Abstract
Stator coils of automobiles in operation generate heat and are cooled by coolant poured from above. The flow characteristic of the coolant depends on the coil structure, flow condition, solid–fluid interaction, and fluid property, which has not been clarified due to its complexities. Since straight coils are aligned and layered with an angle at the coolant-touchdown region, the coil structure is simplified to a horizontal square rod array referring to an actual coil size. To obtain the flow and wetting characteristics, two-phase fluid flow simulations are conducted by using the phase-field lattice Boltzmann method. First, the flow onto the single-layered rod array is discussed. The wetting area is affected both by the rod gap and the wettability, which is normalized by the gap and the averaged boundary layer thickness. Then, the flow onto the multi-layered rod arrays is investigated with different rod gaps. The top layer wetting becomes longitudinal due to the reduction of the flow advection by the second layer. The wetting area jumps up at the second layer and increases proportionally to the below layers. These become remarkable at the narrow rod gap case, and finally, the dimensionless wetting area is discussed at each layer.
Highlights
Electrification of automobiles has been under the spotlight for reducing CO2 emissions.Among electric components in a vehicle, an electric motor is considered one of the most important ones for the powertrains, and its heat removal is crucial for overall improvement.The heat emitted from the electric motor consists of Joule losses, iron losses, stream load losses, and mechanical losses [1,2,3]
For heat removal from the vehicle motor, oil cooling has been used in terms of efficiency; the oil can directly touch the heat source and exchange the heat from the motor [4]
When the rod array is layered, the top layer wetting becomes longitudinal in the narrower rod gap case, and the wetting area increases
Summary
Among electric components in a vehicle, an electric motor is considered one of the most important ones for the powertrains, and its heat removal is crucial for overall improvement. The heat emitted from the electric motor consists of Joule losses, iron losses, stream load losses, and mechanical losses [1,2,3]. For heat removal from the vehicle motor, oil cooling has been used in terms of efficiency; the oil (electrically-insulated coolant) can directly touch the heat source and exchange the heat from the motor [4]. The stator coil shown, one of the main heat sources of the motor, is cooled by the oil poured from the nozzle holes above. Ha et al [5] investigated the cooling of a motor both experimentally and numerically
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