CALCULATION OF OPTIMAL GEOMETRIC PARAMETERS OF SPHERICAL ROLLER TRANSMISSIONS AGAINST THE MAXIMUM EFFICIENCY CRITERION

2019 ◽  
pp. 34-42
Author(s):  
Ekaterina Sergeyevna Lustenkova
Keyword(s):  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Efficiency Criterion

scholarly journals Optimisation of the Geometric Parameters of Longitudinally Finned Air Cooler Tubes Operating in Mixed Convection Conditions

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 111
Author(s):  
Piotr Kopeć ◽  
Beata Niezgoda-Żelasko
Keyword(s):  
Heat Flow ◽  
Mixed Convection ◽  
Optimal Solution ◽  
Finned Tube ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Minimum Mass ◽  
Maximum Heat ◽  
Air Cooler ◽  
Finned Surface

The results of optimisation calculations presented in the article are related to longitudinally finned tubes of a heat pump evaporator operating under natural wind-induced flow of outdoor air conditions. The finned surface is characterised by an unusual, wavy fin shape. The article presents the methodology applied to seeking optimal geometric parameters of the finned tube in which thermal calculations were performed by modelling a mixed convection process on the finned surface using the finite volume method. In the case of maximising the heat flow with the minimum mass of the fins, the optimal solution was dominated by the minimum mass of the fins and thus geometric parameters correspond to the number of fins n = 6, fin height h = 0.065 and fin thickness s = 0.0015 m. Optimisation calculations made for maximum efficiency of the exchanger at constant mass indicated that the tube with ten fins (n = 10) with a height of h = 0.11 m and a thickness of s = 0.0018 m allowed maximum heat flow at the assumed mass of the fins in the exchanger tube model. The article proposes a simplified method of determining the optimal geometric parameters of the profile for any mass and maximum thermal efficiency.

Impact of Manufacturing Variability on Multistage High-Pressure Compressor Performance

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Alexander Lange ◽  
Matthias Voigt ◽  
Konrad Vogeler ◽  
Henner Schrapp ◽  
Erik Johann ◽  
...  
Keyword(s):  
High Pressure ◽  
Pressure Rise ◽  
Leading Edge ◽  
Back Pressure ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Novel Approach ◽  
High Pressure Compressor ◽  
Pressure Compressor

The present paper introduces a novel approach for considering manufacturing variability in the numerical simulation of a multistage high-pressure compressor (HPC). The manufacturing process is investigated by analyzing three of a total of ten rotor rows. Therefore, 150 blades of each of the three rows were 3D scanned to obtain surface meshes of real blades. The deviation of a scanned blade to the design intent is quantified by a vector of 14 geometric parameters. Interpolating the statistical properties of these parameters provides the manufacturing scatter for all ten rotor rows expressed by 140 probability density functions. The probabilistic simulation utilizes the parametric scatter information for generating 200 virtual compressors. The CFD analysis provides the performance of these compressors by calculating speed lines. Postprocessing methods are applied to statistically analyze the obtained results. It was found that the global performance parameters show a significantly wider scatter range for higher back pressure levels. The correlation coefficient and the coefficient of importance are utilized to identify the sensitivity of the results to the geometric parameters. It turned out that the sensitivities strongly shift for different operating points. While the leading edge geometry of all rotor rows dominantly influences the overall performance at maximum efficiency, the camber line parameters of the front stages become more important for higher back pressure levels. The analysis of the individual stage performance confirms the determining importance of the front stages—especially for highly throttled operating conditions. This leads to conclusions regarding the robustness of the overall HPC, which is principally determined by the efficiency and pressure rise of the front stages.

scholarly journals THE CONTACT INTERACTION DYNAMICS OF THE WORKING TOOL OF THE MOLE PLOWSHARE WITH THE SOIL DURING FORMING PROSESS A CHANNEL FOR AN ANTI-FILTRATION SCREEN

2020 ◽  
pp. 81-89
Author(s):  
Olena Solona ◽  
Vladimir Kovbasa ◽  
Igor Kupchuk
Keyword(s):  
Rigid Body ◽  
Contact Interaction ◽  
Large Scale ◽  
Geometric Parameters ◽  
Theoretical Development ◽  
Maximum Efficiency ◽  
Industrial Complex ◽  
Engineering Structures ◽  
Operating Modes ◽  
Working Bodies

Today's realities of agriculture are increasingly prompting the need for the introduction of technologies for subsoil irrigation, as a possible tool to obtain maximum efficiency indicators of agricultural activities of agricultural enterprises. At the same time, the large-scale introduction of intra-soil irrigation technologies at the enterprises of the agro-industrial complex is significantly complicated due to the poor practical and theoretical development of its methods, as well as the lack of extensive experimental verification of this method of irrigation. The development of many processes in the construction of irrigation and engineering structures requires substantiation of the geometric parameters and operating modes of the working bodies that are used to implement these processes. One of the working bodies that is used to form the cavity along which communication is stretched is a mole plow, which, depending on the expected working conditions, may have a different geometric configuration and size. The results of investigations of the interaction of the mole ploughshare with the soil in cavity formation for laying the anti-filtration screen are describe in this article. The authors propose to consider the soil in the form of an elastic-viscous model. By solving the contact problem of the interaction of a rigid body with a deformed medium, the stress components in the soil on the contact surface with the ploughshare are determined, and soil compaction is determined. The components of forces that appear on the surface of the ploughshare because of its interaction with the soil are determined depending on its geometric parameters and the mechanical properties of the soil. This solution is a general approach for the analytical solution of the class of problems of the contact interaction of a rigid body with a deformable medium possessing the properties of elasticity and viscosity.

An Experimental Investigation of Cross-Flow Turbine Efficiency

1994 ◽  
Vol 116 (3) ◽  
pp. 545-550 ◽  
Author(s):  
Venkappayya R. Desai ◽  
Nadim M. Aziz
Keyword(s):  
Experimental Investigation ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Water Entry ◽  
Diameter Ratio ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Outer Diameter ◽  
Turbine Efficiency ◽  
The Cross

An experimental investigation was conducted to study the effect of some geometric parameters on the efficiency of the cross-flow turbine. Turbine models were constructed with three different numbers of blades, three different angles of water entry to the runner, and three different inner-to-outer diameter ratios. Nozzles were also constructed for the experiments to match the three different angles of water entry to the runner. A total of 27 runners were tested with the three nozzles. The results of the experiments clearly indicated that efficiency increased with increase in the number of blades. Moreover, it was determined that an increase in the angle of attack beyond 24 deg does not improve the maximum turbine efficiency. In addition, as a result of these experiments, it was determined that for a 24 deg angle of attack 0.68 was the most efficient inner-to-outer diameter ratio, whereas for higher angles of attack the maximum efficiency decreases with an increase in the diameter ratio from 0.60 to 0.75.

scholarly journals An integrated modeling approach for design and optimization of ejector pumps carrying two-phase fluid

2017 ◽  
Author(s):  
◽  
Khalid Sarhan Almutairi
Keyword(s):  
Nozzle Exit ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Phase Flow ◽  
Two Phase ◽  
Design And Optimization ◽  
Numerical Predictions ◽  
A New Technique

An ejector pump uses a primary flow as a motive fluid to entrain another fluid, and can work with both incompressible flow and compressible flow, in either as a singlephase or two-phase mixture. Determining the behavior of the two-phase flow inside the ejector with different geometric parameters was the objective of this research. Three approaches were used to predict the performance and the capture the flow behavior inside it. An analytical model used the geometric parameters to calculate the loss factors for the first time and work as a basis for the two-phase flow ejectors. A fluid transportation system was built to verify analytical and numerical predictions and to explore optimum. Using a fitting parameter to capture the flow behavior inside the ejector was crucial for the accuracy of the numerical model. The fitting parameter is a new technique that uses an arbitrary fluid to match the induced air measurements numerically with the ones founded experimentally. To apply the three approaches, nine ejectors were built with different geometric parameters. The nozzle exit diameters are tested at three levels while the length mixing tube are tested at three levels as well. The results reveal that the diffuser angle of 5[degrees], the smallest nozzle exit diameter, and the longest mixing tube result on maximum efficiency and highest induced air. More investigation of two-phase ejectors is important to fully understand flow behavior and to increase efficiency. There are many improvements needed to this work in future.

scholarly journals OPTIMIZATION TECHNIQUE OF DRIVING DISC PARAMETERS

2021 ◽  
pp. 317-325
Author(s):  
Yu.V. Konstantinov ◽  
A.P. Akimov ◽  
V.I. Medvedev ◽  
A.G. Terentyev
Keyword(s):  
High Efficiency ◽  
Driving Forces ◽  
Operation Mode ◽  
Optimization Technique ◽  
Specific Energy Consumption ◽  
Kinematic Parameter ◽  
Maximum Efficiency ◽  
Relative Depth ◽  
Efficiency Criterion ◽  
Experimental Values

Flat circular discs in powered operation mode create driving forces. These forces enable to decrease the wheel slippage of the energy saturated tractor of tillage unit and to reduce the specific energy consumption. The objective of this study was to develop a technique that enables to determine the driving disc optimal parameters for maximum efficiency criterion. The earlier developed mathematical model of soil-disc interaction was used for this purpose. Soil properties in the model are characterized by means of two empirical constants. The relative depth and the kinematic parameter determine the disc operation mode. It was shown that the driving disc can operate with high efficiency, if the disc operates at the optimal values of the parameters. The driving disc efficiency can achieve the value about fifty percent. The experimental results confirmed the adequacy of the technique. The discrepancy between the predicted and field experimental values of driving forces and applied moments was about 25%. The proposed technique can be modified to optimize the parameters of other powered rotary tools of tillage machines and units.

scholarly journals Influence of limiting the duration of the armature winding current on the operating indicators of a linear pulse electromechanical induction type converter

2021 ◽  
pp. 3-10
Author(s):  
V.F. Bolyukh ◽  
I.S. Shchukin
Keyword(s):  
Heating Temperature ◽  
Power Device ◽  
Maximum Efficiency ◽  
Induced Current ◽  
Efficiency Criterion ◽  
Operating Cycle ◽  
Capacitive Energy Storage ◽  
Induction Type ◽  
Linear Pulse ◽  
Solutions Of Equations

Introduction. Linear pulse electromechanical converters of induction type (LPECIT) are used in many branches of science and technology as shock-power devices and electromechanical accelerators. In them, due to the phase shift between the excitation current in the inductor winding and the induced current in the armature winding, in addition to the initial electrodynamic forces (EDF) of repulsion, subsequent EDF of attraction also arise. As a result, the operating indicators of LPECIT are reduced. The purpose of the article is to increase the performance of linear pulse electromechanical induction-type converters when operating as a shock-power device and an electromechanical accelerator by limiting the duration of the induced current in the armature winding until its polarity changes. Methodology. To analyze the electromechanical characteristics and indicators of LPECIT, a mathematical model was used, in which the solutions of equations describing interrelated electrical, magnetic, mechanical and thermal processes are presented in a recurrent form. Results. To eliminate the EDF of attraction between the LPIECIT windings, it is proposed to limit the duration of the induced current in the armature winding before changing its polarity by connecting a rectifier diode to it. It was found that when the converter operates as a shock-power device without limiting the armature winding current, the value of the EDF pulse after reaching the maximum value decreases by the end of the operating cycle. In the presence of a diode in the armature winding, the efficiency criterion, taking into account the EDF pulse, recoil force, current and heating temperature of the inductor winding, increases. When the converter operates as an electromechanical accelerator without limiting the armature winding current, the speed and efficiency decrease, taking into account the kinetic energy and voltage of the capacitive energy storage at the end of the operating cycle. In the presence of a diode in the armature winding, the efficiency criterion increases, the temperature rise of the armature winding decreases, the value of the maximum efficiency increases, reaching 16.16 %. Originality. It has been established that due to the limitation of the duration of the armature winding current, the power indicators of the LPECIT increase when operating as a shock-power device and the speed indicators when the LPECIT operates as an electromechanical accelerator. Practical value. It was found that with the help of a rectifier diode connected to the multi-turn winding of the armature, unipolarity of the current is ensured, which leads to the elimination of the EDF of attraction and an increase in the performance of the LPECIT.

Impact of Manufacturing Variability on Multi–Stage High–Pressure Compressor Performance

2012 ◽  
Author(s):  
Alexander Lange ◽  
Matthias Voigt ◽  
Konrad Vogeler ◽  
Henner Schrapp ◽  
Erik Johann ◽  
...  
Keyword(s):  
High Pressure ◽  
Pressure Rise ◽  
Leading Edge ◽  
Back Pressure ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Multi Stage ◽  
High Pressure Compressor ◽  
Pressure Compressor

The present paper introduces a novel approach for considering manufacturing variability in the numerical simulation of a multi–stage high–pressure compressor (HPC). The manufacturing process is investigated by analyzing three of totally ten rotor rows. Therefore, 150 blades of each of the three rows were 3D scanned to obtain surface meshes of real blades. The deviation of a scanned blade to the design intent is quantified by a vector of 14 geometric parameters. Interpolating the statistical properties of these parameters provides the manufacturing scatter for all ten rotor rows expressed by 140 probability density functions. The probabilistic simulation utilizes the parametric scatter information for generating 200 virtual compressors. The CFD analysis provides the performance of these compressors by calculating speed lines. Post–processing methods are applied to statistically analyze the obtained results. It was found that the global performance parameters show a significantly wider scatter range for higher back pressure levels. The correlation coefficient and the coefficient of importance are utilized to identify the sensitivity of the results to the geometric parameters. It turned out that the sensitivities strongly shift for different operating points. While the leading edge geometry of all rotor rows dominantly influences the overall performance at maximum efficiency, the camber line parameters of the front stages become more important for higher back pressure levels. The analysis of the individual stage performance confirms the determining importance of the front stages — especially for highly throttled operating conditions. This leads to conclusions regarding the robustness of the overall HPC, which is principally determined by the efficiency and pressure rise of the front stages.

scholarly journals Choosing the flow part geometric shape of the dredge pumps for viscous fluids

2021 ◽  
Vol 15 (4) ◽  
pp. 75-83
Author(s):  
Guldana Akanova ◽  
Laila Sagatova ◽  
Lazizjon Atakulov ◽  
Umid Kayumov ◽  
Muhammad Istamov
Keyword(s):  
Three Dimensional ◽  
Geometric Parameters ◽  
Viscous Fluids ◽  
Design Stage ◽  
Maximum Efficiency ◽  
Experiment Planning ◽  
Efficient Operation ◽  
Software Simulation ◽  
Inclination Angles ◽  
Flow Part

Purpose. Search for the possibility of increasing the efficiency of dredge pumps for viscous fluids by determining the rational values of the blade-outlet inclination angles in the pump impellers. Methods. During the research, the following is used: theoretical studies of the structure of the viscous fluids flowing through the flow part of dredge pumps; the method of three-dimensional software-simulation modeling of hydrodynamic processes using the Ansys software package; the methods of rational experiment planning for selecting the values of the number of points in the computational grid when optimizing the geometric parameters of the dredge pump impellers; methods of mathematical statistics and correlation analysis. Findings. It has been proven that the main reason for the failure of the flow part components in the dredge pumps is the manifestation of the influence of cavitation processes, which can be eliminated by changing the blade-outlet inclination angles in the pump impellers. A software-simulation complex for the automated design of the flow parts in the dredge pumps has been developed based on the use of optimization algorithms and computational fluid dynamics methods, which makes it possible to design dredge pumps with optimal characteristics that ensure their efficient operation with maximum efficiency values. It has been determined that one of the main factors influencing the head developed by dredge pumps and the efficiency value is the blade-outlet inclination angle in the pump impellers. Originality. Scientific novelty is in the scientific substantiation and development of a simulation-mathematical method for calculating the geometric parameters of the flow part in dredge pumps for viscous fluids at the design stage. Practical implications. The developed method for determining the rational blade-outlet inclination angles of the impellers in the dredge pumps for viscous fluids can be recommended to scientific-research and industrial organizations for use in the improvement, design and operation of the dredge pumps.

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