Energy harvesting from a dynamic vibro-impact dielectric elastomer generator subjected to rotational excitations

Nonlinear Dynamics - A vibro-impact (VI) dielectric elastomer generator (DEG) subjected to rotational excitations is studied in this paper for energy harvesting (EH). The VI DEG that has been...     

Ballistic magnetocumulative generator

The reusable source of a pulsed magnetic field—a ballistic magnetocumulative generator (BMG)—is considered. Electrical engineering analysis of the efficiency of operation of the generator on an active-inductive load is performed. A method for calculating the two-dimensional distribution of the field in the busbars of the generator is developed. Experimental results are obtained for the operation of aBMG model on some types of load. Central Scientific-Research Institute “Burevestnik,” Nizhnii Novgorod 603603. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 22–29, May–June, 1998.     

Nonlinear dynamic singularity analysis of two interconnected synchronous generator system with 1:3 internal resonance and parametric principal resonance

The bifurcation analysis of a simple electric power system involving two synchronous generators connected by a transmission network to an infinite-bus is carried out in this paper. In this system, the infinite-bus voltage are considered to maintain two fluctuations in the amplitude and phase angle. The case of 1:3 internal resonance between the two modes in the presence of parametric principal resonance is considered and examined. The method of multiple scales is used to obtain the bifurcation equations of this system. Then, by employing the singularity method, the transition sets determining different bifurcation patterns of the system are obtained and analyzed, which reveal the effects of the infinite-bus voltage amplitude and phase fluctuations on bifurcation patterns of this system. Finally, the bifurcation patterns are all examined by bifurcation diagrams. The results obtained in this paper will contribute to a better understanding of the complex nonlinear dynamic behaviors in a two-machine infinite-bus (TMIB) power system.     

A pneumatic droplet-on-demand generator

The design of a pneumatic droplet generator to produce small (~0.2 mm diameter) water droplets on demand is described. It consists of a cylindrical, liquid-filled chamber with a small nozzle set into its bottom surface, connected to a gas cylinder through a solenoid valve. Rapidly opening and closing the valve sends a pressure pulse to the liquid, ejecting a single droplet through the nozzle. Gas in the chamber escapes through a vent hole so that the pressure drops rapidly and more droplets do not emerge. We photographed droplets as they emerged from the nozzle, and recorded pressure fluctuations in the chamber. We determined the duration of the pressure pulse required to generate a single drop; longer pulses produced satellite drops. The length of the water jet when its tip detached and the diameter of the droplet that formed could be predicted using results from linear stability analysis. The peak pressure in the cavity could be increased by raising the supply pressure, increasing the width of the pressure pulse, or by reducing the size of the pressure relief vent.     

Gas dynamic aspects of the interaction between a centered compression wave and an incompressible plate

The interaction regime of a centered compression wave and an incompressible plate projected by the detonation products of a condensed explosive is investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 166–168, July–August, 1990.     

Gas dynamic flow properties in the problem of two incompressible plates propelled by explosion products

The method proposed in [1, 2] is used to construct an analytic solution of the problem of two incompressible plates propelled by the explosion products of a condensed explosive. A solution of the problem by the classical methods of the gas dynamics of a perfect gas with =3 was previously obtained in [3]. However, the analysis carried out in [3] does not reproduce the entire wave configuration which may result from the interaction of expansion waves with moving plates and is limited to the study of the flow configuration realized in the case of single reflection of the waves from the plate contact boundary. This leads to overestimation of the limiting projection velocities when the relative masses of the plates are greater than unity.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 148–152, March–April, 1991.     

A novel internal waves generator

We present a new kind of generator of internal waves which has been designed for three purposes. First, the oscillating boundary conditions force the fluid particles to travel in the preferred direction of the wave ray, hence reducing the mixing due to forcing. Second, only one ray tube is produced so that all of the energy is in the beam of interest. Third, temporal and spatial frequency studies emphasize the high quality for temporal and spatial monochromaticity of the emitted beam. The greatest strength of this technique is therefore the ability to produce a large monochromatic and unidirectional beam.     

A cylindrical coaxial MHD generator

A MHD generator with a novel geometry is analyzed as a possible dc power source. The generator channel consists of two coaxial cylinders with a smooth annular space between them through which pressure driven ionized gas flows axially. Magnetic poles and electrodes separated by insulators are embedded in both the inner and outer cylinders. A one-dimensional steady state analysis is presented. It is shown that the internal impedance of the generator is a very sensitive function of the ratio of areas of the charge collecting electrodes to that of the magnetic poles. The generator efficiency analysis, on the other hand, indicates that there is an optimum area ratio corresponding to the maximum conversion efficiency. A comparison of the performance characteristics of this generator with those of a generator of rectangular cross section is presented. The average gas temperature and velocity, the magnetic flux density at the poles, and the volume displacement rate, etc., are assumed identical for the two cases in comparison. It is inferred that the novel channel analyzed herein is, in general, superior to the simple rectangular channel in the energy conversion scheme.Nomenclature a _n - 2a width of the rectangular channel - a _1n , a _2n , b _1n , b _2n constants - B magnetic flux density, both induced and applied - B _r0 maximum value of radial component of B at r=r _i - B ₀ applied magnetic field in the rectangular generator = B _r0 - 2b height of the rectangular channel - C _n r _i r _o ⁿ +r _o r _i ⁿ - C _–n r _i r _o ⁿ +r _o r _i ^–n - c integration constant - D _n - E electric field strength - maximum value of azimuthal component of E at r=r _i - G _n C _–n r _n +C _n r ^– _n - G _–n C _–n r _n –C _n r ^– _n - H _n G _n r ^–1 - H _–n G _–n r ^–1 - I _r total radial current between a pair of opposite electrodes - j electric current density - p pressure of the ionized gas - P number of magnetic poles in each cylinder of the generator - P _HT power loss due to heat transfer to the walls - P _i power input - P _o power output - R _ic internal impedance of the coaxial channel MHD generator consisting of an opposite pair of electrodes associated with the magnetic poles, insulators, and the channel in between, for a unit length of the channel - R _ir internal impedance of the rectangular generator for a unit length of the channel = a/b - R ₀ external load connected to the MHD generator - r radial coordinate of the cylindrical coordinate system - r _i, r _o radii of the inner and outer cylinders, respectively - V fluid velocity - z axial coordinate of the cylindrical coordinate system - _n nP/2 - azimuthal coordinate of the cylindrical coordinate system - _e electrode angular width - _pi pole-insulator angular width - electrical conductivity of the ionized gas - permeability of the medium - _v coefficient of viscosity - (r, ) electric potential - (r _i, )–(r _o, ) potential difference between an opposite pair of electrodes - conversion efficiency of a MHD generator A paper based on some of this material was presented at the International Electron Devices Meeting, Washington (D.C.) October 1967.     

爆炸式电磁感应脉冲发生器

为了探索脉冲发生器新的技术方法,在传统脉冲发生器的基础上,提出了一种依靠爆炸驱动的电磁感应脉冲发生器。介绍了发生器的工作过程,对发生器中炸药的爆炸和冲击过程进行了计算和数值模拟,建立了带有初始电压和初始静磁场的发生器的工作电路模型,得出了感应电压的计算方法。设计了一种通过永磁体提供初始静磁场的脉冲发生器,并分别对装有两种不同炸药的发生器进行了实验。实验表明:爆速较高的炸药驱动发生器可产生峰值更高的电压脉冲。实验结果偏低于计算结果,原因是理论计算中简化了磁芯磁场和冲击波速度。     

A simple piezoelectric droplet generator

 A design for a piezoelectric on-demand droplet generator is presented. Its simple construction and ease of operation distinguish this generator from others previously reported. The droplet generator has been successfully used to produce droplets of aqueous solutions with very high dissolved salt loadings and is currently used to study droplet import and evaporation on a heated surface. Received: 19 February 1997/Accepted: 22 July 1997     

Theory of the hydromagnetic generator

It is shown that in a homogeneous medium, a magnetic field may generate helical motion in a cylinder with constant angular and axial velocities. The generation problem is solved exactly, and analytic expressions for the magnetic field are found. At high velocities the increment of field growth is maximal when the ratio of the velocities is of the order of unity. The maximum increment and frequency are of the order of the velocity to the two-thirds power. The field distribution has the form of a surface wave. The field decay decrement for departure from the cylinder surface is proportional to the square root of its increment.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 47–51, November–December, 1973.     

A versatile 150 kV neutron generator

Summary A 150 kV accelerator has been built, intended chiefly for neutron production, with a special mounting which makes it very easy and convenient to handle. The considerations leading to the ultimate design are reported. Details are given of the construction of the main apparatus, the safety system, the cooling system, and the deuterium supply for the ion source. We further report some investigations concerning targets suitable for the D-D-reaction and some other measurements which have been made with the apparatus.     

Integrity of VVER steam generator tubes

The eddy-current inspection is applied to Vitkovice to non-destructive testing of the steam generator tubes. The steam generator tube specimens, 16 mm by 1.5 mm, are made of AISI 321 steel with stress corrosion cracks. They were tested by the single-frequency eddy current inspection method. Samples with known flaws were metallographically sectioned to determine the actual extent of corrosion degradation. The relation between measurement of the tube wall corrosion damage and actual extent of corrosion attack or stress corrosion cracking (SCC) was determined.Pressurized specimens with machined notches of various geometries were tested up to failure. The effect of flaw depth and length on the burst pressure were evaluated.     

An electromagnetic,plane stress-wave generator

This paper describes a unique device that has been developed for the transient loading of models along straight and curved boundaries and that operates by discharge of a high-energy, high-voltage capacitor bank. In its present configuration, this device can generate uniform pressures from 1500 psi (10 MPa) to pressures that approach 100,000 psi (690 MPa) and that rise from zero to maximum pressure in 2 μs and decay to approximately zero in another 2 μs. The transient stress-wave patterns in photoelastic models loaded with this device have been recorded by a dynamic polariscope. The dynamic polariscope presently in use is identical to a static polariscope except that the light source is of a short enough duration (½ μs) to photographically stop the movement of the photoelastic-fringe patterns caused by the stress wave. With the stress-wave generator and the dynamic polariscope, transient photoelastic patterns have been recorded in a number of models. These patterns indicate that the scatter from duplicate shots performed with this technique is on the order of 3 percent. This represents considerable improvement over the 15-percent scatter normally experienced with sheet-explosive loading techniques. This improvement and the rapid turnaround between shots (approximately 5 min) are distinct advantages this system has over other methods of dynamic loading.     

Optimum synthesis of spatial function generator mechanisms

In this study a numerical method for optimum synthesis of spatial function generator four-bar linkages is presented. The key features of the method are: the embedding of the assembly criterion and of the transmission ratio in the penalty function; the non-derivative minimization procedure; the parametric variation of the first-guess mechanism. The effectiveness of the method is illustrated by means of examples of optimum design. In some examples articulated mechanisms, which can replace cam systems in automatic machinery, are synthesized.

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Sommario In questo studio si presenta un metodo per la sintesi ottimale di quadrilateri articolati spaziali generatori di funzione. Le principali caratteristiche del metodo proposto sono: l'inclusione del criterio di assemblabilità e dell'angolo di pressione nella funzione penalità; l'utilizzazione di un algoritmo di minimizzazione non derivativo; la variazione parametrica del meccanismo di primo tentativo. L'efficacia del metodo è messa in luce tramite una serie di esempi di progetto ottimale; in alcuni di essi sono stati sintetizzati dei quadrilateri spaziali in grado di sostituire i sistemi a camma spaziale nelle macchine automatiche.