Showing papers on "Turbine published in 2000"

Wind turbines : fundamentals, technologies, application, economics

Abstract: Windmills and Windwheels.- Electrical Power from the Wind - The First Attempts.- Basic Concepts of Wind Energy Converters.- Physical Principles of Wind Energy Conversion.- Rotor Aerodynamics.- Loads and Structural Stresses.- Rotor Blades.- Mechanical Drive Train and Nacelle.- Electrical System.- Control Systems and Operation Sequence Control.- Vibration Problems.- The Tower.- The Wind Resource.- Power Output and Energy Yield.- Environmental Impact.- Commercial Applications of Wind Turbines.- Offshore Wind Energy Utilisation.- Wind Turbine Installation and Operation.- Wind Turbine Costs.- Wind Turbine Economics.

The Design of closed loop controllers for wind turbines

Abstract: This article reviews the design of algorithms for wind turbine pitch control and also for generator torque control in the case of variable speed turbines. Some recent and possible future developments are discussed. Although pitch control is used primarily to limit power in high winds, it also has a significant effect on various loads. Particularly as turbines become larger, there is increasing interest in designing controllers to mitigate loads as far as possible. Torque control in variable speed turbines is used primarily to maximize energy capture below rated wind speed and to limit the torque above rated. Once again there are opportunities for designing these controllers so as to mitigate certain loads. In addition to improving the design of the control algorithms, it is also possible to use additional sensors to help the controller to achieve its objectives more effectively. The use of additional actuators in the form of individual pitch controllers for each blade is also discussed. It is important to be able to quantify the benefits of any new controller. Although computer simulations are useful, field trials are also vital. The variability of the real wind means that particular care is needed in the design of the trials. Copyright © 2001 John Wiley & Sons, Ltd.

Wind energy technology and current status : a review

Abstract: The paper provides an overview of the historical development of wind energy technology and discusses the current status of grid-connected as well as stand-alone wind power generation worldwide. During the last decade of the 20th century, grid-connected wind capacity worldwide has doubled approximately every three years. Due to the fast market development, wind turbine technology has experienced an important evolution over time. An overview of the diAerent design approaches is given and issues like power grid integration, economics, environmental impact and special system applications, such as oAshore wind energy, are discussed. Due to the complexity of the wind energy technology, however, this paper mainly aims at presenting a brief overview of the relevant wind turbine and wind project issues. Therefore, detailed information on further readings and related

Control design and dynamic performance analysis of a wind turbine-induction generator unit

Abstract: This paper presents the modeling and control design for a wind energy conversion scheme using induction generators. The scheme consists of a three-phase induction generator driven by a horizontal axis wind turbine and interfaced to the utility through a double overhead transmission line. A static VAr compensator was connected at the induction generator terminals to regulate its voltage. The mechanical power input was controlled using the blade pitch-angle. Both state and output feedback controllers are designed using MATLAB software to regulate the generator output. From the simulation results, the response of closed loop system exhibited a good damping and fast recovery under different type of large disturbances.

Effect of Placing a Diffuser around a Wind Turbine

Abstract: An actuator disc CFD model of the flow through a wind turbine in a diffuser is developed and validated. Further, it is shown theoretically from a 1D analysis that the Betz limit can be exceeded by a factor proportional to the relative increase in mass flow through the rotor induced by the diffuser. The theoretical 1D result is verified by the CFD model. Copyright © 2000 John Wiley & Sons, Ltd.

Rotating Machinery Vibration: From Analysis to Troubleshooting

Abstract: Part I: Primer on Rotor Vibration Vibration Concepts and Methods One-Degree-of-Freedom Model Multi-DOF Models Modes, Excitation, and Stability of Multi-DOF Models Lateral Rotor Vibration Analysis Models Simple Linear Models Formulations for RDA Software Insights into Linear LRVs Nonlinear Effects in Rotor Dynamical Systems Torsional Rotor Vibration Analysis Models Rotor-Based Spinning Reference Frames Single Uncoupled Rotor Coupled Rotors Semidefinite Systems Part II: Rotor Dynamic Analyses RDA Code for Lateral Rotor Vibration Analyses Unbalance Steady-State Response Computations Instability Self-Excited-Vibration Threshold Computations Additional Sample Problems Bearing and Seal Rotor Dynamics Liquid-Lubricated Fluid-Film Journal Bearings Experiments to Measure Dynamic Coefficients Annular Seals Rolling Contact Bearings Squeeze-Film Dampers Magnetic Bearings Compliance Surface Foil Gas Bearings Turbo-Machinery Impeller and Blade Effects Centrifugal Pumps Centrifugal Compressors High-Pressure Steam Turbines and Gas Turbines Axial Flow Compressors Part III Monitoring and Diagnostics Rotor Vibration Measurement and Acquisition Introduction to Monitoring and Diagnostics Measured Vibration Signals and Associated Sensors Vibration Data Acquisition Signal Conditioning Vibration Severity Guidelines Casing and Bearing Cap Vibration Displacement Guidelines Standards, Guidelines, and Acceptance Criteria Shaft Displacement Criteria Signal Analysis and Identification of Vibration Causes Vibration Trending and Baselines FFT Spectrum Rotor Orbit Trajectories Bode, Polar, and Spectrum Cascade Plots Wavelet Analysis Tools Chaos Analysis Tools Symptoms and Identification of Vibration Causes Part IV Trouble-Shooting Case Studies Forced Vibration and Critical Speed Case Studies HP Steam Turbine Passage through First Critical Speed HP-IP Turbine Second Critical Speed through Power Cycling Boiler Feed Pumps: Critical Speeds at Operating Speed Nuclear Feed Water Pump Cyclic Thermal Rotor Bow Power Plant Boiler Circulating Pumps Nuclear Plant Cooling Tower Circulating Pump Resonance Generator Exciter Collector Shaft Critical Speeds Self-Excited Rotor Vibration Case Studies Swirl Brakes Cure Steam Whirl in a 1300 MW Unit Bearing Unloaded by Nozzle Forces Allows Steam Whirl Misalignment Causes Oil Whip/Steam Whirl "Duet" Additional Rotor Vibration Cases and Topics Vertical Rotor Machines Vector Turning from Synchronously Modulated Rubs Air Preheater Drive Structural Resonances Aircraft Auxiliary Power Unit Commutator Vibration-Caused Uneven Wear Impact Tests for Vibration Problem Diagnoses Bearing Looseness Effects Tilting-Pad versus Fixed-Surface Journal Bearings Base-Motion Excitations from Earthquake and Shock Parametric Excitation: Nonaxisymmetric Shaft Stiffness Rotor Balancing Index

Turbine Separation Control Using Pulsed Vortex Generator Jets

Abstract: The application of pulsed vortex generator jets to control separation on the suction surface of a low-pressure turbine blade is reported. Blade Reynolds numbers in the experimental, linear turbine cascade match those for high-altitude aircraft engines and aft stages of industrial turbine engines with elevated turbine inlet temperatures. The vortex generator jets have a 30 deg pitch and a 90 deg skew to the free-stream direction. Jet flow oscillations up to 100 Hz are produced using a high-frequency solenoid feed valve. Results are compared to steady blowing at jet blowing ratios less than 4 and at two chordwise positions upstream of the nominal separation zone. Results show that pulsed vortex generator jets produce a bulk flow effect comparable to that of steady jets with an order of magnitude less massflow. Boundary layer traverses and blade static pressure distributions show that separation is almost completely eliminated with the application of unsteady blowing. Reductions of over 50 percent in the wake loss profile of the controlled blade were measured. Experimental evidence suggests that the mechanism for unsteady control lies in the starting and ending transitions of the pulsing cycle rather than the injected jet stream itself. Boundary layer spectra support this conclusion and highlight significant differences between the steady and unsteady control techniques. The pulsed vortex generator jets are effective at both chordwise injection locations tested (45 and 63 percent axial chord) covering a substantial portion of the blade suction surface. This insensitivity to injection location bodes well for practical application of pulsed VGJ control where the separation location may not be accurately known a priori.

Investigating Three-Dimensional and Rotational Effects on Wind Turbine Blades by Means of a Quasi-3D Navier-Stokes Solver

Abstract: Three-dimensional and rotational viscous effects on wind turbine blades are investigated by means of a quasi-3D Navier-Stokes model. The governing equations of the model are derived from the 3-D primitive variable Navier-Stokes equations written in cylindrical coordinates in the rotating frame of reference. The latter are integrated along the radial direction and certain assumptions are made for the mean values of the radial derivatives. The validity of these assumptions is cross-checked through fully 3-D Navier-Stokes calculations. The resulting quasi-3D model suggests that three-dimensional and rotational effects be strongly related to the local chord by radii ratio and the twist angle. The equations of the model are numerically integrated by means of a pressure correction algorithm. Both laminar and turbulent flow simulations are performed. The former is used for identifying the physical mechanism associated with the 3-D and rotational effects, while the latter for establishing semiempirical correction laws for the load coefficients, based on 2-D airfoil data. Comparing calculated and measured power curves of a stall controlled wind turbine, it is shown that the suggested correction laws may improve significantly the accuracy of the predictions.

Design and finite-element analysis of an outer-rotor permanent-magnet generator for directly coupled wind turbines

Abstract: This paper presents the design and finite-element analysis of a permanent-magnet generator using neodymium-iron-boron magnets for directly coupled wind turbines. For the sake of small size and light weight with extra low speed for direct coupling, the outer rotor structure is used. The simple magnetic equivalent circuit approach is used for initial design iteration, and the finite-element method is applied to analyze the detailed characteristics. Comprehensive experimental tests were conducted to verify the theoretical predictions. Agreement between the theoretical work and testing results was good.

Some aspects of laser surface cladding in the turbine industry

Abstract: Water droplet erosion of leading edge of the blade in a steam turbine could impair its efficiency and lifetime. To overcome this problem, laser cladding of the leading edge with Co-based stellite powder is commonly used. This paper discusses microscopically the effect of power density and beam interaction time in such a cladding process. It is realized that the beam interaction time has a significant effect on solidification and microstructure development process. The results indicate that the dendrite structure shall be fine for short interaction time compared to the coarse structure for long interaction time. Macro- and micro- cross-section electron probe microanalysis (EPMA) and microhardness profile has been employed to characterize the cladding. The results are correlated with the clad quality. Microstructure, hardness and dilution are discussed as a function of the processing parameters. A few of the actual results of the laser cladding of stellite 6L on 12Cr–Ni turbine blades are presented. Since the dilution of the base material into the cladding is significantly low at short interaction times, the clad could retain significant strength after long-term exposure, a unique feature for the turbine industries. Such possible applications are illustrated as well.

Method for removing and recovering co2 from an exhaust gas

Abstract: The present invention relates to a method for removing and recovering CO2 from exhaust gas from a gas turbine based electric power and heat generation process (a main power process) by chemical absorption and description for deposition of CO2 as convenient at the location. The exhaust gas from said main power process is cooled before being fed to a secondary gas turbine based power and heat generation process (a secondary power process) where said exhaust gas is compressed to elevated pressure and used as oxidant in a secondary gas turbine combustion chamber in said secondary power process. The resulting hot exhaust gas from said secondary process is further fed to a turbine connected to an electric power generator where the exhaust gas is depressurised to close to ambient pressure before entering a heat recovery process where the exhaust gas is cooled and further fed to a CO2 separation process for capturing of CO2.

Low pressure EGR system for diesel engines

Abstract: A low pressure EGR system suitable for use as a passive retrofit system is disclosed for moving vehicles equipped with a diesel engine. The EGR loop inlet is positioned upstream of the exhaust particulate filter and downstream of the turbine to utilize backpressure created by the exhaust particulate filter to insure EGR flow in the loop. A catalyzed soot filter in communication with the EGR pickup insures cleansed EGR gases at the EGR return downstream of the air filter and upstream of the compressor. A corrugated EGR line provides cooling of the EGR gases.

Ceramic composite vane with metallic substructure

Abstract: A vane assembly for a turbine assembly includes an inner endcap, an outer endcap, and a body. The body includes a metallic core assembly, a ceramic shell assembly and a support assembly. The metallic core assembly is coupled to the inner and outer endcaps and bears most of the mechanical loads, including aerodynamic loads. The ceramic shell bears substantially all of the thermal stress placed on the vane assembly. The support assembly is disposed between the metallic core assembly and said ceramic shell assembly and is coupled to the metallic core assembly.

Noncontact vibration measurements on compressor rotor blades

Abstract: In turbine engine development, rotor blade vibration measurements are made to ensure the blades are sufficiently durable in later service. These measurements are conventionally taken using strain gauges or the frequency modulated grid. In recent years, a noncontact method of blade vibration measurement has become an increasingly accepted, low-cost alternative technique. This method uses a number of probes installed in the engine casing to sense the points in time at which the blades are passing the probes. When analysed, these blade passing times yield data on blade vibrations. This paper briefly describes the configuration of such a measurement system and the operating principle of two different probe types. An extended explanation is then provided of the various analysis methods in use at MTU. The methods are described by means of the essential equations and elucidated using comprehensive compressor test data.

Supercharging system for gas turbines

Abstract: A supercharging system for gas turbine power plants (11). The system includes a supercharging fan (30, 32) and a controller (50) for limiting turbine power output to prevent overload of the generator (28) at lower ambient temperatures. The controller can limit power output by burner control, inlet temperature control, control of supercharging fan pressure and other options. The system can be retrofit on an existing turbine without replacing the generator and associated parts.

Control of variable speed wind turbines: Dynamic models

Abstract: Owing to concern over the environment, there is much interest in renewable sources of electrical power generation, of which one of the most promising is wind power. Wind turbines exploit this energy source to directly generate electrical power. There are essentially two types of windturbines, namely constant speed and variable speed machines. The purpose of this paper is to investigate the dynamics of variable speed wind turbines and determine suitable models to support the control design task. A basic but widely used dynamic representation of variable speed wind turbines and the corresponding models of the control plant dynamics are initially discussed. More detailed, yet still simple models, are derived separately for the rotor aerodynamics, the drive-train dynamics and the power generation unit dynamics before being combined to form the complete model of the wind turbine dynamics. The resulting combined model, in addition to supporting the control design task, enables the extent, to which the basic mod...

Contra-rotating wind turbine system

Abstract: Wind turbine apparatus includes an upright mast with support bearings underlying and rotatably supporting a hub assembly having inner and outer coaxial shafts telescopically related but radially spaced to permit independent rotation about a generally horizontal axis. An armature winding is provided on the outer shaft and a plurality of dielectrically separated magnets are mounted on the inner shaft at a plurality of circumferentially spaced locations. A first set of rotor blades is mounted on the inner shaft at a plurality of circumferentially spaced locations, the rotor blades extending radially away from the axis of rotation and positioned on the inner shaft for rotating the inner shaft in a first direction about the axis of rotation when subjected to wind-induced air flow. A second set of rotor blades is similarly mounted on the outer shaft axially spaced from the first set of rotor blades for rotating the outer shaft about the axis of rotation in an opposite direction. The hub assembly may be selectively positioned in azimuth so that the first set of rotor blades is relatively closer to the wind-induced air flow, or windward, and the second set of rotor blades is relatively farther from the wind-induced air flow, or leeward. Electrical power is generated as the armature winding on the outer shaft and the plurality of magnets on the inner shaft rotate in opposite directions and power transfer apparatus is provided for drawing off the electrical power from the hub assembly to a distant receiver.

Water current turbine sleeve mounting

Abstract: A flowing water actuatable turbine system, wherein the turbine system is mounted for operational co-operation with water current by means of an upstanding column/pile in such manner as to be axially displaceable length ways of the column/pile. The turbine system is preferably arranged to be rotatably about the longitudinal axis of the column. Floatation means can be provided for operationally supporting the turbines which can include blade pitch control.

Adjustable speed generators for wind turbines based on doubly-fed induction machines and 4-quadrant IGBT converters linked to the rotor

Abstract: Wind turbines are being built at power levels above 1.5 MW. Higher power levels are being anticipated for offshore applications. To limit mechanical stresses and power surges in these high power systems, speed control is necessary. The doubly-fed induction generator (DFIG) system is investigated as a viable alternative to adjust speed over a wide range while keeping the cost of the power converters minimal. A four-quadrant IGBT AC-to-AC converter is used to feed power bi-directionally to the rotor circuit. Decoupled control of active and reactive power can be realized using the dynamic model of the DFIG. Simulations and measurements confirm the validity of the model and the viability of the DFIG wind turbine.

An experimental study of the characteristics of a Darrieus turbine for tidal power generation

Abstract: The Darrieus turbine was initially developed for wind turbines. An example of its application to water turbines is found in the Darrieus turbine installed in a duct for low head power generation, but no example is known of its application in a natural water channel. The authors have developed a Darrieus turbine that is suitable for tidal current power generation with the aim of establishing tidal current power generation technology through demonstrations in test channels and oceans. The efficiency of tidal current power generation is influenced by the characteristics of the turbine. The characteristics of the Darrieus turbine are mainly affected by the solidity and the number of blades. The Darrieus turbine was tested in test channels to find the most suitable values for the rotor solidity and the number of blades. This paper describes and examines those test results. © 2000 Scripta Technica, Electr Eng Jpn, 132(3): 38–47, 2000

Control method for turbocharged diesel engines having exhaust gas recirculation

Abstract: A method of controlling the airflow into a compression ignition engine having an EGR and a VGT. The control strategy includes the steps of generating desired EGR and VGT turbine mass flow rates as a function of the desired and measured compressor mass airflow values and exhaust manifold pressure values. The desired compressor mass airflow and exhaust manifold pressure values are generated as a function of the operator-requested fueling rate and engine speed. The EGR and VGT turbine mass flow rates are then inverted to corresponding EGR and VGT actuator positions to achieve the desired compressor mass airflow rate and exhaust manifold pressure. The control strategy also includes a method of estimating the intake manifold pressure used in generating the EGR valve and VGT turbine positions.

Large vertical-axis variable-pitch wind turbine

Abstract: Several improvements are invented upon a known and well tested selfstarting vertical-axis wind turbine, for economically competitive power production by driving large grid-connected AC generators. It comprises: variable blade pitch-angle from 0 to 60 degrees, following variable wind speed for maximum efficiency and to keep constant turbine speed, variable blade camber limited to optimal lift-to-drag ratio, controled by pitch and cyclical variation of incidence-angle; improved airfoil shape of cambered blades; low cost automatic gear-train for two constant turbine speeds; protection against overload and prevention of power surge during wind gusts; low stress three-legged high tower assembled with nacelle and tail structure on ground level and erected by assembling segments of third leg one section at a time, and reducing costs of concrete footing, tower structure and, hoisting and assembling at ground level, enables a tower to be built to any height required to harness maximum wind energy.

GSP: A Generic Object-Oriented Gas Turbine Simulation Environment

Abstract: NLR’s primary tool for gas turbine engine performance analysis is the ‘Gas turbine Simulation Program’ (GSP), a component based modeling environment. GSP’s flexible object-oriented architecture allows steady-state and transient simulation of any gas turbine configuration using a user-friendly drag&drop interface with on-line help running under Windows95/98/NT.GSP has been used for a variety of applications such as various types of off-design performance analysis, emission calculations, control system design and diagnostics of both aircraft and industrial gas turbines. More advanced applications include analysis of recuperated turboshaft engine performance, lift-fan STOVL propulsion systems, control logic validation and analysis of thermal load calculation for hot section life consumption modeling.In this paper the GSP modeling system and object-oriented architecture are described. Examples of applications for both aircraft and industrial gas turbine performance analysis are presented.Copyright © 2000 by ASME

Ceramic turbine nozzle

Abstract: A turbine nozzle includes ceramic outer and inner bands, with a ceramic vane forward segment integrally joined thereto. A ceramic vane aft segment has opposite ends trapped in complementary sockets in the bands.