Dynamic response of blast loaded Hollow Cylindrical and Truncated Conical shells

Hollow cylindrical and truncated conical shells depict enhanced torsional and shear resistance compared to beams and plates and are ubiquitously used in structures in aeronautics, submarines, wind turbines, pressure vessels, and transmission pylons. Upon extensive localised blast, these elements undergo local and global deformation and failure. The detrimental damage to the shell depends on the stand-off and charge mass and is proportional to the emerged local dynamic stresses and inelastic deformations. Large localised translations relocate the structure’s original pivot point and induce global rotations about the new one which raises the probability of structural collapse. In this work, we examine large plastic deformations of hollow cylindrical and truncated conical shells subject to a range of pulse pressures emanated from high explosives. Fluid-Structure Interaction (FSI)-based Finite Element (FE) models were developed to discern the characteristics of blasts at various stand-offs and functions were proposed to link load parameters to structural, material, and geometric properties

A Qualitative Comparison of ANSYS and OpenFOAM results for Carbon dioxide Plume Transport

This research presents Computational Fluid Dynamics (CFD) simulations in ANSYS® illustrating emissions of to the air. The CFD simulations is employed to study plume transport in urban environment, i.e., Breivika port in the city of Tromsø. The case study presents a two-phase model considering specific wind strength and direction in the city of Tromsø. Geographical coordinates, temperature, and wind data were obtained from the open sources, such as Google Maps, and Norwegian Meteorological Institute. The results from the simulations indicates a potential outcome with respect to various weather conditions. It was revealed for vessels less than 30 meter chimney height, the higher the wind strength, the lower the plume dispersion, causing the plume to stay closer to the terrain. This brings in a concentrated amount of pollutants closer to the public areas. The terrain in the model is recognizable for the Tromsø port’s location. From the CFD results, it is illustrated that onshore wind with high wind strength could affect the environment. The results simulated in OpenFOAM are qualitatively showing the same as visible in ANSYS®

Multiphysics Modelling of Powder Coating of U-Profiles: Towards Simulation-based Optimization of Key-Performance Attributes by Variation of Powder-Parameters

Multiphysics simulation software has been developed to predict the key performance attributes of industrial powder coating applications based on applied process-parameter settings. The software is a Eulerian-Lagrangian finite-volume Multiphysics solver based on OpenFOAM, capable of modelling mass transfer effects between powder-coating pistols and electrically grounded metallic substrates. It considers various factors such as fluid dynamics of process airflow, coating-particle dynamics, particle-substrate interactions, and particle charging mechanisms within the corona. The software is fully compatible with Massive Simultaneous Cloud Computing technology, allowing hundreds of simulated coating scenarios to be computed simultaneously. Experimental validation efforts have been conducted, indicating a high degree of practical relevance of the technology. The current simulation study aims to demonstrate the potential of the simulation software for adjusting coating lines and optimizing powder coating of U-profiles. Specifically, the study focuses on optimizing the key-performance-attributes of the powder coating application with respect to varying material parameters of the applied powder, namely mean particle diameter, standard deviation of Gaussian particle size distribution, and powder particle density. The software predicts and visualizes coating patterns, coating efficiencies, and the batch-based standard deviation of coating thickness on a U-shaped metallic substrate, resulting in concrete and optimized powder settings. The presented results and the applied software are highly relevant for powder material suppliers

Composite conductivity of MIEC-based SOFC anodes : implications for microstructure optimization

Fully ceramic anodes such as LSTN-CGO offer some specific advantages compared to conventional cermet anodes. Ceria- and titanate-based phases are both mixed ionic and electronic conductors (MIEC), which leads to very different reaction mechanisms and associated requirements for the microstructure design compared to e.g. Ni-YSZ. Due to the MIEC-property of both solid phases, the transports of neither the electrons nor the oxygen ions are limited to a single phase. As a consequence, composite MIEC electrodes reveal a remarkable property that can be described as ‘composite conductivity’ (for electrons as well as for ions), which is much higher than the (hypothetical) single phase conductivities of the same microstructure. In composite MIEC anodes, the charge carriers can reach the reaction sites even when the volume fraction of one MIEC phase is below the percolation threshold, because the missing contiguity is automatically bridged by the second MIEC phase. The MIEC properties thus open a much larger design space for microstructure optimization of composite electrodes. In this contribution, the composite conductivities of MIEC-based anodes are systematically investigated based on virtual materials testing and stochastic modeling. For this purpose, a large number of 3D microstructures, representing systematic compositional variations of composite anodes, is created by microstructure modeling. The underlying stochastic model is fitted to experimental data from FIB-SEM tomography. For the fitting of the stochastic model, digital twins of the tomography data are created using the methodology of gaussian random fields. By interpolation between and beyond the digital twin compositions, the stochastic model then allows to create numerous virtual 3D microstructures with different compositions, but with realistic properties. The effect of microstructure variation on the composite conductivity is then determined with transport simulations for each 3D microstructure. Furthermore, the corresponding microstructure effects on the cell-performance are determined with a Multiphysics model that describes the anode reaction mechanism. Especially the impact of the composite conductivities on the cell performance is studied in detail. Finally, microstructure design regions are discussed and compared for three different anode materials systems: titanate-CGO (with composite conductivities), Ni-YSZ (with single-phase conductivities), Ni-CGO (with single-phase ionic and composite electronic conductivities)

Characterization of Particle Motion and Deposition Behaviour in Electro-Static Fields

As a prerequisite for studying and ultimately improving the powder coating process, particle motion and deposition effects within flow- and electro-static fields need to be thoroughly understood and thus characterized. In this context, a range of dimensionless groups is proposed and new means of characterization are presented. Considering the impact of electro-static, fluid-dynamic and gravity forces on coating particle motion, a triangle chart notation to characterize the state of varying particle size classes, is introduced. Furthermore a derivation of the dimensionless particle momentum equation is shown to lead to a dimensionless chart, representing all possible process states of coating. In combination with a Eulerian-LaGrangian, numerical model, the new means of characterization have led to a far better, over all perspective of occurring phenomena and their causes. Some examples are demonstrated here

A thermo fluid dynamic model of wood particle gasification- and combustion processes

In order to qualitatively understand and evaluate the thermo- fluid dynamic situation within a wood gasification reactor, a 1D particle model has been created. The presented tool accounts for the highly in- stationary, kinetic- and thermo chemical effects, leading to partial gasification and combustion of a wood particle embedded within a packed bed collective. It considers the fluid- dynamic situation within the changing porous bulk structure of the packed bed, its impact on species- and heat transition mechanisms, the energy- and mass balances of wood, coal, pyrolysis-gas, wood- gas and off- gas phases, the thermodynamics of locally developing gasification- and combustion reaction equilibria, as well as the presence of the chemical species hydrogen, water, carbon (di-) oxide, methane, oxygen, solid carbon and gaseous, longer chain hydrocarbons from pyrolysis. Model results can be shown to yield very good, qualitative agreement with measurements, found in literature

System Dynamic modelling approach for resolving the thermo- chemistry of wood gasification

For Multiphysics problems that require a thorough understanding of multiple, influential, highly transient process parameters, a System Dynamic model can constitute either an alternative option, or a compact prelude to a more expensive 3-D Finite Element or Finite Volume model. As a rather uncommon example for the application of such a modelling method, this work presents a System Dynamic modelling concept, devised for resolving the thermo-chemistry within a wood gasification reactor. It compares the modelling concept as well as its results to a classic, thermo-chemical solution algorithm based on the minimization of LaGrangian Multipliers for resolving the gasification equilibrium equations. In contrast to the latter, the System Dynamic solver can consider the impact of reaction kinetics as well as molecular mass transfer effects on the gasification equilibrium. Thus the transient production rates of methane, hydrogen, carbon (di-) oxide and water, as well as the residual amounts of pyrolysis gas and oxygen, which occur during the gasification of a wood particle, can be predicted

Euler-Lagrangian Model of Particle Motion and Deposition Effects in Electro-Static Fields based on OpenFoam

In order to study the powder coating process of metal substrates, a comprehensive, numerical 3D Eulerian-LaGrangian model, featuring two particle sub-models, has been developed. The model considers the effects of electro-static, fluid-dynamic and gravity forces. The code has been implemented in C++ within the open source CFD platform OpenFoam®, is transient in nature with respect to the applied LaGrangian particle implementation and the electro-static field calculation and is stationary regarding fluid-dynamic phenomena. Qualitative validation of the developed solver has already been achieved by comparison to simple coating experiments and will hereby be presented alongside a thorough description of the model itself. Upon combining knowledge of the relevant dimensionless groups and the numerical model, a dimensionless chart, representing all possible states of coating, was populated with comprehensive, exemplary cases, which are shown here as well