The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jin Y. Ooi - One of the best experts on this subject based on the ideXlab platform.
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finite element modelling of wall pressures in a cylindrical Silo with conical hopper using an arbitrary lagrangian eulerian formulation
Powder Technology, 2014Co-Authors: Yong Lu, Yin Wang, Jin Y. OoiAbstract:Abstract Silos, especially the ones consisting of cylindrical section with conical hopper, are commonly used for bulk material handling in many industries. Whilst the pressure acting on Silo walls during filling is reasonably well understood, a reliable prediction of pressure during discharge remains an important open problem for Silo design. This paper describes a finite element analysis of the granular flow in a model Silo consisting of a cylindrical section with a conical hopper. The computations were performed using an Arbitrary Lagrangian–Eulerian formulation with an explicit time integration approach to permit large deformations and overcome mesh distortion problems. The finite element results of Silo pressure were temporally averaged and compared with the experimental observations in a model Silo, which shows a satisfactory agreement in the wall pressure distribution. Two critical modelling issues have been addressed in some detail: one is the numerical treatment of the abrupt transition between the cylindrical section and the conical hopper, and the other is the interaction between the granular solid and the Silo walls that is modelled using a dynamic friction model in this study. The simulation results show significant pressure fluctuations during Silo discharge, which are comparable to the fluctuating pressure patterns reported in previous experiments. Two dominant frequencies are identified from the dynamic pressure, and a scrutinization of the simulation results suggests that the causes may be attributable to the propagation of the longitudinal waves within the stored granular solid and the intermittent macro-slip of the granular solid against the Silo wall. These dynamic events could be a source of Silo quaking and honking phenomena.
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discrete element modelling of grain flow in a planar Silo influence of simulation parameters
6th International Conference for Conveying and Handling of Particulate Solids: 3-7 August 2009 Brisbane Convention & Exhibition Centre Queensland Aust, 2009Co-Authors: C Gonzalezmontellano, Francisco Ayuga, Jin Y. OoiAbstract:There is extensive literature concerning the prediction of pressure and flow in a Silo. The great majority of them are based on continuum theories. The friction between the stored material and the Silo wall as well as the inclination of the hopper at its base are considered to be the most influential parameters for the flow pattern within the Silo. In this paper, the filling and discharge of a planar Silo with a hopper at its base has been modelled using DEM. The aim is to investigate the influence of DEM model parameters on the predicted flow pattern in the Silo. The parametric investigation particularly focused on the hopper angle of inclination and the contact friction between particles and walls. The shape of the particles was also considered by comparing spherical and non-spherical particles, thus providing an insight into how particle interlocking might influence solids flow behaviour in Silos. The DEM computations were analysed to evaluate the velocity profiles at different levels as well as the wall pressure distribution at different stages during filling and discharge. A detailed comparison reveals many interesting observations including showing the important role of particle interlocking to predict a flow pattern that is similar to the one observed in real Silos.
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the influence of a cone in cone insert on flow pattern and wall pressure in a full scale Silo
Chemical Engineering Research & Design, 2008Co-Authors: Johannes Hartl, M Wojcik, J. Michael Rotter, Songxiong Ding, Jin Y. Ooi, Gisle G EnstadAbstract:A Silo insert is sometimes placed inside the hopper to improve the flow pattern of solids in a funnel flow Silo. This paper describes a recent experimental investigation of the flow pattern and wall pressures observed during filling and emptying of a cylindrical Silo with and without a cone-in-cone insert. The 2.5 m diameter Silo had an 8 m high cylindrical section and a 44° conical hopper, and was filled with crushed quartz sand. The wall pressures were measured at ten chosen locations using pressure cells mounted on the wall. To investigate the solids flow pattern, markers were placed at fixed positions in the Silo during filling and the residence time for each marker during discharge was observed. The flow pattern can be inferred from the residence time measurements for the markers and the surface profile observations during discharge. These tests show that a cone-in-cone insert can have a strong influence on both the flow pattern during discharge and the pressure acting on the Silo wall and its industrial use should be considered cautiously and implemented with care.
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flow pattern measurement in a full scale Silo containing iron ore
Chemical Engineering Science, 2005Co-Authors: J F Chen, J. Michael Rotter, Jin Y. Ooi, Zhijun ZhongAbstract:Abstract The flow pattern in a Silo is important because it affects both the recovery of solids and the pressures on the Silo wall during discharge. Wherever mass flow is not achieved, the boundary of the flow channel has significant implications for both the functional and structural design of the Silo. Many techniques have been used for the study of flow patterns in model Silos, but most cannot be used at full scale, and very few quality measurements at full scale have ever been made. This paper outlines a full scale experimental study in which the patterns of solids flow and the flow channel boundaries are reliably quantified. The full scale Silo was specially designed, constructed and instrumented to exhibit funnel flow and to make observations of the solids flow pattern and the Silo wall pressures. It had three outlets: one concentric, one fully eccentric and one in between. Three materials were used: iron ore pellets, slag fines and crushed basalt. This paper describes experiments involving iron ore pellets. The Silo was seeded with radio frequency tags whose residence times were measured by detecting them on exit during discharge. The residence time data were studied to deduce the discharge flow pattern. This paper presents the results of three different flow pattern interpretation techniques: the best of them (mass-time relationships) is shown to give a very clear identification of the solids flow pattern and the flow channel boundary.
Yin Wang - One of the best experts on this subject based on the ideXlab platform.
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finite element modelling of wall pressures in a cylindrical Silo with conical hopper using an arbitrary lagrangian eulerian formulation
Powder Technology, 2014Co-Authors: Yong Lu, Yin Wang, Jin Y. OoiAbstract:Abstract Silos, especially the ones consisting of cylindrical section with conical hopper, are commonly used for bulk material handling in many industries. Whilst the pressure acting on Silo walls during filling is reasonably well understood, a reliable prediction of pressure during discharge remains an important open problem for Silo design. This paper describes a finite element analysis of the granular flow in a model Silo consisting of a cylindrical section with a conical hopper. The computations were performed using an Arbitrary Lagrangian–Eulerian formulation with an explicit time integration approach to permit large deformations and overcome mesh distortion problems. The finite element results of Silo pressure were temporally averaged and compared with the experimental observations in a model Silo, which shows a satisfactory agreement in the wall pressure distribution. Two critical modelling issues have been addressed in some detail: one is the numerical treatment of the abrupt transition between the cylindrical section and the conical hopper, and the other is the interaction between the granular solid and the Silo walls that is modelled using a dynamic friction model in this study. The simulation results show significant pressure fluctuations during Silo discharge, which are comparable to the fluctuating pressure patterns reported in previous experiments. Two dominant frequencies are identified from the dynamic pressure, and a scrutinization of the simulation results suggests that the causes may be attributable to the propagation of the longitudinal waves within the stored granular solid and the intermittent macro-slip of the granular solid against the Silo wall. These dynamic events could be a source of Silo quaking and honking phenomena.
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numerical modelling of dynamic pressure and flow in hopper discharge using the arbitrary lagrangian eulerian formulation
Engineering Structures, 2013Co-Authors: Yin Wang, Yong LuAbstract:Abstract Silos and hoppers are commonly used for the storage and handling of bulk solids in industry. Although the pressures acting on the Silo walls during filling are well understood, an accurate prediction of pressures during discharge remains an important open problem for Silo design. This paper describes a finite element analysis of the granular flow in a conical hopper to investigate the dynamic pressure and flow during discharge. The behaviour of the stored solid is modelled using a continuum mechanics approach formulated in an Arbitrary Lagrangian–Eulerian (ALE) frame of reference. With the aid of the ALE approach, in principle almost a complete Silo discharge process may be simulated satisfactorily without mesh distortion problems, which are often encountered in modelling Silo discharge using a continuum approach. Temporally averaged discharge pressure distribution is evaluated from the FE simulation and found to be in good agreement with the commonly quoted theoretical solution. Significant pressure fluctuations are predicted during the initial discharge period, which are comparable to the fluctuating pressure patterns reported in some Silo discharge experiments. Spectral analysis of the predicted pressure fluctuation reveals two dominant frequencies. The causes for these frequency events have been investigated thoroughly in the paper, which lead to the conclusion that compression wave propagation and intermittent shear zones within the granular solid are responsible for the higher and lower frequency event respectively. These dynamic events provide a plausible explanation for Silo quaking and vibration that are associated with Silo discharge. Further parametric study has also been performed to investigate the effect of discharge velocity and wall roughness on these dynamic events.
S I Rani - One of the best experts on this subject based on the ideXlab platform.
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analysis of dust distribution in Silo during axial filling using computational fluid dynamics assessment on dust explosion likelihood
Process Safety and Environmental Protection, 2015Co-Authors: S I Rani, Badhrulhisham Abdul Aziz, Jolius GimbunAbstract:In this study, the dust distribution in a Silo during axial filling was modelled using a commercial computational fluid dynamics (CFD) code. The work focused on the dust concentration distribution in the Silo, for evaluating the likelihood of a dust explosion in the Silo. The simulation was conducted using a combination of renormalized (RNG) k-epSilon and discrete phase models, with standard pressure interpolation and a second order upwind scheme. The predicted dust concentration distribution showed a good agreement with experimental data adopted from the literature. It was found that the dust concentration distribution was influenced by mean velocity and turbulence flow. The simulation results suggest that the cornstarch concentration inside the Silo was always above the lower explosion limit (LEL), hence requiring a mitigating action or a control system to reduce the explosion risk.
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analysis of dust distribution in Silo during axial filling using computational fluid dynamics assessment on dust explosion likelihood
Process Safety and Environmental Protection, 2015Co-Authors: S I Rani, Badhrulhisham Abdul Aziz, Jolius GimbunAbstract:In this study, the dust distribution in a Silo during axial filling was modelled using a commercial computational fluid dynamics (CFD) code. The work focused on the dust concentration distribution in the Silo, for evaluating the likelihood of a dust explosion in the Silo. The simulation was conducted using a combination of renormalized (RNG) k-epSilon and discrete phase models, with standard pressure interpolation and a second order upwind scheme. The predicted dust concentration distribution showed a good agreement with experimental data adopted from the literature. It was found that the dust concentration distribution was influenced by mean velocity and turbulence flow. The simulation results suggest that the cornstarch concentration inside the Silo was always above the lower explosion limit (LEL), hence requiring a mitigating action or a control system to reduce the explosion risk.
Jolius Gimbun - One of the best experts on this subject based on the ideXlab platform.
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analysis of dust distribution in Silo during axial filling using computational fluid dynamics assessment on dust explosion likelihood
Process Safety and Environmental Protection, 2015Co-Authors: S I Rani, Badhrulhisham Abdul Aziz, Jolius GimbunAbstract:In this study, the dust distribution in a Silo during axial filling was modelled using a commercial computational fluid dynamics (CFD) code. The work focused on the dust concentration distribution in the Silo, for evaluating the likelihood of a dust explosion in the Silo. The simulation was conducted using a combination of renormalized (RNG) k-epSilon and discrete phase models, with standard pressure interpolation and a second order upwind scheme. The predicted dust concentration distribution showed a good agreement with experimental data adopted from the literature. It was found that the dust concentration distribution was influenced by mean velocity and turbulence flow. The simulation results suggest that the cornstarch concentration inside the Silo was always above the lower explosion limit (LEL), hence requiring a mitigating action or a control system to reduce the explosion risk.
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analysis of dust distribution in Silo during axial filling using computational fluid dynamics assessment on dust explosion likelihood
Process Safety and Environmental Protection, 2015Co-Authors: S I Rani, Badhrulhisham Abdul Aziz, Jolius GimbunAbstract:In this study, the dust distribution in a Silo during axial filling was modelled using a commercial computational fluid dynamics (CFD) code. The work focused on the dust concentration distribution in the Silo, for evaluating the likelihood of a dust explosion in the Silo. The simulation was conducted using a combination of renormalized (RNG) k-epSilon and discrete phase models, with standard pressure interpolation and a second order upwind scheme. The predicted dust concentration distribution showed a good agreement with experimental data adopted from the literature. It was found that the dust concentration distribution was influenced by mean velocity and turbulence flow. The simulation results suggest that the cornstarch concentration inside the Silo was always above the lower explosion limit (LEL), hence requiring a mitigating action or a control system to reduce the explosion risk.
Jacek Tejchman - One of the best experts on this subject based on the ideXlab platform.
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determination of bulk solid concentration changes during granular flow in a model Silo with ect sensors
Chemical Engineering Science, 2009Co-Authors: Maciej Niedostatkiewicz, Zbigniew Chaniecki, Jacek Tejchman, Krzysztof GrudzienAbstract:Experiments in a cylindrical model Silo were carried out with different initial densities of sand and Silo wall roughness. Solid concentration changes during granular flow in the model Silo were measured with electrical capacitance tomography (ECT) sensors. During Silo flow, strong dynamic effects connected with booming sound occurred. Local one-dimensional (1D) and cross-sectional 2D evolutions of solid concentrations in dry sand during Silo discharge were observed. The 1D phenomena were estimated from the raw data and the 2D phenomena were obtained from the reconstructed data by solving an inverse problem with a linear back projection algorithm.
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Silo music mechanism of dynamic flow and structure interaction
Powder Technology, 2008Co-Authors: Krzysztof Wilde, Magdalena Rucka, Jacek TejchmanAbstract:This papers deals with the strong dynamic effects (called Silo music) appearing during confined granular flow in the cylindrical Silos. Silo experiments with dry cohesionless sand during gravitational outflow were performed in a cylindrical perspex model Silo. During tests the wall accelerations and acoustic signals were recorded and the mode shapes of the Silo structure were determined. In addition, experiments were performed with additional modifications of the Silo structure and Silo flow. A novel simple mechanism of the origin of Silo music was proposed.
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Technical concept to prevent the Silo honking
Powder Technology, 1999Co-Authors: Jacek TejchmanAbstract:Abstract During emptying of tall cylindrical Silos made of aluminium, the phenomenon of the Silo honking is often created. The Silo honking appears in the form of an annoying noise connected to strong vibrations of Silo walls. Full-scale experiments in aluminium Silos containing polymer granulates were performed to investigate this phenomenon. During experiments, accelerations and deformations of the wall, and sound pressures inside and outside the Silo were measured. A reliable, practical method to completely suppress the Silo honking and to significantly reduce dynamic pulsations during Silo emptying was proposed and described in detail. The method was verified with model experiments and full-scale tests.
