The problem of hydraulic calculation of pressure distribution pipelines

Most production technologies require a uniform flow path of liquid from pressure distribution pipelines. To achieve this goal, it is proposed to introduce polymer additives into the liquid flow or to use converging distribution pipelines with a continuous longitudinal slot in the wall. To reduce the uneven operation of the distribution pipeline during discrete liquid dispensing, it is proposed to use cylindrical output rotary nozzles with a lateral orthogonal entry of the jet into the nozzle. The problem is the lack of methods for accurate hydraulic calculation of the operation of distribution pipelines. Adequate calculation methods are based on differential equations. Finding the exact solution of the differential equation of fluid motion with variable path flow rate for perforated distribution pipelines is urgent, because it still does not exist. The available calculation methods take into account only the right angles of separation of the jets from the flow in the distribution pipeline. These methods are based on the assumption that the coefficient of hydraulic friction and the coefficient of resistance of the outlets are constant along the flow. A calculation method is proposed that takes into account the change in the values of these resistance coefficients along the distribution pipeline. The kinematic and physical characteristics of the flow outside the distribution pipeline are also taken into account. The accuracy of calculating the value of the flow rate of water distributed from the distribution pipeline has been experimentally verified. The error in calculating the water consumption by the method assuming that the values of the resistance coefficients are unchanged along the distribution pipeline reaches 18.75 %. According to the proposed calculation method, this error does not exceed 6.25 %. However, both methods are suitable for the design of pressure distribution pipelines, provided that the jet separation angles are straight. Taking into account the change from 90° to 360° of the angle of separation of the jets from the flow in the distribution pipeline will expand the scope and accuracy of calculation methods.

THERMOHYDRAULIC DISTRIBUTION IN TWISTED MICRO HEAT EXCHANGERS MOUNTED IN ANNULAR CHANNELS

The design of twisted heat exchangers provides a possibility to compensate for temperature and mechanical stresses thus ensuring continuous and failsafe operation of the equipment. The authors use fins and multiturn pipe bundles to reduce the mass and size characteristics of the heat exchangers. Such design significantly complicates the calculating method. The main aspect of swirling flows is the presence of radial and axial pressure gradients. When vapor or gas flows swirl, the flow velocity near the walls is much higher than the average values, while at the axis the flow is significantly slower and in some cases its values can become negative. The liquid flowing near the axis has a notably lower pressure, which can cause it to boil. Considerable radial gradients of axial and rotational speed, as well as static pressure contribute to turbulent pulsations. Given that the working fluid flows along a helical line, the flow in the near-wall area is similar to the flow around curved surfaces. The study analyses how the pipe bundle geometry impacts hydraulic distribution and scrutinizes the main components of pressure loss in the twisted heat exchanger. The analysis allowed simplifying the method of hydraulic calculation of the multiturn twisted heat exchanger. Solving the outer heat transfer and hydrodynamics problem for the twisted heat exchanger allowed determining the effect of the main factors and the relationship between the parameters of the coolant and the working mass on the distribution values. The paper presents the equations for determining geometry of the pipes with different coiling diameters, as well as the equation for finding hydraulic distribution in individual pipes in the layers of the pipe bundle. The obtained results can help increase the accuracy of thermal calculation. The authors propose to use sectioning of twisted heat exchangers as a way to reduce hydraulic distribution. Bibl. 12, Fig. 1.

TWO DIAMETERS METHOD FOR BINDING SITES IN HYDRAULIC CALCULATION OF PIPELINE SYSTEMS

The article is devoted to solving the urgent problem of increasing the efficiency of linking sections in the hydraulic calculation of pipeline systems to reduce the material and energy consumption of the system as a whole. The aim of the work is to create an effective method of hydraulic linking of sections of pipelines of microclimate support systems, namely the "two-diameter method" and the establishment of analytical calculations, provided that a meager percentage of the inconsistency of parallel sections. Graphical and analytical dependences on basis of conducted theoretical calculations are presented. Analytical calculation dependences have been established under the condition of achieving a negligible percentage of in consistency of parallel sections. An effective method of hydraulic and aerodynamic linking of parallel sections of pipeline systems has been developed, namely the "two-diameter method".

FEATURES OF THE HYDRAULIC CALCULATION OF HOUSEHOLD DRINKING WATER SUPPLY SYSTEMS OF APARTMENT BUILDINGS

The article is devoted to the practical implementation of changes in the current system of legal regulation in the fi eld of water supply and sanitation of apartment buildings. The results of the analysis of operational and design standards of water consumption are presented. The necessity of adjusting the normative and technical documents in terms of improving the methodological foundations of designing indoor cold and hot water supply systems for an apartment building and creating a legitimate methodological toolkit is shown. Recommendations have been developed to supplement the norms of the set of rules 30.13330.2016 “Internal water supply and sewerage systems of buildings. Updated edition of SNiP 2.04.01-85 *».

Hydraulic calculation of the fire extinguishing system of port facilities

Цель статьи – разработать алгоритм расчёта гидравлических характеристик системы пожаротушения для портовых сооружений. В системе пожаротушения имеется погружной насос, трубопроводы, предназначенные для транспортировки воды от места ее забора, до места возможного возгорания. Использован насос UGP-M-1210-04. Задачи исследования: анализ результатов испытаний; получение эмпирических зависимостей показателей работы насоса от его производительности, исследования работы насоса в сети. Проведены расчеты скорости истекающей струи и полной реактивной силы в рабочей точке насосной установки. Исследовано влияние скорости на реактивную силу. Анализ результатов показывает, что точность расчетов приемлема для инженерных расчетов. Полученный алгоритм расчета может быть использован при проектировании систем тушения пожаров в портовых сооружениях. The purpose of the article is to develop an algorithm for calculating the hydraulic characteristics of a fire extinguishing system for port facilities. The fire extinguishing system has a submersible pump, pipelines intended for transporting water from the place of its intake to the place of possible ignition. The UGP-M-1210-04 pump is used. Research objectives: analysis of test results; obtaining empirical dependencies of pump performance indicators on its performance, research of pump operation in the network. Calculations of the velocity of the expiring jet and the total reactive force at the working point of the pumping unit are carried out. The effect of velocity on the reactive force is investigated. Analysis of the results shows that the accuracy of calculations is acceptable for engineering calculations. The resulting calculation algorithm can be used in the design of fire extinguishing systems in port facilities.

Recommended dependence for hydraulic calculation of gravity drainage networks in order to improve the ecological well-being of cities

In the submitted article comparison of two calculated dependences - formulas of A. Chézyand and N.F. Fedorov used for the hydraulic calculation of gravity drainage networksare presented. For a specific example, dependence is revealed - the A. Chézy formula, which gives the highest accuracy when calculating the hydraulic slope of a gravity pipeline. The appearance of the A. Chézy formula has been clarified due to the introduction of the concept of the reduced inner diameter of the pipes. The graph of the dependence i=f (dred) is plotted, indicating that the refined form of the A. Chézy formula is more accurate. It is recommended to use the A. Chézy formula in a refined form for the hydraulic calculation of gravity drainage networks. It is proposed to develop calculation tables for the hydraulic calculation of drainage networks with internal deposits. The analysis of the calculated dependencies for the hydraulic calculation of gravity drainage networks with internal deposits presented in the paper allows recommending for practical use the formula of A. Chézy refined by the authors, according to which the authors propose to develop the Reference manual “Tables for the hydraulic calculation of gravity drainage networks with internal deposits”.

Development of mathematical models for calculating parameters during transportation of a steam-water mixture

В практике освоения геотермальных месторождений возникает необходимость нахождение взаимосвязи между параметрами потока. При транспортировке пароводяной смеси требуется определение условий, обеспечивающих стабильную работу трубопровода. На отечественных объектах геотермальной энергетики гидравлический расчет трубопроводов пароводяной смеси проводился с использованием компьютерной программы MODEL, разработанной авторами данной работы. Новые вызовы и появление теории устойчивости привели к созданию математической модели SWIP (Steam-Water Inclining Pipeline). В данной статье представлены этапы разработки авторами новой модели, отвечающей современным требованиям In the practice of developing geothermal fields, there is a need to find the dependence between the flow parameters. When transporting a steam-water mixture, it is necessary to determine the conditions that ensure the stability in the pipeline. At domestic geothermal energy, the hydraulic calculation of steam-water mixture pipelines was carried out using the computer program MODEL created by the authors of this work. New challenges and the emergence of the theory of stability led to the creation of a mathematical model SWIP (Stream-Water Inclining Pipeline). This article presents the stages of creating a new model by the authors that meets modern requirements.

Best practice of using air-bubble curtains as part of complex fish protection structures

Приведены результаты исследований работы комплексных рыбозащитных сооружений с использованием воздушно-пузырьковых завес. Дано описание механизма работы комплексных рыбозащитных сооружений и принципа работы воздушно-пузырьковой завесы. На основе гидравлического расчета разработана методика проектирования и применения воздушно-пузырьковой завесы в составе комплексных рыбозащитных сооружений. Приведены результаты исследований по оценке функциональной эффективности построенных комплексных рыбозащитных сооружений. Комплексные рыбозащитные сооружения, имеющие в своем составе запани и воздушно-пузырьковые завесы и работающие в эрлифтном режиме, достаточно эффективно защищают молодь рыб. При правильно подобранных параметрах работы оборудования и выбранном створе размещения сооружений, с учетом гидравлических и технических особенностей водозабора, их эффективность гарантированно превышает нормативные значения. The results of studying the operation of complex fish protection structures with the use of air-bubble curtains are presented. A description of the operating mechanism of complex fish protection structures and the principle of operation of the air-bubble curtain is given. On the basis of a hydraulic calculation, a method for designing and using an air-bubble curtain as part of complex fish protection structures has been developed. The results of estimating the functional efficiency of the built complex fish protection structures are presented. The complex fish protection structures that include debris deflectors and air-bubble curtains and operate in an air-lift mode, effectively protect fish fry. Provided the operating parameters of the equipment and the selected alignment of the structures with account of the hydraulic and technical features of the water intake have been correctly chosen, their efficiency is guaranteed to exceed the standard values.

Calculation and experimental analysis of heat transfer of assemblies of ribbed heat exchange elements

The results of thermal-hydraulic and strength tests of finned tube assemblies welded from KP 20 elements of four sizes are presented. The elements are representing by steel plate 0.4 mm in thickness, covered with a copper film 0.025 mm in thickness. One or two conical necks 17 mm long are extended in the plates. A set of placed in each other cones form a welded finned tube 23/20 mm with a toothed inner surface. As a result of the tests: high strength characteristics of these assemblies were demonstrated (internal pressure of burst under normal conditions is 40 MPa, resistance to sudden changes in temperature and freezing of water in “pipes”); a high average coefficient of thermal conductivity in the thickness of the ribs was confirmed at the level of 75 W/(m×K); the increase in the intensity of the heat transfer process is 2.15 times with the help of technological protrusions on the inner surface of the “pipe” to a turbulent single-phase flow in comparison with the calculated values for “smooth” pipes with a moderate increase in hydraulic resistance; the method of heat-hydraulic calculation of heat exchangers consisting of such “pipes” is proposed. The method is based on the ratios set out in the regulatory document “RD 24.035.05-89”. Thermal and hydraulic calculation of NPP heat exchanging equipment”, with amendments considering the high degree of finning of the tested “pipes” and the asymmetry of the edges of the ribs relative to the axis of the “pipes” bearing pressure, as well as the change in the value of the correction for the smallness of the tube bundle — we also identified areas of effective use of assemblies tested sizes of elements KP 20.