Elastic Tank Research Articles

ОЦЕНКА ВОЗМОЖНОСТИ ЭСКАЛАЦИИ ПОЖАРА ПРИ ХРАНЕНИИ МОТОРНЫХ ТОПЛИВ В ПОЛИМЕРНЫХ ЭЛАСТИЧНЫХ РЕЗЕРВУАРАХ

Due to the increase in oil production and production of petroleum products, as well as their transportation and storage, the range and sizes of reservoirs are increasing. For this purpose, polymer tanks are widely used at Russian enterprises of the fuel and energy complex, including mobile tank farmsand oil depots for the operational storage of oil and petroleum products. However, the polymer materials from which the tanks are made are flammable, which increases their fire hazard level. An assessment of the possibility of fire escalation has been carried out using the example of an oil depot model for storing motor fuels in polymer elastic tanks. The results 
 of calculating the dangerous factors of a spill fire during depressurization of polymer elastic tanks with gasoline and diesel fuel, as well as a graph of the dependence of the intensity of thermal radiation during the ignition of these tanks, are presented in tabular form, and an event tree is constructed. The parameters characterizing the possible escalation of a fire at a motor fuel storage site under quasi-stationary conditions have been determined.
 A methodology is proposed that allows assessing the possibility of realizing the escalating nature of a fire at facilities for storing and handling motor fuels in polymer elastic tanks, and recommendations are also given to prevent the progressive nature of the development of negative events and reduce damage in case of fire.

Experimental study on the wind-induced buckling of open-top storage tanks with wind girders via 3D-DIC technique

Large open-top storage tanks are susceptible to buckling failure under the combination of external and internal wind pressures. Therefore, wind girders are recommended to be installed on the tank wall to improve its buckling capacity. Most previous experiments on buckling of cylindrical shells typically measured the response at a certain point with a single displacement sensor, and the buckling modes are not readily available. In this study, a measurement technique based on the three-dimensional digital image correlation method is utilized to analyze the buckling behavior of several elastic tank models with aspect ratios of 0.5 and 0.2 in the boundary layer turbulence. The critical buckling pressure and instantaneous displacement field on the windward side of models with and without wind girders are presented and compared with the results of finite element analysis. In addition, the effects of wind girders and imperfections are further discussed. The results indicate that the deformation of the tank wall can change the wind pressure, making it more difficult to return to the pre-buckling state. The wind girders can significantly restrain the buckling deformation and increase the critical buckling load. However, as the wind girders become rigid, the strengthening effect becomes almost constant, and the stiffened tanks are more sensitive to initial geometric imperfections. Based on the cylindrical shell buckling theory and existing calculation methods, an empirical formula for the critical buckling wind pressure of open-top storage tanks with different numbers of wind girders in the boundary layer is proposed.

The Mutual Effect Study of Horizontal and Vertical Loads on the Elastic Tank Partially Filled with Liquid

Modern equipment elements in the energy, chemical industry, transport, aviation, and space engineering work under conditions of increased technological loads, at high temperatures and pressure levels. At the same time, the equipment is usually exposed to external loads of various natures. Hydroelastic phenomena must also be taken into account in designing and modernizing tanks and storage facilities for flammable and combustible substances. Flammable and combustible liquid accumulation leads to the increased environmental and fire hazard of such objects. The possible dangerous liquid leakage and tank depressurization negatively affect the surrounding area environment state. A fire in the tank is one of the most dangerous emergencies that could lead both to significant material and environmental damage and to human casualties. The paper treats the environmental hazards reducing problem from liquid hydrocarbon spills from storage tanks, which lead to destructive effects on all environment components especially during emergency situations. It has been established for sufficiently thin tank elastic walls, the fundamental frequency during coupled oscillations could be much lower than the frequency of the fluid in the shell with rigid walls. As the thickness of the tank wall increases, this effect becomes insignificant, and the lower oscillation frequency of the shell with liquid approaches the oscillation frequency of the liquid in a rigid tank. Parametric resonance and sub-resonance effects have been treated.

The influence of fluid-structure interactions 2-ways on dynamic characteristics of flexible tank

This paper investigates the influence of two-way fluid-structure interactions (FSI) on the dynamic characteristics of flexible storage liquid tanks. A coupled finite volume method FVM and finite element method FEM (FVM/FEM) was developed to simulate a flexible water tank subjected to seismic loading. FVM is used to simulate the fluid domain and FEM is used to capture the structural domain. The two-dimensional interaction equation is solved at the contact surface between the elastic tank wall and the fluid by tuning the relaxation parameter and convergence conditions. The model investigates the influence of considering two-way FSI on the dynamic characteristics of a tank flexible to a rigid tank wall. The results show that the frequency of flexible tank walls differs from that of rigid walls, especially the hydrodynamic pressure of liquid motion acting on the tank. A “threshold value” is revealed to distinguish flexible or rigid tanks. If the tank stiffness exceeds this threshold, then the thicker the tank is, the lower the hydrodynamic pressure. However, if the tank stiffness is less than this threshold, the thinner the tank is, the lower the hydrodynamic pressure. Further experiments on a fluid container under harmonic excitation are carried out using a shaking table to verify the dynamic behavior in comparison to numerical results. Good agreement is observed between numerical, analytical, published, and experimental data.

Hydroelastic linearized vibrations taking into account prestressed effects due to internal liquid weight: Numerical vs. experimental results

This paper concerns the numerical simulation of the hydroelastic vibrations of an elastic tank containing a free surface liquid, around a geometrically nonlinear equilibrium configuration that takes into account the prestress effect due to the liquid weight. The computational methodology is the following. Firstly, the hydrostatic pressure on the fluid–structure interface is considered as a non-uniform follower force which depends on the liquid height. Therefore, the prestressed equilibrium at a given free-surface level, called current configuration in the paper, is computed as a geometrically nonlinear problem, in which the height of the liquid is considered as an evolution parameter. We start from an empty structure, defined as the reference configuration, which is progressively filled to reach the level of the chosen configuration. Therefore the calculation of hydroelastic vibrations of a tank filled with liquid as a function of a emptying rate is straightforward. The methodology is validated with experimental results extracted from literature.

Hydroelastic vibrations of shells of revolution under combined vertical and horizontal loadings

The operation of modern structures occurs under conditions of high technological loads. Shells of rotation are among the most applicable structural elements. The operating conditions of such elements provide for the influence of the environment such as the interaction of elastic shell elements with liquid or gas. The oscillations of the elastic shell of rotation, which are partially filled with liquid, under external loads in the vertical and horizontal directions simultaneously, are considered in the paper. The liquid is supposed to be ideal and incompressible, and its motion under the applied loads is irrotational. This allows us to introduce the velocity potential to calculate the pressure of the fluid on the surface of the shell and determine the function which describes the level of the free surface lift. At the first stage, the frequencies and forms of free oscillations of the shell with liquid are determined. These frequencies are usually divided into two separate spectra: the free surface vibration frequency and the elastic wall vibration frequency. The boundary element method is used for numerical implementation. It is found that for sufficiently thin elastic tank walls, the fundamental frequency of the coupled vibrations can be much lower than the frequency of the fluid in a shell with rigid walls. As the tank wall thickness increases, this effect becomes insignificant, and the lower vibration frequency of the shell with liquid approaches the vibration frequency of the liquid in a rigid tank. The second stage of the study is related to the analysis of combined horizontal and vertical loads. The cases when the load frequencies are close to the fundamental frequency of sloshing and to the lower frequency of vibration of elastic walls are considered. The effect of parametric resonance has been investigated. The influence of the presence of partitions on the motion of the shell with the liquid at free and forced oscillations has been found out.

Change of the form of the vertical elastic tank with a liquid

The kind of a hydrostatic equation for the vertical elastic tank, for example, a fuel tank of a rocket on a starting table is proved. The hydrostatic equation is received on the basis of specified Bernoullis equation. The substantiation is lead with the help of Laplaces formula for pressure under an elastic surface of a liquid which can arise both due to forces of a superficial tension, and due to an elastic thin-walled shell as in the present task. The form of the vertical elastic tank with a rigid bottom and the rigid top band, filled with a lied liquid is received. It is shown that it is necessary to use special record of the Gooks law for reception of the form of the tank. The analysis of this form is carried out. Distribution on height of the tank of hydrostatic pressure, volumetric density of energy of the stretched elastic wall, and also the sum of these sizes is shown. Hydrostatic pressure at which level there is a maximal increase in the area of the elastic tank is found.

Топливопроницаемость термопластичных полиуретанов после воздействия соляного тумана

The effect of salt mist exposure on the surface structure and permeability of thermoplastic polyurethane used in the production of temporary storage tanks and transportation of diesel fuel was investigated. After exposure to salt mist, the analysis of microphotographs showed the alignment of the surface of the polymer material. IR spectroscopy revealed a change in the chemical composition of thermoplastic polyurethane, and the appearance of a quaternary ammonium salt, which leads to an increase in the polarity of polymer macromolecules and increases the relaxation rate of the polymer material structure. An approach to modeling the natural loss of diesel fuel during storage in elastic tanks is proposed. The model parameters allowed us to quantify the effect of salt mist on the diffusion permeability of thermoplastic polyurethane for diesel fuel. At a storage temperature below 60 °C after exposure to salt mist, the tightness time increases and the natural loss of diesel fuel decreases during storage in the tank.

A process to verify numerical models for seismic fluid-structure interaction in advanced reactor vessels

Seismic design and qualification of a liquid-filled advanced nuclear reactor will have to account for fluid-structure interaction (FSI). Interaction between the tank, internal components, and contained liquid will rely on analysis of numerical models that must be verified and validated. This study demonstrates a verification process for models of a base-supported cylindrical tank by comparing numerical predictions and analytical solutions. The numerical models are consistent with the assumptions made to derive analytical solutions, namely, either a rigid or a linear elastic tank, ideal fluid, and small-amplitude, unidirectional, horizontal inputs. One software platform is used to illustrate the process. Seismic FSI analysis is performed using the Arbitrary Lagrangian-Eulerian (ALE) and Incompressible Computational Fluid Dynamics (ICFD) solvers in LS-DYNA. Reported responses are those used for design, including hydrodynamic pressures on the tank wall, shear forces and moments at the tank base, and wave heights of the contained liquid. The accuracy of the numerical results is discussed. The numerical models are verified for calculating the pressures on the tank wall and reactions at its base. Accurate simulation of wave action is challenging for both solvers. Recommendations for modeling, code development, and steps for verification are provided. Although focused on reactor vessels and one software platform, the verification process described herein is broadly applicable to liquid-filled vessels and other finite element codes.

Abrasion of Thermoplastic Polyurethanes for Elastic Tanks Intended for Temporary Fuel Storage

Abrasion of Thermoplastic Polyurethanes for Elastic Tanks Intended for Temporary Fuel Storage

Procedure for evaluation of tightness of polymer tanks for transportation of fuel by air

The analysis of methods for assessing the diffusion permeability of polymer materials is carried out. The limitations of the methods for determining the tightness time and the rate of fuel bleeding from elastic tanks based on thermoplastic polyurethanes are shown. To solve the set tasks, an approach is proposed related to establishing dependencies of the kinetics of diesel fuel bleeding in the coordinate system of the conditional time, which was calculated as the square root of the process time. The tightness time and rate of fuel bleeding depends on the degree of filling of the tank during testing.

Methods and Technologies for Creating a New Generation of Fuel Storage and Transportation Facilities

The main scientific an practical results in the field of creating petroleum products supply facilities of a new generation based on the modified polymeric materials are presented. The technical requirements, evaluation methods, techniques and technologies for the modification of polymeric materials to create elastic tanks and pressure lay-flat pipelines for fuel are presented. The compliance of the operational properties of the developed fuel storage and transportation facilities with the modern requirements has been established.

Uncertainty quantification for dynamics of geometrically nonlinear structures coupled with internal acoustic fluids in presence of sloshing and capillarity

In this paper, we propose an uncertainty quantification analysis, which is the continuation of a recent work performed in a deterministic framework. The fluid–structure system under consideration is the one experimentally studied in the sixties by Abramson, Kana, and Lindholm from the Southwest Research Institute under NASA contract. This coupled system is constituted of a linear acoustic liquid contained in an elastic tank that undergoes finite dynamical displacements, inducing geometrical nonlinear effects in the structure. The liquid has a free surface on which sloshing and capillarity effects are taken into account. The problem is expressed in terms of the acoustic pressure field in the fluid, of the displacement field of the elastic structure, and of the normal elevation field of the free surface. The nonlinear reduced-order model constructed in the recent work evoked above is reused for implementing the nonparametric probabilistic approach of uncertainties. The objective of this paper is to present a sensitivity analysis of this coupled fluid–structure system with respect to uncertainties and to use a classical statistical inverse problem for carrying out the experimental identification of the hyperparameter of the stochastic model. The analysis show a significant sensitivity of the displacement of the structure, of the acoustic pressure in the liquid, and of the free-surface elevation to uncertainties in both linear and geometrically nonlinear simulations.

Experimental study on characteristic of sloshing impact load in elastic tank with low and partial filling under rolling coupled pitching

A series of experiments covering lowest three natural frequencies of rolling coupled pitching were conducted to investigate liquid sloshing with low liquid depth. The test results show that the most violent liquid sloshing in rolling and pitching is located in the vicinity of the first order natural frequency (f1). When the excitation frequency of rolling and pitching is located between 0.98f1 and 1.113f1, roof-bursting phenomenon of liquid appeared, and the maximum impact pressure is at 1.09f1. When the external excitation frequency is at 1.113f1, the number of sloshing shocks decreases sharply. Furthermore, the space distribution of the impact pressure on the left bulkhead and the top bulkhead was analyzed. It is concluded that with low liquid filling, the impact load is greater near the free surface and the top of tank, and the impact position of the side bulkhead increases with the increasing of the frequency near the resonant frequency.

Numerical Study of 3-D Liquid Sloshing in an Elastic Tank by MPS-FEM Coupled Method

The sloshing phenomenon in a partially loaded oil tanker or liquid natural gas ship is a typical fluid-structure interaction problem involving multi-physics, violent free-surface flow, and nonlinear structural response. In the past decades, the complex phenomenon has been commonly investigated without consideration of the hydro-elastic behaviors of the bulkheads. In our previous work, the liquid sloshing phenomenon in a two-dimensional (2-D) elastic tank was numerically studied. However, the bulkheads of the tank will deform within the three-dimensional (3-D) space in reality. So, it is necessary to study the 3-D sloshing problem in an elastic tank. In this article, a hybrid approach is developed within the Lagrangian system. The moving particle semiimplicit (MPS) method is used to simulate the evolution of 3-D flow with a violent free surface, and the finite element method (FEM) is used for the numerical analysis of structural response due to the impact loads of the sloshing flow. To couple the MPS method and the FEM method, an interpolation scheme based on the kernel function of the particle method is proposed for the communication on the isomerous interface between the fluid and structure domains. The reliability of force and deformation interpolation modules is validated by two tests. Then, the sloshing phenomenon in a 3-D elastic tank is numerically investigated and compared against the previous published 2-D results. By varying the Young's modulus of the tank walls, characteristics regarding the evolutions of free surface, variation of impact pressures, and dynamic responses of the structures are presented. 1. Introduction To support the transportation demands of natural resources, more and more vessels, such as the very large crude carriers and the liquid natural gas carriers, are manufactured. For these huge structures, risks such as local deformation or even damage of cargo-containment systems resulting from sloshing phenomena subsequently increase. Therefore, it is necessary to take the elasticity of the tank walls into account in the research of sloshing phenomena (Dias & Ghidaglia 2018). However, the phenomena involving the vibrations of the tank walls are complex. In the process of sloshing wave interacting with elastic bulkheads, the fragmentation, splash, and fusion of water are observed. Meanwhile, the structures vibrate nonlinearly under the impact loads resulting from the sloshing wave. These phenomena are hard to simulate realistically by the traditional mesh-based methods.

Abradability of Thermoplastic Polyurethane for Flexible Fuel Storage Tanks

In this paper, we analyzed various methods for abradability testing polymer materials. An optimal test method reflecting the operating conditions of the elastic tank was established. The method takes into account the duration of the abrasive action at a constant friction force and varying friction force. A model that relates the duration of the action of a constant friction force and various friction force is obtained. A complex relationship between abradability and the friction force is shown.

Experimental Study on the Influence of External Excitation Frequency Change on Liquid Sloshing Impact in Elastic Tank

The sloshing impact of liquid in elastic tank under combined excitation was studied by physical model experiments, and the sloshing impact characteristics of liquid on the side wall of tank with low liquid loading rate under different external excitation frequencies were analyzed. The results show that under the combined excitation of rolling and pitching motion, the sloshing impact load at the free surface is the largest, while the sloshing impact load far from the free liquid surface is smaller. However, when the external excitation frequency of rolling and pitching motion is located at the resonant frequency and larger than resonant frequency, the sloshing impact load in individual regions appears abnormal phenomenon. When the external excitation frequency of rolling and pitching moves from far away from the resonance frequency to near or even slightly beyond the resonance frequency, the sloshing impact load at the free liquid surface presents a small decline stage, a sharp rise stage and a small rise stage, respectively.

Elastic response of a light-weight floating support structure of FOWT with guywire supported tower

To obtain fundamental knowledge on the elastic response characteristics of a light-weight floating support structure of a FOWT (floating offshore wind turbine) with guywire supported tower, basic load transmission mechanism was investigated. Static analysis with elastic frame model, numerical analysis and wave tank experiment with elastically and dynamically similar segmented backbone model were conducted to clarify the dynamic elastic response characteristics of the structure. In the numerical analysis, analysis code of a rotor-floater-mooring-control coupled response NK-UTWind developed in University of Tokyo is used. It is clarified that when the rigidity of the frame structural part is low compared with guywire, the load is mainly borne by guywire under pitch motion. It was found that the tension fluctuation of guywire becomes large at wave period of 6 s when the inertial force due to pitch motion is large, and at wave period of 18–20 s when inclination of tower is larger the tension fluctuation also becomes large due to the overturning moment.

Experimental Study on Sloshing Characteristics in the Elastic Tank Based on Morlet Wavelet Transform

Hydroelastic effect of sloshing is studied through an experimental investigation. Different excitation frequencies are considered with low-fill-depth and large amplitude. Morlet wavelet transform is introduced to analyze the free surface elevations and sloshing pressures. It focuses on variations and distributions of the wavelet energy in elastic tanks. The evolutions of theoretical and experimental wavelet spectra are discussed and the corresponding Fourier spectrums are compared. Afterwards, average values of the wavelet spectra are extracted to do a quantitative study at various points. From the wavelet analysis, sloshing energies are mainly distributed around the external excitation frequency and expanded to high frequencies under violent condition. In resonance, experimental wavelet energy of the elevation in elastic tanks is obviously less than that in the rigid one; for sloshing pressures, the elastic wavelet energy close to the rigid one and conspicuous impulse is observed. It recommends engineers to concern the primary natural frequency and impulsive peak pressures.

MPS-FEM coupled method for sloshing flows in an elastic tank

As more and more liquid carriers with huge size are manufactured to support the transportation demand of natural resources, risks such as local deformation or even damage of cargo containment systems resulting from sloshing phenomenon subsequently increase, and it's necessary to take the elasticity of tank walls into account in the researches of sloshing phenomenon. In present paper, we numerically studied the interaction between liquid sloshing flow and elastic bulkheads of liquid carrier by fully Lagrangian particle method, MLParticle-SJTU solver, which is an in-house solver developed based on the moving particle semi-implicit (MPS) method. Coupled with the finite element method (FEM), the MLParticle-SJTU solver is extended to numerical analysis of elastic structural response due to the impact loads of sloshing flows. To validate the feasibility of the MPS-FEM coupled solver in dealing with fluid structure interaction (FSI) problems, a benchmark of dam-breaking flow interacting with elastic lateral wall is studied firstly and results show good agreement with published data. Then, the sloshing phenomenon in an elastic tank is numerically investigated. By varying the Young's modulus of tank walls, interesting characteristics regarding evolutions of free surface, variation of impact pressures, dynamic responses of the structures in both time and frequency domains are presented.