Esgee to Present at SAE World Congress 2018: Spark Plug Life Simulation

by esgee-webmaster | Mar 5, 2018 | Announcements, News

Esgee Technologies will present “Modeling of Electrode Erosion for Prediction of Spark Plug Lifetime” at the SAE International World Congress Experience 2018, April 10-12, at the Cobo Center in Detroit, Michigan.

Abstract:

The maximum lifetime of a spark plug is limited by electrode erosion.  Over the course of millions of repeated sparking events, the electrode material ablates and the electrode gap increases which degrades performance.  Once a critical gap is reached, the spark plug is no longer operational and must be replaced.  Due to the long relevant time scales over which erosion occurs, and the difficulty of analyzing the spark plug environment during operation, determining spark plug lifetime typically requires extensive field testing.

The objective of this work is use a computational model that can accurately simulate the electrode erosion process and make predictions on the effective lifetime.  The problem is challenging in that there are a vast range of time scales, all of which must be resolved to model the erosion.  Time scales range from milliseconds needed to resolve arc physics up to days and weeks for time timescales of electrode deformation due to ablation.

As a first step, dynamic coupling between arc physics and an ablating, eroding electrode is developed. An existing commercial arc solver code-VizSpark, capable of modelling the spark event with high fidelity, is used to model the arc physics which determine the net heat fluxes to the electrodes.  The electrodes are modelled using an immersed object method, which allows them to dynamically change in shape as the simulation progresses.  Mass flux from the electrodes due to ablation is modelled using temperature dependent metal vapor pressure curves.  As mass is removed from the electrode-gas interface, the immersed object dynamically deforms, which in turn modifies the gap voltage and the arc physics.  Overall, this approach provides predictive capability for the arc-induced erosion over the entire life-time of the spark-plug.

Sample Results:

Esgee to Present at SAE World Congress 2018: Arc Quenching in EV Relays

by esgee-webmaster | Mar 5, 2018 | Announcements, News

Esgee Technologies will present “Simulation of Arc Quenching in Hermetically Sealed Electric Vehicle Relays” at the SAE International World Congress Experience 2018, April 10-12, at the Cobo Center in Detroit, Michigan.

Abstract

High-voltage relays perform a key role in determining safety and protections of Electric Vehicles(EV)/ hybrid automotive systems. The primary function of a high voltage relay is to mechanically separate electrodes under a short circuit situation, and isolate the motor drive electronics from impending damage due to high currents (~1000 A).  As the relay breaks contact, significant arcing can occur due to high currents. Several methods can be applied to ensure immediate mitigation of arc within the relay, thereby reducing the electrical cutoff time. One such technique is to draw the arc towards the walls of a hermetically sealed chamber (using external magnets), and quenching it as it makes contact with the wall. Other techniques involve using an inert gas within the chamber to prevent arcing to occur in the first place.

This paper discusses the numerical modeling of arc formation and mitigation inside sealed electric vehicle relay. A high-fidelity, multi-dimensional, equilibrium arc solver-VizSpark is used to model the dynamics of arc formation and mitigation. Electrode motion is modeled using an immersed object method.  The effect of several parameters such as pressure, gas composition and magnetic field strength on arc propagation speeds and cut-off time are studied.

Sample Figures: