Calculation Of Pressure Losses Research Articles

Theoretical calculation and simulation analysis of hydraulic joint pressure loss based on fluid dynamics

To study the pressure loss in the runner during the rotating transmission of the hydraulic joint, the local pressure loss of the hydraulic joint is simplified, and the theoretical estimation method of the pressure loss of the hydraulic joint is proposed. Based on the finite element software Comsol, the numerical analysis of the hydraulic joint is carried out to study the effect of the regularity of different fluid inlet and outlet angles and the width of the annular runner on the pressure loss of the runner. The results show that the relative numerical simulation result error of the theoretical calculation of fluid pressure loss is within 20%, and the theoretical calculation method proposed in this paper can guide the rapid evaluation of slip ring pressure loss. The pressure loss of the slip ring increases at first and then decreases gradually with the increase of the fluid inlet and outlet angle. When the angle of the fluid inlet and outlet is 30, the pressure loss of the hydraulic joint is the largest. The pressure loss of the hydraulic joint gradually decreases with the increase of the width coefficient of the runner. When the width coefficient increases to a certain value, the pressure loss reduction effect of the runner is weakened, and the optimal runner width is 0.8-1.2 times the design width of the equal section.

IMPROVEMENT OF METHODS FOR CALCULATION OF GAS-LIQUID SLUG OF FLOW IN PIPELINES

To calculate pressure losses during transportation of gas-liquid fluids in flowlines, it is important to correctly estimate the effective density and viscosity of the mixture, which increases the accuracy of calculating the tangential stresses required to determine hydraulic pressure losses at the liquid-wall boundary. The determining parameter when calculating the effective values of the density and viscosity of the mixture is the coefficient liquid holdup in the cross section of the pipeline. The article analyzes the applicability of empirical methods for modeling two-phase gas-liquid currents when calculating liquid holdup in slug body of a intermittent (slug) flow in horizontal pipelines. A description is given of the mechanistic approach proposed by Zhang to calculate the liquid holdup in the slug body used in one of the most famous modern models of gas-liquid flow — TUFFP Unified model. The results of calculating the actual liquid holdup in the slug body using the TUFFP Unified model hydrodynamic model are presented, showing good consistency of the calculated data with experimental ones for vertically located pipelines, and unsatisfactory consistency for currents in horizontal pipes. The purpose of the article is to improve the methods of calculating the gas-liquid slug structure of the current using the TUFFP Unified model, by improving the accuracy of calculating the liquid holdup in the slug body at the horizontal location of the flowline. The proposal to use in the TUFFP Unified model a new approach to assessing the stable diameter of the gas bubble of the dispersed-bubble flow regime in the body of a liquid slug made it possible to increase the reliability of calculating the liquid holdup in the slug body with a horizontal location of the pipeline.

INCREASING THE GASLIFT EFFECTIVENESS BY ADJUSTING MULTIPHASE FLOW HYDRAULIC CHARACTERISTIC

Real media that are encountered in hydrocarbon production industry are normally represented by systems, comprised of at least two phases, of which one is dispersed and distributed in another. As it is known, production, gathering, preparation and transport of oil and natural gas are based on multiphase technology, comprised of lifting the hydrocarbons from the formation to the surface, transport to the separation facilities, separation and intrafield transport of multiphase mixtures, consisting of oil, natural gas, formation water and mechanical particles. This article strives to determine the optimal work regimes of production of gaslift systems based on the relations between production rates and gas pressure in cylindrical flows. Knowing the parameters of the well borehole as well as the parameters of the produced fluid and gas injection rates it is possible to determine the optimal flow regime as a derivative of a function of pressure losses versus production rates (ΔP/Q). This function is called the flow hydraulic characteristic, and it is this function, by optimizing which an optimal flow regime of the gaslift operated well can be achieved. Estimation the hydraulic characteristic relies heavily on calculation of pressure losses of the gaslift producing well. These losses consist of two independent factors: gravitational and frictional. Frictional pressure losses have linear dependence versus the flow rate, while gravitational losses exhibit an inverse, hyperbolic, correlation to changes in flow rate. To get the full picture of the pressure loss both aspects must be accurately calculated from the given field data. In order to do so, it is important to estimate real gas content of the multiphase flow, which is a complex function of direction and velocity of the multiphase flow, gas and liquid flow rates, gas slippage, etc. Once the pressure losses have been calculated it is comparatively simple to optimise the gas flow rate to adjust the hydraulic characteristic, guiding the gaslift production process towards optimal production rates. Keywords: Gaslift, multiphase flow, pressure losses, joint transport, gas content.

Experiment and numerical simulation of the performance on scaled compressor cascade and development of a prediction model

In this study, performance variations and predictions of scaled compressor cascades were investigated. A high-subsonic profile from a rotor section of a certain axial compressor was studied. Tests as well as two-dimensional (2D) and three-dimensional (3D) CFD simulations of cascades of different scale ratios were performed to obtain the flow data of 2D and 3D flow conditions. According to the results, a scaling criterion based on aspect ratio of cascade test for the full range of incidence angles was proposed. Test results shows that aspect ratio of 2.16 is sufficient only in the minimum loss condition for test to reflected the performance of the 2D profile. When the aspect ratio was larger than 4.32, the flow at the mid-span of the tests and 3D-CFD results had good two-dimensionality at the range of twice-minimum-loss incidence angles. The relative deviation of 2D and 3D performance was less than 5%. The total pressure loss and deviation angle increased after scaling down. These results were attributed to the change in the Reynolds number corresponding to the scale. Prediction models were proposed for the calculation of the total pressure loss and deviation angle of the original profiles using the results of the scaled profiles based on the boundary layer theory. The models mainly take into account the Reynolds number, and they are applicable for conditions in which the Reynolds number exceeds the critical Reynolds number.

Method for calculating pressure losses in the pipelines of slurry shield tunneling based on coupled simulation of computational fluid dynamics and discrete element method

AbstractHydraulic mucking/transport or slurry pipelining are widely used in dredging, trenching, (deep sea) mining, tunnel boring, and many other applications. Slurry pipelining during slurry shield tunneling is a classic instance of complex hydraulic mucking systems, which is characterized by the complex rheological behavior of the slurry and the inclusion of large and irregular particles. These characteristics make it difficult to estimate the pressure losses along slurry pipelines, compared to other hydraulic mucking systems. This study established a powerful method for predicting the pressure losses in long‐distance slurry pipelining of slurry shield tunneling based on computational fluid dynamics–discrete element method (CFD‐DEM)‐coupled simulations. Rheological tests were carried out to provide reliable slurry flow parameters for CFD calculations. Irregular pebbles with different sizes were digitally scanned using 3D scanning technology, and the scanned models were applied to the DEM. This method was successfully applied to a slurry shield tunnel project in Beijing, China. The mechanical properties of the fluid phase and particle phase were revealed by modeling a typical slurry pipeline. A comparison of the pressure losses along slurry pipelines was made between the proposed method and field data, indicating the validity of the established method. The simulation results indicate that when the slurry flows through the elbow, a secondary flow will be formed due to centrifugal force. Pebbles of different sizes show different motion responses under the combined action of gravity and slurry coupling force. The turbulent flow of particles will increase the frictional pressure losses in the elbow area, compared to the straight section. This work provides a valuable reference for the layout of the slurry circulation system of similar projects.

Flow Field and Pressure Loss Characteristics at Rotary Drillstring Joints

A thorough understanding and accurate calculation of the annulus pressure losses are paramount to drilling design and construction. However, due to the influence of the drillstring rotation and the abrupt dimensional variation at the joint, it is difficult to calculate the pressure loss by theoretical analysis in the annulus at the drillstring joints. Considering the geometric nonlinearity of drillstring joints and the unsteady flow of annular fluid caused by pipe rotation, based on the turbulence model k − ε , the flow field characteristics demonstrate the annulus pressure losses at the drillstring joint are studied by numerical simulation. Simulation results indicate that drillstring rotation speed, annular gap, and eccentricity greatly influence flow field and pressure losses at drillstring joints. The annular pressure loss would increase with the decrease of the annular gap and eccentricity but decrease with the increase of the drillstring rotation rate. The investigation method and results would help guide the design of drilling hydraulic parameters.

Pressure losses in apparatuses with swirling flows

We consider the method of calculating the pressure in apparatuses with swirling flows, depending on the different materials. The influence on the calculation of pressure losses in the two-phase swirling flows of various parameters for the organization of fuel combustion processes, mass and heat transfer, dust collection. Dependence of pressure drop on the amount of energy consumed and the choice of blowers for apparatuses with swirling flows. The causes of pressure drops in two-phase swirling flows are given and listed. The loss of gas kinetic energy in apparatuses with twisted and counter twisted flows of gas suspensions exceeds losses from all other causes, that only this loss should be taken into account. The peculiarities of design and pressure losses in vortex pressureless apparatuses are considered. The results of investigating the dependence of pressure losses in the apparatus on the air flow rate through the vortex chamber and the results of investigating the effect of the ratio of flow rates through the apparatus channels are presented.

Коррозионные отложения в системах подачи воды и их учет при калибровке моделей

The paper presents a comparison analysis of hydraulic calculations by various methods with actual measurements of pressure losses on an operating water main. There is identified equivalence of the compared methods for calculating pressure losses in operated metallic pipes. To ensure acceptable accuracy, it is crucial to select the calculated diameter and average roughness. During the period of over one year, there were carried out experiments on formation of corrosive deposits` layer on the surface of an unprotected steel pipe in low-flow conditions.

Energy-efficient vacuum evaporation units for concentration in the dairy industry

The application of various types of evaporation plants for concentration of solutions was analyzed. It was noted that the most promising for thickening dairy products are film-type vacuum-evaporation units with mechanical compression of secondary steam. The heating chamber of the evaporator is made in the form of a vertical shell-and-tube heat exchanger with the supply of heating steam into the intertube space and with the downward movement of product solutions in the vertical boiling tubes. Based on the analysis of known studies on hydrodynamics and heat exchange of film processes (condensation, film heating and evaporation and steam separation), a conclusion was made about the lack of data for calculating pressure losses in the steam circuit of the evaporator with sufficient accuracy. To solve this problem, improved methods of calculating the hydraulic resistance of the intertube steam path of the heating chamber and the two-phase flow of the product film and secondary steam in evaporative boiling tubes have been developed using the published results of hydrodynamic resistance research. Pressure losses for the movement of secondary steam in the lower chamber of the evaporator include losses for acceleration of the steam released from the falling film of the product. It is shown that the hydraulic depression of the movement of steam in the intertube space of the heating chamber, depending on the type of scheme, can be from 2.3% to 77% compared to the working temperature pressure of the heating surfaces. The four-way flow scheme of the heating steam used in the design of the vacuum-evaporation unit ensures a reduction of hydraulic losses by up to 15%. A technical and economic analysis of the costs of operating a vacuum-evaporation unit with a productivity of 10 t/h of vaporized steam was performed, according to which the lowest reduced costs were established at a temperature drop of 5˚C on the compressor. The results of the research were used in the development of structures and the manufacture of vacuum-evaporation units with mechanical and mixed (mechanical and thermal) compression at PrJSC "Kalyniv Machine-Building Plant" (Kalynivka, Vinnytsia Region). 10 vacuum evaporation units with a capacity of 5 to 20 t/h of evaporated moisture were manufactured and put into operation.

Selection of an Optimum Drilling Fluid Model to Enhance Mud Hydraulic System Using Neural Networks in Iraqi Oil Field

In drilling processes, the rheological properties pointed to the nature of the run-off and the composition of the drilling mud. Drilling mud performance can be assessed for solving the problems of the hole cleaning, fluid management, and hydraulics controls. The rheology factors are typically termed through the following parameters: Yield Point (Yp) and Plastic Viscosity (μp). The relation of (YP/ μp) is used for measuring of levelling for flow. High YP/ μp percentages are responsible for well cuttings transportation through laminar flow. The adequate values of (YP/ μp) are between 0 to 1 for the rheological models which used in drilling. This is what appeared in most of the models that were used in this study. The pressure loss is a gathering of numerous issues for example rheology of mud), flow regime and the well geometry. An artificial neural network (ANN) that used in this effort is an accurate or computational model stimulated by using JMP software. The aim of this study is to find out the effect of rheological models on the hydraulic system and to use the artificial neural network to simulate the parameters that were used as emotional parameters and then find an equation containing the parameters μp, Yp and P Yp/ μp to calculate the pressure losses in a hydraulic system. Data for 7 intermediate casing wells with 12.25" hole size and 95/8" intermediate casing size are taken from the southern Iraq field used for the above purpose. Then compare the result with common equations used to calculate pressure losses in a hydraulic system. Also, we calculate the optimum flow by the maximum impact force method and then offset in Equation obtained by (Joint Marketing Program) JMP software. Finally, the equation that was found to calculate pressure losses instead of using common hydraulic equations with long calculations gave very close results with less calculation.

Выбор геометрии выходного устройства газотурбинной установки с минималь- ными потерями давления

Object and purpose of research. This paper discusses gas turbine exit unit consisting of axial-radial diffusor and pockettype volute. The purpose of the study was to select the exit unit geometry that would offer minimum losses of total pressure. Subject matter and methods. Experimental results obtained for the models of gas turbine exit units. Calculation of total pressure losses in SolidWorks package with Flow simulation extension. Correction coefficients were obtained through regression analysis. The exit unit geometry offering minimum losses of total pressure was obtained using the theory of experiment planning. Main results. The study yielded correction coefficients to the calculation results obtained in SolidWorks package with Flow simulation extension. Exit unit geometry offering minimum losses of total pressure has been successfully found. The effect of strut location in the radial part of diffusor in terms of pressure losses has been quantified. Conclusion. This study enables early identification of exit unit geometry with minimum total pressure losses, so it is valuable for practical gas turbine design.

Effects of the water spray system on the air-driving force required in longitudinally ventilated road tunnels

In the presence of a water spray system, the fire-induced pressure losses in a road tunnel can change, but this effect is currently not considered in the design of longitudinally ventilated tunnels. In this study, theoretical analyses are combined with FDS modelling to investigate the pressure losses due to flow acceleration, stack effect and friction in tunnels that use a water mist or a deluge system. Analytical models for pressure loss calculations have been derived, which indicate the evaporation rate of the water sprays, the spray-induced flow resistances and the decay coefficient of the mean sectional temperature rise are the three key parameters required for the model. According to dimensional analyses, the spray-induced resistance is a function of the momentum ratio between the water spray and the air flow, and the evaporation rate is mainly determined by the fire size and the total mass flow rate of water sprays. Corresponding empirical correlations are proposed. Comparisons between analytical results and FDS simulations concluded the proposed correlations are reliable and can give accurate predictions.

CFD Modeling of Pressure Drop through an OCP Server for Data Center Applications

Modeling IT equipment is of critical importance for the simulations of flow and thermal structures in air cooled data centers. Turbulent flow undergoes a significant pressure drop through the server due to the energy losses originating from the internal components. Therefore, there is an urgent need to develop a fast and an accurate method for the calculation of pressure losses inside server components for data center applications. In this study, high resolution numerical simulations were performed on an OCP (Open Compute Project) server under various inlet flow rates for inactive and active conditions. Meanwhile, one key challenge of modeling complete geometry of the server results from using an intense mesh even for a single server. To address this challenge, the server was modeled as a porous zone to mimic inertia and viscous resistance in a realistic way. Comparison of the results of porous and complete models showed that the proposed model could calculate pressure drop accurately even when the number of cells in the server was reduced to 0.3% of the complete model. Porosity coefficients were determined from the numerical simulations conducted in a broad range of air discharge for both active and inactive conditions. Errors in the calculation of pressure drop may result in a significant deviation in the prediction of the temperature rise over the server. Thus, the present model can effectively be used for the fast and accurate prediction of pressure drop inside a server component rather than solving internal flow on an intense mesh, while simulating airflow inside an air-cooled data center, which is crucial for the design safety of data centers. Finally, calculated porosity coefficients can be used for the prediction of the pressure drop in a server, while designing data centers based on numerical simulations.

Методика и опыт первичного проектирования трансзвукового осевого компрессора

The article considers the basic principles underlying the program for the calculation and designing gas turbine engine axial compressors. Calculation of pressure losses and deflection ability of the cascades is based on the formulas of A. Komarov. The model involves empirical coefficients, the values of which were selected during program verification based on the results of testing multistage compressors and compressor stages. The basic equations and the algorithm for calculating pressures and velocities are given under the condition of radial balance. The application of computer programs based on these models in designing a gas turbine engine four-stage compressor of moderate power with a total pressure ratio of 3.2 and a given speed is shown. For the first compressor stage, two options with different flow rates are compared. The first option was designed according to the classic recommendation to get close to the same mechanical energy of the gas at the exit of the stage along the radius. The second option was designed for a lower flow coefficient, but ensuring the radial balance, requires introducing a significant non-uniformity of mechanical energy supply along the radius. Due to the lower kinetic energy, the stage efficiency of the second variant is 1.9 % higher, despite the fact that the loss coefficients of the blade cascades are lower in the first variant. The question remains as to how much the inevitable mixing losses in the second variant will reduce its efficiency in the process of equalizing the mechanical energy of the gas

The new method for hydraulic calculations of a district heating (DH) network

How to estimate the exact value of pressure losses within a district heating (DH) network been in service for decades, which a pump at pumping station should compensate to achieve maximum benefits and the lowest costs relative to the scenario of the started process of transition to 4th generation district heating (4GDH)? Geographic Information System (GIS) software Zulu© was used to model a DH network and evaluate how specific location will affect hot water flow rates. Pressure, roughness and hydraulic resistance profiles were plotted using hydraulic optimisation software ZuluThermo©– GIS Zulu© add-in. While the new arrangement does not reduce pressure losses themselves, the corrected arrangement provides economic advantage due to lower operation costs and more stable hydraulic profiles. That means that end sections of DH network between the transmission line and consumers become more effective. By calculating pressure loss and temperature degradation the method also allows to detect an optimum location to connect a new consumer where the minimum modernisation is needed. Working with data-driven network models makes it possible to obtain a lot of positive effects at the same time including the main - the DH utility sells more heat and becomes more profitable as the losses are lower. • To ensure low-temperature energy supply, its consumption for pumping is assessed. • Steady-state calculation method is used to evaluate pressure and flow distribution. • To verify, portable ultrasonic flow rate meter&traditional pressure sensors are used. • Electricity consumption is decreased by 394.74 kW, the saving effect is up to 6%. • Effect is achieved by lowering losses, clarifying friction factor&relative roughness.

Thermal-hydraulic stability investigations of once through helically coiled steam generators for SMR applications

Once-through steam generators with helically-coiled tubes (OTSG-HC) are susceptible to density wave instability phenomena. In order to investigate the stability performance of the CAREM-25 OTSG-HC, a new stability model is presented. Such a model being linear and strictly non-diffusive is able to represent arbitrary heat flux profiles, which is essential to study realistic cases. The OTSG-HC tubes are modeled by three different regions representing the liquid zone, the boiling zone, and the superheated vapor zone. Moreover, the coolant from the primary side is coupled with a model representing the phenomena present in CAREM-25. A convenient parameter space for stability representation is found and used to characterize the CAREM-25 OTSG-HC stability performance.In this work, special attention is paid to the calculation of the friction pressure losses in the coolant flowing through the helically coiled tubes. For this reason, a best estimate correlation is implemented and used in the model together with a sophisticated axial power profile model which allows representing realistic boundary conditions. As a result, it is confirmed the crucial importance of correctly representing the axial power profile transferred in the helically coiled tubes. In addition, it is found the commonly used uniform axial power profile leads to non-conservative stability predictions particularly at low power conditions. The latter is explained by the underestimation of the boiling and superheating lengths, which is proved to have a destabilizing effect.Stability maps are presented in terms of the transferred power and the primary coolant operational pressure, i.e. QSG-PPri plane. It is observed that when modeling realistic power profiles, the less stable operational condition of the OTSG-HC is found at very low powers, for all analyzed range of primary pressures. In addition, a weak stability dependence of the OTSG-HC with the pressure of the primary side is observed. Finally, the system is stabilized in the region of interest and its stability performance quantified.

Theory of the Vom Berg Rheological Model and Its Use in Cloud-Native Application

Various technological fluids, such as drilling muds, drill-in fluids, fracturing fluids, spacers, washes and cement slurries are used in the wellbore drilling process. The fundamental issue, which needs to be addressed in order to become acquainted with the phenomena occurring during fluids flow through a circulatory system, is to establish mutual dependencies between a stream of fluid being pumped and flow resistances. The awareness of these dependencies enables the optimisation of hydraulic parameters in order to minimise costs and maximise drilling works safety. This article presents rheological models of drilling fluids and proposes the application of a new rheological model, not used in the drilling industry so far, namely the Vom Berg model. The model has been presented in other publications; however, there is an unsolved and unpublished problem of determining the effect of rheological parameters of the model on the value of resistance to laminar and turbulent flow. In this article, algorithms and Cloud-Native application enabling numerical determination of rheological properties of the Vom Berg fluid are presented. What is more, an algorithm for calculating pressure losses during the laminar flow of fluid in a pipe is provided. Taking an example from the industry, a practical application of the proposed calculation methodology is presented.

Development of Prediction Models for Pressure Loss and Classification Efficiency in Classifiers

This paper presents the development of prediction models for pressure loss and classification efficiency in classifiers. Classifiers belong to one of the most important classification devices in gas particle processing and a fast and accurate determination of pressure loss and cut size is of great interest. The first model developed in this work allows the calculation of pressure loss as a function of geometric and operational parameters. It is based on a number of measured values that are obtained from previous numerical simulations (CFD). The maximum deviation of the model is less than 20% and the model operates in real time. However, the model requires calibration for each type of classifier. The second model for classification efficiency is based on a simplified two-dimensional approach in which the flow profile and particle trajectories are determined exclusively for the area between two classifier blades. The model is applicable for all geometrical and operational parameters and calculates the desired parameters within a few minutes, with a maximum error rate of 25%. In combination, the two models allow for the process optimization of classifiers in complete systems.

CFD modeling of turbulent flow for Non-Newtonian fluids in rough pipes

Non-Newtonian fluids are pumped under laminar and turbulent regimes through pipes in numerous industries. Proper calculation of pressure losses is essential to optimize available horsepower. In actual practice, no pipe surface is smooth. Pipe roughness has significant influence on the pressure loss for turbulent flow. In this study, a mechanistic model is developed to predict pressure losses of Herschel-Bulkley and Power-Law fluids in rough pipes for the turbulent flow regime. A numerical scheme is applied to the proposed model to obtain an approximate solution. The proposed model is separated into two sub-problems in order to obtain a numerical solution. One is solved analytically for the viscous sublayer, which is determined by pipe roughness and the other is solved numerically by the virtue of the central difference approximation along with the frozen non-linear term for the turbulent core region. Moreover, an experimental study is conducted using two different high viscous polymer base fluids with two different concentrations and three different rough pipe diameters. The mechanistic model results are compared with experimental data in this study and presented by Subramanian (1995). Absolute Average Percent Error (AAPE) of 13.3% is calculated for the proposed model compared to experimental measurements.

Гидравлический расчет трубопровода с учетом длин влияния местных сопротивлений и их интерференции

The design and calculation of pipelines taking into account the mutual influence of local resistances is an urgent task in the hydraulics of pressure flows. The analysis and results of the hydraulic calculation of the Valtec metal-polymer pipeline are given, taking into account the lengths of the influence of local resistances of their mutual influence (interference). Tabular data on the lengths of influence of local resistances, coefficients of mutual influence used in the developed program of the Delhi (Object Pascal) environment are given. A graph of the dependence of specific pressure losses per 1 meter of pipeline length on the flow rate for the Valtec pipeline with an equivalent roughness of Δe/ d = 0.007 mm, obtained experimentally and data for a similar pipeline according to the reference data tables with an equivalent roughness of Δe / d = 0.01 mm, is presented. The results of the calculations and the interface of the Delphi 7 environment application program with the data in a tabular form for the hydraulic calculation of the total pressure losses in pipelines are shown, taking into account reference and experimental values of coefficients of local resistances. The data of the results of the hydraulic calculation of the total head losses, taking into account the specifi c linear pressure loss per 1 meter of the pipeline length without local resistances, are given to determine the head losses by length. The developed program can be used in the design, layout and hydraulic calculation of metal-polymer pipelines with specifi ed parameters.