Relation between Spark-Ignition Engine Knock, Detonation Waves, and Autoignition as Shown by High-Speed Photography
Abstract
A critical review of literature bearing on the autoignition and detonation-wave theories of spark-ignition engine knock and on the nature of gas vibrations associated with combustion and knock results in teh conclusion that neither the autoignition theory nor the detonation-wave theory is an adequate explanation of spare-ignition engine knock. A knock theory is proposed, combining the autoignition and detonation-wave theories, which introduces the idea that the detonation wave develops in autoignired or after-burning gases and ascribes comparatively low-pitched heavy knocks to autoignition but high-pitched pinging knocks to detonation waves with the possibility of combinations of the two types of knock. Analysis of five shots of knocking combustion, taken with the NACA high-speed motion-picture camera at the rate of 40000 photographs per second reveals propagation speeds ranging from 3250 to more than 5500 feet per second. The range of propagation speeds from 3250 to more than 550 feet per second is held to be consistent with the proposed combined theory but not with either the simple autoignition theory or the simple detonation-wave theory.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1946
- Accession Number
- ADA298134
Entities
People
- Cearcy D. Miller
Organizations
- Glenn Research Center