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Liquid Slosh Damping: Experimental and Numerical Developments

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (15 June 2022) | Viewed by 11754

Special Issue Editor


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Guest Editor
Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
Interests: computational fluid dynamics; CFD

Special Issue Information

Dear Colleagues,

This Special Issue is devoted to new developments in the quantification of liquid-slosh-induced energy dissipation resulting from the EU H2020 Sloshing Wing Dynamics (SLOWD) project. SLOWD aims to investigate the use of fuel slosh to reduce the design loads on aircraft structures. This goal is being achieved through investigating the damping effect of sloshing on the dynamics of flexible wing-like structures carrying liquid (fuel) via the development of experimental set-ups complemented by novel numerical and analytical tools. This Special Issue includes related novel developments which include industrially relevant CFD benchmark solutions. The key data presented in the articles will be available online.

Prof. Dr. Arnaud Malan
Guest Editor

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Keywords

  • liquid slosh damping
  • Sloshing Wing Dynamics (SLOWD)
  • aircraft structures
  • CFD benchmark solutions

Published Papers (7 papers)

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Research

31 pages, 31657 KiB  
Article
Numerical Calculation of Slosh Dissipation
by Leon Cillie Malan, Chiara Pilloton, Andrea Colagrossi and Arnaud George Malan
Appl. Sci. 2022, 12(23), 12390; https://doi.org/10.3390/app122312390 - 3 Dec 2022
Cited by 5 | Viewed by 1325
Abstract
As part of the Sloshing Wing Dynamics H2020 EU project, an experimental campaign was conducted to study slosh-induced damping in a vertically excited tank filled with liquid water or oil and air. In this work, we simulate these experiments using two numerical approaches. [...] Read more.
As part of the Sloshing Wing Dynamics H2020 EU project, an experimental campaign was conducted to study slosh-induced damping in a vertically excited tank filled with liquid water or oil and air. In this work, we simulate these experiments using two numerical approaches. First, a single-phase, weakly compressible liquid model is used, and the gas flow (air) is not modeled. For this approach, a proven Smoothed Particle Hydrodynamics (SPH) model is used. In the second approach, both phases are simulated with an incompressible liquid and weakly compressible gas model via a Finite Volume Method (FVM) using Volume-of-Fluid (VOF) to track the liquid phase. In both approaches, the energy distribution of the flow is calculated over time in two- and three-dimensional simulations. It is found that there is reasonable agreement on the energy dissipation evolution between the methods. Both approaches show converging results in 2D simulations, although the SPH simulations seem to have a faster convergence rate. In general, the SPH results tend to overpredict the total dissipation compared to the experiment, while the finite volume 2D results underpredict it. Time histories of the center of mass positions are also compared. The SPH results show a much larger vertical center of mass motion compared to the FVM results, which is more pronounced for the high Reynolds number (water) case, probably linked to the absence of the air phase. On the other hand, the limited center of mass motion of the FVM could be linked to the need for higher spatial resolutions in order to resolve the complex gas–liquid interactions, particularly in 3D. Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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20 pages, 1664 KiB  
Article
Embedded One-Dimensional Orifice Elements for Slosh Load Calculations in Volume-Of-Fluid CFD
by Elrich Botha, Leon Cillie Malan and Arnaud George Malan
Appl. Sci. 2022, 12(23), 11909; https://doi.org/10.3390/app122311909 - 22 Nov 2022
Cited by 1 | Viewed by 1490
Abstract
For CFD liquid sloshing simulations, fine computational mesh resolutions are typically required to model the flow within small flow passages or orifices found in fuel tanks. This work presents a method of replacing the fine computational mesh elements within orifices with large one-dimensional [...] Read more.
For CFD liquid sloshing simulations, fine computational mesh resolutions are typically required to model the flow within small flow passages or orifices found in fuel tanks. This work presents a method of replacing the fine computational mesh elements within orifices with large one-dimensional mesh elements that integrate seamlessly with standard finite volume computational elements with the intended advantage of reducing the overall computational cost of CFD simulations. These one-dimensional elements conserve mass and momentum for two-phase flow in incompressible Volume-Of-Fluid CFD. Instead of fully resolving the momentum diffusion term, empirical correlations are used to account for the viscous losses within the orifices for both two- and three-dimensional simulations. The one-dimensional orifice elements are developed and validated against analytical and experimental results using the finite volume CFD code Elemental®. Furthermore, these elements are tested in a violent sloshing simulation and compared with full-resolution numerical results as well as experimental results. The elements are shown to decrease computational cost significantly by reducing the number of computational elements as well as increasing the simulation time step sizes (due to an increase in element sizes). Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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17 pages, 7587 KiB  
Article
On the Efficacy of Turbulence Modelling for Sloshing
by Omar Ahmed Mahfoze, Wendi Liu, Stephen M. Longshaw, Alex Skillen and David R. Emerson
Appl. Sci. 2022, 12(17), 8851; https://doi.org/10.3390/app12178851 - 2 Sep 2022
Cited by 2 | Viewed by 1476
Abstract
As part of a wider project to understand the applicability of utilising slosh-based damping for wing-like structures, simulations of partially filled tanks subjected to harmonically oscillating and vertical motion are presented. The Volume of Fluid modelling approach is used to capture the air–water [...] Read more.
As part of a wider project to understand the applicability of utilising slosh-based damping for wing-like structures, simulations of partially filled tanks subjected to harmonically oscillating and vertical motion are presented. The Volume of Fluid modelling approach is used to capture the air–water interface and different turbulence models based on the Reynolds Averaged Navier–Stokes equations employed. No-model simulations are also conducted to demonstrate the efficacy of using turbulence models in the simulation of sloshing flows. Accuracy of the models is assessed by comparing with recent well-validated experimental data in terms of the damping effect of the sloshing. A wide range of excitation amplitudes are considered in the study to demonstrate the effectiveness of different turbulence models in representing the flow feature of weak and very violent sloshing. The results show that standard turbulence models can produce an excessive dissipation, especially at the interface, leading to inaccuracies in the estimation of sloshing dynamics of the violent sloshing. This issue is absent in the no-model simulations, and better results are obtained for all tested sloshing conditions, suggesting approaches to mitigate this interfacial dissipation within RANS-based modelling is an important consideration for future direction. Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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18 pages, 5908 KiB  
Article
Linear and Nonlinear Reduced Order Models for Sloshing for Aeroelastic Stability and Response Predictions
by Marco Pizzoli, Francesco Saltari and Franco Mastroddi
Appl. Sci. 2022, 12(17), 8762; https://doi.org/10.3390/app12178762 - 31 Aug 2022
Cited by 2 | Viewed by 1376
Abstract
This paper makes use of sloshing reduced-order models to investigate the effects of sloshing dynamics on aeroelastic stability and response of flying wing structure. More specifically, a linear frequency-domain operator derived by an equivalent mechanical model is used to model lateral (linear) sloshing [...] Read more.
This paper makes use of sloshing reduced-order models to investigate the effects of sloshing dynamics on aeroelastic stability and response of flying wing structure. More specifically, a linear frequency-domain operator derived by an equivalent mechanical model is used to model lateral (linear) sloshing dynamics whereas data-driven neural-networks are used to model the vertical (nonlinear) sloshing dynamics. These models are integrated into a formulation that accounts for both the rigid and flexible behavior of aircraft. A time domain representation of the unsteady aerodynamics is achieved by rational function approximation of the fully unsteady aerodynamics obtained via the doublet lattice method. The case study consists of the so called Body Freedom Flutter research model in two different configurations with one or two tanks partially filled with liquid with a mass comprising 25% of the aircraft structure. The results show that linear sloshing dynamics are able to change the stability margin of the aircraft in addition to having non-negligible effects on rigid body dynamics. On the other hand, vertical sloshing acts as a nonlinear damper and eventually provides limit cycle oscillations after flutter onset. Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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30 pages, 7961 KiB  
Article
Simulating Slosh Induced Damping, with Application to Aircraft Wing-like Structures
by Wendi Liu, Omar Ahmed Mahfoze, Stephen M. Longshaw, Alex Skillen and David R. Emerson
Appl. Sci. 2022, 12(17), 8481; https://doi.org/10.3390/app12178481 - 25 Aug 2022
Cited by 1 | Viewed by 1568
Abstract
The added damping generated by liquid sloshing in a tank has been utilized in a number of civil applications, including aviation, to reduce the vibration of the system. As part of a wider EU H2020 project called SLOWD (Sloshing Wing [...] Read more.
The added damping generated by liquid sloshing in a tank has been utilized in a number of civil applications, including aviation, to reduce the vibration of the system. As part of a wider EU H2020 project called SLOWD (Sloshing Wing Dynamics), the presented study performed numerical simulations on the slosh-induced damping of liquid in tanks that were under free decay oscillations and embedded in an aircraft wing-like structure. A new open-source partitioned fluid–structure interaction software framework is presented and employed for the numerical simulations. Periodic sloshing waves and violent vertical fluid motions are observed in the study. These demonstrate the effects of slosh-induced damping under different excitation amplitudes of the structure and a varying number of baffled regions within the tank. Various sloshing patterns caused by different combinations of the excitation amplitude and compartment numbers lead to different induced dampings of the free decay motion. We observed a distinctly non-monotonic function on the slosh damping when the initial excitation amplitude is small (i.e., 0.25), with a 59% reduction when we increase the number of baffled compartments from one to four, and a 153% increase when moving from one to eight compartments. This is due to the change in the sloshing wave frequency, resulting in a significant change in the impact of the fluid between the tank ceiling and the wave crests. When the initial excitation amplitude is large (i.e., 1.0), there is no significant change in the slosh-induced damping when changing the number of compartments in the tank, for the range of parameters considered, due to the highly turbulent fluid motion. This work is expected to form the basis of further, more detailed studies within the context of the SLOWD project and its ever-expanding experimental data output. Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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29 pages, 11430 KiB  
Article
Experimental and Numerical Characterization of Violent Sloshing Flows Using a Single Degree of Freedom Approach
by Jon Martinez-Carrascal, L. M. González-Gutiérrez and Javier Calderon-Sanchez
Appl. Sci. 2022, 12(15), 7897; https://doi.org/10.3390/app12157897 - 6 Aug 2022
Cited by 2 | Viewed by 1708
Abstract
In this work, the most fundamental aspects of an aeronautical sloshing problem have been studied using an alternative and simplified model. This model consists of a single degree of freedom version of the original problem which keeps the essence of the fluid structure [...] Read more.
In this work, the most fundamental aspects of an aeronautical sloshing problem have been studied using an alternative and simplified model. This model consists of a single degree of freedom version of the original problem which keeps the essence of the fluid structure interaction and also the most relevant physical aspects of the industrial case. Two independent methodologies have been used: first an experimental rig has been designed to measure and visualize different magnitudes of the problem and also a smoothed particle hydrodynamics formulation has been adapted to obtain a local representation of the flow interaction. Two very different fluids in terms of viscosity have been tested, and the differences in terms of the characteristics of the sloshing regimes, free surface fragmentation and relative kinetic energy have been described and compared. Apart from the comparison of the results obtained by both methodologies in terms of tank acceleration, sloshing forces and free surface evolution, a deep study of the sloshing force has been performed. This study focuses on a deeper understanding of the different aspects that constitute the sloshing force, such as its synchronization with the tank movement, the relation to the movement of the liquid’s center of mass and the physical projection of the force on the pressure and viscous parts. Additionally, a reconstruction of the sloshing force as a sum of the pressure signal recorded by a finite number of pressure sensors has been also performed. Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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24 pages, 7604 KiB  
Article
Effect of Fuel Sloshing on the Damping of a Scaled Wing Model—Experimental Testing and Numerical Simulations
by Lucian Constantin, Joe J. De Courcy, Branislav Titurus, Thomas C. S. Rendall, Jonathan E. Cooper and Francesco Gambioli
Appl. Sci. 2022, 12(15), 7860; https://doi.org/10.3390/app12157860 - 4 Aug 2022
Cited by 6 | Viewed by 1891
Abstract
Vertical sloshing of liquid-filled tanks has been shown to induce substantial dissipative effects. Building upon these previous results obtained on simpler sloshing systems, a scaled wing prototype is presented here, equipped with a fuel tank that allows the observation of liquid sloshing and [...] Read more.
Vertical sloshing of liquid-filled tanks has been shown to induce substantial dissipative effects. Building upon these previous results obtained on simpler sloshing systems, a scaled wing prototype is presented here, equipped with a fuel tank that allows the observation of liquid sloshing and quantification of induced dynamic effects. Based on experiments conducted at a 50% filling level for a baffled wing fuel tank model, substantial additional damping effects were demonstrated with liquid inside the tank regardless of the vertical acceleration amplitude. A numerical model based on a finite element wing structural model and a surrogate 1DOF fluid model was explored, with numerical simulations showing good agreement compared to experiments throughout the decaying motion of the system. Full article
(This article belongs to the Special Issue Liquid Slosh Damping: Experimental and Numerical Developments)
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