Fluid Mass Distribution Research Articles

A Quantitative Ultrasonic Travel-Time Tomography to Investigate Liquid Elaborations in Industrial Processes.

This work presents an ultrasound tomography imaging system and method for quantitative mapping of the sound speed in liquid masses. It is highly desirable to be able to inspect vessel fluid mass distribution, notably in the chemical and food industrial operations. Optimization of industrial reactors has been crucial to the improvement of industrial processes. There is a great need to investigate how and if tomographic imaging sensors could aid the automatic control of these process tanks. Single-measurement ultrasound techniques and especially spectrometric methods have been a subject of study of industrial applications. Tomographic systems provide key multi-dimensional and spatial information when compared to the well-established single-channel measurement system. Recently, ultrasound tomography has attracted a great deal of interest in a wide spectrum of industrial applications. The system has been designed as 32 piezoelectric ring-array positioned in a 30 cm tank, with an excitation frequency of 40 kHz. Two-dimensional transmission travel-time tomography was developed to reconstruct the fluid mass distributions. Prior experiments are mainly based on inclusions of a few centimetres and on a liquid solution of different concentrations. They have been conducted to test the spatial and quantitative resolution of the ultrasound imaging device. Analysing the reconstructed images, it is possible to provide accurate spatial resolution with low position errors. The system also demonstrated inclusion movement with a temporal resolution of 4 frames per second (fps) in dynamical imaging sense. Sound velocity quantitative imaging was developed for the investigation of ultrasonic propagation in different liquids. This work, for the first time, shows how quantitative sound velocity imaging using transmission mode time of flight data could be used to characterize liquid density distribution of industrial reactors. The results suggest that ultrasound tomography can be used to quantitatively monitor important process parameters.

Simulation of working fluid mass distribution in small-scale Organic Rankine Cycle system under sub-critical conditions

Distribution of working fluid mass will significantly impact off-design performance of the Organic Rankine Cycle. In this paper, both the evaporator and the condenser are divided into three different zones, and the impact of heat transfer correlations and void fraction models selection on the working fluid mass calculation results have been discussed. Afterwards, impact of evaporation and condensation temperatures on working fluid mass distribution in each zone calculated by proposed correlations and models have been evaluated. Four common working fluids which feature different physical properties are taken into account. Results indicate that the selection of heat transfer correlations and void fraction models shows great importance for the calculation of working fluid mass in condenser but rarely affects the calculation results in evaporator. Accordingly, condensation correlation of Shah (1979) and void fraction model of Premoli (1971) is proposed for the discussed system. Furthermore, in condenser the working fluid mass monotonically decreases as the condensation temperature increases, while in evaporator the working fluid mass firstly rises and then falls when the evaporation temperature increases. It can be found that the relevant evaporation temperature at which the largest working fluid mass occurs is related to critical temperatures of the employed working fluids.

Stability of gravito-coupled complex gyratory astrofluids

We analyze the gravitational instability of complex rotating astrofluids in the presence of dynamic role of dark matter in a homogeneous hydrostatic equilibrium framework. The effects of the lowest-order fluid viscoelasticity, Coriolis force, fluid turbulence and inter-layer frictional coupling dynamics are concurrently considered in spatially-flat geometry. The Coriolis rotation is relative to the center of the entire fluid mass distribution, contributed by both the gyratory bright (visible) and dark (invisible) sectors, conjugated via the mutual gravitational interaction. The turbulence effects are included via the modified Larson equation of state. We use a regular Fourier-based linear perturbation analysis over the rotating fluid field equations to obtain a unique form of quartic dispersion relation with variable coefficients. We numerically carry out the dispersion analysis in two extreme limits: hydrodynamic (low-frequency) and kinetic (high-frequency) regimes. It is demonstrated that, in the former regime, the gas as well as dark matter rotations have stabilizing effects on the Jeans instability of the bi-fluidic admixture. In contrast, in the latter, the rotations play destabilizing roles on the instability. An interesting feature noted here is that the magnitude of the group velocity of the fluctuations throughout increases with both the gas and dark matter rotation frequencies, and vice-versa. We, finally, hope that the obtained results could be helpful in understanding the top-down kinetic mechanisms of bounded structure formation via gravitational collapse dynamics.

Density and Viscosity Behavior of a North Sea Crude Oil, Natural Gas Liquid, and Their Mixtures

The friction theory (f-theory) for viscosity modeling, combined with a recently developed characterization procedure, which includes an accurate method to describe the fluid mass distribution, commonly used cubic equations of state, and a Peneloux-type volume translation scheme, have been shown to accurately model the saturation pressures, densities, and viscosities of petroleum systems ranging from natural gases to heavy crude oils. The applicability of this overall modeling technique to reproduce measured bubble points, densities, and viscosities of a North Sea crude oil, a natural gas liquid, and their mixtures has been investigated. The approach has been successfully applied to the modeling of the experimental data of these fluid systems to within an acceptable accuracy.

PVT Characterization and Viscosity Modeling and Prediction of Crude Oils

In previous works, the general one-parameter friction theory ( f-theory) models have been applied to the accurate viscosity modeling of reservoir fluids. As a base, the f-theory approach requires a compositional characterization procedure for the application of an equation of state (EOS), in most cases a cubic EOS, to the description of the oil phase properties. Normally, such a procedure provides a method for characterizing an oil into a number of compound groups along with the critical constants and parameters that are required by the EOS. Thus, in this work, a compositional characterization method based on an accurate description of the fluid mass distribution is presented. The characterization procedure accurately matches the fluid saturation pressure. Additionally, a Péneloux volume translation scheme, capable of accurately reproducing the fluid density above and below the saturation pressure, is also presented. The combination of the mass characterization scheme presented in this work and the f-theory, can also deliver accurate viscosity modeling results. Additionally, depending on how extensive the compositional characterization is, the approach presented in this work may also deliver accurate viscosity predictions. The modeling approach presented in this work can deliver accurate viscosity and density modeling and prediction results over wide ranges of reservoir conditions, including the compositional changes induced by recovery processes such as gas injection.

An analysis of strong discontinuities in a saturated poro-plastic solid

We present in this paper an analysis of strong discontinuities in fully saturated porous media in the infinitesimal range. In particular, we describe the incorporation of the local effects of surfaces of discontinuity in the displacement field, and thus the singular distributions of the associated strains, from a local constitutive level to the large-scale problem characterizing the quasi-static equilibrium of the solid. The characterization of the flow of the fluid through the porous space is accomplished in this context by means of a localized (singular) distribution of the fluid content, that is, involving a regular fluid mass distribution per unit volume and a fluid mass per unit area of the discontinuity surfaces in the small scale of the material. This framework is shown to be consistent with a local continuum model of coupled poro-plasticity, with the localized fluid content arising from the dilatancy associated with the strong discontinuities. More generally, complete stress–displacement–fluid content relations are obtained along the discontinuities, thus identifying the localized dissipative mechanisms characteristic of localized failures of porous materials. The proposed framework also involves the coupled equation of conservation of fluid mass and seepage through the porous solid via Darcy's law, and considers a continuous pressure field with discontinuous gradients, thus leading to discontinuous fluid flow vectors across the strong discontinuities. All these developments are then examined in detail for the model problem of a saturated shear layer of a dilatant material. Enhanced finite element methods are developed in this framework for this particular problem. The finite elements accommodate the different localized fields described above at the element level. Several representative numerical simulations are presented illustrating the performance of the proposed numerical methods. Copyright © 1999 John Wiley & Sons, Ltd.

Slosh wave and geyser excitations due to liquid hydrogen shut-off during draining in microgravity

The dynamical behavior of liquid hydrogen shut-off during draining, and shut-off at the moment of the incipience of a suction dip have been investigated. It shows that a large amplitude surge is observed for liquid in the container at the moment of liquid hydrogen shut-off in reduced gravity. It also shows that slosh waves accompanied by a strong geyser are developed for surge-related flow fields induced by liquid hydrogen shut-off at the incipience of a suction dip. In the slosh wave excitation, both a lower gravity environment and higher flow rate before the shut-off of liquid draining are responsible for the initiation of greater amplitude slosh waves. Slosh wave excitation, due to shut-off during liquid hydrogen draining, shift the fluid mass distribution in the container which imposes time-dependent variation in the spacecraft moment of inertia. This provides important information necessary for on-orbit guidance and attitude control of spacecraft.

Liquid settlement, resettlement, slosh wave excitation and geyser motion during during reorientation in microgravity

A key objective of cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal impulsive acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. Characteristics of slosh waves of various frequencies excited by the resettling flow field are discussed. Slosh wave excitations shift the fluid mass distribution in the container which impose time dependent variations in spacecraft moment of inertia. This information is important for spacecraft control during the course of liquid reorientation.

Liquid hydrogen slosh waves excited by constant reverse gravity acceleration of geyser initiation

The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank before main engine restart poses a microgravity fluid behavior problem. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. In this study slosh wave excitation induced by the resettling flowfield during the course of liquid reorientation with the initiation of geyser for liquid-filled levels of 30, 50, 65, 70, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitations will affect the fluid stress distribution exerted on the container wall and shift the fluid mass distribution inside the container, which imposes the time-dependent variations in the moment of inertia of the container. This information is important for the spacecraft control during the course of liquid reorientation.

Medium-frequency impulsive-thrust-excited slosh waves during propellant reorientation with a geyser

Slosh wave excitation induced by a resettling flowfield activated by 1.0-Hz impulsive thrust during the course of liquid reorientation with the initiation of geyser for liquid-fill levels of 30, 50, 65, 70, and 80 percent has been studied. Characteristics of slosh waves of various frequencies excited by the resettling flowfield are discussed. Slosh wave excitations shift the fluid mass distribution in the container which imposes time-dependent variations in spacecraft moment of inertia. This information is important for spacecraft control during the course of liquid reorientation.

Excitation of slosh waves associated with low frequency impulsive reverse gravity acceleration of geyser initiation

The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank prior to main engine restart poses a microgravity fluid behavior problem. The purpose of the present study is to investigate the stability of the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. In this study slosh wave excitation induced by the resettling flow field activated by 0.1 Hz low frequency, impulsive reverse gravity acceleration, during reorientation with the initiation of geyser for liquid fill levels of 30, 50, 65, 70 and 80%, have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitations shift the fluid mass distribution in the container which impose time dependent variations in spacecraft moment of inertia. This information is important for the spacecraft control during the course of liquid reorientation.