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Particle Methods 1

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08:35
conference time (CEST, Berlin)
Effect of Impact Angle for a Bird Strike Case
26/10/2021 08:35 conference time (CEST, Berlin)
Room: F
E. Kayar (Turkish Aerospace Industries, TUR)
E. Kayar (Turkish Aerospace Industries, TUR)
Bird or drone strike are considered as one of the most harsh phenomenon in aviation industry compared to the rest of the aircraft loads like landing or manuvering for both military and commercial flights during its life cycle. Collision in milliseconds results in highly plastic behavior in most of the cases so that flight may face dramatic dynamic scenarios. Statistics show that the probabilty of strike on fuselage, leading edge, engine blades, radome, canopy or windscreen may vary due to the height, speed of the flight and the region. So, crashworthiness studies are carried out to investigate the capability & charachteristics of the material and the design to stand strike loads and prevent possible damages and assure a safe get home landing for multiple cases. Structural integrity is the major goal to design desired characteristics. To ensure this, standards (i.e. EASA 25.631, FAA) describe the specifications including the mass of the bird & impact velocity in addition to the resultant deflection at the component or expected damage. Additionally, test & FEA correlation studies are investigated according to these standards prior to release the final optimized model. In this study, bird strike analyses for multiple impact angles are carried out using explicit finite element software LS-Dyna. Smooth particle hydrodynamics (SPH) technique is implemented instead of arbitrary Lagrangian Eulerian (ALE) methodology to simulate the effect of the impact. Honeycomb and composite parts are included in the leading edge structural FEA model in addition to the metallic parts. The effect of impact angle which may be dominated by attack angle or yaw, roll pitch angles of the flight is going to be investigated. The thin-walled skin of the leading edge made of layered composite subjected to in and out of plane stresses as well while the inner honeycomb structure absorbs energy. On the other hand, metallic parts are modelled using Johnson Cook material model. This work demonstrates some of the outcomes of an ongoing project. Experiment series using high speed cameras is planned to validate precisely builded FEA models.
SPH approach, High velocity impact, Bird strike, Layered composites, Crashworthiness
08:55
conference time (CEST, Berlin)
Shape Optimization of Tire Tread Pattern to Minimize Water Splashing on Vehicle Body Using Particle Method CFD Simulation
26/10/2021 08:55 conference time (CEST, Berlin)
Room: F
S. Tokura (Prometech Software, Inc., JPN)
S. Tokura (Prometech Software, Inc., JPN)
With the electrification of power, the enhancement of safety equipment, and the sophistication of automatic driving systems, many electrical components such as sensors, radars, and cameras have been installed in automobiles in recent years. It is necessary to take waterproof measures for these electrical components and to take measures to prevent wetness by water as much as possible. For underbody, which requires strength, anti-corrosion coating measures are required to prevent damage caused by water exposure containing chemical substances such as anti-freezing agents. Therefore, the manufacturing cost for the protection from water splashing is not so small. One of the ways to reduce the cost of the damage countermeasures is to reduce the amount of water that hits the lower part of the vehicle body. For this purpose, it is considered that the reduction of the water splashing caused by the tires is effective. In this paper, we applied a shape optimization method based on numerical simulation and tried to minimize the amount of water being splashed on the underbody by optimizing the tread pattern shape of the tire. In simulating such problems, it is necessary to model the water splashing caused by tire rotation from the road surface to the vehicle body surface. As a numerical computation method that can efficiently track the separation, collision, and coalescence of many water droplets in a wide space, the computation method based on the particle method is considered more suitable than the mesh-based conventional CFD computation. Besides, using the mesh-free particle method has the advantage that the remeshing does not be required when changing the shape of the flow path. Therefore, in this paper, we adopted Particleworks, a CFD software that uses MPS (Moving Particle Simulation), which is one of the major particle methods, for numerical simulation. In addition, CAD-based parametric shape optimization software CAESES was used to optimize the shape of complex tread patterns, and by efficiently repeating the optimization computation cycle, the optimum shape could be obtained in a short time.
Shape optimization, Particle method, MPS, CFD, Meshfree
09:15
conference time (CEST, Berlin)
Large Bore Engine Lubrication System: Oil Flow and Pressure Analysis by Moving Particle Simulation
26/10/2021 09:15 conference time (CEST, Berlin)
Room: F
L. Perinel, I. Gallici, A. Cherini (Wärtsilä Italia S.p.A, ITA); G. Parm ( EnginSoft S.p.A, ITA)
L. Perinel, I. Gallici, A. Cherini (Wärtsilä Italia S.p.A, ITA); G. Parm ( EnginSoft S.p.A, ITA)
Lubrication is a crucial aspect when talking about efficiency and durability of any moving machine parts and, in particular, for large internal combustion engines. As per definition a lubrication system is designed to deliver a reasonably stable and clean oil film at the correct temperature and with the proper flow. It must accomplish several purposes like prevent direct contact between moving parts, reduce friction, reduce wear, provide cooling, sealing and cleaning effect, adsorb shocks and reduce noise. All these functions together, contribute to components and systems lifetime and ultimately to the overall engine operation. Predicting and simulating engine lubrication performances is therefore particularly challenging both in terms of oil splash in the sump and in terms of forced flow in the oil circulation system. Referring to the latter, a CFD model of the oil channels needs to take into account the inertial effect due to the complex motion of the engine parts, and it has to be able to simulate the transient nature of the flow with far different spatial scales at the same time. In large combustion engine having some meter-long crankshaft, the flow inside bearings and the leakage through small gaps strongly affect the oil flow and pressure behaviour. In this study the attention was focused on the big-end-bearings oil feeding system of an 18-cylinders engine configuration, which is one of the biggest existing gas 4-stroke engine ideal for base load application. Wärtsilä and EnginSoft built a Moving Particle Simulation model, a mesh-less method to solve the Navier-Stokes equations, which allows simulating very complex geometries with moving parts. The Wärtsilä engine model included all the relevant moving items, like crankshaft, bearings, connecting rod and pistons with their motion. The modelling and simulation of the engine using Finite Volume CFD techniques would be unfeasible due to the geometrical complexity of the oil system and above all due to the motion of the engine parts, which would make the management of the mesh motion not practicable. By simulating the flow through the channels, the Moving Particle Simulation model allowed calculating the transient pressure behaviour in crucial areas. The comparison of two bearing configurations highlighted differences in terms of pressure stability, peaks and low values that could potentially lead to cavitation issues. The results of the comparative analysis are presented and explained, together with accompanying illustrations.
large bore engine, lubrication, bearings, Moving Particle Simulation, mesh-less CFD
09:35
conference time (CEST, Berlin)
Multiple-level Adaptive Particle Refinement for SPH Method
26/10/2021 09:35 conference time (CEST, Berlin)
Room: F
M. de Leffe (Siemens Digital Industries Software, FRA)
M. de Leffe (Siemens Digital Industries Software, FRA)
Improving accuracy while reducing computational cost is the permanent challenge of Computational Fluid Dynamics (CFD). An extremely efficient technology dedicated to particle-based simulation methods such as the Smoothed-Particle Hydrodynamics (SPH) is the Adaptive Particle Refinement (APR). Particle local refinement consists in using fluid particles of different sizes, depending on the region of the flow. Critical regions are solved using small, refined particles, while regions of lower interest are solved only using a small number of coarse particles. With such techniques, the number of particles – therefore the computational cost – remains as low as possible, while the expected accuracy is met in required areas. Particle refinement techniques are challenging, as particles may move to and from areas of interest. Advanced algorithms are therefore required to subdivide coarse particles as they enter refinement areas, and merge small particles that are leaving it. When multiple-level refinement comes into play, the successive particle splits and merges become technically all-the-more challenging. Therefore, this capability, even though extremely valuable, remains out-of-reach for most open-source and commercial SPH software, and those implementing it rely on predefined fixed refinement areas. In many cases, the exact location of the zones of interest, and thus requiring potential refinement, is not known a priori and may also move time-after-time. Indeed, the critical refinement area location may depend on the resolved flow itself. In such cases, particle refinement areas need to be defined implicitly and not a priori. Criteria, such as “regions close to the free surface” or “regions nearby such body” are good examples of expected capabilities. When the local refinement technology automatically adapts to appropriately refine implicitly-defined areas, it is called Adaptive Local Refinement. We will expose in our presentation various APR techniques that can be implemented in SPH solvers, as well as results on different industrial test cases with the characteristics and advantages of the various refinement approaches.
Computational Fluid Dynamics, Mesh-Free Methods, Particle Methods, SPH, APR
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