scholarly journals СРАВНИТЕЛЬНЫЙ АНАЛИЗ МЕТОДОВ РАСЧЁТА АМПЛИТУД КОЛЕБАНИЙ ДАВЛЕНИЯ, СОЗДАВАЕМЫХ КАВИТАЦИОННЫМ ГЕНЕРАТОРОМ

2018 ◽  
pp. 58-68
Author(s):  
Юрий Алексеевич Жулай ◽  
Юрий Александрович Кваша ◽  
Алексей Дмитриевич Николаев
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Specific Energy Consumption ◽  
Fluid Pressure ◽  
Experimental Studies ◽  
Industrial Plant ◽  
Design Stage ◽  
Oscillatory Process ◽  
Pressure Oscillations ◽  
Element Discretization

One of the devices implementing energy-saving technologies is a Venturi tube of special geometry, called the cavitations generator of fluid pressure oscillation (hereinafter referred to as the generator). It converts the steady-state flow of process fluid into a discrete-impulse flow of increased power and has the simplicity of manufacturing that lacks moving parts, does not require additional energy sources and seamlessly fits into existing equipment. The practical use of the generator in engineering, metallurgy, the chemical industry and in mining, can reduce the specific energy consumption by up to 50%. The purpose of this paper is a comparative analysis of the existing methods for calculating the amplitudes of pressure oscillations generated by the generator and the choice of a method that makes it possible to determine the amplitudes with an acceptable accuracy. The technique is based on the determination by various computation methods of peak-to-peak values of the fluid pressure from the cavitations flow regime. The results are presented in the form of calculated dependences of the of peak-to-peak oscillation values of the fluid pressure on the value of the cavitations parameter and their comparison with the experimental data. Scientific novelty. It is established that the method using the finite-element discretization of the generator and outlet pipeline construction with fluid moving in it satisfactorily describes the parameters of the oscillatory process in various elements of the hydraulic system. However, the model requires some correction in the part of the description of the basic dependencies describing the dynamics of the cavitations flow in the generator, if it is necessary to more agreement with the experimental data. This model is convenient for carrying out multi-purpose research works, including experimental data correction, but its application for engineering calculations causes certain difficulties in the part of programming and the length of preparation for the calculations. The refined linear mathematical model of the generator makes it possible to obtain a quantitative agreement between the experimental and theoretical dependences of the amplitude of fluid pressure oscillations on the cavitations parameter by engineering methods. The practical significance of the results obtained is that the refined linear mathematical model of the generator makes it possible to establish at the design stage a rational regime of the hydroimpulse action of the generator (the peak-to-peakvalues of fluid pressure oscillations) at a certain pressure in the process pipeline of an industrial plant and does not require additional experimental studies

scholarly journals Belt conveyor failure simulation at the design stage with transverse displacements of the belt

2020 ◽  
Vol 168 ◽  
pp. 00056
Author(s):  
Vitalii Monastyrskyi ◽  
Serhii Monastyrskyi ◽  
Denis Nomerovskyi ◽  
Borys Mostovyi
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Fourier Transform ◽  
Adaptive Control ◽  
Design Stage ◽  
Belt Conveyor ◽  
Failure Simulation ◽  
The Fourier Transform ◽  
External Forces ◽  
The Mathematical Model

To find possible conveyor failures at the design stage means to determine a transverse belt displacement and compare the obtained data with the permissible ones. The dynamic problem of the belt movement on the conveyor has been defined. Resistance and external forces, limits of the belt displacement have been determined. The transverse belt displacement can be described by partial differential equations. To solve the problem, the Fourier transform has been used. Change patterns in the transverse belt conveyor displacement dependent on conveyor’s parameters, type of load, and skewing of the idlers along the conveyor have been obtained. The results agree with experimental data. The method of adaptive control of the transverse belt displacement has been described. The essence of this method is to adapt the model of the moving belt in the conveying trough to changed conditions and to reveal the uncertainty of the control with the known parameters of the mathematical model.

On the Relationship Between Added Mass and Added Damping

2002 ◽  
Author(s):  
H. G. D. Goyder
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Strong Dependence ◽  
Fluid Pressure ◽  
Theoretical Models ◽  
Added Mass ◽  
Measured Data ◽  
Interesting Consequence ◽  
Phase Angles ◽  
The Relationship

A surprising relationship exists between the amplitude and phase of a vibrating system. For an item vibrating in a fluid flow the phase of the fluid pressure (relative to the motion of the structure) can be deduced from the amplitude of the pressure. This strong dependence of the phase on the amplitude provides a means for checking the correctness of measured data and severely constrains the form that a mathematical model can take. The relationship between amplitude and phase is completely general and the paper gives various examples from theoretical models and experimental data. One interesting consequence of this relationship follows from the observation that phase angles only exist because of damping. Hence damping, due to the fluid, is linked to added mass.

scholarly journals Experimental studies of iron transformations kinetics and autocatalysis during its physicochemical removal from underground water

2021 ◽  
Author(s):  
S. Yu Martynov ◽  
V. L. Poliakov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Experimental Studies ◽  
Underground Water ◽  
Model Parameters ◽  
Kinetic Coefficients ◽  
Transfer Equations ◽  
The Mathematical Model ◽  
Autocatalytic Effect ◽  
Forms Of Iron

Abstract The mathematical model of physicochemical iron removal from groundwater was developed. It consists of three interrelated compartments. The results of the experimental research provide information in support of the first two compartments of the mathematical model. The dependencies for the concentrations of the adsorbed ferrous iron and deposited hydroxide concentrations are obtained as a result of the exact solution of the system of the mass transfer equations for two forms of iron in relation to the inlet surface of the bed. An analysis of the experimental data of the dynamics of the deposit accumulation in a small bed sample was made, using a special application that allowed to select the values of the kinetic coefficients and other model parameters based on these dependencies. We evaluated the autocatalytic effect on the dynamics of iron ferrous and ferric forms. The verification of the mathematical model was carried out involving the experimental data obtained under laboratory and industrial conditions.

scholarly journals Parameterising continuum models of heat transfer in heterogeneous living skin using experimental data

2018 ◽  
Author(s):  
Sean McInerney ◽  
Elliot J Carr ◽  
Matthew J Simpson
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Heat Conduction ◽  
Layered Structure ◽  
Experimental Studies ◽  
Synthetic Data ◽  
Spatial Location ◽  
Recent Experimental Data ◽  
Data Set ◽  
Experimental Constraint

AbstractIn this work we consider a recent experimental data set describing heat conduction in living porcine tissues. Understanding this novel data set is important because porcine skin is similar to human skin. Improving our understanding of heat conduction in living skin is relevant to understanding burn injuries, which are common, painful and can require prolonged and expensive treatment. A key feature of skin is that it is layered, with different thermal properties in different layers. Since the experimental data set involves heat conduction in thin living tissues of anesthetised animals, an important experimental constraint is that the temperature within the living tissue is measured at one spatial location within the layered structure. Our aim is to determine whether this data is sufficient to reliably infer the heat conduction parameters in layered skin, and we use a simplified two-layer mathematical model of heat conduction to mimic the generation of experimental data. Using synthetic data generated at one location in the two-layer mathematical model, we explore whether it is possible to infer values of the thermal diffusivity in both layers. After this initial exploration, we then examine how our ability to infer the thermal diffusivities changes when we vary the location at which the experimental data is recorded, as well as considering the situation where we are able to monitor the temperature at two locations within the layered structure. Overall, we find that our ability to parameterise a model of heterogeneous heat conduction with limited experimental data is very sensitive to the location where data is collected. Our modelling results provide guidance about optimal experimental design that could be used to guide future experimental studies.NomenclatureA brief description of all variables used in the document are given in Table 1.Table 1:Variable nomenclature and description.

scholarly journals EXPERIMENTAL STUDIES OF WEARING AND TEARING OF ASPHALT CONCRETE SURFACING UNDER THE ACTION OF WATER PRESSURE IN MICROPORES

2021 ◽  
pp. 83-92
Author(s):  
V. V. Volkov ◽  
V. A. Kozlov ◽  
V. N. Melkumov
Keyword(s):  
Experimental Data ◽  
Asphalt Concrete ◽  
Water Pressure ◽  
Fluid Pressure ◽  
Experimental Studies ◽  
Hydrodynamic Effect ◽  
Depth Of Penetration ◽  
Wear And Tear ◽  
The Impact ◽  
Whole Life Cycle

Statement of the problem. The goal of this study is to identify the effect of wet surfacing on its wear and tear. The mechanism of influence of transport loading in the presence of moisture and experimental methods of measurement of its influence on wear and tear of the top layer of asphalt concrete are discussed. Results. The contribution of the presence of moisture in the upper layer of the pavement to its wear and tear in the form of track formation was identified, and the hydrodynamic effect of water in the micropores of the pavement was investigated. Experimental data on the values of water pressure in the pores of the asphalt-concrete pavement in the moistened state under the action of the wheels of the moving traffic flow were obtained. Therefore it became possible to identify the maximum values of the pressure effect, the depth of penetration of the fluid pressure front and its effect on the destruction of the surfacing.Conclusions. The analysis of the data showed not only the presence of brittle fracture, but also the impact of moisture moving in the pores of asphalt concrete, exceeding its structural strength. Using experimental data, regression dependences of the wear and tear value on the standard flow parameters were obtained. For the operated surfacings regression dependence enables one to predict the size of wear and tear for the whole life cycle of the road.

scholarly journals Experimental studies of the method of mutual load of induction motors

2020 ◽  
pp. 44-49
Author(s):  
V. V. Kharlamov ◽  
◽  
D. I. Popov ◽  
P. S. Sokolov ◽  
L. E. Serkova ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Experimental Data ◽  
Mathematical Model ◽  
Induction Motors ◽  
Experimental Studies ◽  
Electromechanical System ◽  
Experimental Equipment ◽  
Frequency Converters ◽  
Parameter Values ◽  
The Mathematical Model

The article presents the results of comparison of experimental studies and mathematical modeling of the stand for testing induction motors by the method of mutual load. A detailed description of the composition of the experimental equipment, which is based on a pair of frequency converters and connected to them a pair of engines of the АИС71В4 type with a nominal power of 0,75 kW, the shafts of which are rigidly connected by a coupling. The mathematical model of the electromechanical system used in the calculations is presented, and its main assumptions are listed. A table of parameter values and graphs obtained from calculated and experimental data are presented. The analysis of the obtained data shows the possibility of using the considered mathematical model with the existing assumptions in the design of electrical complexes intended for testing induction motors by the method of mutual load

scholarly journals MODELING OF SOLAR RADIATION FOR USE IN RENEWABLE ENERGY AND IN CONSTRUCTION THERMAL PHYSICS

2018 ◽  
Vol 40 (1) ◽  
pp. 44-50
Author(s):  
B.I. Basok ◽  
B.V. Davydenko ◽  
V.G. Novikov ◽  
R.Ya. Sorokovoy
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Renewable Energy ◽  
Solar Radiation ◽  
Experimental Studies ◽  
Program Code ◽  
Solar Insolation ◽  
Thermal Physics ◽  
The Mathematical Model ◽  
Design And Construction

The work is devoted to the estimation of the intensity and energy of solar radiation at the earth's surface. The aim of the research is to develop a mathematical model of solar radiation, necessary for the design of devices for renewable energy, as well as in the design and construction of buildings and structures. The mathematical model of solar radiation is realized in the Python code. The program code allows you to calculate the intensity of solar radiation and solar insolation on any day of the year. The model is verified by the results of experimental studies of solar radiation in the Odessa region and by the results of our own experimental data.

High Cycle Fatigue Cracks at Radial Fan Impellers Caused by Aeroelastic Self-Excited Impeller Vibrations: Part 2 — Mechanism and Mathematical Model

1999 ◽  
Author(s):  
Alexander Ni
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
High Cycle Fatigue ◽  
Dynamic Behaviour ◽  
Fatigue Cracks ◽  
Model Fit ◽  
Acoustic Properties ◽  
Cycle Fatigue ◽  
Pressure Oscillations ◽  
The Mathematical Model

Abstract The radial impeller of the main fan of hydrogen cooled generator has been noted to sustain fatigue failure. Experimental data pointed out to the impeller selfexcitation as the cause of the failure. According to the mechanism and the mathematical model suggested in the paper the impeller selfexcitation is due to the feedback between the natural impeller vibrations and the acoustic field in the side room adjacent to the impeller. The impeller vibrations induce the pressure oscillations in the side room that in turn influence the impeller. Under special conditions of the fan dynamic behaviour and the acoustic properties of the fan side room this feedback leads to the selfexcitation. The suggested mechanism and the model fit all the experimental data. Their validity has been also later confirmed by the maintaince experience of other similar machines.

scholarly journals THE INFLUENCE OF PRESSURE, NOSE DIAMETER AND TILT ANGLE LENGTH WHOLE SHOULDER

Fire Safety ◽  
2020 ◽  
Vol 35 ◽  
pp. 10-15
Author(s):  
E. Hulida ◽  
V. Lendіel ◽  
M. Smolinska ◽  
O. Mulko
Keyword(s):  
Mathematical Model ◽  
Water Supply ◽  
Forest Fires ◽  
Fluid Pressure ◽  
Experimental Studies ◽  
Nonlinear Mathematical Model ◽  
Step Method ◽  
Fire Extinguishing ◽  
Flow Length ◽  
Continuous Stream

The results of the analysis of the technical and reference literature related to the technical fire extinguishing means showed that there is no complete data regarding the technical characteristics of the carriage trunks, which relate to the length of the continuous water jet depending on the fluid pressure, the diameter of the nozzle, the angle of its inclination and placement heights above the ground. The firefighting barrel trunks are mainly used for localization and extinguishing of open fires (for example, in open warehouses of timber, forest fires, etc.). In the process of eliminating such fires, it is necessary to control the flow of a continuous jet into the fire cell by changing the pressure, the diameter of the nozzle, the angle of the barrel and the like. Therefore, to solve this problem in terms of controlling the process of extinguishing a fire, the task is to conduct experimental studies and to obtain on the basis of the experimental results of an empirical mathematical model, which would take into account the influence on the length of the continuous jet of the above factors. According to the results of experimental studies, to obtain a mathematical model for determining the length of flow of a continuous stream of water by a flap barrel from the variables that influence the process of its control during the elimination of fire. To achieve this goal, it is necessary to solve the following tasks: 1) to carry out experimental studies to determine the length of the flow of continuous jet of water with a pallet barrel from the variables that affect the process of its management in the elimination of fire; 2) mathematically process the results of the experiment and obtain a mathematical model to determine the flow length of a continuous stream of water supplied by a carriage shaft; 3) to develop a methodology for controlling the process of choosing the length of a continuous stream of water, which is fed by a carriage barrel when extinguishing a fire. Experimental studies were conducted using a fractional experiment to solve the first problem. For experimental research used: 1) fire truck MAZ AC-4-60 (5309) -505M; 2) PLS-20P carriage barrel; 3) fire hoses for connecting the carriage barrel to the centrifugal pump of the fire tanker; 4) roulette at 5 m; 5) a goniometer for measuring and setting the angle of the barrel relative to the earth's surface; 6) barrel nozzles d = 25 mm and d = 32 mm. Based on the results of the experiment, a nonlinear mathematical model was developed to determine the flow length of a continuous stream of water supplied by a carriage shaft. The model developed also takes into account the effect on the length of the jet supply the height of placement of the carriage trunk above the ground. The mathematical model for determining the flow length of a continuous jet of water with a carriage trunk gave the opportunity to develop a method of controlling the flow length of a continuous jet of water. Conclusions and specific suggestions: The results of experimental studies to determine the length of the flow of continuous jet of water by a barrel trunk from variable factors made it possible to clarify the technical capabilities of carriage trunks and to develop a method of controlling the process of water supply in the event of fire elimination. A nonlinear mathematical model was developed to determine the flow length of a continuous jet of water by a carriage barrel, the adequacy of which was tested according to the Fisher criterion. To control the process of water supply, depending on the required distance to the fire, a step-by-step method is proposed to increase or decrease the length of the continuous flow of water by a flap barrel.

scholarly journals EXPERIMENTAL STUDIES OF HEAT EXCHANGE DURING WATER COOLING AND STEAM CONDENSATION IN DEMOVER RADIATOR SECTIONS

2021 ◽  
Vol 1 (38) ◽  
pp. 107-114
Author(s):  
V. Mogila ◽  
M. Kovtanets ◽  
M. Morneva
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Cooling System ◽  
Experimental Studies ◽  
Road Transport ◽  
Thermal Calculation ◽  
Mode Of Operation ◽  
Simulation Results ◽  
The Mathematical Model

The Department of Railwayand Road Transport, lift and care system of Volodymyr Dahl East Ukrainian National University, an energy-saving cooling system for diesel locomotives using phase transitions of the coolant has been developed. The proposed cooling system allows to maintain constant optimal temperatures of cooling objects at ambient temperatures ± 40 ºC and in any mode of operation of the diesel engine. For thermal calculation of the radiator section operating in the mode of the steam condenser, the mathematical model of process of heat transfer from steam to walls of a flat tube at condensation is developed that considers geometrical features of section of a tube. The adequacy of this mathematical model is verified by comparing the simulation results with the obtained experimental data. During the tests, the outlet water temperature, inlet and outlet air temperature, and air pressure in front of and behind the radiator were measured. Having the values of wall temperature, steam temperature and condensate, knowing the value of steam consumption and the experimental heat transfer coefficient, it becomes possible to verify the adequacy of the mathematical model by comparing the simulation results with the obtained experimental data. Schemes of bench equipment, test methods, experimental planning and basic calculation dependences required for testing serial radiator sections of a locomotive in the standard mode of operation and in the mode of steam condensers are presented.

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