scholarly journals Study of efficiency of liquid steel homogenization with blowing through blocks of various designs

2018 ◽  
pp. 76-80
Author(s):  
L Molchanov ◽  
N Sheremeta ◽  
Y Synehin
Keyword(s):  
Rational Design ◽  
Gas Flow ◽  
Video Recording ◽  
Similarity Criteria ◽  
Practical Significance ◽  
Design Parameters ◽  
Production Cycle ◽  
Metal Bath ◽  
Metal Melt ◽  
Process Gases

At modern metallurgical plants, blowing of steel with process gases is an obligatory component of the production cycle. In this case, it is most difficult to organize the supply of stirring gas through the bottom of a metallurgical unit. In the practice of metallurgical production, blowing units of various designs (slotted, channel and with non-directional porosity) are used to inject process gases under such a scheme. Considering that the influence of the design of the bubbler of the bottom blowing unit on the efficiency of mass transfer in a metal bath has not been studied, the aim of this study was to determine the influence of the design of the blowing unit on the efficiency of homogenization of the metal melt. To achieve this goal, the method of physical water modelling was used, based on a modified π-theorem. In order to obtain adequate results, similarity numbers (homochromicity number, dimensionless volume flow number, linear simplex and density simplex) were defined to describe the process of fluid homogenization, and an experimental installation was built that allows video recording of experiments with high image quality. According to the simulation results, photographs were obtained illustrating the dynamics of changes in the level of liquid homogenization over time (assessed by the indicator redistribution rate in the bath volume) for blowing units of various designs and different gas flow rates. The scientific novelty of the conducted research is the determination of similarity criteria describing the process of homogenization of a metal melt when blowing with an inert gas. The practical significance lies in the proposed innovative design of the blowing unit, for which rational design parameters and necessary and sufficient for rapid homogenization parameters of the blowing were defined.

scholarly journals ANALYSIS OF THE EXISTING ROUTE NETWORK OF THE CITY OF MARHANETS

2021 ◽  
pp. 60
Author(s):  
O. OHAR ◽  
I. BERESTOV ◽  
S. BANTYUKOV ◽  
N. KRUHLOVA
Keyword(s):  
Rational Design ◽  
Assessment Method ◽  
Optimization Criterion ◽  
Practical Significance ◽  
Design Parameters ◽  
Technological Parameters ◽  
Railway Stations ◽  
Route Network ◽  
Technological Assessment ◽  
Technological Evaluation

Purpose. The purpose of the work is to determine the directions for improvement the methods of formation of structures of track development of railway stations and their technical and technological assessment. Method. To determine the areas for improvement the methods of forming structures of track development of railway stations and their technical and technological evaluation, it is necessary to analyze the known scientific approaches, identify their weaknesses and strengths. Based on the analysis of these approaches to develop generalized procedures for the formation of rational structures of track development and evaluation of technical and technological parameters of railway stations. To develop the first procedure, it is necessary to choose the optimization criterion. Results. The paper analyzes the known scientific approaches to the formation of structures of track development of railway stations and their technical and technological evaluation. As a result, it was determined that the most effective way to calculate the design parameters of railway stations is to use automated design procedures, effective ways to calculate technological parameters and evaluate design decisions is to use simulation methods. The generalized procedures of formation of rational designs of track development of railway stations and their technical and technological estimation are offered. Scientific and practical significance. Improved procedures for the formation of rational structures of track development of railway stations and their technical and technological evaluation, which in contrast to the existing ones are based on determining the costs of the railway station with the cumulative total for the calculation period or project life cycle. The implementation of rational design solutions will ensure the implementation of the specified size of train and shunting operations of railway stations with a sufficient reserve of capacity and minimum costs. In addition, the results of technical and technological assessment of track development structures can be the basis for adjusting certain requirements for the construction of station necks.

scholarly journals Geometric Design-based Dimensional Synthesis of a Novel Metamorphic Multi-fingered Hand with Maximal Workspace

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Wei An ◽  
Jun Wei ◽  
Xiaoyu Lu ◽  
Jian S. Dai ◽  
Yanzeng Li
Keyword(s):  
Geometric Design ◽  
Practical Significance ◽  
Design Parameters ◽  
Control Algorithms ◽  
Discretization Method ◽  
Dimensional Synthesis ◽  
Symmetrical Structure ◽  
Design And Optimization ◽  
Total Length

AbstractCurrent research on robotic dexterous hands mainly focuses on designing new finger and palm structures, as well as developing smarter control algorithms. Although the dimensional synthesis of dexterous hands with traditional rigid palms has been carried out, research on the dimensional synthesis of dexterous hands with metamorphic palms remains insufficient. This study investigated the dimensional synthesis of a palm of a novel metamorphic multi-fingered hand, and explored the geometric design for maximizing the precision manipulation workspace. Different indexes were used to value the workspace of the metamorphic hand, and the best proportions between the five links of the palm to obtain the optimal workspace of the metamorphic hand were explored. Based on the fixed total length of the palm member, four nondimensional design parameters that determine the size of the palm were introduced; through the discretization method, the influence of the four design parameters on the workspace of the metamorphic hand with full-actuated fingers and under-actuated fingers was analyzed. Based on the analysis of the metamorphic multi-fingered hand, the symmetrical structure of the palm was designed, resulting in the largest workspace of the multi-fingered hand, and proved that the metamorphic palm has a massive upgrade for the workspace of underactuated fingers. This research contributed to the dimensional synthesis of metamorphic dexterous hands, with practical significance for the design and optimization of novel metamorphic hands.

Robust Design Techniques for Evaluating Fuel Cell Thermal Performance

2006 ◽  
Author(s):  
Kenneth J. Kelly ◽  
Gregory C. Pacifico ◽  
Michael Penev ◽  
Andreas Vlahinos
Keyword(s):  
Fuel Cell ◽  
Heat Generation ◽  
Thermal Performance ◽  
Gas Flow ◽  
Internal Heat ◽  
Flow Path ◽  
Coolant Flow ◽  
Design Parameters ◽  
Fuel Cell Stack ◽  
Path Design

The National Renewable Energy Laboratory (NREL) and Plug Power Inc. have been working together to develop fuel cell modeling processes to rapidly assess critical design parameters and evaluate the effects of variation on performance. This paper describes a methodology for investigating key design parameters affecting the thermal performance of a high temperature, polybenzimidazole (PBI)-based fuel cell stack. Nonuniform temperature distributions within the fuel cell stack may cause degraded performance, induce thermo-mechanical stresses, and be a source of reduced stack durability. The three-dimensional (3-D) model developed for this project includes coupled thermal/flow finite element analysis (FEA) of a multi-cell stack integrated with an electrochemical model to determine internal heat generation rates. Sensitivity and optimization algorithms were used to examine the design and derive the best choice of the design parameters. Initial results showed how classic design-of-experiment (DOE) techniques integrated with the model were used to define a response surface and perform sensitivity studies on heat generation rates, fluid flow, bipolar plate channel geometry, fluid properties, and plate thermal material properties. Probabilistic design methods were used to assess the robustness of the design in response to variations in load conditions. The thermal model was also used to develop an alternative coolant flow-path design that yields improved thermal performance. Results from this analysis were recently incorporated into the latest Plug Power coolant flow-path design. This paper presents an evaluation of the effect of variation on key design parameters such as coolant and gas flow rates and addresses uncertainty in material thermal properties.

Numerical Investigation of the Effect of Diffuser and Volute Design Parameters on the Performance of a Centrifugal Compressor Stage

2016 ◽  
Author(s):  
Lei Yu ◽  
William T. Cousins ◽  
Feng Shen ◽  
Georgi Kalitzin ◽  
Vishnu Sishtla ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Gas Flow ◽  
Pressure Rise ◽  
Design Parameters ◽  
Compressor Stage ◽  
Flow Distortion ◽  
Cross Sectional ◽  
Centrifugal Stage ◽  
And Performance ◽  
The Impact

In this effort, 3D CFD simulations are carried out for real gas flow in a refrigeration centrifugal compressor. Both commercial and the in-house CFD codes are used for steady and unsteady simulations, respectively. The impact on the compressor performance with various volute designs and diffuser modifications are investigated with steady simulations and the analysis is focused on both the diffuser and the volute loss, in addition to the flow distortion at impeller exit. The influence of the tongue, scroll diffusion ratio, diffuser length, and cross sectional area distribution is examined to determine the impact on size and performance. The comparisons of total pressure loss, static pressure recovery, through flow velocity, and the secondary flow patterns for different volute designs show that the performance of the centrifugal compressor depends upon how well the scroll portion of the volute collects the flow from the impeller and achieves the required pressure rise with minimum flow losses in the overall diffusion process. Finally, the best design is selected based on compressor stage pressure rise and peak efficiency improvement. An unsteady simulation of the full wheel compressor stage was carried out to further examine the interaction of impeller, diffuser and the volute. The unsteady flow interactions are shown to have a major impact on the performance of the centrifugal stage.

scholarly journals ON THE ISSUE OF DETERMINING THE CRITICAL CUTTING SPEED OF THE MECHANISM FOR FORMING AND TRIMMING THE FALSE EDGE OF THE DORNIER RAPIER LOOM

2021 ◽  
Vol 53 (3) ◽  
pp. 37-40
Author(s):  
Svitlana V. Bukina ◽  
Tatiana A. Sitnikova
Keyword(s):  
Rational Design ◽  
Mutual Influence ◽  
Cutting Speed ◽  
Design Parameters ◽  
Working Process ◽  
Forming Mechanism ◽  
Rational Design Parameters ◽  
Calculation Results ◽  
Knife Blade ◽  
The Impact

In this paper, an attempt is made to develop a method for determining the critical cutting speed of the threads of the false edge of the edge-forming mechanism of the weaving rapier machine. The proposed calculation method takes into account the impact nature of the cutting process at a critical speed, which allows taking into account the mutual influence of the parameters of the working process and more fully assess the mechanics of this process, in which the intensity of the cutting force and the value of the contact stress take the maximum value. The paper calculates the critical cutting speed for some of the main types of threads used and the parameters of the knife blade. The presented calculation results can be used to select rational design parameters of the knife blade, depending on the type of processed threads, when designing and researching new edge-forming mechanisms on looms.

scholarly journals A Set of Economic and Mathematical Models for Assessment of Agricultural Crop Cultivation Technologies

2019 ◽  
Vol 8 (2) ◽  
pp. 3829-3833
Keyword(s):  
Mathematical Models ◽  
Assessment Model ◽  
Information Support ◽  
Practical Significance ◽  
Production Cycle ◽  
Agricultural Crop ◽  
Crop Cultivation ◽  
Software Complex ◽  
Technological Processes ◽  
Crop Farming

Research objectives. The paper describes the process of development of a set of mathematical models for assessment of agricultural production technologies to be used as the basis of a software complex module for managing technological processes in crop farming. The reported study was funded by RFBR according to the research project № 18-37-00148. Methods. Given the specifics of management in agriculture, it is worth noting that the lack of objective information across the production cycle in crop farming and the subsequent misalignment with an optimum technology results in overshooting labour and material costs, lost profits for the enterprise or even losses. These issues have to be addressed through advanced studies of economic and mathematical models and methods for analysis and assessment of economic efficiency of agricultural crop cultivation technologies and the development of a comprehensive automated information support system for decision-making in crop farming management. Results. A methodology is proposed for selecting economically efficient technological processes in crop farming, involving the sequential application of results obtained through the analysis of technological process criteria by the methods of binary decision matrices, cobweb diagrams and the matrix assessment model, taking into account their orientation at the economic performance of crop farming. Practical significance and applicability of results. The authors developed a complex of software and information support and assessment of technological processes in crop farming, with experimental trials showing improved efficiency of crop farming production through the well-reasoned selection of agricultural crop cultivation technologies.

Flow Structure and Heat Transfer in Stagnation Flow CVD Reactor

2010 ◽  
Author(s):  
Nasir Memon ◽  
Yogesh Jaluria
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Flow Reactor ◽  
Chemical Vapor ◽  
Design Parameters ◽  
Stagnation Flow ◽  
Inlet Length ◽  
The Impact

An experimental study is undertaken to investigate the flow structure and heat transfer in a stagnation flow Chemical Vapor Deposition (CVD) reactor at atmospheric pressure. It is critical to develop models that predict flow patterns in such a reactor to achieve uniform deposition across the substrate. Free convection can negatively affect the gas flow as cold inlet gas impinges on the heated substrate, leading to vortices and disturbances in the normal flow path. This experimental research will be used to understand the buoyancy-induced and momentum-driven flow structure encountered in an impinging jet CVD reactor. Investigations are conducted for various operating and design parameters. A modified stagnation flow reactor is built where the height between the inlet and substrate is reduced when compared to a prototypical stagnation flow reactor. By operating such a reactor at certain Reynolds and Grashof numbers it is feasible to sustain smooth and vortex free flow at atmospheric pressure. The modified stagnation flow reactor is compared to other stagnation flow geometries with either a varied inlet length or varied heights between the inlet and substrate. Comparisons are made to understand the impact of such geometric changes on the flow structure and the thermal boundary layer. In addition, heat transfer correlations are obtained for the substrate temperature. Overall, the results obtained provide guidelines for curbing the effects of buoyancy and for improving the flow field to obtain greater film uniformity when operating a stagnation flow CVD reactor at atmospheric pressure.

scholarly journals Deflection Mechanism and Safety Analysis of Coal Mine Shaft in Deep Soil Strata

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jihuan Han ◽  
Jiuqun Zou ◽  
Chenchen Hu ◽  
Weihao Yang
Keyword(s):  
Coal Mine ◽  
Rational Design ◽  
Coal Pillar ◽  
Design Parameters ◽  
Deep Soil ◽  
Mine Shaft ◽  
Dynamic Prediction ◽  
Probability Integral Method ◽  
Mining Conditions ◽  
Shaft Deflection

The main shaft and auxiliary shaft in the Guotun Coal Mine underwent large deflections, with deflection values of 359 mm and 322 mm, respectively. These two deflections represent the first occurrence of such large vertical shaft deviations in the soil strata in China. The deflection problem has seriously affected the hoisting safety and lining safety and has become a serious impediment to the sustainable production of mines. Therefore, the deflection mechanism must be determined. For this purpose, based on mining subsidence theory, the spatial probability integral method and a more accurate time function were used to establish a model, called 3D dynamic prediction model, for predicting the shaft movement. The formulas for calculating the lining stress caused by coal mining were based on established models. With measured shaft deflection data, the prediction parameters for deep soil strata were calculated on the basis of an inversion analysis. A comparative analysis of measured and calculated deflection values revealed that the reason for shaft deflection in Guotun Coal Mine is the insufficient size of the protection coal pillar (PCP); namely, the design parameters of the PCP in current codes are not applicable to the deep soil strata. As a result, under the asymmetric mining conditions, mining causes the shaft to deflect without damage and under the symmetric mining conditions, mining causes the lining to fracture. The results have an extremely important significance for the prevention and control of shaft deflection, for the rational design of PCP, and for the sustainability of mine production.

scholarly journals Application of Acoustic Emission Technique to the Evaluation of Coal Seam Hydraulic Flushing Effect

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1705 ◽  
Author(s):  
Rongxi Shen ◽  
Xuan Zhang ◽  
Enyuan Wang ◽  
Hongru Li ◽  
Xu Han ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Coal Seam ◽  
Gas Flow ◽  
Damage Mechanics ◽  
Water Pressure ◽  
Quantitative Relationship ◽  
Practical Significance ◽  
Effect Evaluation ◽  
Permeability Enhancement ◽  
Ae Signals

Hydraulic flushing has the advantages of reducing coal stress and improving coal seam permeability, so it is widely used in high gas outburst coal seams in China. However, the effect evaluation of stress relief and permeability enhancement will be necessary before coal mining. In this paper, an acoustic emission (AE) experiment system of coal seam hydraulic flushing was established, and the AE characteristics of coal during hydraulic flushing were studied. The results show that the changes in AE signals are basically consistent with those in load and water pressure. In addition, the quantitative relationship between the signals and the damage of coal around the borehole is revealed by the theory of damage mechanics. The in-situ AE test of hydraulic flushing was performed in the Liangbei Coal Mine, by measuring gas flow and coal stress simultaneously. The variation of AE activities and the effect evaluation of hydraulic flushing were analyzed. The results reveal that the changes in coal seam stress are basically consistent with those of AE signals. After the flushing has been completed for 1–3 h, the coal seam stress decreases rapidly, and the AE counts and intensity reach the peak. Therefore, this study proposes a new method for evaluating the effect of coal seam hydraulic flushing by AE, which has a very important practical significance.

Numerical Simulation and Experimental Study on Tar Decomposition of Low-Pressure Ejection Type Burner

2015 ◽  
Vol 1092-1093 ◽  
pp. 200-206
Author(s):  
De Fan Qing ◽  
Mao Kui Zhu ◽  
Yang Cheng Luo ◽  
Ya Long Zhang ◽  
Ai Rui Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Low Pressure ◽  
Orthogonal Test ◽  
Nozzle Diameter ◽  
Design Parameters ◽  
Minor Effect ◽  
Gas Flow Rate ◽  
Tar Cracking

The tar decomposition of low-pressure ejection type burner was researched. The burner used software to simulate and analyse impact of the nozzle diameter d, the gas flow rate V and the distance of the nozzle to the wall L on tar cracking. The orthogonal test were used for design parameters d, V and L, the optimization values of these three parameters were carried out, and experimental method was used for test the numerical simulation results. Numerical simulation and experimental results showed that the greatest impact on tar cracking is the nozzle diameter d, the minor effect is the distance of the nozzle to the wall L and the weakest effect is the gas flow rate V, and when the nozzle diameter d=4 mm, the distance L=18 mm and the gas flow rate V=0.10 m3/h, the tar cracking is the most efficiency.

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