ACADEMIA NAVALĂ „MIRCEA CEL BĂTRÂN” CONSTANŢA BULETIN ŞTIINŢIFIC VOLUMUL XI – 2008 COLEGIUL DE REDACŢIE Redactor şef: Comandor DAN HĂULICĂ Comandantul (rectorul) Academiei Navale „Mircea cel Bătrân” Redactor şef adjunct: Cpt.cdor.prof.univ.dr.ing. GHEORGHE SAMOILESCU Membri: Academician RADU P.VOINEA – Academia Română Prof.univ.dr.ing. LORIN CANTEMIR – Universitatea Tehnică „Gh. Asachi” Iaşi Prof.univ.dr.ing. GHEORGHE BOBESCU – Universitatea „Transilvania” Braşov Prof.univ.dr.ing. VASILE CĂTUNEANU – Universitatea „Politehnica” Bucureşti Prof.univ.dr. MIRCEA LUPU – Universitatea „Transilvania” Braşov Redactori: Prof.univ.dr.ing. TRAIAN FLOREA Conf.univ.dr. ION COLŢESCU Conf.univ.dr.ing. ILIE PATRICHI Conf.univ.dr. LIDIA ATANASIU Conf.univ.dr. DELIA LUNGU Cpt.cdor.conf.univ.dr.ing. BEAZIT ALI Lt.cdor.conf.univ.dr.ing. FLORIN NICOLAE Cpt.cdor.conf.univ.dr.ing. MIHAI PRICOP Lt.cdor. DINU ATODIRESEI Secretar de redacţie: Cpt.ing. FILIP NISTOR Adresa redacţiei: Str. Fulgerului nr.1, 8700 Constanţa Tel. 0241/626200/1149; fax: 0241/643096 e-mail: [email protected] CUPRINS ELECTRICAL ENGINEERING F. BOZIANU, V. BOZIANU, The Aspects on the Electroconductor Fluid motion in the Toroidal Mercury Induit Gyro-Motor………………………………………. 5 V. DOBREF, O. TĂRĂBUŢĂ, Dynamic Modeling of the Flow of an Underwater Remotely Operated Vehicle (rov) Used Against Maritime Minefields…………………………………………………………………………... 16 V. DOBREF, O. TARABUTA, Sensorless Control of Permanent Magnet Synchronous Motor (pmsm) by the Aid of a Reference Adaptive System………...... 22 S. GHEORGHIU, F. DELIU, Electric Drives With Field Orientated Control for Naval Mechanisms……………………………………………………………….… 27 Ghe. SAMOILESCU, A.R. SAMOILESCU, The Electric Charge Accumulation to oil Tankers……………………………………………………………………….… 34 Ghe. SAMOILESCU, Specific Naval Equipment……………………………….…. 39 A. SOTIR, M. CONSTANTINESCU, Ghe. SAMOILESCU, I. DATCU, The Simulation of the Effects of the Radiant Electromagnetic Perturbations Upon a Digital Electronic Circuit Realised With a Type Risk Microcontroller…………… 44 S. GROZEANU, Experimental Researches Over the Possibility of Sea Water Propulsion by Induced Currents…………………………………………………… 51 MECHANICAL ENGINEERING AND MATHEMATICS M. PRICOP, V. ONCICA, V. CHIŢAC, The Influence of the Shallow Waters to Ship’s Hull Vertical Vibration……………………………………………………... 57 Ghe. DOGARU, A Generalization of Leibniz – Newton Formula………………… 68 Ghe. DOGARU, Computations of Some Trigonometric Sums Using Matrix Calculus…………………………………………………………………………….. 73 S. GROZEANU, T. PAZARA, An Experimental Method and Device Demonstrating Quantified Absorption of Energy by Atoms……………………….. 77 S. GROZEANU, Theoretical Researches Over the Quality Factor of an Induction Mhd Thruster……………………………………………………………………….. 83 D. LASCU, I. COLŢESCU, Solving a Gauss – Kuzmin Theorem for Rcf Using Rscc………………………………………………………………………………… 88 T. PAZARA, Sound Absorbing Materials…………………………………………. 98 I. POPOVICIU, Algebraic Domain Decomposition Methods……………………... 106 SOCIAL SCIENCES A. BALTAG, F. NISTOR, Value-Added Services of Logistics Centers in Port Areas……………………………………………………………………………….. 121 A. BEJAN, Cardiorespiratory Fitness Assessment………………………………... 126 V. ENE-VOICULESCU, Methods in The Romanian Naval Pentathlon Performance for Utility Swimming………………………………………………… 130 V. NAZARE, The Evolution of Navy Education During the Inter-War Period…… 136 V. NAZARE, The Actuality of Gusti’s Analysis Regarding Dictatorship…………. 144 N. G. OPRIŞAN, Some Elements Concerning the Assessment of the Training and the Capabilities to Performance by Physiological Testing of Swimmers………….. 151 C. C. POPA, The New Architecture of Economies’ Typology Into Globalization Context……………………………………………………………………………… 157 S. COSMA, S. COSMA, Key Performance Indicators Used in Transport Mode Benchmarking………………………………………………………………………. 162 S. COSMA, S. COSMA, Economic Acronyms…………………………………….. 172 FOREIGN LANGUAGES G. EFTIMESCU M. BOERU, Negotiation and Process Syllabus in Practice…….. 177 L. CIZER, The Conscription in France……………………………………………. 183 A. BARBU, What About Hotel California?............................................................... 185 E. KAITER, Globalization and Education...Then and Now……………………….. 189 M. C. MANOLESCU, Old vs Modern Methods of Teaching English……………... 196 R. A. MATEŞ, Person - Related American Slang…………………………………. 199 C. SANDIUC, First Day Icebreakers – Getting to Know your Students………….. 202 D. C. ZECHIA, Brainstorming on the Process of Writing…………………………. 207 4 THE ASPECTS ON THE ELECTROCONDUCTOR FLUID MOTION IN THE TOROIDAL MERCURY INDUIT GYRO-MOTOR PhD. Prof. F. BOZIANU „Mircea cel Batran” Naval Academy PhD. Eng. V. BOZIANU Abstract: In this paper the authors have tried to do their modest part to the study of the electro-kinetic and magneto-hydrodynamic phenomena occurring in the operation of the liquid armature gyro-motor both the theoretical and experimental points of view. From the studies done by the authors it results that this mercury induit rotates in concentric layers at different speeds representing a very interesting and unknown phenomenon till now. In the liquid armature electric machines, in this case, the mercury induit gyro- motor, an interaction between the magnetic field and an electro-conductor liquid (mercury) travelled by a current takes place. As a result of this interaction, the electric energy is converted into a mechanical energy of the fluid, mercury, which is the carrier of angular momentum, too. Theoretically, it has been proved that this motion is special under the electromagnetic field conditions differing from the fluid motion in the pipes in the absence of electromagnetic field; this characteristic of motion was confirmed by the experimental results. The tangential speed of the electroconductor fluid in the mercury duct is influenced by the variation of pole pitch with channel radius due to the constructional form of the toroidal stator. Experimentally, it has been found that the mercury moves in layers, their thickness depends on the relation between the intermolecular attraction forces and Lorentz forces which put in motion the electroconductor fluid. Keywords: fluid motion, gyro-motor, toroidal mercury induit 1 Considerations on the electroconductor fluid motion The problem of rotating motion of electroconductor fluids near the side walls of the channels is approached in many literature works. By admitting the existence of a boundary layer of turbulent type and that the entire viscous dissipation is caused only near the walls, we can determine the conditions which establish the speed distribution in the whole operating range of mercury gyro-motors. As compared to the classical fluid mechanics the study of electro-conductor fluid motion stability is more difficult because we must also take into account the disturbances caused by the secondary effects of the electromagnetic field. We can maintain that the presence of this field has a stabilizing effect on the motion, this is proved by experiments 5 So, Murgatroyd, analyzing the experimental results obtained by Hartmann, Lazarus, Lock etc. proposed the following criterion regarding the conversion from the laminar (viscous) flow to the turbulent flow, inside the boundary layer: H 2 th(H ) R 250 a a ecr (1) H a th(H a ) where: Ha = is Hartmann’s number given by the expression: H B R a h 2 In which: B = magnetic induction; Rh = equivalent hydraulic radius; σ = fluid electro-conductibility; η = dynamic viscosity. Branover and Lielausis, by their researches, confirmed the justness of this proposed criterion. So, by studying the electro-conductor fluid flow in the presence of electromagnetic field and by passing the semi-empirical laws of Prandtl type by Harrisi, they obtained a calculation relation for the hydraulic loss factor: 0 (1 2S) (2) where: λ0 = is the hydraulic loss factoring the absence of fields ( B, E 0 ) S = Stuart’s number H 2 S a (3) Re Among the patterns proposed by different authors, the nearest one to our pattern is the one which admits the existence of a friction layer of “disk-crown” type in the rotational motion at which the fluid has constant properties, the field is homogeneous and parallel to the disk axis. We admit the existence of only one speed component, the tangential speed which varies with the radius according to a law given by the expression: n v r (4) The flow is considered to be stationary and symmetrical about an axis, so: v v 0 ; 0 t Considering the cylindrical coordinate system (r, θ, x) with the axis x passing through the disk centre and parallel with induction B , the fluid having its density ρ, its kinetic viscosity υ and its electric conductibility σ constant, we can introduce the dimensionless values: 2 B0 r x vr v ; ; ; ; ; M 2 Fr F v M B0 v0 v0 6 M vx jr j M jx Fx ; g1 ; g2 ; g3 ; v0 B0 v0 B0 B0 (5) where: -υr ,υ0, υx are the speed components in the boundary layer; -jr , j0, jx are the current densities related to the three axes. Now, we can write the dimensionless equations of the boundary layer, such as: 2 Fr n 2 Fr 1 2 Fr (1 n)Fr Fr Fx (1 F ) 2 Fr F 1 n F 2 F (1 n)Fr Fr F Fx 2 (1 F ) (6) Fr 1 n Fx (1 n) Fr 0 Putting the limiting conditions: Fr = 0; F = 0; Fx= 0; g3= 0 pentru 0 Fr = 1; F = 1; pentru (7) By eliminating Fx from the first three equations and by integrating from 0 to ∞ for the limiting conditions we obtain the following equations: 2 2n 1 2 1 2 Fr (1 n) Fr d Fr d (1 F )d Fr d 0 0 0 0 1 n F (1 n) Fr (1 F )d Fr (1 2F )d (1 F )d 0 0 0 (8) The solution of the system (8) is determined for ξ ≥ 1 under the form of a power series with negative exponent of ξ . The first terms are kept, so we can write: 1 1 1 F e e 2 r 3 3 (9) F 1 e -Fθ is a function with monotone variation with which we can determine the dimensionless value: (1 f )d (10) 0 that marks the motion layer. We can note that its value is 1 if we use the dimensionless variables chosen. Considering those mentioned above, we admit as the parameters of the motion * layer and α, defining the maximum value of the function Fr , so that the M solutions (9) can be written under the following form: 7 1 1 2 F e e r 3 3 (11) F 1 e The parameters α and δ will be functions of ξ and they will have to prove the limiting conditions.