On Interaction Of A Liquid Film With An Obstacle

In this paper mathematical models for liquid films generated by impinging jets are discussed. Attention is stressed to the interaction of the liquid film with some obstacle. S. G. Taylor [Proc. R. Soc. London Ser. A 253, 313 (1959)] found that the liquid film generated by impinging jets is very sensitive to properties of the wire which was used as an obstacle. The aim of this presentation is to propose a modification of the Taylor's model, which allows to simulate the film shape in cases, when the angle between jets is different from 180°. Numerical results obtained by discussed models give two different shapes of the liquid film similar as in Taylors experiments. These two shapes depend on the regime: either droplets are produced close to the obstacle or not. The difference between two regimes becomes larger if the angle between jets decreases. Existence of such two regimes can be very essential for some applications of impinging jets, if the generated liquid film can have a contact with obstacles

EJ-HEAT: A Fast Explicit Jump Harmonic Averaging Solver for the Effective Heat Conductivity of Composite Materials

The stationary heat equation is solved with periodic boundary conditions in geometrically complex composite materials with high contrast in the thermal conductivities of the individual phases. This is achieved by harmonic averaging and explicitly introducing the jumps across the material interfaces as additional variables. The continuity of the heat flux yields the needed extra equations for these variables. A Schur-complent formulation for the new variables is derived that is solved using the FFT and BiCGStab methods. The EJ-HEAT solver is given as a 3-page Matlab program in the Appendix. The C++ implementation is used for material design studies. It solves 3-dimensional problems with around 190 Mio variables on a 64-bit AMD Opteron desktop system in less than 6 GB memory and in minutes to hours, depending on the contrast and required accuracy. The approach may also be used to compute effective electric conductivities because they are governed by the stationary heat equation

On Interaction Of A Liquid Film With An Obstacle

In this paper mathematical models for liquid films generated by impinging jets are discussed. Attention is stressed to the interaction of the liquid film with some obstacle. S. G. Taylor [Proc. R. Soc. London Ser. A 253, 313 (1959)] found that the liquid film generated by impinging jets is very sensitive to properties of the wire which was used as an obstacle. The aim of this presentation is to propose a modification of the Taylor's model, which allows to simulate the film shape in cases, when the angle between jets is different from 180°. Numerical results obtained by discussed models give two different shapes of the liquid film similar as in Taylors experiments. These two shapes depend on the regime: either droplets are produced close to the obstacle or not. The difference between two regimes becomes larger if the angle between jets decreases. Existence of such two regimes can be very essential for some applications of impinging jets, if the generated liquid film can have a contact with obstacles

EJ-HEAT: A Fast Explicit Jump Harmonic Averaging Solver for the Effective Heat Conductivity of Composite Materials

The stationary heat equation is solved with periodic boundary conditions in geometrically complex composite materials with high contrast in the thermal conductivities of the individual phases. This is achieved by harmonic averaging and explicitly introducing the jumps across the material interfaces as additional variables. The continuity of the heat flux yields the needed extra equations for these variables. A Schur-complent formulation for the new variables is derived that is solved using the FFT and BiCGStab methods. The EJ-HEAT solver is given as a 3-page Matlab program in the Appendix. The C++ implementation is used for material design studies. It solves 3-dimensional problems with around 190 Mio variables on a 64-bit AMD Opteron desktop system in less than 6 GB memory and in minutes to hours, depending on the contrast and required accuracy. The approach may also be used to compute effective electric conductivities because they are governed by the stationary heat equation

Traenkverfahren und Vorrichtung zur Ueberwachung der Durchtraenkung eines Traegermaterials

DE 19745404 A UPAB: 19990603 NOVELTY - For the impregnation of a carrier material, by immersion, the dielectric constant of the material changes during impregnation. A value (C) is measured, related to the dielectric constant, which gives the impregnating penetration (D) of the carrier material. DETAILED DESCRIPTION - In an INDEPENDENT CLAIM the monitoring system has a conductor (3) so that the carrier material acts as a dielectric to affect the electrical capacity of the conductor (3), which is measured. The conductor can be an electrically conductive strip, around the carrier material, with the electrical lead of the conductor rod. To measure the value (C), the electrical capacity is used of an electrical conductor, with the carrier material acting as a dielectric. The timed run (C(t)) of the measurement gives the timed run (D(t)) of the impregnation. A functional relationship (DR(C)) between a reference impregnation (DR) and the measured value gives the functional relationship of the impregnation. The timed run (D(t)) of the impregnation (D) is expressed as D(t)=DR(C(t)), where D is the impregnation, DR the reference impregnation, C the measured value and especially capacity, and t is the time. The amount of impregnation is defined as the ratio of impregnated and non-impregnated vols. of the carrier material. To determine the stages of impregnation, according to given parameters, each stage has a reference impregnation provided by a simulation model with a spaced distribution in the carrier material with at least one zone which is not impregnated and one zone which is impregnated. At least one dry zone (4) has an initial dielectric constant and at least one damp zone (5) has another dielectric constant. Each reference impregnation (DR), together with the dielectric constants, is associated with a measured value (C) to give the required functional relationship (CD(C)). Using a porous carrier material, the spaced distribution of the reference impregnation (DR) uses the Darcy law for a current of a Newton impregnation medium or by using a suitable modification of the Darcy law for a non-Newton impregnation medium. From the impregnation (D), the penetration depth is derived of the impregnation medium in the carrier material, in a timed run of the penetration and at least one factor of the filtration coefficient, flow resistance, permeability and relative porosity, which also gives the viscosity of the impregnating medium. The material can be the fibers, to be impregnated and form the compound material, or the carrier material is an electrical insulation. USE - The system is for the impregnation of a carrier for use in resin transfer molding, using a compound material of fibers impregnated with a resin. It can be used for applications such as for the insulation of a conductor rod at the stator of a generator and especially a turbo generator, or the impregnation of the coil of the stator of a generator, and especially a turbo generator, in a total immersion impregnation, and the impregnation indicates if there is an impregnation fault. ADVANTAGE - The system gives an effective impregnation of the carrier material, with positive indications of a fault in the process

A method for the analysis and control of mica tape impregnation processes

The impregnation of mica tape insulations usually is monitored with dielectric capacitance measurements. In this work, a method is developed that translates measured capacitance and loss into an average drag coefficient that characterizes flow resistance, which is the critical parameter of the process. In a first step, the impregnation depth is determined based on an appropriate model of the dielectric measurement. The impregnation depth curve and its derivative are then used to compute the average drag coefficient, which is defined in the framework of a standard porous media flow model. The method has been developed and tested for cylindrical insulators. Appropriate extensions to rectangular insulators are indicated

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