rotor was volatile, and the dished rotor movement was unstable. Thus, nanomaterials must be added to reduce the thermal coupling fluctuations in the dished rotor and improve the accuracy of the measurement error and drift rate.
Optimum design configuration of Savonius rotor through wind tunnel experiments
Energy Technology Data Exchange (ETDEWEB)
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)