<div class="section abstract"><div class="htmlview paragraph">The electric or hybrid vehicles need fast switching operation in order to ensure the quick-response of the motors. This process is carried out by compact direct-current contactors which are designed to perform the switching over multiple cycles. During the contact separation, the gas between the contacts breaks down and the resulting thermal arc provides a conductive channel that sustains the current. Until the arc is quenched, the current continues to flow through the contacts despite the physical separation. This unintended flow of current could lead to a larger response time than the safe operation limits. We perform high-fidelity simulation of thermal arc in hydrogen-nitrogen mixture environment under external magnetic field of 1 Tesla. The hydrogen enrichment level is kept at 0%, 40%, 50% and 80%. The contacts are separated at 8 m/s. It is demonstrated that the increase in hydrogen concentration leads to smaller arc lifetime thereby improving the circuit interruption performance.</div></div>
In SI engines, the initial stages of flame kernel formation play an important role in determining the overall thermal efficiency and in reducing the cycle-to-cycle variability. Introducing a cross-flow within the spark gap has shown to reduce the combustion fluctuations by shortening this initial ignition period and activating a larger volume of the fuel-air mixture. This work presents a computational study of spark discharges in high cross-flow ignition environments using a high-fidelity, multi-physics equilibrium plasma solver. The numerical framework is designed to simultaneously model chemically reacting fluid flow coupled with electromagnetics, surface ablation physics and external circuit dynamics in a fully coupled manner. The spark channel is simulated in a constant volume combustion chamber under different operating conditions and cross flow velocities. The simulation model is validated by comparing several key parameters associated with the discharge such as the breakdown voltage, dwell current, restrike timing, and spark stretch against experimental measurements.
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