scholarly journals Determining the features of oscillations in prestressed pipelines

2021 ◽  
Vol 6 (7 (114)) ◽  
Author(s):  
Ulanbator Suleimenov ◽  
Nurlan Zhangabay ◽  
Akmaral Utelbayeva ◽  
Mohamad Nasir Mohamad Ibrahim ◽  
Arman Moldagaliyev ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Material Consumption ◽  
Dynamic Stresses ◽  
Study Results ◽  
Experimental Parameters ◽  
Winding Wire ◽  
Pipeline Wall ◽  
Pipeline Model ◽  
Oscillation Decrement ◽  
Stress Parameters

This paper considers the structural solution for a main above-ground pipeline with a pre-stressed winding, which makes it possible to improve the efficiency of operation and reduce material consumption. The results from studying experimentally the features in the operation of prestressed pipelines under static operating loads are given. It is shown that the radial movements of the wall of a pre-stressed pipeline are constrained by the strained winding, which prevents its deformation. It was revealed that increasing the tension force of the winding wire reduces circular stresses in the pipeline wall by 1.3...1.6 times and increases meridional ones by 1.2...1.4 times. The experimental study into the models of prestressed pipelines with free vertical and horizontal oscillations has established the dependence of frequency characteristics on the operating conditions and pre-stress parameters. It was found that the envelope amplitude on the oscillogram of free attenuated oscillations takes the shape of an exponent, which indicates the damping effect of the pre-stress. Analysis of the change in the dynamic characteristics of the models depending on the pre-stress force has revealed that the frequencies of free oscillations increase by 1.5÷1.6 times while the oscillation decrement decreases by 1.2÷1.25 times. This paper reports the results of studying the influence of pre-stress parameters on the stressed-strained state of the pipeline model under forced horizontal and vertical oscillations. It is shown that the diagrams of circular dynamic stresses and deformations in the models of a prestressed pipeline are smoother compared to similar characteristics of a conventional pipeline tested at the same experimental parameters. The study results have made it possible to quantify the features in the operation of a pre-stressed pipeline under static and dynamic influences, taking into consideration the pre-stress parameters and operating conditions.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals A Numerical Investigation into the PAT Hydrodynamic Response to Impeller Rotational Speed Variation

2021 ◽  
Vol 13 (14) ◽  
pp. 7998
Author(s):  
Maxime Binama ◽  
Kan Kan ◽  
Hui-Xiang Chen ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Distribution Systems ◽  
Water Distribution ◽  
Production Efficiency ◽  
Operating Conditions ◽  
Energy Regulation ◽  
Speed Increase ◽  
Energy Field ◽  
Long Run ◽  
Study Results

The utilization of pump as turbines (PATs) within water distribution systems for energy regulation and hydroelectricity generation purposes has increasingly attracted the energy field players’ attention. However, its power production efficiency still faces difficulties due to PAT’s lack of flow control ability in such dynamic systems. This has eventually led to the introduction of the so-called “variable operating strategy” or VOS, where the impeller rotational speed may be controlled to satisfy the system-required flow conditions. Taking from these grounds, this study numerically investigates PAT eventual flow structures formation mechanism, especially when subjected to varying impeller rotational speed. CFD-backed numerical simulations were conducted on PAT flow under four operating conditions (1.00 QBEP, 0.82 QBEP, 0.74 QBEP, and 0.55 QBEP), considering five impeller rotational speeds (110 rpm, 130 rpm, 150 rpm, 170 rpm, and 190 rpm). Study results have shown that both PAT’s flow and pressure fields deteriorate with the machine influx decrease, where the impeller rotational speed increase is found to alleviate PAT pressure pulsation levels under high-flow operating conditions, while it worsens them under part-load conditions. This study’s results add value to a thorough understanding of PAT flow dynamics, which, in a long run, contributes to the solution of the so-far existent technical issues.

scholarly journals A Review of the Flow-Induced Noise Study for Centrifugal Pumps

2020 ◽  
Vol 10 (3) ◽  
pp. 1022 ◽  
Author(s):  
Chang Guo ◽  
Ming Gao ◽  
Suoying He
Keyword(s):  
Optimization Design ◽  
Sound Field ◽  
Operating Conditions ◽  
Response Analysis ◽  
Centrifugal Pumps ◽  
Noise Optimization ◽  
Operating Stability ◽  
Study Results ◽  
Flow Induced Noise ◽  
Negative Impacts

Flow-induced noise is a significant concern for the design and operation of centrifugal pumps. The negative impacts of flow-induced noise on operating stability, human health and the environment have been shown in many cases. This paper presents a comprehensive review of the flow-induced noise study for centrifugal pumps to synthesize the current study status. First, the generation mechanism and propagation route of flow-induced noise are discussed. Then, three kinds of study methodologies, including the theoretical study of hydrodynamic noise, numerical simulation and experimental measurement study, are summarized. Subsequently, the application of the three study methodologies to the analysis of the distribution characteristics of flow-induced noise is analyzed from aspects of the noise source identification and comparison, the frequency response analysis, the directivity characteristics of sound field and the noise changing characteristics under various operating conditions. After that, the analysis of the noise optimization design of centrifugal pumps is summarized. Finally, based on previous study results, this paper puts forward the unsolved problems and implications for future study. In conclusion, the information collected in this review paper could guide further study of the flow-induced noise of centrifugal pumps.

Investigation of Volatile Reducing Substances as an Indicator of Decomposition for Raw and Processed Foods

1969 ◽  
Vol 52 (6) ◽  
pp. 1135-1141
Author(s):  
Barbara R Moorhouse ◽  
Harold Salwin
Keyword(s):  
Freeze Drying ◽  
Aeration Rate ◽  
Operating Conditions ◽  
Processed Foods ◽  
Reference Solution ◽  
Empirical Procedure ◽  
Freeze Dried ◽  
Experimental Parameters ◽  
Raw Foods ◽  
Reducing Substances

Abstract Volatile reducing substances (VRS) in foods were determined by an empirical procedure in which volatiles are stripped by aeration from an aqueous extract of a sample, passed through alkaline potassium permanganate, and measured by the extent of permanganate reduction. Experimental parameters were investigated as a step toward developing a standardized procedure. Dilute methanol was investigated as a reference solution, the equipment described in published procedures was simplified, and some operating conditions were controlled. The amount of permanganate reduction increased with length of aeration, but variations in aeration rate from 1360 to 1790 ml/min were not critical. The method was applied to ground beef, shrimp, and peaches. The raw food materials were stored at ice or refrigeration temperatures until they reached a decomposed state. Samples withdrawn at intervals during storage were processed and preserved by freezing or by freeze-drying. The content of VRS in raw samples increased as the foods decomposed. The VRS were partly lost during cooking and completely lost during freeze-drying. Therefore, the VRS content appears to have promise as an index of decomposition for a variety of raw foods and possibly for some cooked foods, but not for foods that have been freeze-dried.

scholarly journals Multi-objective optimization of an industrial styrene reactor using Harmony Search Algorithm

2013 ◽  
pp. 190-196
Author(s):  
Saurabh Shukla ◽  
Ankit Anand
Keyword(s):  
Search Algorithm ◽  
Harmony Search ◽  
Harmony Search Algorithm ◽  
Operating Conditions ◽  
Multi Objective Optimization ◽  
Industrial Practice ◽  
Multi Objective ◽  
Decision Variables ◽  
Optimization Study ◽  
Study Results

Multi-objective optimization of industrial styrene reactor is done using Harmony Search algorithm. Harmony search algorithm is a recently developed meta-heuristic algorithm which is inspired by musical improvisation process aimed towards obtaining the best harmony. Three objective functions – productivity, selectivity and yield are optimized to get best combination of decision variables for styrene reactor. All possible cases of single and multi-objective optimization have been considered. Pareto optimal sets are obtained as a result of the optimization study. Results reveal that optimized solution using harmony search algorithm gives better operating conditions than industrial practice.

scholarly journals Effect of Dynamic Stress on Heavy Duty Centrifugal Pump Assembly through Fluid Structure Interaction.

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1655-1659
Keyword(s):  
Centrifugal Pump ◽  
Dynamic Stress ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Water Current ◽  
Fluid Structure Interactions ◽  
Heavy Duty ◽  
Dynamic Stresses ◽  
Fluid Structure ◽  
Pump Assembly

The objective of the project is to reduce the vibration and fatigue in rotor of the centrifugal pump based on fluid structure interactions, when it rotates by the momentum of water current at different flow rate and to arrive at optimum operating conditions and perform structural analysis to determine deflection and frequency by using ANSYS 16.2.dynamic stresses are predicted at various nodal position, this would lead to suggest the method to reduce the frequency due to vibration.Computational fluid dynamics (CFD) study using Ansys 16.2 has been carried out to accomplish the objective of the work.

scholarly journals Application of Mineral Compounds for a High-Voltage Portable Grounding System: An Experimental Study

Electronics ◽  
2021 ◽  
Vol 10 (16) ◽  
pp. 2043
Author(s):  
Rizwan Ahmad ◽  
Mahmoud Kassas ◽  
Chokri B. Ahmed ◽  
Faisal Khan ◽  
Sikandar Khan ◽  
...  
Keyword(s):  
Power System ◽  
Research Work ◽  
Xrd Analysis ◽  
Electric Power System ◽  
Operating Conditions ◽  
Element Analysis ◽  
Lightning Strikes ◽  
Grounding System ◽  
Ground Resistance ◽  
Study Results

Electrical grounding is an indispensable part of the power system network. The grounding system is mainly affected by grounding resistance and the nature of the soil. High ground resistance produces the phenomenon of soil ionization, surface arching, and back flashover. A conventional grounding system requires the deep digging of electrodes, thus creating maintenance difficulties. This research work focuses on the safe operation of an electric power system from external and internal impulses arising due to lightning strikes or short circuits. The study proposes an application of mineral samples as grounding materials, and bentonite is used as backfilling material in portable grounding systems. A detailed experimental analysis was conducted under controlled conditions to evaluate the performance of selected materials in high-resistance soil. The problem of a deeply driven electrode is addressed by designing the portable grounding system. The study results demonstrate that the proposed portable grounding system could be installed in troubled environments such as forests, deserts, and rocky terrains. To measure the breakdown voltages of the proposed samples, X-ray Diffraction (XRD) analysis and other laboratory tests were conducted. The electric field intensities are extracted through Finite Element Analysis (FEA). The experimental and simulation findings show the expected performance of mineral samples under various operating conditions. The findings of this study can guide the practitioners for safe and efficient operations of portable electrical grounding systems.

scholarly journals MEASURING TEMPERATURE OF THE MEDIUM OF SHIP COMPRESSOR PIPING USING TEMPERATURE OF THE OUTER WALL

2018 ◽  
pp. 81-86
Author(s):  
Alexander Evgenyevich Semenov ◽  
Sergey Anatolyevich Putilin
Keyword(s):  
Heat Transfer ◽  
Theoretical Data ◽  
Outer Wall ◽  
Operating Conditions ◽  
Measured Temperature ◽  
Medium Temperature ◽  
Factors Affecting ◽  
Operating Modes ◽  
Piping Systems ◽  
Pipeline Wall

To determine the temperature of the medium in the ship's piping systems there are used readings of contact thermometers, pyrometers and thermal scans which measure the temperature of the pipeline rather accurately. Aside from corrections for accuracy of the measurement of the wall temperature, it is necessary to move towards measuring temperature of the medium. Readings of the temperature of the pipeline wall differ from the readings of the medium temperature inside the pipeline, so it is necessary to calculate and find the temperature of the medium in the pipeline. After solving a system of equations describing the phenomenon of heat transfer through the cylindrical surface, there has been worked out the technique of measuring temperature of the pipeline medium, according to the measured temperature of the pipe wall. The conditions of heat transfer can vary for different pipelines and media. The paper gives calculated temperature corrections for different operating conditions of the pipeline. To carry out calculations, a computer program has been written in the Mathcad mathematical package. Temperature corrections have been calculated to determine the medium temperature inside the pipeline using the temperature value of the outer wall of the pipeline. There has been carried out analysis of various factors affecting temperature changes: heat transfer to the air, heat transfer of medium inside the pipeline, wall thickness and contamination. Verification of theoretical data has been made on a ship of the compressor unit. The experiment confirmed the possibility of measuring temperature of the medium inside the pipeline, according to the temperature of pipeline surface using the developed corrections. Devices measuring the temperature of the pipeline walls can be used as additional measurement to enhance informativeness of testing results, analysis of operating modes, and improve the operation reliability of ship piping systems

scholarly journals Decomposition of Technological Processes for Evaluating the Performance of Production Line for Pre Sowing Treatment of Seeds

2018 ◽  
Vol 12 (3) ◽  
pp. 22-27 ◽  
Author(s):  
E. I. Kubeyev ◽  
B. S. Antropov
Keyword(s):  
Crop Production ◽  
Crop Yields ◽  
Positive Impact ◽  
Effective Means ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Validity And Reliability ◽  
Early Maturity ◽  
Technological Processes ◽  
Study Results

An important step in improving the efficiency of crop production is the development of scientifically valid technologies and technical means of pre­sowing preparation and treatment of seeds. Among the various methods that have a positive impact on crop growth, early maturity and resistance to adverse conditions, one of the most promising is seed pelleting. (Research purpose) The reasonability of the use of pelleted seeds (dragees) was shown the shell composition of which includes the substances necessary for active growth and increase resistance to adverse effects, and, in addition, it provides a more accurate seeding. We substantiate the need for improvements to existing technologies and agricultural equipment (for example, seed pelleting machine). due to the significant lack of high­tech means of mechanization of seed pre­sowing preparation at domestic agricultural enterprises. (Materials and methods) Experimental studies have been carried out with the use of computer mathematical modeling. Results of experiments were processed by methods of mathematical statistics, statistical analysis and data processing package, research application package, filtering, analysis and modeling of technological processes. Physical and mechanical properties and quality indicators of seeds and fillers have been determined in accordance with the applicable state standards. (Results and discussion) Use has been made of a program that includes obtaining information about the processes to solve the problems of experimental studies carried out by machines for pre­-sowing treatment of seeds in accordance with the developed models of their functioning; the choice of the most effective means of measuring, recording and processing information about the operation of machines and equipment in normal operating conditions; as well as checking the effectiveness of the developed methods and tools to ensure the quality of the process in case of accidental disturbances. (Conclusions) The authors have studied main parameters and operating modes of a seed pelleting installation. An average values of the process parameters of the pre­sowing treatment of seeds have been calculated under the conditions of normal functioning of machinery and equipment taking into account the validity and reliability of the obtained characteristics. The authors have developed the technological fundamentals of the artificial coating of seed surface. The study results can be used as practical recommendations for the organization of pre­sowing treatment of seeds in order to increase seed germination and crop yields.

Analysis of Freeway Traffic Incident Conditions by Using Second-Order Spatiotemporal Traffic Performance Measures

2005 ◽  
Vol 1925 (1) ◽  
pp. 20-28 ◽  
Author(s):  
Sherif Ishak ◽  
Ciprian Alecsandru
Keyword(s):  
Performance Measures ◽  
Second Order ◽  
Operating Conditions ◽  
Data Sets ◽  
Freeway Traffic ◽  
Contour Maps ◽  
Traffic Conditions ◽  
Statistical Measures ◽  
Study Results ◽  
Texture Characterization

The characteristics of preincident, postincident, and nonincident traffic conditions on freeways are investigated. The characteristics are defined by second-order statistical measures derived from spatiotemporal speed contour maps. Four performance measures are used to quantify properties such as smoothness, homogeneity, and randomness in traffic conditions in a manner similar to texture characterization of digital images. With real-world incident and traffic data sets, statistical analysis was conducted to seek distinctive characteristics of three groups of traffic operating conditions: preincident, postincident, and nonincident. The study results showed that the spatiotemporal characteristics of each of the three groups were not discernible. Although the distributions of performance measures within each group are statistically different, no consistent pattern was detected to imply that certain characteristics could increase the likelihood of incidents or identify precursory conditions to incidents.

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