Cylindrical Container Research Articles

Effect of heating on topology of vortex breakdown in Vogel–Escudier flow

This paper examines the effect of unstable thermal stratification on vortex breakdown in Vogel–Escudier flow. A three-dimensional direct numerical simulation of Navier–Stokes and energy equations are used to simulate a flow inside a cylindrical container generated by rotating the top lid. The top and bottom are kept at two constant temperatures such that unstable stratification is maintained. The rotation speed is related to the Reynolds number (Re), and buoyancy is linked to the Rayleigh number (Ra). The streamline and vertical velocity contour plots indicate different regimes of the flow depending on the Re and Ra. The convection dominated (CD) regime has a characteristic large-scale circulation similar to the Rayleigh–Bénard convection, and the rotation dominated (RD) regime has a central axial vortex and breakdowns. A transitional regime between RD and CD regimes is also identified from energy consideration. The influence of Ra on a vortex breakdown bubble and its relation to azimuthal vorticity is investigated in detail. Consistent with the literature on Vogel–Escudier flow, the azimuthal vorticity is shown to be essential for the breakdown in the presence of buoyancy as well. In the low Re limits, the energy of flow tends to be associated with the r–z plane velocity field, while at large Re, the energy is associated with the out-of-the-plane velocity field. Thermal plumes align along the axis for large rotations and are affected by the vortex breakdown bubble. The velocity perturbation structures and plumes show a remarkable distinction between rotation and convection-dominated regimes in the topology.

A numerical analysis on the performance of DHW storage tanks with immersed PCM cylinders

• Original model to investigate the performance of storage tanks with solar coil and PCM. • Simulation of storage tanks that serve a public swimming pool. • Simulation of storage tanks' operation in different working conditions. Thermal energy storage tanks have a fundamental role in the preparation and simultaneous distribution of domestic hot water. These tanks are supplied with thermal energy via classical means, based on electrical energy and fuel combustion, and via renewable energy sources. This study investigates the possibility of reducing the storage tank’s accumulation volume by employing phase change materials to store high densities of thermal energy at constant temperatures. A mathematical model was developed to simulate the operation of storage tanks equipped with immersed solar coil, also taking into account the addition of phase change materials encapsulated in cylindrical containers. The mathematical model was validated based on literature data. The simulation program also determines the temperature of the primary heat transfer fluids, prepared by a solar collector system and a flat plate heat exchanger coupled with a gaseous fuel boiler. The program was used to study the performance of storage tanks that serve a public swimming pool, a type of building that is characterized by a high demand of domestic hot water. To the best knowledge of the authors, this scenario was not reported in the literature. The study revealed that the nominal volume of the storage tanks can be reduced by 25% in comparison to the classic alternative, by using phase change materials as thermal storage. Also, the tanks equipped with phase change material achieved a reduction of fuel consumption and CO 2 emissions by (5.00-11.97) % in comparison to the classic solution.

Experimental study of two organic phase change materials in cylindrical containers for battery module thermal management: a comparative analysis

Thermal runaway in battery Electric Vehicles (EV) is one of the most significant threats to their safety and overall performance. In this study, the use of saturated fatty acid and paraffin wax as phase change materials stored separately in a battery-like container, which acts as a thermal absorber for heat dissipation management, is analyzed. The melting characteristics between these two materials are relatively different, as shown from the Differential Scanning Calorimetry results. The fatty acid used in this study has a narrow melting point with its peak at 56°C, while the paraffin mixture has a wide range starting from as low as 37°C. The effect of such different profiles is translated to the difference in the measured temperature profiles. In passive thermal management based on PCM alone, the latent heat capacity is more important than having a melting range when the amount of PCM as heat absorber is strictly limited. However, when the PCM is evenly distributed, the paraffin tubes would have a better thermal profile than the fatty acid ones. Meanwhile, when the air blower is operated hence forming a hybrid thermal management system, there is almost no significant difference between the two PCM under investigation.

Sloshing in vertical cylinders with circular walls: The effect of radial baffles

The behavior of sloshing eigenvalues and eigenfunctions is studied for vertical cylindrical containers that have circular walls and constant (possibly infinite) depth. The effect of breaking the axial symmetry due to the presence of radial baffles is analyzed. It occurs that the lowest eigenvalues are substantially smaller for containers with baffles going throughout the depth; moreover, all eigenvalues are simple in this case. On the other hand, the lowest eigenvalue has multiplicity two in the absence of baffle. It is shown how these properties affect the location of maxima and minima of the free surface elevation and the location of its nodes.

Physical 1g modelling of defective small-scale piled-raft systems founded in sand

The need for understanding the interaction between the elements of a piled-raft foundation system becomes relevant when one of the piles collapses, presents a defect related to the installation procedure, or when it is sought to optimise the number of piles to meet the criteria of load capacity and admissible settlement. In the paper, 20 small-scale 1g load tests were performed in model piled-raft foundations placed within a cylindrical container. Pluviated sand under vertical loading was adopted to evaluate the cross-correlated qualitative behaviour of piled rafts with and without the presence of a single defective pile in systems of four, nine and 16 piles. The defects were simulated by the variation of the length of the pile, considering it shorter or absent, at distinct positions on the system – that is, corner, edge and centre of the raft locations. The results indicate that the position of the defective pile may be more detrimental to the foundation stiffness and load capacity than the level of damage of the pile, such as the cases evolving the presence of defective piles in the corner position.

INFLUENCE OF ELECTROMAGNETIC FIELD OF EXTREMELY LOW FREQUENCIES ON HYGROSCOPIC PROPERTIES OF WHEAT GRAIN MASS

The research results of the influence of electromagnetic field (EMF) of extremely low frequencies (ELF) on hygroscopic properties of Shestopalivka wheat variety of 2019 harvest have been given. Grain processing was performed on the experimental stand that consisted of the polymeric cylindrical container for grain, solenoid coil, generator of electromagnetic waves GZ-112/1 and a power amplifier of low frequency. The output signal of generator was set in the form of sine wave and controlled by oscillograph C1-78. The studies were performed at EMF frequencies of 10, 16, 24 and 30 Hz. Magnetic induction of grain treatment was constant and equaled 10 mTl. The duration of grain processing was 6 minutes.The equilibrium moisture content of wheat grain was determined by the tensometric method at temperatures t 9 °C and 23 °C and relative humidity φ 33…36 % and 82…82.5 %. The necessary conditions of air were created in desiccators with solutions of sulfuric acid placed in thermostats and refrigerators.It has been determined that the equilibrium moisture of wheat grain processed by EMFof ELF – is in the range of 12.17…20.56 %, and unprocessed grain – in the range of 12.62…21.03 %. Regardless of the frequency of EMF, equilibrium moisture content of the grain wheat processed by EMF varies according to the known laws – decreases with temperature increase and increases with increasing of air relative humidity. It has been shown that the impact of processing by EMF of ELF on the equilibrium moisture contentof wheat grain is manifested at different frequencies in different ways, which is likely due to the resonance phenomena. It has been established that the processing of grain by EMF with frequencies of 10...30 Hz practically has no effect on the equilibrium moisture content of grain at 23 °C and a relative humidity of 33...82.5 % which remains practically at the level of the unprocessed grain. It has been shown that the processing of grain by EMF with frequencies of 24 and 30 Hz under conditions of t = 9 °C and φ = 33 % leads to higher equilibrium moisture content compared to unprocessed wheat grain from 14.45 % to 16.85...16.95 %. Processing of grain with frequencies of 10 and 16 Hz under the same conditions, on the contrary – leads to a decrease in the level of equilibrium moisture content to 13.74…13.86 %. Empirical coefficients have been determined and the equation has been proposed that describes the dependence of equilibrium moisture content of not processed and processed wheat grain by EMF with frequency 10...30 Hz on temperature and relative humidity of the ambient air.

On the shape of air–liquid interfaces with surface tension that bound rigidly rotating liquids in partially filled containers

Abstract The interface shape of a fluid in rigid body rotation about its axis and partially filling the container is often the subject of a homework problem in the first graduate fluids class. In that problem, surface tension is neglected, the interface shape is parabolic and the contact angle boundary condition is not satisfied in general. When surface tension is accounted for, the shapes exhibit much richer dependencies as a function of rotation velocity. We analyze steady interface shapes in rotating right-circular cylindrical containers under rigid body rotation in zero gravity. We pay special attention to shapes near criticality, in which the interface, or part thereof, becomes straight and parallel to the axis of rotation at certain specific rotational speeds. We examine geometries where the container is axially infinite and derive properties of their solutions. We then examine in detail two special cases of menisci in a cylindrical container: a meniscus spanning the cross-section and a meniscus forming a bubble. In each case, we develop exact solutions for the respective axial lengths as infinite series in powers of appropriate rotation parameters, and we find the respective asymptotic behaviors as the shapes approach their critical configuration. Finally, we apply the method of asymptotic approximants to yield analytical expressions for the axial lengths of the menisci over the whole range of rotation speeds. In this application, the analytical solution is employed to examine errors introduced by the assumption that the interface is a right circular cylinder; this assumption is key to the spinning bubble method used to measure surface tension.

Melting of PCM inside a novel encapsulation design for thermal energy storage system

Phase Change Materials (PCMs) encapsulated inside different shape and size enclosures have been playing an important role in designing thermal energy storage (TES) systems for a wide range of applications. In the present work, transient heat transfer and the melting process of n-octadecane PCM encapsulated in a novel Pear-Shaped Thermal Energy Storage (PS-TES) system with and without constraint are numerically investigated and verified with experimental visualizations. An adiabatic cylindrical rod, placed at the axis of symmetry of the pear-shaped enclosure, is used to create the constraint. A mathematical model is developed and numerically solved to study energy transport processes inside the proposed PS-TES systems. The heat transfer characteristics such as melt fraction, Nusselt number, and energy stored in the system and their temporal variation during the melting process are determined. The melting process is visualized numerically to track the solid-liquid interface during the melting process as well. Comparison of results from the unconstrained and constrained cases reveals that the existence of the adiabatic constraint inside the system decreases the melting rate, as the total time required to complete the melting process in the constrained melting (~178 min) is almost twice that of unconstrained melting (~97 min). The effect of the Rayleigh number on the melt fraction, Nusselt number, and the stored energy is studied and discussed as well. Furthermore, a comparison between the melt fraction results for pear-shaped system and a convectional cylindrical container with the same height and same volume shows that the complete melting time for the PS-TES system (~97 min) is less compared to the one for the cylindrical case (~108 min). A comprehensive experimental setup is also developed using a constant temperature bath and thermal regulator to visualize melting images and track the melting front during the phase change process. Numerical images of heat transfer field and solid-liquid interface, as well as the temporal variation of melt fraction in both test cases, are compared with experimental visualizations, and an excellent agreement is reported.

A semi-analytical study of the three-dimensional liquid sloshing in a horizontal cylindrical tank with an arbitrary liquid depth

In this paper, a semi-analytical study is presented to solve the linear liquid sloshing frequencies and mode shapes of a three-dimensional partially filled horizontal cylindrical container. The internal liquid of the tank is regarded as the incompressible, inviscid fluid, whose velocity potential function satisfies the Laplace function and the free surface gravity wave function. According to the sloshing modal shapes, the velocity potential function is expressed as symmetric and antisymmetric modes, respectively. The normal velocities of the fluid are set to be zero to model the rigid boundary condition on the fluid-structure interface of the container. Two coordinate systems are introduced in the model. The fluid field coordinate system is set at the midpoint of the free liquid surface. The other coordinate system, the structure coordinate system, is established at the geometric center of the tank cross-section. Through the coordinate transformation and the continuous boundary condition, the motion equation of the system could be obtained. The Galerkin method is employed to solve the governing equation and acquire the sloshing frequencies. Simultaneously, a series of experiments are carried out to investigate the sloshing movement with different liquid depths, and the low-order sloshing frequencies and mode shapes are obtained through the experiments. The accuracy of the semi-analytical method is verified by comparing the results with the published results, the finite element results, and the experimental results. The effects of the liquid depths and the tank length on the sloshing motion are investigated as well.

Formation of spiral waves in cylindrical containers under orbital excitation

The lowest swirling wave mode arising in upright circular cylinders as a response to circular orbital excitation has been widely studied in the last decade, largely due to its high practical relevance for orbitally shaken bioreactors. Our recent theoretical study (Horstmann et al., J. Fluid Mech., vol. 891, 2020, A22) revealed a damping-induced symmetry breaking mechanism that can cause spiral wave structures manifested in the so far widely disregarded higher rotating wave modes. Building on this work, we develop a linear criterion describing the degree of spiralisation and classify different spiral regimes as a function of the most relevant dimensionless groups. The analysis suggests that high Bond numbers and shallow liquid layers favour the formation of coherent spiral waves. This result paved the way to find the predicted wave structures in our interfacial sloshing experiment. We present two sets of experiments, with different characteristic damping rates, verifying the formation of both coherent and overdamped spiral waves in conformity with the theoretical predictions.

The effects of fins number and bypassed energy fraction on the solidification process of a phase change material

Nowadays, utilizing latent heat thermal energy storage systems containing phase change materials (PCMs) has been considered one of the best ways for integrating and optimizing thermal energy systems. Although using fins has been suggested by many researchers for the heat transfer enhancement in these systems, this technique is not sufficient in some cases. So, finding its reasons is the main purpose of this paper. For this aim, four different cylindrical containers, one without fins and the others with radial fins, were intended. Then, solidification of the PCM inside the containers under the constant and time-dependent first, second, and third type boundary conditions was modeled by the finite volume method based on the enthalpy formulation. To analyze fins performance, bypassed energy fraction (β) criterion was proposed. The results show that under the first type boundary condition, the value of β is zero, and the fins have a major effect on the heat transfer enhancement, but under the second and third type boundary conditions, the value of this parameter is significant, and the fins have a lower effect. Furthermore, it is found that by increasing the fins number, the value of β and complete freezing time decreased. The results of this study were compared and validated with the results of the analytical approach.

Hydrodynamic ram effect driven by a hollow spherical hypervelocity projectile

This paper presents two numerical simulations of hypervelocity impacts of a spherical hollow aluminium projectile (V0 = 2940 m/s) onto a hollow, cylindrical containment with water filling, serving as representative filling substance for fluids. The paper focuses on the following subject:(A) Numerical investigation of the unsteady, kinetic energy penetration induced flow field inside the containment.(B) Differences of the processes with and without the containment.A central requirement for this paper, is to adapt ANSYS/AUTODYN-3D solvers capabilities to compute the hypervelocity impact induced flow of the three material aggregates a) solid (aluminium, polycarbonate) b) liquid (water) c) gaseous (air) in the computational model, to bring up the gaseous cavity behind the penetrating hollow sphere. The evolution of the growth of the air cavity (diameter) in the water phase is a main result of this study. The air cavity growth is fed by the inflow of atmospheric air from outside the containment.© 2015 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Asia-Oceania Association for Fire Science and Technology.

Natural Modes of Liquid Sloshing in a Cylindrical Container with an Elastic Cover

Liquid sloshing and its interaction with an elastic cover in a cylindrical tank is considered. The velocity potential for the fluid flow is expanded into the Bessel-Fourier series as commonly used. An efficient scheme is then developed, which allows the plate deflection to use the same type of expansion as the potential. When these two series are matched on the interface of the fluid and the plate, together with the edge conditions, the unknown coefficients in the two expansions can be easily obtained. This is much more convenient than the common procedure where a different expansion is used for the plate and upon matching each term in the series of the plate is further expanded into the series used for the potential. Through the developed method, an explicit equation is derived for the natural frequencies and extensive results are provided. The corresponding natural mode shapes and principal strains distribution of the elastic cover are also investigated. Results are provided and the underlining physics is discussed. To verify the obtained results, the problem is also solved through a different method in which the potential is first expanded into vertical modes. Another explicit equation for the natural frequencies is derived. While the equation may be in a very different form, through the residual theorem, it is found that the second equation is identical to the first one.

Experimental, analytical, and numerical investigation of multi-chambered fluid-filled barrier for highway crash attenuators

Guardrail end terminals and roadside crash cushions are common technologies deployed to absorb and redirect the energy of a colliding vehicle. The purpose of these devices is to reduce damage to structures and vehicles while limiting the effects these collisions have on motorists. The primary mode of energy absorption of these structures is through physical deformation. This physical deformation can often create hazardous scenarios for vehicle occupants. This paper shows the study of a new (patent pending) crash attenuator composed of a multi-chambered, fluid-filled barrier. Kinetic energy of the colliding vehicle is transferred to the fluid and through the internal structure. As fluid moves through the structure, energy is dissipated through viscous friction; therefore, reducing the peak forces experienced by the vehicle and its occupants and reducing damage to the structure and the vehicle. Experiments were conducted using a mechanical ram to impact a dual-chambered cylindrical plastic container partially filled with water. The impact event was recorded using a high-speed camera and the acceleration impulse was measured using an accelerometer attached to the ram. The results of this study show that the addition of interior chambers and fluid decreased the reaction forces by nearly 50% and a two-fold increase in energy absorbing efficiency as compared to an empty structure. Analytical and numerical approaches were used to assess the energy dissipation due to plastic deformation of the structure. The addition of fluid and internal chamber reduced the plastic deformation of the sample by 9.1% as compared to the empty structure. This confirms the ability of the present structure to maintain low reaction forces while reducing damage to the structure and in turn increasing barrier lifetime. The present barrier technology can potentially replace existing guardrail end terminal and crash cushion systems and due to its small footprint, can be utilized in areas where traditional systems cannot be deployed due to space constraints.

Turbulent flow of liquid lead alloy in oxygen-controlled corrosion erosion test facility

The CORELLA (CORrosion Erosion test facility for Liquid Lead Alloy) facility allows corrosion erosion tests in molten lead alloys at controlled oxygen content and temperature under flowing conditions. Its exposure chamber consists of a cylindrical container, partially filled with the liquid metal. An inner rotating cylinder drives the liquid metal flow. The specimens of interest are fixed vertically inside the chamber such that the lead alloy flows around the specimens on both sides. In this numerical study, the turbulent flow of liquid lead–bismuth eutectic is solved for various specimen configurations, filling heights, and rotational speeds of the inner cylinder. Hereby, the deformation of the free liquid surface is taken into account using a rotationally symmetric approximation. Highly turbulent flow is found even for 200 rpm (revolutions per minute), the lowest rotational speed investigated. The velocity of the liquid metal along the specimens’ lateral surfaces reaches values up to 1.5 m/s for a rotational speed of 1200 rpm, the limit of experimentally stable conditions. Due to the sudden flow constrictions and expansions around the specimens, a much higher effect of the flow on corrosion erosion is expected than for simple pipe flow at the same bulk velocity.

Shear coefficient of spin viscosity estimation through velocity profiles of a ferrofluid under the effect of an external rotating magnetic field of low amplitude and frequency

The present article describes a numerical strategy for the estimation of the shear coefficient of spin viscosity for a ferrofluid sample confined to a cylindrical container and exposed to the effect of an external rotating magnetic field with a low amplitude and frequency. As far as we know, there are no experimental measurements of such coefficient. Furthermore, the few analytical values reported differ in several orders of magnitude. First, we describe briefly the mathematical model of the system and its numerical solution. Then, the definition of the direct and inverse problems is given as a part of the methodology for estimating such coefficient. Finally, we solve the inverse problem using simulated measurements and two global optimization algorithms. We generate this type of measurements by adding white Gaussian noise signals to the numerical solution of the ferrohydrodynamic mathematical model. Several noise levels in the range of 10 to 40 dB were used to increase the number of scenarios for validation purpose. Results showed an excellent agreement between the estimated values and those used in the numerical solution of the mathematical model. A statistical analysis revealed a normal distribution that was dependent on the noise level. This variation did not affect the results, but showed instead the validity of the proposed method. Additionally, this strategy stands as a computational tool for validating experimental results of the future in situ measurements. Tables 7, Figs 11, Refs 17.

Dynamic behavior of elevated and ground-supported, base-isolated, flexible, concrete cylindrical fluid containers

Liquid storage tanks are vital and have great importance in industrial facilities. One of the best ways to protect the fluid storage tanks against earthquake forces is the use of seismic isolation systems. These systems protect such structures against possible damage during an earthquake by allowing acceptable displacements at the base of the superstructures while preventing the superstructure from entering the nonlinear phases. One of the common methods for computer modeling of these structures is the use of equivalent mechanical models. It should be noted that, the mentioned equivalent mechanical models, are suggested for design of tanks by Standards and Codes. However, they are appropriate for rigid-wall tanks. On the other hand, the recent studies show that the seismic response of a rigid tank may be considerably less than that of a similar flexible tank. In this study, by using a state-of-the-art equivalent mechanical model of cylindrical concrete containers, that considers the issue of wall flexibility, the seismic responses of ground-supported and elevated concrete containers affected by the bi-directional horizontal motion of the earthquake is investigated. The results show that, by selecting the best mechanical properties of seismic base isolation systems, the seismic responses of these tanks can be greatly improved.

Numerical investigation on the thermal behavior of a Tubular-PCM-Enclosure: impact of HTF-inner tube location

The present paper summarizes a numerical study investigating the behavior of a phase change material PCM filling up a cylindrical container. The PCM is located between two tubes, the inner tube cares for the Heat Transfer Fluid HTF and it is proposed to produce a heat flux. The investigation focuses mainly on comparing the effect of changing the inner tube position, i.e., up, center, and down, in the melting process. Results showed that moving the inner tube downward leads to a decreased melting time and the rate of the thermal energy storage becomes better.

Development of a high-speed ultrasonic tomography system for measurements of rising bubbles in a horizontal cross-section

The present study deals with high-speed ultrasonic tomography (UT) as a powerful tool to characterize the behavior of multiphase flows. A major goal of the work is to improve the temporal resolution for the detection of transit flow structures and time-dependent phenomena such as the incidence of rising gas bubbles. A special transducer with a wide divergence angle of 110° and a vertical height of the measurement volume of approx. 4 mm was developed and tested. The system thus enables the acquisition of cross-sectional images at a frame rate of up to 1000 frames/s. Scatter noise was eliminated using a time series filtering method. This UT system was applied to a chain of gas bubbles rising in a cylindrical container with an internal diameter of 50 mm. The measurement system provides qualitative observations of the turbulent dynamics of bubbly flows including bubble-bubble interactions, such as the coalescence of individual bubbles.

Counterflow slip in a two-fluid whirlpool

This experimental study reveals a counterflow slip at the interface of two immiscible fluids filling a sealed vertical cylindrical container whose bottom disk rotates while other walls are stationary. An advanced particle image velocimetry helps us analyze and quantify streamline patterns and velocity profiles of the steady axisymmetric flows of both fluids. As the angular velocity of a disk increases, starting from zero, three changes occur in topology of the upper-fluid flow while topology of the lower-fluid flow remains invariant. These changes result in the counterflow slip at the entire interface, whose nature is speculatively discussed and requires further research.