Search

The flow head of an orifice-type capacitive flow sensor for a conducting liquid consists of a vertically mounted metallic orifice plate in a horizontal pipeline made of insulating material and a rigidly grounded metallic ring or sensing ring placed surrounding the pipeline at a small distance from the orifice plate where the capacitance between the orifice plate and the sensing ring follows a linear relationship with flow rate as reported in the literature. In this paper, a further study on the effect of position of the sensing ring on the sensor capacitance has been carried out along with the modification of the simple parallel plate capacitance principle described in the earlier work by the real disk-type capacitance principle. From this paper, it has been observed that for any position of the sensing ring near the orifice plate, the sensor capacitance decreases linearly with the increase of flow rate and follows the modified capacitance principle similarly as that observed in earlier work. It has also been observed that the sensing ring distance-sensor capacitance product increases almost linearly with the increase of sensing ring distance. From the experimental study of the proposed orifice type capacitive flow sensors installed on two different pipelines, the said modified theory of the sensor appears to be verified in the present paper where the experimental results are reported. [ABSTRACT FROM AUTHOR]

Measurement and transmission of flow rate of a conducting liquid through a pipe line is generally done by using electromagnetic flow meter which consists of a large electromagnet and a pair of sensing electrodes along with electronic system and involves large cost and size. In the present paper, a very simple flow sensing system for a conducting liquid is proposed and this system does not require any electromagnet and involves very low cost. Moreover in modern instrumentation system the signal transmission through optical communication system is being more preferred where the transmitted signal does not suffer from measurement error due to electromagnetic interference. So an MZI based optical communication technique has been described in the present paper. The proposed technique consists of only four insulated conducting electrodes in contact with the flowing liquid along with an electro-optic system for signal conditioning and transmission of the measured signal to a remote location. The performance of the sensor and the transmission system has been analyzed in the form of a bridge network with bridge arms represented by lumped parameter polarization impedances among the electrodes. The theoretical equations explaining the operation of the bridge network with a stabilized sinusoidal ac source and MZI based electro-optic system have been derived. A proto type unit has been designed, fabricated and its function has been studied experimentally and the experimental results are reported in the paper. A very good linear characteristic under streamline condition of the proposed unit has been observed with very good repeatability and very small uncertainty of measurement. The graphical abstract is shown below. [ABSTRACT FROM AUTHOR]

Abstract: The behavior of micrometer-sized weak magnetic insulating particles migrating in a conductive liquid metal is of broad interest during strong magnetic field processing of materials. In the present paper, we develop a numerical method to investigate the solid–liquid and particle–particle interactions by using a computational fluid dynamics (CFDs) modeling. By applying a strong magnetic field, for example, 10 Tesla, the drag forces of a single spherical particle can be increased up to around 15% at a creeping flow limit. However, magnetic field effects are reduced when the Reynolds number becomes higher. For two identical particles migrating along their centerline in a conductive liquid, both the drag forces and the magnetic interaction will be influenced. Factors such as interparticle distance, Reynolds number and magnetic flux density are investigated. Shielding effects are found from the leading particle, which will subsequently induce a hydrodynamic interaction between two particles. Strong magnetic fields however do not appear to have a significant influence on the shielding effects. In addition, the magnetic interaction forces of magnetic dipole–dipole interaction and induced magneto-hydrodynamic interaction are considered. It can be found that the induced magneto-hydrodynamic interaction force highly depends on the flow field and magnetic flux density. Therefore, the interaction between insulating particles can be controlled by applying a strong magnetic field and modifying the flow field. The present research provides a better understanding of the magnetic field induced interaction during liquid metal processing, and a method of non-metallic particles manipulation for metal/ceramic based materials preparation may be proposed. [Copyright &y& Elsevier]

The polarization impedance-type flow transducer has a very simple construction in the form of four metal electrodes immersed in a conducting liquid flowing through a pipe line. The polarization impedance nonlinearly varies with excitation frequency, current density, and flow rate of the conducting liquid. Therefore, in this paper, an attempt is made to study the effect of excitation frequency on the output of electrode polarization impedance-type flow transducer. Incremental frequency plane analysis of the transducer has been performed, and its characteristic equation has been derived. An experiment is performed to study the effect of excitation frequency, and the experimental results are reported in this paper. The experimental data are found to follow the properties of electrode polarization impedance established by other workers. [ABSTRACT FROM PUBLISHER]

The flow rate of a conducting liquid is generally measured by an electromagnetic flowmeter, which requires a magnetization coil and a set of sensing electrodes. However, the size and cost of the flow head of this flowmeter generally become very high due to the large size of the magnetizing coil and core material. In this paper, a novel low-cost bridge-type technique of flow measurement of a conducting liquid has been described. In this technique, the lumped-parameter impedances among four electrodes placed at a radial distance apart in a flow-sensing tube form a Wheatstone bridge network. Each of these impedances is a combination of electrode polarization impedances and other impedances. Since the electrode polarization impedances are functions of the flow rate of the conducting liquid and some other parameters, the polarization impedances between two electrodes placed in two locations along the flow path of the conducting liquid may be taken as a measure of the flow rate of the liquid, with the other parameters remaining constant. The nonlinearity of these impedance variations with the flow rate is minimized by the proposed bridge-circuit near-balanced condition. The bridge is excited by a stabilized sinusoidal oscillator and balanced at the no-flow condition of the liquid. The output of the bridge network is converted into a 1- to 5-V dc signal in a signal conditioner circuit. The design aspects, theoretical analysis, and calibration data are presented in this paper. The experimental characteristic of the flowmeter is found to follow the theoretical equation and has good repeatability over the entire operating zone. [ABSTRACT FROM AUTHOR]

This paper considers the problem of the stability in the small of the steady‐state spinning of a rotor with a cylindrical cavity partly filled with a viscous, incompressible, conducting liquid in a magnetic field. The responses of the butt‐end boundary layers and the resultant force exerted by the liquid on the rotor performing circular precession of small radius are determined. The plane of the viscoelastic restraint parameters of the rotor axis was D‐partitioned into regions with different degrees of instability is constructed. Steady‐state spinning near the boundary of the region of stability in the space of parameters is studied assuming nonlinear responses of the supports. It is shown that passage through the boundary of the region of stability leads to bifurcation of the steady‐state spinning regime, resulting in periodic motion of the type of circular precession. The origin ofperiodic motion from steady‐state spinning can be subcritical or supercritical. [ABSTRACT FROM AUTHOR]

The problem of diffraction of a plane SH shock wave on a semi-infinite crack for a model of porous medium for the case of energy loss due to intercomponent friction is considered. Formulas for the scattered wave in terms of Laplace transforms with respect to the time are obtained. [Copyright &y& Elsevier]