scholarly journals CHARACTER OF MANIFESTATION OF NONLINEARITIES FOR VIBRATION DISTURBANCE OF MOTION OF ELLIPSOIDAL RESERVOIR WITH LIQUID WITH A FREE SURFACE

2020 ◽  
pp. 47-50
Author(s):  
O. Limarchenko ◽  
O. Klimenkov ◽  
O. Nefedov ◽  
O. Konstantinov
Keyword(s):  
Free Surface ◽  
Translational Motion ◽  
Dynamical Behavior ◽  
Normal Modes ◽  
Considerable Effect ◽  
Practical Implementation ◽  
Nonlinear Properties ◽  
Liquid Free Surface ◽  
System Of Parameters ◽  
Resolving System

The problem with vibration disturbance of the reservoir of ellipsoidal shape, partially filled with a liquid, is under consideration. For the construction of the model, we use the before developed method, based on the use of non-Cartesian parametrization of the domain, occupied by a liquid. And the method of the auxiliary domain for satisfying boundary conditions on tank walls above the unperturbed free surface of a liquid, where the liquid can pass in its perturbed motion. The liquid is considered as ideal incompressible. The mathematical model of the system is constructed based on the variational formulation of the problem in the form of the Hamilton–Ostrogradskiy principle. The motion of a liquid free surface is given in the form of decomposition with respect to normal modes of oscillations. Amplitude parameters of oscillations of a liquid free surface together with parameters of the translational motion of the reservoir form a complete independent system of parameters, for which the resolving system of ordinary differential equations is constructed. The constructed model includes nonlinear properties of the system and corresponds to the model of the combined motion of the liquid with the reservoir. According to its structure, the model has considerable similarities with the case of the cylindrical reservoir. The practical implementation of the method is done for vibration disturbance of the system motion in the horizontal plane for the case of extended and compressed ellipsoidal reservoirs. The analysis of the character of manifestation of the dynamical behavior of the system in different ranges of frequencies of motion disturbance shows that mainly this system behaves as a system with the soft type of nonlinearities. The system output to the steady mode of oscillations is not observed. Modulation of oscillations of a liquid free surface is considerably manifested for most modes. Increased attention is paid to the study of regularities of variation of a period of the oscillation modulation. It was ascertained that due to compression of the spectrum of liquid oscillations with the increase of the wavenumber, the simultaneous considerable effect of several frequencies is manifested in the system reservoir–liquid, which leads to complex modulation envelope lines.

scholarly journals VERIFICATION OF THE CONTROL ALGORITHM FOR RESERVOIRS WITH LIQUID BASED ON THE COMPENSATION OF THE FORCE RESPONSE IN DIFFERENT RANGES OF MANIFESTATION OF NONLINEARITIES

2020 ◽  
pp. 51-56
Author(s):  
O. Limarchenko ◽  
O. Nefedov ◽  
O. Sirenko
Keyword(s):  
Free Surface ◽  
Translational Motion ◽  
Small Dimension ◽  
System Component ◽  
Force Response ◽  
Weakly Nonlinear ◽  
Nonlinear Properties ◽  
Combined Motion ◽  
Internal Forces ◽  
Controlling Actions

Problem about motion of a reservoir with liquid with a free surface is considered based on the compensation of a force response of the liquid on reservoir walls. Such an approach is selected since usual methods of control of mechanical system motion are mostly intended for linear systems of relatively small dimension. However, models of dynamics of the combined motion of reservoirs with liquid are described with relatively high-dimensional nonlinear systems ordinary differential equations. For obtaining the mathematical model of combined motion of a reservoir with liquid with a free surface we use the Hamilton–Ostrogradskiy variational principle, for which it is possible to determine analytically all internal forces of interaction of system component parts. Namely using this algorithm, we determine the main vector of forces of the liquid pressure on reservoir walls (force response of liquid). The algorithm of the motion control of the reservoir with liquid is based on the inclusion of the compensation of the liquid force response to controlling actions, this reduces the motion of the system reservoir–liquid, where the effect of forces from oscillating liquid on the reservoir motion is eliminated. This algorithm was tested for problems of impulse and vibration disturbance of the translational motion of the system in the horizontal plain. We consider the disturbance of the system motion by a force rectangular impulse applied to the reservoir wall, the duration of the impulse is lesser than a quarter of the period of a liquid free oscillations according to the first normal mode. Amplitudes of the impulse were selected with the purpose of analysis of the behavior of the controlled system in different ranges of manifestation of nonlinearities. We state the problem to verify the accuracy of this algorithm for three ranges of manifestation of nonlinear properties in the system, namely, for the linear range (amplitudes of waves on a free surface h do not exceed 0,1 of the radius of a free surface (  <0,1R); for the weakly nonlinear range (  <0,2R) and for the strongly nonlinear range with maximum amplitudes of waves about  =0,32R. Numerical modeling enables the determination of errors of developed algorithm, which does not exceed 0,5 %, although they insignificantly increase with the increase of amplitudes of oscillations on a free surface of liquid. At the same time perturbations on a free surface of liquid for the controlled motion are always greater than for the uncontrolled motion.

Profilometry of a liquid-free surface with large slope variations

1997 ◽  
Vol 36 (13) ◽  
pp. 2905
Author(s):  
Luis P. Thomas ◽  
Roberto Gratton ◽  
Beatriz M. Marino
Keyword(s):  
Free Surface ◽  
Liquid Free Surface

Методика практического восстановления параметров формы поверхностных двухмерных дефектов с учетом нелинейных свойств ферромагнетика

2021 ◽  
pp. 46-55
Author(s):  
А.В. Никитин ◽  
А.В. Михайлов ◽  
А.С. Петров ◽  
С.Э. Попов
Keyword(s):  
Magnetic Field ◽  
Free Surface ◽  
Numerical Experiments ◽  
Input Data ◽  
Metal Plate ◽  
Two Dimensional ◽  
Nonlinear Properties ◽  
Data Errors ◽  
The Magnetic Field

A technique for determining the depth and opening of a surface two-dimensional defect in a ferromagnet is presented, that is resistant to input data errors. Defects and magnetic transducers are located on opposite sides of the metal plate. The nonlinear properties of the ferromagnet are taken into account. The components of the magnetic field in the metal were reconstructed from the measured components of the magnetic field above the defect-free surface of the metal. As a result of numerical experiments, the limits of applicability of the method were obtained. The results of the technique have been verified experimentally.

scholarly journals A Meta Study on the Implications of Thermoelectric Generation on Hybrid Photovoltaic Systems

2018 ◽  
Vol 5 ◽  
pp. 104-118
Author(s):  
Jamison Ghinis ◽  
Clifford Leslie
Keyword(s):  
Hybrid Systems ◽  
Considerable Effect ◽  
Operating Conditions ◽  
Energy Output ◽  
Maximum Efficiency ◽  
Practical Implementation ◽  
Total Efficiency ◽  
Maximum Output ◽  
Pv System ◽  
Specific Temperature

The focus of this paper is a meta-study analysis of the efficiency of hybrid thermal and photovoltaic (PV) energy systems and how various materials and specific temperature ranges for thermoelectric (TE) generation can increase their efficiency. This meta-study focuses on papers obtained from ACS NANO, Scopus, Web of Science and Nature which discuss the theoretical and practical implementation of TE and PV systems, with various hybrid systems being considered. Analysed is the Figure of Merit from various hybrid TE and PV integrated systems, the effect of energy efficiency and power generation on different PV system temperatures, and output over area. The total efficiency of the hybrid system is found to have a considerable effect in all papers analysed, with an increase of 5 to 10 percent efficiency in energy output due to the thermoelectric generator (TEG) section, with this maximum efficiency occurring approximately in a 25 kelvin range [1]. A maximum output of 125 W peaks can be maintained for systems efficiently over 600 W/m2 modules, this is an up to 5 percent total efficiency increase in power output in the previously discussed 25 kelvin range [2]. The papers proposed demonstrate the more efficient implementations, potential for further study and implementation of hybrid systems within specific temperature and operating conditions.

Hydrodynamics of contact of a falling drop with a liquid free surface

2016 ◽  
Vol 51 (2) ◽  
pp. 127-135 ◽  
Author(s):  
A. Yu. Il’inykh ◽  
Yu. D. Chashechkin
Keyword(s):  
Free Surface ◽  
Liquid Free Surface
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