C10
Multiphysics 5

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08:35
conference time (CEST, Berlin)
Optimizing Gearbox Lubrication With a Fully Integrated PLM Process, Using GPU Based Lattice Boltzmann and Multi-physics Solvers
27/10/2021 08:35 conference time (CEST, Berlin)
Room: C
J. Ginés (Dassault Systemes, ESP); P. Gabriel (Dassault Systemes K.K., JPN)
J. Ginés (Dassault Systemes, ESP); P. Gabriel (Dassault Systemes K.K., JPN)
A gearbox is at the center of most power machinery and vehicles. Because of its place in the powertrain, the gearbox efficiency directly affects the device’s overall energy consumption, and reliability. Be it in a car, truck, heavy-duty equipment, wind-turbine or even helicopter, gearboxes failure can lead to a complete stop; lubrication issues account for 54% of failures, inducing expensive maintenance costs or insurance claims. A well-optimized lubrication design can help reduce your insurance and repair costs by half, and lower your vehicle consumption by more than 10%. OEMS are being pushed to evaluate new development methodologies to design more efficient and reliable products faster. Verifying the correct lubrication of powertrain components, such as gearboxes, has always proven a difficult experimental task. Translucent acrylic parts would need to be built specifically for testing, and quantitative data proved hard to come by. With Lattice Boltzmann based fluid simulation solutions however, accurate quantitative data about the lubrication of complex rotating geometry can easily be obtained. In this presentation, we will first show how the lubrication of a gearbox can be accurately estimated with multi-phase simulation using actual design and motion. Not having any need for modeling, on top of the use of multi-phase, is necessary to get validated results for low to high gear rotation speeds. Also, the use of GPU based solver will lower the simulation cost and help replacing testing. Then, we will show how the gearbox can be improved by enabling designers to implement design changes directly from a model based Product Lifecycle Management system. These improvements will focus on assessing wetted surface and churning loss to determine how product alteration affects reliability and efficiency of the gearbox system. Design cycles are getting shorter and shorter; to match this demand we will also demonstrate how a fully integrated workflow can drastically reduce turnaround time for lubrication simulation. Lastly, we will show that the multi-physics performance of the gearbox can be further improved by using automated optimization tools, and combing them with multi-body dynamics solutions.
Gearbox lubrication, GPU, PLM, Optimization, Lattice Boltzmann
08:55
conference time (CEST, Berlin)
Hood Fluttering Caused by Unsteady Aerodynamic Loads by On Route Vehicles’ Interaction
27/10/2021 08:55 conference time (CEST, Berlin)
Room: C
A. Pérez Peña (ESI Spain, ESP); Á. Segura Santillana, J. Comas Font,T. Angulo de Diego, V. Cermeño Escobar (SEAT SA. ESP); R. Almenar (ESI, DEU)
A. Pérez Peña (ESI Spain, ESP); Á. Segura Santillana, J. Comas Font,T. Angulo de Diego, V. Cermeño Escobar (SEAT SA. ESP); R. Almenar (ESI, DEU)
Over the last few years, automotive manufacturers have been optimizing the weight of the vehicles by using lighter materials and reducing the thickness of sheet metal panels. As a result of the reduction in thickness, deformation of panels under standard loads has increased in many cases. These higher deformations do not mean that the vehicle quality is lower in terms of functional performance, however they are perceived by the Customers as poor product quality and should be avoided. One of these “standard load cases” appears when one car overtakes another vehicle (truck, pick-up or other). In this case, the turbulent structures in the wake of the car in-front reach the overtaking car, causing time- and space-variant pressure oscillations on the panels which cause vibrations. In the case of the hood, these vibrations can be of several millimeters at the trailing edge and may be visible from the driver point of view. Such issues are typically detected at the late testing stages, leading to costly design improvements. These effects can be virtually predicted by automated chained simulations easy to set up to allow its assessment and necessary design changes along the vehicle development iterations. In collaboration between SEAT and ESI Group, a computational methodology has been developed to detect such issues early in the vehicle engineering process, chaining Computational Fluid Dynamics (OpenFOAM) for the aerodynamic predictions and Finite Elements (Virtual Performance Solution - VPS) for the structural predictions. The application of this process with virtual prototypes enables engineers to detect such problems long before the actual physical prototypes are built and propose solutions to minimize the impact and avoid low perceived quality by the Customers. This paper describes the application of the developed methodology in detecting the vibrations in the early design stage and proposing countermeasures. The process showed in this paper opens the door to many other load cases, in which combinatorial CAE analyses are relevant, that can be evaluated virtually to improve the vehicle quality impacting the design in early stages of the development.
Aerodynamics, Overtaking Vehicles, Fluttering, Lightweight, Computational Fluid Dynamics, Finite Element, Virtual Prototypes
09:15
conference time (CEST, Berlin)
Approaching Reality: CFD Simulations of Positive Displacement Compressors With More Details in Geometry and Physics
27/10/2021 09:15 conference time (CEST, Berlin)
Room: C
A. Spille, J. Hesse (CFX Berlin Software GmbH, DEU)
A. Spille, J. Hesse (CFX Berlin Software GmbH, DEU)
The numerical simulation of positive displacement compressors (or expanders), like screw or scroll compressors, is more complex compared to dynamic pumps, turbines or fans. The gas transport in size-changing chambers with very small clearances between the rotors, and between rotors and casing, demands complex meshes that change with each time step. Furthermore, the physical effects are complex, too: high-speed leakage flows occur, heat is generated by compression and friction and heats up rotors and casing, causing thermal deformation that changes clearance sizes, and often liquid phases due to oil injection (as lubricant, coolant and sealant) or condensation (in steam expanders or refrigerant compressors) are important. Most CFD simulations so far focus on gas transport and compression in non-deforming geometries only. We present simulation strategy and results with the commercial programs TwinMesh (for mesh generation and pre-processing) and ANSYS CFD (for CFD and CHT simulations) that allow the accurate prediction of compressor performance on fine structured meshes including multi-phases, CHT, and thermal and structural deformations in reasonable times. The results allow the time-resolved calculation of global quantities like forces, torque, power consumption, and local quantities like pressure, velocity, temperature, phase distribution, or heat fluxes. Losses due to throttling effects or leakages can be detected and minimized, effects of changes in rotor profile, inlet and outlet ports, or injection strategies can be visualized and compared. Furthermore, the interaction of surrounding system components like pipes, valves, vessels with the compressor can be examined through co-simulations with the 1D CFD solver Flownex. The presentation gives an overview on pre-processing and solution steps and shows examples for several compressor simulations: For a two-sided screw compressor, pressure and thermal loads on the rotors are computed from CFD and used for deformation calculation; a two-stage compressor in a full vapour-compression refrigeration cycle with R22 in gaseous and liquid state is shown; and a 3D screw compressor is simulated in a 1D CFD network of a pressurized air supply station to describe storage vessel loading.
Computational Fluid Dynamics, compressor, Co-simulation, Heat transfer, multi-phase flow, thermal deformation
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