A Rotary Magnetic Damper or Brake Consisting of a Number of Sector Magnets and a Circular Conductor

1989 ◽  
Vol 111 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Kosuke Nagaya ◽  
Yasuo Karube
Keyword(s):  
Analytical Solution ◽  
Magnetic Flux ◽  
Eddy Current ◽  
Experimental Tests ◽  
Numerical Calculations ◽  
Damping Coefficient ◽  
Braking Force ◽  
Theoretical Results ◽  
Good Agreement

This paper is concerned with a method for analyzing a rotary magnetic damper (eddy current brake) consisting of a number of sector magnets and a circular conductor. The analytical solution to obtain an eddy current, a braking force, and a damping coefficient is obtained by dividing the magnetic flux into the narrow sectors. Numerical calculations have been carried out for the variation of the flux range, the position, and the number of the magnets. Experimental tests are also carried out to verify the present theoretical results. The theoretical results are in good agreement wtih the experimental ones.

Vibration Characteristics of Straight Blades of Asymmetrical Aerofoil Cross-Section

1969 ◽  
Vol 20 (2) ◽  
pp. 178-190 ◽  
Author(s):  
W. Carnegie ◽  
B. Dawson
Keyword(s):  
Analytical Solution ◽  
Cross Section ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Limited Range ◽  
First Order ◽  
Special Cases ◽  
Theoretical Results ◽  
Theoretical Procedure ◽  
Good Agreement

SummaryTheoretical and experimental natural frequencies and modal shapes up to the fifth mode of vibration are given for a straight blade of asymmetrical aerofoil cross-section. The theoretical procedure consists essentially of transforming the differential equations of motion into a set of simultaneous first-order equations and solving them by a step-by-step finite difference procedure. The natural frequency values are compared with results obtained by an analytical solution and with standard solutions for certain special cases. Good agreement is shown to exist between the theoretical results for the various methods presented. The equations of motion are dependent upon the coordinates of the axis of the centre of flexure of the beam relative to the centroidal axis. The effect of variations of the centre of flexure coordinates upon the frequencies and modal shapes is shown for a limited range of coordinate values. Comparison is made between the theoretical natural frequencies and modal shapes and corresponding results obtained by experiment.

Grinding Process Instability

1969 ◽  
Vol 91 (3) ◽  
pp. 597-606 ◽  
Author(s):  
B. Bartalucci ◽  
G. G. Lisini
Keyword(s):  
Closed Loop ◽  
Experimental Tests ◽  
Grinding Wheel ◽  
Closed Loop System ◽  
Regenerative Effect ◽  
Machine Tool Structure ◽  
Chatter Vibrations ◽  
Grinding Machine ◽  
Theoretical Results ◽  
Good Agreement

The paper describes a theoretical investigation on chatter vibrations of cylindrical plunge grinding. The system grinding machine-grinding wheel-workpiece is represented as a closed loop system with two feedback paths, one due to the machine tool structure, the other to the regenerative effect of the grinding wheel. Theoretical results are in good agreement with the experimental tests.

On a Magnetic Damper Consisting of a Circular Magnetic Flux and a Conductor of Arbitrary Shape. Part I: Derivation of the Damping Coefficients

1984 ◽  
Vol 106 (1) ◽  
pp. 46-51 ◽  
Author(s):  
Kosuke Nagaya ◽  
Hiroyuki Kojima
Keyword(s):  
Boundary Condition ◽  
Exact Solution ◽  
Magnetic Flux ◽  
Electromagnetic Fields ◽  
Arbitrary Shape ◽  
Fourier Expansion ◽  
Polar Coordinates ◽  
Damping Coefficients ◽  
Theoretical Results ◽  
Good Agreement

Theoretical results for finding the damping coefficients of a magnetic damper consisting of a circular magnetic flux and an arbitrarily shaped conductor have been obtained. In the analysis the exact solution in polar coordinates for the governing equation of the electromagnetic fields is utilized. The boundary condition for arbitrarily shaped boundaries of the conductor is satisfied directly by means of the Fourier expansion collocation method. To discuss the accuracy of the present approximate results, the analysis also has been performed on damper consisting of a circular flux and a circular conductor. The comparison between the present results and the exact ones for the typical damper shows very good agreement.

Calculation of eddy current losses using the electrodynamic similarity laws

2014 ◽  
Vol 63 (1) ◽  
pp. 107-114
Author(s):  
Dariusz Koteras
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Numerical Calculations ◽  
Eddy Current Losses ◽  
Similarity Laws ◽  
Good Agreement ◽  
Element Method

Abstract The results of the eddy currents losses calculations with using electrodynamics scaling were presented in this paper. Scaling rules were used for obtain the values of the eddy currents losses. For the calculations Finite Element Method was used. Numerical calculations were verified by measurements and a good agreement was obtained

scholarly journals Modeling of vapor bubble growth at subatmospheric pressures

2021 ◽  
Vol 2039 (1) ◽  
pp. 012035
Author(s):  
I V Vladyko ◽  
I P Malakhov ◽  
A S Surtaev ◽  
A A Pil’nik ◽  
A A Chernov
Keyword(s):  
Experimental Data ◽  
Analytical Solution ◽  
Growth Model ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Numerical Calculations ◽  
Superheated Water ◽  
Thermal Growth ◽  
Simulation Results ◽  
Good Agreement

Abstract In this paper, the results of numerical calculations of a vapor bubble growth in superheated water at different pressures are presented. Modeling is based on a previously developed by the authors semi-analytical solution. The results are verified by experimental data obtained at atmospheric and subatmospheric pressures. The presented simulation results and experimental data are in good agreement. The advantage of the solution over the earlier ones (based on the thermal growth model) is shown.

The Study of the Depression Occurred under Different Types of Impellers

2016 ◽  
Vol 841 ◽  
pp. 116-121 ◽  
Author(s):  
Lucian Mândrea ◽  
Gabriela Oprina ◽  
Corina Băbuţanu ◽  
Dorian Marin ◽  
Gabriel Negreanu
Keyword(s):  
Analytical Solution ◽  
Theoretical Approach ◽  
Numerical Results ◽  
Variable Radius ◽  
Different Types ◽  
Hydraulic Turbines ◽  
Theoretical Results ◽  
Good Agreement

The paper presents the analytical solution used to calculate the depression which appears under different types of impellers. This solution can be useful as a preliminary calculus to estimate the magnitude of the depression created at different rotational speeds, in order not to damage the equipment from different systems, such as hydraulic turbines. The authors obtain the variable radius of the depression zone, the pressure inside the depression zone and the depression height. The theoretical approach, the calculus itself and the numerical results presented in the article are original. In order to validate the proposed calculus, experiments were carried out using two experimental setups. The performed measurements showed a good agreement of the experimental and theoretical results.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

scholarly journals Semi-Analytical Solution to Assess CO2 Leakage in the Subsurface through Abandoned Wells

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2452
Author(s):  
Tian Qiao ◽  
Hussein Hoteit ◽  
Marwan Fahs
Keyword(s):  
Analytical Solution ◽  
Storage Site ◽  
Co2 Leakage ◽  
Transient Pressure ◽  
Flow Paths ◽  
Abandoned Wells ◽  
Diffusivity Equation ◽  
Carbon Dioxide Co2 ◽  
Good Agreement

Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of abandoned wells penetrating the reservoir caprock may cause leakage flow-paths for CO2 to the overburden. Assessment of time-varying leaky wells is a need. In this paper, we propose a new semi-analytical approach based on pressure-transient analysis to model the behavior of CO2 leakage and corresponding pressure distribution within the storage site and the overburden. Current methods assume instantaneous leakage of CO2 occurring with injection, which is not realistic. In this work, we employ the superposition in time and space to solve the diffusivity equation in 2D radial flow to approximate the transient pressure in the reservoirs. Fluid and rock compressibilities are taken into consideration, which allow calculating the breakthrough time and the leakage rate of CO2 to the overburden accurately. We use numerical simulations to verify the proposed time-dependent semi-analytical solution. The results show good agreement in both pressure and leakage rates. Sensitivity analysis is then conducted to assess different CO2 leakage scenarios to the overburden. The developed semi-analytical solution provides a new simple and practical approach to assess the potential of CO2 leakage outside the storage site. This approach is an alternative to numerical methods when detailed simulations are not feasible. Furthermore, the proposed solution can also be used to verify numerical codes, which often exhibit numerical artifacts.

scholarly journals Experimental Methods for Measuring the Viscous Friction Coefficient in Hydraulic Spool Valves

2021 ◽  
Vol 13 (13) ◽  
pp. 7174
Author(s):  
Massimo Rundo ◽  
Paolo Casoli ◽  
Antonio Lettini
Keyword(s):  
Friction Coefficient ◽  
Viscous Friction ◽  
Experimental Tests ◽  
Experimental Methods ◽  
Displacement Transducer ◽  
A Posteriori ◽  
Displacement Control ◽  
Spool Valves ◽  
The University ◽  
Good Agreement

In hydraulic components, nonlinearities are responsible for critical behaviors that make it difficult to realize a reliable mathematical model for numerical simulation. With particular reference to hydraulic spool valves, the viscous friction coefficient between the sliding and the fixed body is an unknown parameter that is normally set a posteriori in order to obtain a good agreement with the experimental data. In this paper, two different methodologies to characterize experimentally the viscous friction coefficient in a hydraulic component with spool are presented. The two approaches are significantly different and are both based on experimental tests; they were developed in two distinct laboratories in different periods of time and applied to the same flow compensator of a pump displacement control. One of the procedures was carried out at the Fluid Power Research Laboratory of the Politecnico di Torino, while the other approach was developed at the University of Parma. Both the proposed methods reached similar outcomes; moreover, neither method requires the installation of a spool displacement transducer that can significantly affect the results.

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