Academic literature on the topic 'Electrodisharge generator of elastic vibrations'
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Journal articles on the topic "Electrodisharge generator of elastic vibrations"
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Kvasov, I. N., K. Yu Fetisov, M. A. Aleksandrov, and A. A. Gladenko. "Well productivity and reservoir recovery enhancement with using vibration wave impact technology." Oil and Gas Studies, no. 4 (September 9, 2021): 73–83. http://dx.doi.org/10.31660/0445-0108-2021-4-73-83.
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The use of physical fields of elastic vibrations in methods of increasing well productivity and oil recovery is presented. Borehole hydrodynamic generators of elastic vibrations are the most preferable for performing vibration-wave treatments of the bottom-hole zone. Many generator designs lack reasonable parameters for the generated pressure fluctuations. In this regard, it is necessary a bench and oilfield research practice of hydrodynamic generators various designs with an objective hardware assessment of their operating parameters.
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Cherpakov, Alexander V., Ivan A. Parinov, and Rakesh Kumar Haldkar. "Parametric and Experimental Modeling of Axial-Type Piezoelectric Energy Generator with Active Base." Applied Sciences 12, no. 3 (February 7, 2022): 1700. http://dx.doi.org/10.3390/app12031700.
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A computational and experimental approach to modeling oscillations of a new axial-type piezoelectric generator (PEG) with an attached mass and an active base is considered. A pair of cylindrical piezoelements located along the generator axis is used as an active base. Plate-type piezoelectric elements, made in the form of two bimorphs on an elastic PEG base, use the potential energy of PEG bending vibrations. Energy generation in cylindrical piezoelectric elements occurs due to the transfer of compressive forces to the piezoelectric element at the base of the PEG during excitation of structural vibrations. The active load scheme is selected separately for each piezoelectric element. Numerical simulation was performed in the ANSYS FE analysis package. The results of modal and harmonic analysis of vibrations are presented. A technique for experimental analysis of vibrations is presented, and a laboratory test setup is described. Numerical and experimental results are presented for the output characteristics of a piezoelectric generator at a low-frequency load. For one of the versions of the generator and a certain displacement amplitude for a frequency of 39 Hz, in the results of a comparative experimental analysis at a load of 10 kΩ, the maximum output power for each cylindrical piezoelectric element was 2138.9 μW, and for plate-type piezoelectric elements, respectively, 446.9 μW and 423.2 μW.
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Kuievda, Yu V., and S. M. Baluta. "PARAMETER IDENTIFICATION METHOD OF THE TURBINE-GENERATOR SHAFT ELASTIC MODEL FOR TORSIONAL VIBRATIONS SIMULATION." Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini 2017, no. 47 (July 18, 2017): 37–44. http://dx.doi.org/10.15407/publishing2017.47.037.
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Zumbach, M., G. Schweitzer, and K. Schoellhorn. "On-Line Thermal Balancing Technique for a Large Turbo-Generator." Journal of Vibration and Acoustics 114, no. 1 (January 1, 1992): 60–66. http://dx.doi.org/10.1115/1.2930235.
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In this paper a new technique is proposed to rebalance automatically a large turbo-generator during operation. The sensitivity of the rotor unbalances to thermal asymmetries in the rotor is exploited by mounting some heating elements and using them as actively controlled actuators. The shaft vibrations are measured and used as input signals of the feedback controller. Unbalances thus can be compensated during rotor operation. A theoretical model of the thermo-elastic rotor has been developed and an appropriate closed-loop control system has been designed. The simulation results are verified on a special test rig with digital control allowing for varioius control strategies and various operating conditions.
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Guzev, Mikhail, Evgenii Kozhevnikov, Mikhail Turbakov, Evgenii Riabokon, and Vladimir Poplygin. "Experimental Studies of the Influence of Dynamic Loading on the Elastic Properties of Sandstone." Energies 13, no. 23 (November 25, 2020): 6195. http://dx.doi.org/10.3390/en13236195.
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Under dynamic loading, the geomechanical properties of porous clastic rocks differ from those in quasistatic loading. A small experimental rig was built to directly assess the influence of vibrations on the uniaxial compressive strength (UCS), Young modulus, and Poisson’s ratio. A piezoelectric actuator powered by a signal from an oscillator was used in the rig as a generator of vibrations. A laser sensor and eddy current probe measured the longitudinal and transverse deformation. Tinius Hounsfield and Instron Series 4483 installations were used to determine the geomechanical properties of new red sandstone in a quasistatic regime. The boundaries of elastic deformations determined in the quasistatic loading were implemented in the dynamic loading. To perform the experiments in the elastic zone (on the graph of stress (σ)–strain (ε)), small samples with diameters ranging between 7.5 and 24.7 mm were manufactured. The investigation demonstrated that the Young’s modulus of the sandstone increased with increasing values of the dynamic load and frequency.
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Tsvetkov, G., and V. Kostitsyn. "Increase of Accuracy of Well Bottom Position Determination by Minimization of Seismic Vibration Finding Errors." Applied Mechanics and Materials 682 (October 2014): 154–59. http://dx.doi.org/10.4028/www.scientific.net/amm.682.154.
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In the given work, on the basis of the carried out researches at the decision of seismic surveying tasks an attempt on advancement of methods and means of excitation of elastic vibrations by the generator of seismic vibrations (GSV) is made. The geometry of the real GSV differs from the ideal axially symmetric form resulting in deviations of parameters of geometry of mass (deviations of the centre of mass, main central axes of inertia), and is a consequence of the static and dynamic disbalance.The character of forces and moments acting on the GSV, as a whole and on separate units, depends on quality of the law of change of total force of resistance of escapement and return of plunger; dynamic loads resuling in occurrence of transverse waves at excitation of seismic vibrations deterioting the accuracy of determination of well bottom position are formed.
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Soloviev, A. N., and D. A. Ermakov. "Mathematical and Computer Modeling of Piezoelectric Generator for Energy Harvesting Devices." Mathematics and Mathematical Modeling, no. 1 (May 20, 2019): 1–14. http://dx.doi.org/10.24108/mathm.0119.0000176.
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The paper deals with modeling a Piezoelectric Generator (PEG) that includes piezoactive elements, inertial mass, plate and rack. The PEG under consideration can be an element of the energy storage device in the capacity of the source of energy provided from vibrations of elements of structures and machines.The main objective of the paper is to gain the PEG efficiency by finding the optimal geometric parameters for finding the highest output potential.The elastic and piezoceramic media are modeled within the framework of the linear theory of electroelasticity. As a research tool, CAE package ACELAN is used in which three-dimensional and axisymmetric device models are built. The numerical experiments performed a modal and harmonic analysis that enabled us to identify the most effective operating frequencies.
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Wolszczak, Piotr, Grzegorz Litak, and Krystian Lygas. "Analysis of dynamics of a vertical cantilever in rotary coupling to the moving frame with movement limiters." MATEC Web of Conferences 241 (2018): 01021. http://dx.doi.org/10.1051/matecconf/201824101021.
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The efficiency of the mechanical energy harvesting with the use of vibrating elements can be improved by synchronizing stimulation vibrations and own linear frequencies of systems as well as super or sub harmonics induced by non-linear phenomena. The article presents numerical cross-sectional study of the mechanical system. The system consists of an elastic beam set vertically, which the lower end is fixed in the rotary support, and is stimulated to move in the horizontal axis. The upper end of the beam is free but below its level there are bumpers limiting the free rotation of the beam. Numerical studies took into account the variability of the frequency and amplitude of the excitation beam movement, and horizontal distance between bumpers. Beam deflection was observed, on the basis of which the amount of energy generated by the piezo element was estimated. Nonlinear phenomena and analysis of frequency synchronization of vibrations improving the energy effect of an energy generator are presented.
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Xiang, Ling, Shixi Yang, and Chunbiao Gan. "Torsional Vibration of a Shafting System under Electrical Disturbances." Shock and Vibration 19, no. 6 (2012): 1223–33. http://dx.doi.org/10.1155/2012/986769.
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Torsional vibration responses of a nonlinear shafting system are studied by a modified Riccati torsional transfer matrix combining with the Newmark-βmethod. Firstly, the system is modeled as a chain consisting of an elastic spring with concentrated mass points, from which a multi-segment lumped mass model is established. Secondly, accumulated errors are eliminated from the eigenfrequencies and responses of the system's torsional vibration by this newly developed procedure. The incremental transfer matrix method, combining the modified Riccati torsional transfer matrix with Newmark-βmethod, is further applied to solve the dynamical equations for the torsional vibration of the nonlinear shafting system. Lastly, the shafting system of a turbine-generator is employed as an illustrating example, and simulation analysis has been performed on the transient responses of the shaft's torsional vibrations during typical power network disturbances, such as three-phase short circuit, two-phase short circuit and asynchronous juxtaposition. The results validate the present method and are instructive for the design of a turbo-generator shaft.
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Ragulskis, Kazimieras. "Mechanical systems of precise robots with vibrodrives, the vibrating mass of the exciting force of which performs impacts into deformable support and direction of the exciting force coincides with the line of relative motion of the system." Mechanics 27, no. 5 (October 12, 2021): 408–14. http://dx.doi.org/10.5755/j02.mech.27470.
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Manipulator consisting from one sided self stopping mechanism and two masses which interact through an elastic – dissipative member is investigated. The drive of the manipulator is the generator of mechanical vibrations. With such elements the system is nonlinear. A separate case is investigated when static positions of equilibrium of both masses are located in one point. Because of this spectrums of eigenfrequencies are linear and infinite. All those facts mean that the operation of the manipulator is optimal.
Fast development of robots gives rise to the investigations of increasing intensity creating various types of robots especially in the area of high precision. Mechanical systems of robot must perform laws and trajectories of motion, positioning in space with highest possible precision as well as ensure dynamicity of highest possible stability. Those aims are achieved in the presented paper by creating a structure of the best design, based on vibroimpacts as well as by choosing corresponding nonlinear parameters of the system. The investigation is performed by analytical – numerical method. The obtained results enable to create mechanical systems for precise robots.
Dissertations / Theses on the topic "Electrodisharge generator of elastic vibrations"
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Вінніков, Денис Вікторович. "Електрофізичний вплив потужного підводного іскрового розряду на процеси обробки речовин." Thesis, Національний науковий центр "Харківський фізико-технічний інститут", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/33188.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена вдосконаленню електророзрядного обладнання, що використовується для обробки речовин сильно струмовим підводним іскровим розрядом. Проведено аналіз здобутих властивостей матеріалів та рідин в залежності від електричних параметрів розрядного кола, розмірів міжелектродного проміжку, конструкцій електрогідравлічних реакторів і тиску у реакторі. Запропоновані технологічні рекомендації щодо вдосконалення обладнання та процесів електрофізичного впливу на матеріали і рідкі середовища. В дисертації вдосконалено математичну модель щодо дослідження ранньої стадії розвитку іскрового каналу потужного іскрового розряду в парі води та у парогазовій оболонці. Вперше виявлено можливість швидкої (5–20 с) зміни окислювально-відновного потенціалу рідин в бік від'ємних значень з помірним підвищенням водневого показника. Проведено діагностику зміни фізико-хімічних властивостей води. Визначено склад та розміри частинок, що утворюються під час електричної ерозії електродів, запропоновано хімічну схему їх впливу на властивості води. Виявлено можливість подрібнення матеріалів, що моделюють відпрацьоване ядерне паливо, з метою вдосконалення методів його переробки. Оптимізовано параметри розрядного кола та реактора для подрібнення гумовотехнічних виробів у середовищі рідкого азоту. Доведено можливість обробки та зменшення розмірів зерен металів, що переплавляються в вакуумно-дугових пічках під впливом механіко-акустичних імпульсів, які утворюються високовольтними потужними підводними іскровими розрядами.Thesis for the scientific degree of the candidate of engineering sciences by specialty 05.09.13 – Technology of Strong Electric and Magnetic Fields. – National Science Center "Kharkiv Institute of Physics and Technology", Ministry of education and science of Ukraine National Technical University "Kharkiv Politechnic University" Kharkiv, 2017. This thesis is devoted to the improvement of the electric discharge equipment that is used for the substance treatment by heavy-current underwater spark discharges. The properties of materials and liquids were analyzed as a function of the electric parameters of discharge circuit, in particular, the charging voltage, the capacitance and the spark gap size. The structures of electrohydraulic reactors that are used for the treatment of general mechanical rubber goods and materials that simulate in the first approximation the spent solid nuclear fuel were developed and modernized to improve the methods of fuel recycling. The liquid degassing intensification method was suggested to initiate underwater spark discharges in the electrohydraulic reactor under the evacuation. The electrode system was created to provide the ordered motion of a pulsating steam and gas cavity in the water space at a reduced pressure in the reactor. A structure of the electric discharge generator of elastic vibrations that allows us to have an influence on the metal melts in vacuum-arc furnaces has been developed. It has been proved that mechanical acoustic vibrations generated by spark discharges in the liquid have a positive effect on the distribution of admixtures in treated metals and a decrease in the size of crystal grains. Technological recommendations on the improvement of the processes of electrophysical impact on the materials and liquid media were given. A mathematical model used for the investigation of the progress of current conducting channel that short-closes the spark gap at an early stage of its development, in particular a process of the expansion of current conducting channel and steam-gas cavity was improved. An opportunity for a fast (5–20 s) change in the redox potential of the liquid to the side of negative values with a moderate increase in the pH value was revealed for the first time. It has been shown that a change in the redox potential depends on the input of total energy into the treated volume. We established that a change in the redox potential is related to the processes that occur inside the steam-gas cavity, in particular chemical transformations that occur in its volume and the formation of electric erosion products of the electrodes that result in the chemical changes in the composition of treated medium. The size and dimensions of the particles that are formed during the electric erosion of electrodes have been defined. The chemical diagram of their influence on water properties has been suggested. A degree of the change in the redox potential is related to a number of formed polydisperse particles. Nanosize particles (37 % of the total volume of particles) with an increased physical and chemical activity were revealed.
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Вінніков, Денис Вікторович. "Електрофізичний вплив потужного підводного іскрового розряду на процеси обробки речовин." Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/33183.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена вдосконаленню електророзрядного обладнання, що використовується для обробки речовин сильно струмовим підводним іскровим розрядом. Проведено аналіз здобутих властивостей матеріалів та рідин в залежності від електричних параметрів розрядного кола, розмірів міжелектродного проміжку, конструкцій електрогідравлічних реакторів і тиску у реакторі. Запропоновані технологічні рекомендації щодо вдосконалення обладнання та процесів електрофізичного впливу на матеріали і рідкі середовища. В дисертації вдосконалено математичну модель щодо дослідження ранньої стадії розвитку іскрового каналу потужного іскрового розряду в парі води та у парогазовій оболонці. Вперше виявлено можливість швидкої (5–20 с) зміни окислювально-відновного потенціалу рідин в бік від'ємних значень з помірним підвищенням водневого показника. Проведено діагностику зміни фізико-хімічних властивостей води. Визначено склад та розміри частинок, що утворюються під час електричної ерозії електродів, запропоновано хімічну схему їх впливу на властивості води. Виявлено можливість подрібнення матеріалів, що моделюють відпрацьоване ядерне паливо, з метою вдосконалення методів його переробки. Оптимізовано параметри розрядного кола та реактора для подрібнення гумовотехнічних виробів у середовищі рідкого азоту. Доведено можливість обробки та зменшення розмірів зерен металів, що переплавляються в вакуумно-дугових пічках під впливом механіко-акустичних імпульсів, які утворюються високовольтними потужними підводними іскровими розрядами.Thesis for the scientific degree of the candidate of engineering sciences by specialty 05.09.13 – Technology of Strong Electric and Magnetic Fields. – National Science Center "Kharkiv Institute of Physics and Technology", Ministry of education and science of Ukraine National Technical University "Kharkiv Politechnic University" Kharkiv, 2017. This thesis is devoted to the improvement of the electric discharge equipment that is used for the substance treatment by heavy-current underwater spark discharges. The properties of materials and liquids were analyzed as a function of the electric parameters of discharge circuit, in particular, the charging voltage, the capacitance and the spark gap size. The structures of electrohydraulic reactors that are used for the treatment of general mechanical rubber goods and materials that simulate in the first approximation the spent solid nuclear fuel were developed and modernized to improve the methods of fuel recycling. The liquid degassing intensification method was suggested to initiate underwater spark discharges in the electrohydraulic reactor under the evacuation. The electrode system was created to provide the ordered motion of a pulsating steam and gas cavity in the water space at a reduced pressure in the reactor. A structure of the electric discharge generator of elastic vibrations that allows us to have an influence on the metal melts in vacuum-arc furnaces has been developed. It has been proved that mechanical acoustic vibrations generated by spark discharges in the liquid have a positive effect on the distribution of admixtures in treated metals and a decrease in the size of crystal grains. Technological recommendations on the improvement of the processes of electrophysical impact on the materials and liquid media were given. A mathematical model used for the investigation of the progress of current conducting channel that short-closes the spark gap at an early stage of its development, in particular a process of the expansion of current conducting channel and steam-gas cavity was improved. An opportunity for a fast (5–20 s) change in the redox potential of the liquid to the side of negative values with a moderate increase in the pH value was revealed for the first time. It has been shown that a change in the redox potential depends on the input of total energy into the treated volume. We established that a change in the redox potential is related to the processes that occur inside the steam-gas cavity, in particular chemical transformations that occur in its volume and the formation of electric erosion products of the electrodes that result in the chemical changes in the composition of treated medium. The size and dimensions of the particles that are formed during the electric erosion of electrodes have been defined. The chemical diagram of their influence on water properties has been suggested. A degree of the change in the redox potential is related to a number of formed polydisperse particles. Nanosize particles (37 % of the total volume of particles) with an increased physical and chemical activity were revealed.
Conference papers on the topic "Electrodisharge generator of elastic vibrations"
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Bendjeddou, Z., E. Longatte, A. Adobes, and M. Souli. "Steam Generator Tube Vibrations: Experimental Determination Versus ALE Computation of Fluidelastic Forces." In ASME 2003 Pressure Vessels and Piping Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/pvp2003-1966.
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In heat exchanger tube bundles like in many others industrial applications, fluid structure interaction is a crucial problem to overcome. Flow-induced tube vibration in tube bundles is due to two main kinds of physical effects: (1) fluid-elastic forces caused by structure motion; (2) turbulent forces due to vortex generation at high Reynolds numbers. The second component, turbulent excitation, is independent on structure motion and may generate wear and fatigue damage while the first component may lead to fluid-elastic instability inducing high amplitude displacement and possible tube short term failure. In this context many studies are carried out in order to develop methods for the identification of critical flow velocity in tube arrays. In the present work two methods are presented: (1) the first one relies on experimental measurements, it is fitted with analytical modeling and provides fluid-elastic coefficients; (2) the second one relies on numerical simulation using Computational Fluid Dynamics Codes (CFD) involving moving boundary techniques; it provides fluid force estimates and in some cases it makes it possible to simulate tube vibrations. The first part is devoted to experimental determination of fluid-elastic forces. A numerical method for prediction of fluid-elastic effects in fluid at rest is presented in the second section. Results of both methods are compared in the third part.
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De Marqui, Carlos, Alper Erturk, and Daniel J. Inman. "Effect of Segmented Electrodes on Piezo-Elastic and Piezo-Aero-Elastic Responses of Generator Plates." In ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1285.
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In this paper, the use of segmented electrodes is investigated to avoid cancellation of the electrical outputs of the torsional modes in energy harvesting from piezo-elastic and piezo-aero-elastic systems. The piezo-elastic behavior of a cantilevered plate with an asymmetric tip mass under base excitation is investigated using an electromechanically coupled finite element (FE) model. Electromechanical frequency response functions (FRFs) are obtained using the coupled FE model both for the continuous and segmented electrodes configurations. When segmented electrodes are considered torsional modes also become significant in the resulting electrical FRFs, improving broadband (or varying-frequency excitation) performance of the generator plate. The FE model is also combined with an unsteady aerodynamic model to obtain the piezo-aero-elastic model. The use of segmented electrodes to improve the electrical power generation from aeroelastic vibrations of plate-like wings is investigated. Although the main goal here is to obtain the maximum electrical power output for each airflow speed (both for the continuous and segmented electrode cases), piezoelectric shunt damping effect on the aeroelastic response of the generator wing is also investigated.
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Demirel, Burak, Mu¨min Tolga Emirler, Ahmet Yo¨ru¨kog˘lu, Nebahat Koca, and U¨mit So¨nmez. "Compliant Impact Generator for Required Impact and Contact Force." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68796.
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A novel design of compliant slider crank mechanism is introduced and utilized as an impact force generator and contact force generator. This class of compliant slider mechanisms incorporates an elastic coupler which is an initially straight flexible beam and buckles when it hits the stopper. The elastic pin-pin coupler (a buckling beam) behaves as a rigid body prior to the impact pushing the rigid slider. At a certain crank angle the slider hits a stopper generating an impact force. Impact force can be changed by changing the angular velocity of the crank, therefore; achieving a desired velocity of the slider. Moreover, after the impact when the vibrations die out the maximum contact force can also be predetermined by designing the coupler dimensions (length, width, thickness and the amount of compression). Contact duration (crank angle) can also be changed and adjusted in this mechanism by changing the adjustable location of the impacted object.
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Lhuillier, Vincent. "Reproducing Fluid-Elastic Coupling Forces on a U-Tube With a Hybrid Testing Approach." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65511.
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In the nuclear industry, flow-induced vibrations of Steam Generator (SG) tubes are extensively studied for safety justifications and for optimizing the maintenance policies of these components. This paper presents a hybrid testing approach that reproduces the coupled fluid-elastic forces acting on the SG-tubes, by means of an active control system. By modal control strategy and precise pole placement, it is possible to recreate in dry conditions the dynamics of the tube in the turbulent secondary flow. Since the quality of pole placement strongly depends on the model accuracy, this paper also presents the identification method of the instrumented tube.
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Adobes, Andre´, Joe¨l Pillet, Franck David, and Michae¨l Gaudin. "Influence of Steam Generator Tube Bundle Vibrations on the Operating Diagram of a Nuclear Plant During Stretch Out." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93239.
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During the normal cycle of a pressurized water reactor, boron concentration is reduced in the core until fuel burns up. A stretch out of the normal cycle is however possible afterwards, provided primary coolant temperature is reduced. In those stretch out periods, nuclear operators want to keep constant thermal power exchanged in the steam generator, in order to preserve its performances. Under that constraint, the required reduction in primary coolant temperature involves both a decrease of secondary cooling system pressure and an increase of tube bundle vibrations. Since neither pressure nor vibrations should exceed some given thresholds in order to preserve component integrity, the reduction of primary coolant temperature has to be limited. Nuclear plant operators thereafter need an operating diagram, i.e. a diagram that provides minimum allowed primary coolant temperature versus power rate. In that context, we propose a method to derive such a diagram, by combining, on the one hand a code for simulating primary and secondary fluid flows in steam generators and, on the other hand, a software that allows one to predict fluid elastic tube bundle instabilities. That method allows one to take into account both tube fouling and plugging. It is now used by French utility “Electricite´ De France”, in order to check or supplement the analysis that are provided by steam generator manufacturers.
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Benmalek, Wissam, Manuel Collet, Emmanuel Foltete, Morvan Ouisse, and Mathieu Corus. "Numerical Simulation and Experimental Validation of Gap Supported Tube Subjected to Fluid-Elastic Coupling Forces for Hybrid Characterization Tests." In ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3033.
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Steam Generator (SG) tubes are subjected to fluid-elastic coupling forces and impacts against support plates & anti-vibration bars. Understanding their vibrations is crucial not only at the design stage, but also to optimize the SG maintenance policy and to lengthen the SG service life. The aim of our research is to provide a better understanding of the conjugate stabilizing effects of impacts and coupling with fluid-elastic forces. Since fluid-elastic forces are difficult to simulate and expensive to reproduce experimentally, the fluid coupling forces of our numerical model are represented using velocity dependent damping and stiffness matrices, both for the fluid and the tube. Their effect is experimentally reproduced having recourse to active vibration control in the frame of specifically designed “hybrid” experimental tests. In this paper, we present a method for modeling tube vibrations in order to estimate the conjugate effects of the coupling between the fluid elastic forces and impacts. This strategy lowers the costs and avoids the difficulties associated to the case of fluid in the experiments. Our numerical model will be implemented in the active control loop in the next step of the study.
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Karlsson, Martin, and Jan-Olov Aidanpa¨a¨. "Dynamic Behaviour in a Hydro Power Rotor System Due to the Influence of Generator Shape and Fluid Dynamics." In ASME 2005 Power Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pwr2005-50079.
Full textAbstract:
Hydro power rotors are subjected to fluid and electromagnetic forces. In this paper measurements and simulations are shown for a hydro power rotor system. The simulation includes the influence of fluid forces in the turbine as well as the electro magnetic pull in the generator. The mechanical rotor system is modelled with the generator and the turbine treated as two rigid bodies, connected to an elastic shaft supported by three bearings. The fluid model in the turbine is based on results from the scientific literature. A model is suggested for the electro magnetic pull due to eccentricity and the shape of the stator core and the rotor rim. Results from the simulation are compared and analyzed with frequency spectrum from vibrations measurements. One can conclude that the unbalance together with geometric properties of the turbine and generator, are possible sources of the most dominant frequency peak in the measurements.
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Deri, Enrico, Joël Nibas, and André Adobes. "A New Test-Bench for Studying Vibrations of Tubes in Parallel Triangular Bundles Under Two-Phase Cross-Flow." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28245.
Full textAbstract:
Flow-induced vibrations of Steam Generator (SG) tube bundles are a major concern for the operators of nuclear power plants. In order to predict damages due to such vibrations, EDF has developed the numerical tool GeViBus, which allows one to evaluate safety margins and thereafter to optimize the SG maintenance policy. The software is based on a semi analytical model of fluid-dynamic forces and dimensionless fluid force coefficients which need to be assessed by experiment. The database of dimensionless coefficients is steadily updated in order to cover all tube bundle configurations found in EDF power plants. Within this framework, we present a new test rig dedicated to the parallel triangular tube arrangement submitted to a two-phase cross-flow. A new test loop is constructed as well, allowing fluid-elastic instability to be induced on the test rig for various qualities. The details of the experimental arrangement are presented together with the preliminary validation tests.
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Golebiowski, Mateusz, Rainer Nordmann, and Eric Knopf. "Rotordynamic Investigation of Spiral Vibrations: Thermal Mode Equation Development and Implementation to Combined-Cycle Power Train." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25430.
Full textAbstract:
Rotation of vibration vector caused by thermally induced unbalance changes is a frequently observed phenomenon in large rotating machinery. The heat arising from the friction losses, which are generated at the interfaces between rotating and statoric components of the machine, is partly absorbed by the shaft. This heat input is typically not uniform around the shaft circumference and the resulting temperature difference causes the rotor to bow. The excitation resulting from the sum of mechanical unbalance and thermal bow will lead to a slowly rotating (in the synchronously rotating coordinates system) whirl vector, whose magnitude can decrease or increase in time. A generic understanding of this effect (B.L. Newkirk in 1926, [4]) had been followed by a number of physical models representing specific heat exchange mechanisms (W. Kellenberger [3], J. Schmied [6], P. Morton [11]). A hot spot on the shaft surface can be generated at various locations of a shaft-line. Typical components responsible for thermally induced modulation of vibration vector are journal bearings, seal rings, labyrinth seals (in case of a soft rubbing). Furthermore carbon brushes sliding on the slip ring, supplying the DC current to the field winding of the generator rotor, were identified as a source of nonuniform heat input that may excite spiral vibrations (L. Eckert and J. Schmied in [7], [8]). These local heat input phenomena affect consequently the vibration behavior of the overall shaft train. This paper provides a new approach to the quantitative description of a heat exchange mechanism which leads to the hot spot generation on the surface of a slip ring. A new thermal equation has been formulated, which determines the stability and frequency of the thermal mode. Characteristics of spiral vibration are discussed based on the analytical solution of the Jeffcott rotor model coupled with the proposed thermo-elastic equation. The implementation of the described method to a full shaft-line model of a combined cycle, single shaft power train was done using the Finite Element Method. The results of this calculation were validated against measurement data. The paper shows how the applied computational approach can be used to extend stability margin of the spiral vibration in turbo-generator shaft trains.
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Lee, Jonghun, Che-Chun Chang, Nikolaos I. Xiros, and Michael M. Bernitsas. "Integrated Power Take-Off and Virtual Oscillator System for the VIVACE Converter: VCK System Identification." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11430.
Full textAbstract:
The first step in the development of an integrated system encompassing Power Take-Off (PTO) with virtual Mass-Damping-Spring (VMCK) for the VIVACE Converter (Vortex Induced Vibration for Aquatic Clean Energy) is achieved. VIVACE converts hydrokinetic energy of ocean/river currents to mechanical energy using Vortex Induced Vibrations (VIV). Subsequently, its PTO converts the mechanical energy to electricity. The objective integrated system acts as VMCK to support the hydro-mechanical component of VIVACE. The second function of the system is to act as PTO to implement the electro-mechanical component converting the harnessed mechanical energy to electrical energy without suppressing the hydro-mechanical energy harnessing mechanism of VIV. Vortex Induced Vibrations (VIV) are motions induced on long elastic bodies with bluff cross-section placed with their long axis perpendicular to a fluid flow due to periodic irregularities in this fluid-structure interaction phenomenon. In this paper, a single cylinder of VIVACE is considered. Even in this simplest case, the underlying physics of this phenomenon is strongly nonlinear. Special care is needed in designing systems that either support or enhance VIV or harvest the energy of VIV oscillations. In the first physical model of VIVACE, a mass-damper-spring arrangement was employed in the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan to transmit mechanically the power to an electrical generator, which converted it to useful electrical power. A Virtual mass-damping-spring (VMCK) mechanism is intended to substitute the existing physical elements in the MRELab consisting of an electric motor driven by a power electronic converter allowing for programmable mass, stiffness and damping values. The integrated VMCK system enables improved control of the mechanism originally generating and supporting VIV as well as improved power take-off efficiency and capability. The VMCK system employs advanced switching control of the power transfer process so that VIV for a given damping is not affected. The first step taken in this paper towards development of the integrated system consists of the identification of the VCK system. The mechanical transmission system consists of a belt and two pulleys. The cylinder in VIV is attached to one side of the belt causing it to oscillate and in turn drive the pulleys.