The Rise of Electrification
As electrified powertrains become an increasingly important technology in the pursuit for cleaner transportation, the electromobility (emobility) industry is expanding rapidly around the globe. Emobility encompasses both fully and partially electric vehicles, including battery electric vehicles, plug-in hybrids, mild hybrids, and fuel cell electric vehicles. With the production of electrified powertrains rising, methods for analyzing and optimizing such emobility systems are in growing demand. Computational fluid dynamics (CFD) is a powerful tool for studying fluid-related processes in a range of emobility application areas, such as batteries, electric motors, power electronics, and fuel cells. With state-of-the-art modeling capabilities, CONVERGE CFD software is well-suited to simulations of 3D coupled flow, heat transfer, and chemistry in complex geometries with moving or stationary boundaries. In addition, CONVERGE’s autonomous meshing dramatically reduces time-to-solution, so you can quickly obtain high-fidelity results.
Manufacturers of electric motors are moving toward higher power densities in their designs, which requires more efficient removal of the heat generated by the motor. High motor temperatures can cause demagnetization of the permanent magnets and the breakdown of the winding insulation, both of which are catastrophic for the motor. Therefore, the motor power and associated efficiency are strongly tied to the effectiveness of the cooling strategy. CONVERGE can simulate a wide range of cooling methods, including air cooling, water jacket cooling, and oil cooling. And CONVERGE isn’t limited to electric motors—you can also simulate cooling in battery packs, power electronics, and more.
Battery Thermal Runaway
In a lithium-ion battery pack, thermal runaway occurs when a cell reaches a temperature that triggers a cascade of exothermic reactions, causing the temperature to continue to increase. CONVERGE allows you to perform cooling analyses under normal operating conditions and additionally study the effects of thermal runaway and battery venting. With CONVERGE’s robust conjugate heat transfer modeling, you can determine if a runaway cell will cause adjacent cells to initiate thermal runaway. You can also track the propagation of species in the case of cell venting and assess the change in temperature of the solids in the area in which the venting occurs. CONVERGE’s SAGE detailed chemistry solver enables you to assess battery safety by simulating scenarios in which a spark ignites vented gas inside the battery pack. The detailed chemistry solver is fully coupled to the flow solver for maximum accuracy and efficiency.
CONVERGE contains a set of meshing features designed to simplify your workflow and reduce the time it takes to set up a simulation. At runtime, CONVERGE automatically generates an optimized Cartesian mesh that perfectly represents your geometry—no user meshing required! And since CONVERGE doesn’t use templates, you can easily simulate unique geometries, such as innovative rotor designs or complex coolant passages. For moving geometries, CONVERGE regenerates the mesh at each time-step to accommodate the motion without deforming the mesh, resulting in a more accurate solution. Additionally, throughout the simulation, Adaptive Mesh Refinement intelligently refines the mesh to capture complex phenomena, like the flame front in a battery pack ignition simulation or large temperature gradients in your cooling analysis.
Certain simulations may benefit from adding a local non-Cartesian mesh, for example, to resolve a thermal boundary layer around the cells in your battery pack or to resolve small rotor-stator gaps. CONVERGE allows you to create an inlaid mesh in a portion of your simulation doman, which can, in certain circumstances, offer increased accuracy at a lower overall cell count.
Accelerating CHT Simulations
Simulating conjugate heat transfer (CHT) is critical for obtaining accurate results in many emobility applications, including cooling and thermal runaway. But CHT calculations can be computationally expensive due to the disparate time scales of heat transfer in fluids and solids. With CONVERGE, you can use the super-cycling method to overcome this time scale disparity. In super-cycling, the fluid solver is periodically frozen while the heat transfer in the solid is allowed to progress to steady-state. This method significantly reduces the time it takes to run a CHT simulation.
The fixed flow method is another acceleration strategy you can employ for cases in which the flow changes less rapidly than other physical phenomena in your computational domain. By freezing the flow field and solving the flow for only short periods of time, you can reduce the computational expense of the simulation. This is particularly useful for cases that require simulating a lengthy period of time, for example, the heating of adjacent cells by the venting of a thermal runaway cell in a battery pack.
CONVERGE Solver Options
The CONVERGE CFD solver offers options for a broad array of emobility simulations: steady-state or transient, incompressible or compressible, and density-based or pressure-based. Do you need a highly accurate solution for your case? Do you need results as soon as possible? You can tailor CONVERGE’s solver options to meet your specific simulation needs. Whether you’re running a steady-state cooling analysis or a transient ignition simulation, CONVERGE has you covered.