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Published June 2019 | public
Journal Article

Impact Resistance of Spark Plug's Ceramic Insulator During Ultra-high-Pressure Combustion Under Deto-Knock Conditions

Abstract

The ceramic insulators of spark plugs in gasoline engines are especially prone to damage when deto-knock occurs. To understand the damage process and mechanism, the present work investigated the impact resistance of ceramic insulators using detonation waves as impact sources. A test device that generates detonation waves was developed, representing a novel means of evaluating the knock resistance of ceramic insulators. Various impact types and detonation intensities were employed, and detonation initiation and propagation at peak pressures greater than 100 MPa were assessed using synchronous high-speed direct photography and pressure measurements. The test results demonstrate that ceramic insulators tend to break at the base of the breathing chamber when damaged by a single high peak pressure detonation wave impact. In contrast, multiple low pressure impacts eventually break the insulator into multiple fragments. The data also show that the positioning of a ground electrode upstream of the ceramic insulator greatly increases the resistance of the ceramic to the detonation impact. A two-dimensional computational fluid dynamics simulation coupled with a chemical kinetics analysis demonstrated that this improved resistance can be ascribed to a reduced peak pressure that appears after the detonation wave diffracts from the electrode prior to contacting the ceramic insulator.

Additional Information

© 2019 China Society of Automotive Engineers (China SAE). Received: 13 February 2019; Accepted: 19 April 2019; First Online: 28 May 2019. This work was supported by National Natural Science Foundation of China (Grant Nos. 91541206 and 51706121) and China Postdoctoral Science Foundation (Grant No. 2017T100076). On behalf of all authors, the corresponding authors state that there is no conflict of interest.

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023