Hydrodynamic calculation of wedge-shaped system «slider-guide» operating on compressible lubricant in presence of melt on surface of guide

In the article on the basis of the equation of motion of the compressible lubricant for the «thin layer», continuity, state, and the equation describing the profile of the molten contour taking into account the formula of mechanical energy dissipation the asymptotic and self-similar solution is found for the extreme (when the speed tends to infinity) and non-extreme case. As a result of solving the problem, a refined mathematical calculation model of a wedgeshaped sliding support with a low-melting metal coating on a movable contact surface is obtained, which compensates for an emergency lack of lubricant and provides a stable hydrodynamic lubrication mode

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

Design for Flexible Connector of Multi-Floating Structure

For the connector between the modules of a regular hexagonal multi-floating structure, it designed a flexible connector based on hinge joints and spin joints, which allowed part of rolling, pitching and torsion between adjacent modules to release bending moment and strain. A 221m multi-floating structure hydrodynamic calculation model was modeled in this paper. Firstly, the connector loads under the regular waves were calculated by ANSYS Aqwa. Secondly, structural model of a flexible connector was built by SolidWorks basing on the finite element theory. It analyzed structural strength of the flexible connectors under different load conditions of a series of wave direction angles by ANSYS Static Structral. Lastly, the results show that the design of the multi-floating structure connectors met the design requirements in different working conditions.

Comparative Hydrodynamic Analysis by Using Two−Dimensional Models and Application to a New Bridge

This document develops a methodology that evaluates the impact on the environment of the rivers produced by the creation of civil infrastructures. The methodology is based on the two-dimensional hydrodynamic calculation by using shallow water equations both in the conditions prior to the creation of the infrastructure, and in the new conditions after the infrastructure is created. Subsequently, several characteristics, such as water depth and velocity, among others, are compared between the initial and final conditions, and a two-dimensional zoning of the changes observed is obtained. The methodology herein presented is useful to verify the impact that the implantation of different infrastructures around the river currents could produce. In addition, it is also relevant for carrying out a study taking into account different infrastructure options related to river currents, as well as for selecting the most suitable one. By using the methodology presented, changes on the regime of the currents caused by the infrastructures can be deduced, including a qualitative and quantitative zoning of the changes, with a special emphasis on some characteristics, such as depth and velocity. The methodology is applied in a case study for the creation of a road bridge over the Jalon River in Spain.

Development of hydrodynamic calculation method for selective water intake process in the reservoir with continuous density stratification along the entire depth

Разработан гидродинамический метод расчета селективного водозаборного процесса в водоеме с непрерывной по всей глубине плотностной стратификацией. В качестве математической модели водозаборного процесса использована краевая задача линейной теории поверхностных гравитационных волн малой амплитуды в идеальной несжимаемой и неоднородной жидкости. Получена совокупность расчетных формул, которая позволяет решить задачу водоснабжения промышленных предприятий, в том числе тепловых и атомных электростанций, из водоемов с непрерывной плотностной стратификацией. Предлагаемый метод расчета позволяет определить скорость водозабора через окно и высоту водозаборного окна, которые обеспечивают надлежащее положение поверхности раздела, соответствующее заданной плотности (температуры) забираемой воды. The purpose of this work is to develop the hydrodynamic calculation method for selective water-intake process applied to the problem of water supply to industrial enterprises, including thermal and atomic power stations using the reservoirs with the continuous density stratification. In the method of solving the problem, the variation of density along the depth is approximated by an exponential function. The water is taken through a window arranged on the side of the water body. The boundary value problem for the linear theory of surface gravity waves of small amplitude in an ideal incompressible and inhomogeneous fluid is used as a mathematical model of the water intake process. As a result, a set of calculation formulas has been obtained that allows solving the problem of water supply to industrial enterprises, including thermal and nuclear power stations, from water bodies with a continuous density stratification along the depth. Computational experiments have been performed, the results of which are given in the form of graphs of the dependence of the thickness of the bottom layer of water sucking the window on the density Froude number and on the height of the water intake window. The following conclusions are made on the basis of the comparison of the developed hydrodynamic calculation method compared with the existing hydraulic method: 1. In the existing hydraulic method of calculation, only the law of the dependence of the thickness of the suction ground layer of water on the density Froude number is described, however the nature of its dependence on the height of the water intake window is not established. 2. In the hydrodynamic calculation method of selective water-intake process developed in the article, the law of the dependence of the sucking through the window water ground layer thickness both on the density Froude number and on the height of waterintake window is established. 3. In connection with the aforementioned deficiency of the hydraulic calculation method, in reservoirs characterized by a continuous density stratification in depth, calculations and design of selective water intake devices should be carried out according to the hydrodynamic method developed in the article.