Analysis fluid sloshing when road tanker experience sudden breaking - A computational approach

Sloshing can occur as an outcome of a disturbance to a partly filled fluid road tanker. As an effect, the vibrant behavior of fluid is observed when subjected to the sudden breaking of a roadway tanker, because it significantly affects the stability leading to rollover of the tank structure. So to avoid the instability and rollover condition. The baffle is used as suppression media to suppress the vibrant behavior of the fluid. This research work is carried out with aid of a computational approach using the ALE technique. The ALE approach is tested with different configurations of tanks mainly clean bore tanks, single baffle tanks, two baffle tanks,s, and three baffle tanks with 50%,60%, and 80% filling ratios respectively. The outcome of this research paper to examine several factors for preventing accidents of road tankers when experiencing sudden breaking conditions

Analysis fluid sloshing when road tanker experience sudden breaking - A computational approach

Sloshing can occur as an outcome of a disturbance to a partly filled fluid road tanker. As an effect, the vibrant behavior of fluid is observed when subjected to the sudden breaking of a roadway tanker, because it significantly affects the stability leading to rollover of the tank structure. So to avoid the instability and rollover condition. The baffle is used as suppression media to suppress the vibrant behavior of the fluid. This research work is carried out with aid of a computational approach using the ALE technique. The ALE approach is tested with different configurations of tanks mainly clean bore tanks, single baffle tanks, two baffle tanks,s, and three baffle tanks with 50%,60%, and 80% filling ratios respectively. The outcome of this research paper to examine several factors for preventing accidents of road tankers when experiencing sudden breaking conditions

Liquid slosh and its influence on braking and roll responses of partly filled tank vehicles

Liquid cargo contained in a partly-filled tank is known to experience the sloshing movement when subjected to manoeuvre-induced disturbances. Large amplitude slosh can be induced within a partly-filled road tank vehicle under mild to severe directional manoeuvres, which could severely degrade the vehicle stability and directional control limits. A three-dimensional computational fluid dynamics slosh model is implemented for the partly-filled cleanbore and baffled tanks on the basis of the Navier-Stokes equations incorporating the VOF technique. A comprehensive experimental study is conducted to analyze the fluid slosh within a scale model tank with and without the baffles under continuous as well as single-cycle sinusoidal lateral and longitudinal acceleration excitations. The three-dimensional fluid slosh responses are further investigated for full scale baffled and unbaffled vehicle tanks using the validated fluid slosh model. The fluid slosh characteristics are analyzed under different fill volumes corresponding to a constant load and subjected to excitations representing steady-turning, straight-line braking, braking-in-turn and path change maneuvers. The fluid slosh analyses are also carried out to explore the anti-slosh effectiveness of baffles and to evaluate the effects of baffle design factors, such as equalizer and the orifice size. The influences of transient fluid slosh on the tank vehicle stability and responses are studied by incorporating the fluid slosh model to in-plane vehicle models. The two-dimensional roll-plane slosh models of partly-filled tanks of different cross-sections are integrated with the roll moment equilibrium of an articulated vehicle to derive the vehicle roll stability limits. The roll stability analyses are performed for circular and "Reuleaux triangular" tanks under the conditions of constant and variable cargo loads. The results attained are compared with the quasi-static solutions to demonstrate the role of transient slosh loads on the roll stability limits. The three-dimensional slosh model of a partly-filled tank is also integrated into a 7-DOF pitch plane model of a tridem truck to analyze its straight-line braking characteristics in the presence of fluid slosh. The straight-line braking responses of the coupled tank-vehicle model with and without baffles are analyzed under different fill volumes but constant load for different magnitudes of braking treadle pressure and road surface adhesion limit

Vibration of a circular cylindrical tank containing liquid

Interest in the motion of a liquid contained in a circular cylinder has been generated by the desire to predict the response of a liquid propellent in a moving space vehicle

Numerical & Experimental Study of Sloshing of Liquid in a Rectangular Tank

Due to advancement in automobile technology, various types of automobile noises have been reduced significantly and hence sloshing noise has become a major irritant for passengers. Past studies have concluded that the slosh noise is directly connected with the pressure fluctuation dp/dt which in turn can be provided by CFD study of flow dynamics of working fluid in the fuel tank. The present work includes experimental and CFD study of flow dynamics of working fluid in a rectangular tank. Experiments have been performed on indigenously developed Impact test setup. Experiments were conducted with varying fill level, varying sensor location and varying deceleration and the axial acceleration from experiment has been taken as input for CFD analysis. Commercial CFD solver STAR CCM+ was used to perform the CFD simulations. Image validation and dynamic pressure validation has been done to compare the CFD results with experiments

NUMERICAL STUDY OF LIQUID SLOSHING IN LNG TANKS COUPLED WITH SHIP MOTIONS

Ph.DDOCTOR OF PHILOSOPH

Development of design criteria for novel 3D-printed quadric-surfaced sludge digesters for wastewater infrastructure

The quadric-surfaced sludge digester (QSD), also known as the egg-shaped sludge digester, has proven its advantages over traditional cylindrical digesters recently. A reduction in operational cost is the dominant factor. Its shell can be described as a revolution of a parabola with the apex and base being either tapered or spherical. This shape provides a surface free of discontinuities, which is advantageous regarding the efficiency during mixing. Since the shape does not produce areas of inactive fluid motion within the tank, sludge settlement and an eventual grit build-up are avoided. The stresses developed in the shell of the sludge digester, vary along the meridian and equatorial diameters. A non-dimensional parameter, ξ, defines the height-to-diameter aspect ratio which is used to delineate the parametric boundary conditions of the shell’s surface. Three groups of analyses were conducted to determine the orthogonal stresses in the shell of the QSD. The first-principles numerical models ran reasonably quickly, and many iterations were made during the study. The results showed that they were in within the range 5.34% to 7.2% to 2D FEA simulations. The 3D FEA simulations were within the range of 8.3% to 9.2% to the MATLAB time-history models. This is a good indicator that the first principles numerical models are an excellent time-saving method to predict the behaviour of the QSD under seismic excitation. Upon examining the criteria for the design, analysing the results for the 2D FEA simulations showed that the fill height is not a significant variable with sloshing however the 3D FEA showed that the hydrostatic pressure is a significant variable. With the maximum tensile stress of the 3D-printed ABS being 24.4 MPa, the overall maximum stress of 5.45 MPa, the material can be a viable option for the use of QSD construction in small island developing states (SIDS)

Experimental data-driven reduced-order modeling of nonlinear vertical sloshing for aeroelastic analyses

This thesis focuses specifically on the study of nonlinear sloshing effects caused by large tank motions in a direction perpendicular to the free liquid surface with emphasis on aeronautical applications. Sloshing is a phenomenon that typically occurs in aircraft tanks as they are subjected to loads caused by gusts, turbulence and landing impacts. This type of sloshing leads to a noticeable increase in overall structural damping, yet it is generally not modeled in the design phase of modern aircraft. The identification and study of such dissipative effects may enable the development of less conservative aircraft configurations in the future, allowing for increasingly lighter structures and reduced environmental impact. The present thesis proposes a combined experimental and numerical approach aimed at obtaining reduced-order models for vertical sloshing, to be subsequently integrated into aeroelastic modeling and applications for the assessment of their effects on overall performance. An experimental campaign is first carried out to characterise the nonlinear dissipative behaviour of vertical sloshing for different filling levels. Specifically, a controlled electrodynamic shaker is employed to provide vertical displacement by means of sine-sweep excitation. By exploiting vertical harmonic motion, it is shown how the frequency and amplitude of the imposed excitation significantly influence the dissipative capabilities of the sloshing liquid. The same experiment is used to create a database - with an acquisition phase that considers vertical sloshing as an isolated system - to build a neural-network-based reduced-order model. The dynamics to be modeled is considered as a black box process, leading to the identification of a surrogate model driven only by input/output signals, regardless the knowledge of the internal dynamics. In order to assess the capability of the identified reduced order model for sloshing, the same tank used to generate the training data is mounted at the free end of a cantilever beam to create a new experimental setup in which a fluid-structure interaction scenario is expected. Indeed, this experiment provides experimental data for the validation of the identified dynamic model by comparison with numerical data. The comparison is carried out using a dynamic virtual simulation model corresponding to the experiment, in which the numerical model of the beam interacts with the reduced-order model simulating the sloshing dynamics. Finally, the experimentally validated reduced-order model is used in two different aeroelastic applications - wing prototype and flying wing model - to finally predict the dissipative effects induced by vertical sloshing on the aeroelastic response. Aeroelastic response analyses under pre- and post-critical conditions showed how the vertical sloshing dynamics helps to alleviate the dynamic loads due to severe gusts while providing limit cycle oscillation beyond the flutter margin

Real-time fluid simulations under smoothed particle hydrodynamics for coupled kinematic modelling in robotic applications

Although solids and fluids can be conceived as continuum media, applications of solid and fluid dynamics differ greatly from each other in their theoretical models and their physical behavior. That is why the computer simulators of each turn to be very disparate and case-oriented. The aim of this research work, captured in this thesis book, is to find a fluid dynamics model that can be implemented in near real-time with GPU processing and that can be adapted to typically large scales found in robotic devices in action with fluid media. More specifically, the objective is to develop these fast fluid simulations, comprising different solid body dynamics, to find a viable time kinematic solution for robotics. The tested cases are: i) the case of a fluid in a closed channel flowing across a cylinder, ii) the case of a fluid flowing across a controlled profile, and iii), the case of a free surface fluid control during pouring. The implementation of the former cases settles the formulations and constraints to the latter applications. The results will allow the reader not only to sustain the implemented models but also to break down the software implementation concepts for better comprehension. A fast GPU-based fluid dynamics simulation is detailed in the main implementation. The results show that it can be used in real-time to allow robotics to perform a blind pouring task with a conventional controller and no special sensing systems nor knowledge-driven prediction models would be necessary.Aunque los sólidos y los fluidos pueden concebirse como medios continuos, las aplicaciones de la dinámica de sólidos y fluidos difieren mucho entre sí en sus modelos teóricos y su comportamiento físico. Es por eso que los simuladores por computadora de cada uno son muy dispares y están orientados al caso de su aplicación. El objetivo de este trabajo de investigación, capturado en este libro de tesis, es encontrar un modelo de dinámica de fluidos que se pueda implementar cercano al tiempo real con procesamiento GPU y que se pueda adaptar a escalas típicamente grandes que se encuentran en dispositivos robóticos en acción con medios fluidos. Específicamente, el propósito es desarrollar estas simulaciones de fluidos rápidos, que comprenden diferentes dinámicas de cuerpos sólidos, para encontrar una solución cinemática viable para robótica. Los casos probados son: i) el caso de un fluido en canal cerrado que fluye a través de un cilindro, ii) el caso de un fluido que fluye a través de un alabe controlado, y iii), el caso del control de un fluido de superficie libre durante el vertido. La implementación de estos primeros casos establece las formulaciones y limitaciones de aplicaciones futuras. Los resultados permitirán al lector no solo sostener los modelos implementados sino también desglosar los conceptos de la implementación en software para una mejor comprensión. En la implementación principal se consigue una simulación rápida de dinámica de fluidos basada en GPU. Los resultados muestran que esta implementación se puede utilizar en tiempo real para permitir que la robótica realice una tarea de vertido ciego con un controlador convencional sin que sea necesario algún sistema de sensado especial ni algún modelo predictivo basados en el conocimiento.Programa de Doctorado en Ingeniería Eléctrica, Electrónica y Automática por la Universidad Carlos III de MadridPresidente: Carmen Martínez Arévalo.- Secretario: Luis Santiago Garrido Bullón.- Vocal: Benjamín Hernández Arreguí