Method Of Hydraulic Calculation Research Articles

질량유량 기반의 스프링클러헤드 수별 급수관 구경 선정방법에 관한 연구

The purpose of this study is that there are two methods for designing firefighting piping: the hydraulic calculation method and the conventional piping method. In the field, the conventional piping method according to the ‘Fire Safety Performance Standards for Sprinkler Equipment’ [Appendix 1] is preferred. There is no mention of the basis and physical meaning of the number of heads for each water supply pipe diameter in the conventional piping method, and the types of pipes that can be used have also increased. Since there was no confirmation as to whether it was appropriate to calculate the number of heads according to [Appendix 1] for each type of pipe, an attempt was made to establish a basis through comparison of regulations in each country and hydrodynamic calculations.
 The research method was to confirm the basis of the ‘Fire Safety Performance Standards for Sprinkler Equipment’ [Appendix 1] through analysis of relevant standards in the US, UK, and Korea. Based on the flow rate in the pipe, the mass flow rate-based head and the number of pipe heads were calculated and compared. As for the type of pipe, KS D 3507, which is the most commonly used, was used as a standard, and KS D 5301 and 3595 pipes were compared to determine whether the number of heads was appropriate. In addition, in order to check the limits of branch piping based on the flow speed limit of branch piping (6 ㎧) and the flow speed limit of other piping (10 ㎧), 25A (25 Su), 32A (30 Su), 40A (40 Su), we checked for changes by increasing the number of branch pipes to 50A (50 Su).
 Through this study, it was confirmed that the basis for the method for calculating water supply pipe diameter by number of sprinkler heads is in NFPA 13. Based on the pipe flow rate, the number of heads was calculated by comparing the head number based on mass flow rate for the head and pipe. Using KS D 3507 as the calculation standard in [Appendix 1], it was confirmed that KS D 5301 and 3595 pipes can be sufficiently used as a result of comparative comparison considering the degree of irradiation. In addition, as a result of increasing the number of branch pipes, it was determined that it was appropriate to use branch pipes up to 40A, and it was confirmed that there was no change as the number of branch pipes increased.
 Through comparison of the standards and the number of heads based on mass flow rate, the basis of ‘Fire Safety Performance Standards for Sprinkler Equipment’ [Appendix 1] was confirmed, and it was confirmed that all KS D 3507, 5301, and 3595 are applicable. In the case of KS D 3595, there are 60 Su and 75 Su as names corresponding to 65A, so it was judged that flexibility in design could be achieved.

An adaptive double-Newton-iteration hydraulic calculation method for optimal operation of the meshed district heating network

An adaptive double-Newton-iteration hydraulic calculation method for optimal operation of the meshed district heating network

Hydraulic characteristics of sewer pipelines with internal deposits

This article focusses on the review of formulas for the hydraulic calculation of gravity drainage networks with internal deposits. In the existing practice of calculating gravity flow networks, there are methods of hydraulic calculation only for new pipes. At the same time, on the walls of pipelines, under certain conditions, layers of deposits with different structure can be formed, which affect the values of hydraulic characteristics of the system. The aim of the work is to identify the calculation dependencies for pipelines with deposits in gravity drainage networks. Hypotheses and formulas for the pipeline calculation, as well as the existing provisions of regulatory documentation in the field of wastewater disposal are used. Calculation dependences for pipelines with deposits are revealed, and the concept of reduced diameter of pipes is introduced. The directions of further study of influence of thickness of a layer of deposits in a flume part of pipes on values of their hydraulic characteristics and necessity of development of tables for hydraulic calculation of pipes of gravity drainage networks with internal deposits are allocated.

Обоснование методов гидравлических расчетов оросительных каналов

Purpose: justification of the applicability of various methods of hydraulic calculations of irrigation canals of land reclamation systems. It is recommended to use five types of hydraulic tasks allowing determining the following main parameters of irrigation canals for each type: conveying capacity (first type), canal slope (second type), roughness coefficient (third type), water flow depth (fourth type), cross-section dimensions of the irrigation canal (fifth type). Materials and methods. The well-known classical methods and dependences of N. N. Pavlovsky, B. A. Bakhmetev, R. R. Chugaev, A. A. Agroskin, Shezi and other scientists were taken as a basis during the research. Results. Methods for determining the main hydraulic characteristics of irrigation canals, including: canal discharge and slope and roughness coefficient are considered. These methods allow making calculations by the selection and graphical methods. The fifth type of problems is a series of independent solutions, where the effective width also calculated graphically is used. An analysis of the calculation results shows that for problems of the first type, the Chezy coefficients and hydraulic discharge decrease with an increase in the channel roughness coefficient values. Based on the calculated data obtained, canal discharge change chart depending on the roughness coefficient of the channel was constructed. Conclusions. The conditions for application of various methods of hydraulic calculation of irrigation canals were determined based on the results of the research. The values of the roughness coefficients of irrigation canals in impervious lining – concrete monolithic and reinforced concrete from prefabricated slabs are given. Summary calculation results for six different examples are presented.

Simulation of the lift of two sequentially installed gates of the Karkidon reservoir

The article considers the condition for the deflection of the gates of the water supply systems of the Karkidon reservoir, due to the turbulent current. The method of hydraulic calculation of conduits, locks with two successively installed gates is presented. The conditions providing satisfactory hydraulic conditions behind the gates of water galleries are investigated, with the aim of ensuring the safe operation of hydro systems of reservoirs. As you know, as a result, closing the upper gate on the lower gate II creates additional resistance. This is a resistance that gradually decreases as it opens. The pressure is divided between both gates, and the hydraulic regime behind each of them is improved compared to the regime with one gate with the same pressure. Analytical formulas are given that determine the value of the pressure behind the first gate and the condition for the equality of pressures behind both gates. The methods proposed by a number of theoretical and experimental works of other authors, as practice shows, are not very effective, the main shortcomings of these works were identified: an increase in the length of the gate section, since the gates must be located at a considerable distance from each other; high requirements for the control system of the gates, since when the stroke of the gates deviates from the selected mode, the pressure is redistributed between them, and the hydraulic conditions behind one of them deteriorate sharply. Therefore, our proposed simulation of the rise of two successively installed gates of the Karkidon reservoir is practical.

ОБ АКТУАЛЬНОСТИ РАЗРАБОТКИ СПРАВОЧНЫХ ПОСОБИЙ ПО ГИДРАВЛИЧЕСКОМУ РАСЧЕТУ ИЗНОШЕННЫХ ИНЖЕНЕРНЫХ СЕТЕЙ ГОРОДСКОЙ ИНФРАСТРУКТУРЫ

When designing and reconstructing engineering networks of urban infrastructure, design organizations use a set of classical formulas for hydraulic calculation of pipelines. They don’t take into account changes in hydraulic potential during operation, and it leads to significant errors. This justifies the need to develop and refine reference manuals for hydraulic calculation of worn-out metal water supply, sewerage and heating networks of urban infrastructure. A specific example graphically demonstrates the influence of the thickness of the layer of internal deposits on the accuracy of the hydraulic calculation of pipes, i.e. on the determination of the parameters of their hydraulic potential. Based on the proposed methods of hydraulic calculation of pipes, we proved the relevance of revise the special reference manuals with taking into account actual changes in the values of hydraulic characteristics of metal pipelines in the process of their operation, in particular, the value of the coefficient of hydraulic efficiency of the pipeline.

Analysis results of data obtained in natural field research in mountain river Sokhsoy

Forecasting and preventing silting of hydraulic structures, irrigation canals, and reservoirs, as well as improving methods for maintaining their throughput, is particularly important. In this regard, special attention is paid to research work aimed at improving hydraulic calculation methods, taking into account the variability of channel factors in the design and construction of hydraulic structures planned for construction. This article analyzes the factors influencing the occurrence of the deformation process in the channels based on the information obtained in the natural field conditions.

An Adaptive Double-Newton-Iteration Hydraulic Calculation Method for Optimal Operation of the Meshed District Heating Network

An Adaptive Double-Newton-Iteration Hydraulic Calculation Method for Optimal Operation of the Meshed District Heating Network

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.

Experimental and computational study of a low-pressure natural circulation loop

The experimental and analytical study of single-phase flow and heat transfer in natural circulation loop has been carried out. Experiments were performed on water and ethanol that are the liquids with significantly different thermophysical properties. Experimental apparatus was a rectangular shaped loop with vertical flow up leg. The flow up and flow down legs of the loop are joined to the separator-condenser at the top of the loop. The upper limit of heat flux densities in the experiments was set with the consideration for flow regime to remain in single phase state along the whole heated length. Wall temperature time records being registered at different distances from the inlet to the heated zone indicate the occurrence of temperature fluctuations near the exit from heated zone even at relatively low heat flux densities. This fact displaces a complex changing of velocity profiles along the tube with vortex formation and occurrence of flow instability. Experimental data on longitudinal wall temperature distributions of heated section have been used to test a modified method of hydraulic calculation of the loop. It was pointed out that in spite of long year (since early 1950s) experimental, analytical and numerical investigations of natural circulation loops no suitable predicting recommendations for heat transfer and friction have been proposed till today for engineering hydraulic calculations of single-phase natural circulation loops.

Hydraulics of the subcritical Ventury channels

The purpose of the research is to develop and verify the method of hydraulic calculation of the Venturi channel in the flooded outflow mode. The criterion that separates the flooded and free flow regimes is the ratio of the flow depth in the throat of the Venturi channel hm to the critical depth hc exceeding one (hm/hc > 1). The article theoretically and experimentally substantiates a method for determining the flow rate in a flooded Venturi canal using two control cross-sections, one of which is in the upper basin of the canal, the other in its throat. The differential equation for an uneven flow in a non-prismatic channel was obtained in the form (13). The analysis showed that in a flooded Venturi channel with a subcritical flow at Froude numbers less than one (Fr <1), the denominator of equation (13) is always greater than zero; therefore, at the entrance to the channel in the region of constriction, when db/dl < 0, the depth is downstream decreases (dh/dl < 0), and in the lower diffuser, where db/dl > 0, the flow depth increases (dh/dl > 0). Thus, the curve of the flow surface has a dip in the throat of the flooded Venturi channel. Integration of differential equation (13) made it possible to obtain the function of changing the Froude numbers in the flow along the length of the flooded Venturi channel (16), and then, using relations (17), to determine the depths and flow velocities. The verification showed that the calculated data are in good agreement with the experimental ones. The deviations between calculation and experiment do not exceed ±3%. This makes it possible to recommend the outlined methods for application in engineering practice.

Development and Verification of Multiphysical Coupling Calculation Code for Typical Pressured Water Reactor Core

Abstract Strong feedback phenomenon between the reactor physical and thermal-hydraulic has an important impact on the design and safety analysis of pressured water reactor (PWR). In order to accurately simulate the strong coupling effect of hydraulic in PWR, a reactor multiphysical coupling calculation code is developed, in which the three-dimensional (3D) space–time neutron dynamic equation is solved by the nodal expansion method (NEM) and nodal green's function method (NGFM); the coolant temperature and fuel temperature are solved by single channel model and the cylinder heat conduction model, respectively. The 3D light water reactor (LWR) benchmark and the Nuclear Energy Agency Committee on Reactor Physics (NEACRP) PWR rod ejection benchmark are used to verify the neutronics model and coupling calculation solution ability, respectively. The results show that: (1) the NEM and NGFM have high accuracy in solving the 3D space–time neutron dynamics equation; (2) the results of neutronics and thermal-hydraulic coupling steady/transient calculation such as core normalized power and fuel Doppler temperature are in good agreement with those of the NEACRP PWR benchmark, and the calculation accuracy is equivalent to similar software. Four coupled reactor physics and thermal hydraulic calculation modes are used to analyze the influence of different reactor physics calculation methods and thermal hydraulic calculation methods on the key parameters of PWR transient process in this paper. The results show that the mode of NGFM + finite volume method (FVM) can more accurately simulate the reactor core normalized power peak and fuel Doppler temperature.

Distributed-Framework Basin Modeling System: Ⅲ. Hydraulic Modeling System

A distributed-framework basin modeling system (DFBMS) was developed to simulate the runoff generation and movement on a basin scale. This study is part of a series of papers on DFBMS that focuses on the hydraulic calculation methods in runoff concentration on underlying surfaces and flow movement in river networks and lakes. This paper introduces the distributed-framework river modeling system (DF-RMS) that is a professional modeling system for hydraulic modeling. The DF-RMS contains different hydrological feature units (HFUs) to simulate the runoff movement through a system of rivers, storage units, lakes, and hydraulic structures. The river network simulations were categorized into different types, including one-dimensional river branch, dendritic river network, loop river network, and intersecting river network. The DF-RMS was applied to the middle and downstream portions of the Huai River Plain in China using different HFUs for river networks and lakes. The simulation results showed great consistency with the observed data, which proves that DF-RMS is a reliable system to simulate the flow movement in river networks and lakes.

ОСОБЕННОСТИ РАСПРЕДЕЛЕНИЯ ПОТОКОВ ЖИДКОСТИ В ПЛАСТИНЧАТЫХ ТЕПЛООБМЕННИКАХ

The relevance of the work of information and diagnostic systems in the field of monitoring of plate heat exchange equipment is considered. The reliability of the monitoring devices requires an accurate mathematical description of the thermo hydrodynamic processes in the heat exchange channels. The classical description of these processes implies a uniform distribution of the flow rate of the working medium along the length of the plate package, which in turn implies equal conditions for the formation of salt deposition products on the heating surfaces of the plate heat exchanger. The use of dependencies that take into account the equality of costs for a package of plates reduces the reliability of diagnostics of the efficiency of hot water devices of the plate type. Since the geometric space formed by the plates is represented by parallel channels connected by sections of transit collectors, the method of resistance characteristics is proposed as a method of hydraulic calculation of the distribution features of liquid flows through heat exchange channels. The dependence of the design features of the location of the interplate channels relative to the input of the coolant into the distribution manifold is revealed. It is found that, the flow rate of the circulating coolant is less in the channels most remote from the inlet pipe than in the nearest channels. The hypothesis of the influence of the relative position of the channels in relation to the inlet pipe is confirmed by numerical studies of the hydrodynamic regime of the plate heat exchanger.

ОСОБЕННОСТИ ГИДРАВЛИЧЕСКИХ И ФИЛЬТРАЦИОННЫХ РАСЧЕТОВ ОСУШИТЕЛЬНО-ОРОСИТЕЛЬНОЙ СИСТЕМЫ

Calculations of the main characteristics of the conducting network of the drainage and irrigation system are given. The method of hydraulic calculation of the conducting network of the trapezoidal cross-section to be reconstructed is presented. The following data are taken as the initial data: the depth of the flow, the area of the live section, the wetted perimeter, the slope of the channel bed, the roughness coefficient. In this case, the roughness coefficient should be specified according to the reference data, taking into account the state of the riverbed. The following channel parameters are subject to calculation: hydraulic radius, Shezi coefficient, average flow rate and water flow rate. Based on the results of the calculations, average flow rates and water consumption are given in a tabular form, and graphs of the dependencies are constructed. The method for determining water losses from main channels in the earth bed includes the determination of the weighted average filtration coefficient of the ground base according to surveys (drilled wells), the calculation of free filtration, and then taking into account the close occurrence of UGV at a depth of 0.3-2.5 m, the propped filtration is determined according to SP 100.13330.2016 and the efficiency of the channels is calculated. Based on the results of hydraulic calculations of the main channels of the drainage and irrigation system, the main hydraulic characteristics for the main channel of the MC are obtained at the roughness coefficients for the morphostore 1 n = 0.030 and for morphostore 2 n = 0.040. For the main channel MC2, the characteristics are obtained at n = 0.040 and n = 0.030, which differ significantly from each other. For the main channel MC2, the characteristics are obtained at n = 0.040 and n = 0.030. For the main drainage collector of the gas turbine engine, the results of the hydraulic parameters are given at n = 0.040, n = 0.055 morphostvora 4. According to the results of filtration calculations, the values of fi ltration losses from the main channels were obtained for propped filtration, when the UGV is in the range of 0.3-2.5 m, the efficiency of the main channel was h = 0.971 ìê , what exceeds the standard value for the joint venture 100.13330.2016 – h = 0.90 íîð . The summary results of filtration calculations are presented.

Achieving reliability and energy savings in operate of pumping stations

Hydromechanical equipment of pumping stations of irrigation systems, including the main equipment of pumping stations of the Amu-Bukhara machine channel, was taken as the object of research. The study aims to assess the operating conditions of pumping stations and improve the main units' reliability by developing new units that ensure reliable and resource-saving operations. An important consequence of using new elements of irrigation systems during reconstruction is an increase in the unit capacity of regulated pumping units, which gives additional energy savings and reduces technological costs by 15-20%. The practical significance of the research results is based on the developed methods of hydraulic calculation of the flow in the flow section of the pumps, the assessment of reliability during operation under various conditions of the quality of the pumped water, and the criteria of its state.

Technology of water supply to water inlets of pumping stations

The aim of the research is to increase the efficiency of pumping stations operation by improving the methods of uniform spreading of the flow from the front chamber and the water intake of the pumping station and the development of constructive measures to improve the hydraulic conditions of the flow supply to the pumps. This goal is achieved by the fact that the device for supplying water to the water intake contains guiding elements. The improvement of the method of hydraulic calculation of the flow in the front chamber and the water intake chamber is carried out on the example of the head pumping station of the Jizzakh cascade. In the process of research, standard methods of full-scale and bench tests of pumps, methods of mathematical and hydraulic modeling, statistical processing of results and the creation of mathematical models based on the laws of hydromechanics were used.The project substantiates the choice of a technical solution to improve the hydraulic structure of the flow in front of the impeller of the pumps of the Jizzakh head pumping station. The authors have developed new technical solutions, including an element for influencing the flow, installed in the water intake chamber of the pumps. This makes it possible to expand the ranges of stable, cavitation-free operation of the pump, to ensure an increase in the reliability of water supply to the pumping station, without resorting to complex and expensive reconstruction measures.

Results of hydraulic tests of the ACO Qmax system pipeline

Polymer corrugated pipelines are a very promising type of construction that has many advantages over concrete and reinforced concrete structures that are widely used today for collecting and diverting surface runoff from residential areas and enterprise sites. To collect and divert surface runoff from residential areas and enterprise sites, the hydraulic characteristics of the drainage system made of corrugated polymer culverts of ACO Qmax are studied by computational and experimental methods. The experiments were carried out in the laboratory of Hydraulics and hydro-mechanics at different flow rates and different slopes. The kinematic and dynamic characteristics of the water flow in the pipeline were determined: the velocity, the roughness coefficient, and the hydraulic resistance coefficient were measured at different values of the pipeline filling. It is found that the characteristics of the water flow obtained by the computational method using a computer program differ from the experimental values, the reason for which, apparently, in the shortcomings of the computational program and the lack of accuracy of experimental measurements. Experimental studies were conducted to adjust the calculation methods of such pipelines used in the design and verification of hydraulic calculation methods of corrugated pipelines based on the software product ACO Qmax.

Hydraulic resistances of derivation channels of hydropower facilities

Currently, many authors have studied the uniform axisymmetric pressure head laminar and turbulent movement of water in hydraulic smooth and rough (with uniform roughness) pipes of circular cross-section. The results obtained in the study of a plane-parallel turbulent flow in pressure channels allow here only to outline the structure of the corresponding dependencies and to clarify the simplest case of unpressurized fluid movement, when this movement can also be reduced to plane-parallel or, in other words, to movement in channel of infinitely large width with a flat bottom. In all other cases, the only way to solve the problem is experiment. But the possibilities of the experiment are limited, as are limited, and in a number of cases debatable, and the information accumulated to date on the uniform free-flow motion of fluid in channels of various cross-sectional shapes. The unpressurized uniform movement of fluid in channels of various cross-sectional shapes has been completely insufficiently studied. The construction of numerous free-flow watercourses, as well as machine channels of pumping stations, requires scientifically based calculation methods. For the correct establishment of hydraulic calculation methods, a sufficiently deep study of the physical essence of the phenomena occurring in the free-flow derivation channels is necessary. The extensive construction of numerous free-flow watercourses, as well as hydroelectric power plant (HPP) derivation channels, requires scientifically based calculation methods. For the correct establishment of hydraulic calculation methods, a sufficiently deep study of the physical essence of the hydraulic phenomena occurring in the free-flow derivation channels of HPPs is necessary.

POROUS CONSTRUCTIONS OF WATER INTAKE STRUCTURES

Abstract. Water intake is an essential element of the water supply complex, normal operation of which depends on the quality of the water delivered to the consumer. Therefore, the water supply system should be effectively protected from various contaminants from the source, ice slurries, and juvenile fish. The authors analyze the operation of existing coarse screen devices in channel water intakes; identify their main disadvantages, such as: mechanical jamming (clogging) of the screen holes with debris, leading to its failure and the need to replace, as well as the laborious cleaning and the high cost of screen materials. The article notes that during operation there is an increase in the pressure drop affecting the screen due to the accumulation of a large amount of contaminants on its surface, which could lead to a throughput and a significant amount of pollution. To improve the quality of filtered water and operating conditions, the authors proposed to provide porous pipes installation instead of flat removable screens in the receiving section of the intake well. The material for their manufacture is a polymer concrete, based on crushed granite stones or gravel and a polymer binder – epoxy resin. The article shows the scheme of intake well pipes installation, describes the principle of the proposed design, shows a graph obtained as a result of hydraulic calculation. This design has a number of advantages over flat screens: automation of flushing, less clogging, greater throughput, lack of biofouling, high strength characteristics, low hydraulic resistance and durability. A porous polymer concrete-based structure, which is a pipe system that increases the reliability of water intakes, improves the quality of the water taken from the source and the conditions of operation, has been proposed. The method of hydraulic calculation of porous pipes makes it possible to optimize their design parameters, to determine the diameter and pressure loss in them, which is very important when designing water intakes. The aim of further research is to study the dynamics and degree of porous devices clogging by suspension at different concentrations in natural water.