Влияние дискообразных непроводящих включений на электропроводность материала на постоянном токе

The influence of non-conductive disk-like inclusions (fractures) on the conductivity of a conducting medium in direct current is considered. To find the additional specific electrical resistance due to cracks, a self-consistent problem for the current density has been solved. In this case, a hydrodynamic analogy was used between the motion of an ideal incompressible fluid during potential flow around solids and electric current flowing around fractures. The functional dependences of the resulting relative additional specific electrical resistance of the material on the fracturing coefficient for thick and thin samples are found. A graphical visualization of these dependences shows that for a thick specimen, for all real values of the coefficient of fracturing, it is linear and is determined by the shape of the fractures. For a thin sample, the dependence of the relative additional the specific electrical resistance of the material on the fracturing coefficient is proportional to the thickness of the sample and is nonlinear. The obtained dependences of the additional electrical resistivity can be used, in particular, as a non-invasive method for determining the fracturing coefficient of rock samples conducting electric current.

Ways to improve the energy efficiency of shaft centrifugal pumps

The increase in the efficiency and competitiveness of mining enterprises is limited by the insufficient efficiency and adaptability of the currently used centrifugal pumps. Using the vortex theory of turbomachines, Theorems Stokes’ and Helmholtz, the principles of hydrodynamic analogy and superpositions, a mathematical model of the hydrodynamic calculation of centrifugal pumps with adaptive vortex sources integrated into the impeller blades is obtained. A significant influence on the hydrodynamic parameters and adaptability of pumps of the energy characteristics of adaptive vortex sources has been proved. Criteria for the similarity of the hydrodynamic process of fluid flow in the interscapular channels of impellers and adaptive vortex sources and their influence on the hydrodynamic characteristics of pumps are obtained. Mathematical and experimental modeling uses a regression equation to calculate the parameters of vortex chambers and their impact on the efficiency and adaptability of pumps. The optimal geometric parameters of the vortex chambers, the diameter of which does not exceed 5…7 % of the impeller diameter, increase the hydrodynamic loading by at least 13 %, the nominal efficiency. not less than 6 %, adaptability not less than 8 %. On the basis of the proposed developed mathematical model, after the positive test results obtained on the laboratory pump K 20/30, tests were carried out on the CNS 300-300 pump

Turbomachine criteria for similarity of natural size proportionality

Introduction. It is possible to give rise to synergy as a result of science-intensive industries combination with innovative eco-technologies for subsoil use only by developing a brand new approach to nature-like auxiliary technologies. Insufficient adaptability of turbomachines that ensure industrial safety increases the production cost of the mining and oil and gas complexes of the Russian Federation by more than 15%, reducing its competitiveness. Research methodology. Based on the hypothesis of the hydrodynamic analogy of the mechanisms of deceleration of the flow around the airfoil and the formation of its profile resistance, Karman's theory of attached and free vortices, the Zhukovsky-Chaplygin-Kutta hypothesis, the method of conformal transformations, the theory of similarity, the method of singular points by Chaplygin S. A., the criteria for the similarity of natural proportionality are obtained, that is, for the hydrodynamic similarity of the mechanism of energy interaction between the blades of the turbomachine impeller and the wing of a bird. Results. It has been proved that the dominant control over the nature-like proportionality of the aerodynamics of turbomachines is the ratio between the speed and flow acceleration circulation around the airfoil. It has been established that the coefficients of the airfoil resistance, lift and aerodynamic quality of the airfoil cascade are hydrodynamic analogs of the coefficients of the circulation of the velocity and acceleration of the flow and their ratio. Conclusions. It has been experimentally confirmed that the use of the proposed criterion of natural proportionality in the design of turbomachines increases their coefficient of aerodynamic adaptability by more than 2 times, increasing the area of economical operation by 83%.

A possible way of unification of the gravity (Newton) and electric (Coulomb) forces by using a hydrodynamic analogy

Although the gravity is the most important force acting on the Universe scale, on small scales the electrical interaction prevails. Indeed, the Coulomb force between two charged particles is very high as compared to the gravity force between the masses carrying electric charges. Therefore, a solution would be to connect the two forces by extending the hydrodynamic analogy successfully introduced in the author’s previous works. These papers provide a model for gravity, an important conclusion being the dependence of the gravity coefficient in Newton formula on the age of the Universe. Unlike mass-energy, the total electric charge in the Universe is null. Therefore, we must consider limited regions of the Universe (example: atoms, nuclei) to express Coulomb's strong forces. In the following we take into consideration that any electric charge (electrons, protons, quarks etc.) is carried by a mass. Unlike the gravity force which is modeled by hydrodynamic sources on a global scale, Coulomb’s force is modeled by an equivalent vortex mass on a local scale.