Search

The study analyzes the influence exerted by the body, guide and their materials on the pull strength of electromagnets in electromagnetic hammers. The pull strengths of electromagnets without positive and negative poles are evaluated.

Advancement of wave action stimulation and cross-well seismic imaging in mineral mining governs the need for downhole sources of elastic vibrations. The presented periodic electromagnetic seismic source is equipped with a mechanical–hydraulic drive for fixturing in a hole and for impulse transition to rock, and an electromagnetic impactor for pressure pulse generation. This article presents the experimental studies into the operation of the seismic source of three structural layouts. The features of the operation are discussed. The supply voltage dependences of the main parameters of the seismic source are obtained, and the practical application recommendations are formulated.

The article presents a case-study of mathematical modeling of electromagnetic and electromechanical processes in a downhole vibration exciter EM drive. The authors propose the mathematical model of EM drive on the basis of a double-acting EM machine. This model maintains a wide-range analysis of transient and quasi-stable operating regimes. The algorithm and implementation of the model using the structural modeling methods and means in the Matlab Simulink environment are described. The model verification is carried out by means of comparison of the simulation and physical models of EM drive within the configuration of downhole pulse vibration exciter. The appropriateness of the model is proved. The authors give recommendations on further improvement of the model and its accuracy in calculation of dynamic behavior of drives.

The experimental research of processes running in a linear pulse electromagnetic motor of a downhole vibration generator is described. Based on the research findings, design requirements and recommendations on basic geometrical proportions of the equipment are formulated.

The researchers analyze energy processes running in an autonomous electric power system consisting of a synchronous permanent magnet generator and a semiconductor converter. Current, voltage and capacity of key components of the system are evaluated, and the system operation modes are determined for the variable magnitude and character of applied load at the constant voltage output frequency. Parametrical law is proposed to control semiconductor frequency converter serially connected to load and generating reactive power. The influence of the converter on the basic design parameters, energy specifications of the synchronous generator and the system as a whole are evaluated.

Aimed at improving efficiency of non-explosive vibroseis method, the new concept of using a solenoid impact actuator enables essential increase in useful mechanical work with the limited external diameter. The results of the finite element modeling of magnetic field are reported. The authors have found the force and energy characteristics of the actuator and the prospects for its application in a casing with the external diameter limited to 120 mm.

Under consideration is feasibility of voltage stabilization in permanent-magnet synchronous generator with variable frequency in self-contained systems of power supply. The method of stabilization is based on varying speed of rotation of generator shaft. The authors have derived analytical expression for regulating characteristics and determined required ranges for rotational frequency variation at preset parameters of generator and loading. The symmetry conditions are found for a regulating characteristic relative to rotational speed change.

The authors propose a calculation procedure for electromagnetic processes running in converters with clamp diodes based on the numerical simulation and method of switching functions. The procedure is specific for the capacity to calculate basic indices of energy efficiency of semiconductor converters in various work modes. Moreover, the procedure is universal in terms of number of voltage levels and number of phases. Owing to modern computation techniques, the time and labor inputs in the calculation is greatly reduced. The proposed procedure has been experimentally tested.

The article analyzes processes running in an oil pool under contour water flooding and resulting in formation of bypassed oil. Based on stability criteria, the authors discuss destabilization of the residual oil pockets by vibration so that the bypassed oil becomes proved & developed.

The paper proposes the analysis of three design and control scenarios for the system intendeded to generate the variable-frequency and constant-voltage electric energy on the basis of a synchronous generator and a paralleled semiconductor converter. The research scientists demonstrate the stabilization of the synchronous generator voltage, evaluation of basic electrical parameters, and the relationship between them and operation modes of the system.

The processes in the system composed of a continuous magnet synchronous generator and a three-phase bridge back emf rectifier are under analysis in this article. Such systems are usable in self-contained facilities to charge accumulation cells in mines and open pits. The authors determine possible regimes of the systems under varying rate speeds of synchronous generator shaft and altered commutation delay angles of the controlled rectifier, derive analytical expressions for determining parameters of the analyzed system, and find generated power limit.

The paper explains a number of phenomena that are observed in the surface vibrational treatment of oil and gas reservoirs based on the thriving theory of pendulum waves, e.g., a ring-shape response of a productive stratum and a time lag in the response, seismic luminescence and its spectrum, etc. The authors give data on velocity groups of pendulum waves in stressed block hierarchy of rock masses and substantiate the choice of the wave velocity group to be generated by the powerful surface vibro-sources designed at the Institute of Mining. The theoretical and phenomenological formulas given in the paper are of assistance in the development and improvement of the surface vibrational technologies for the enhancement of oil and gas recovery.

It is established experimentally that, in block geomedia, under conditions of sustained (months) uniaxial loading, the normal tension cracks can appear and develop under the action of stresses which are less than the ultimate strength in uniaxial compression of the corresponding geomaterial samples by an order. The features distinguished in the experiment on failure of one-dimensional block model of geomedium are compared with the results of visual and instrumental observations of failure character of the ore masses of the Talnakh-Oktyabrsky deposit.

Development of construction principles and creation of automated systems for physical modeling of the block geomedium behavior in the varying unequally component stress field are considered currently as one of the strategic problems in nonlinear geomechanics. The scheme of stand for physical modeling and measuring-computational equipment oriented to the solution for fundamental problems of geomechanics are presented.

The results are presented for physical modeling, which make it possible to answer a question whether there are any bases for the hypothesis (proposed by M. V. Kurlenya and V. N. Oparin) that at the prefailure stages, the focus zones of rock bursts, earthquakes, and other dynamic events become similar to a peculiar “geomechanical laser system,” i. e., an acoustically active medium capable of coherent seismic-energy radiation. In this context, possible consistency of the acoustic signals formed in structural elements of block media, in terms of both the frequency spectrum and the phase component, is a key issue. In existing approaches to the analysis of the mechanisms of focus zones of dynamic rock-pressure manifestation, as a rule, the fact that quasi-static processes of elastic energy accumulation in the forming focus zones always proceed against an acoustic background (from natural microseisms to complex wave phenomena accompanying pulsed seismic effects from remote earthquakes, explosions, etc.) is ignored. In view of the anomalously low friction in block media (discovered at the Institute of Mining, Siberian Branch, Russian Academy of Sciences), the type of the stress-strain state in geoblocks and the amplitude-period characteristics of the “seismic background” may be decisive in the realization of dynamic event. Therefore, it is natural to ask what happens, for example, to microseisms or acoustic wave packets, that are regular in frequency, in the focus zones of future dynamic events depending on the level of stresses prevailing there. Experimental data are considered for one of the most simple cases where the focus zone is modeled by a set of homogeneous blocks with a stress concentrator in the form of a cylindrical cavity (a “plane” model), while the quasi-static process of external loading is represented by uniaxial compression from a press with weak lateral thrust. The “acoustic background” is specified in a peripheral block of the model in a monochromatic regime. This model relates directly to the acoustic monitoring of the limiting states of rocks around underground workings. It is proved that the prefailure stages of model are characterized not only by convergence of the resonance frequencies in the block system but also by amplification of the harmonic-signal amplitude due to conversion of the stored elastic energy of the structural elements to energy of acoustic signals. The law of exponential decay of harmonic signals from a radiation source is violated here, and the model of the geomaterials becomes an acoustically active medium operating as a peculiar “geomechanical laser system.”