Ettertenning

Ettertenning is a Norwegian term that translates roughly to “after-ignition” and is used to describe a secondary ignition event that occurs after the initial ignition in a technical context. The concept appears in both propulsion and energetic applications, where heat, residual fuel, or hot spots can ignite additional fuel after the primary ignition has taken place.

In internal combustion engines, ettertenning refers to a phenomenon where fuel ignition is not confined to the initial spark event but continues or resumes due to hot spots, high temperatures, or residual combustion products in the chamber. This can lead to abnormal combustion behavior, engine knock, reduced efficiency, increased emissions, or mechanical stress. Factors that can influence ettertenning include ignition timing, flame speed, air-fuel mixture quality, combustion chamber design, and cooling effectiveness. Mitigation involves optimizing ignition control, mixture preparation, and engine design to promote complete and controlled combustion.

In the field of explosives and blasting, ettertenning denotes a secondary detonation that follows the primary blast, often caused by inadequate priming, confinement, or residual energy. It represents a safety concern in mining and demolition operations and is managed through careful blast design, proper sequencing, and strict safety protocols to minimize unintended secondary detonations.

Etymologically, the term combines etter- meaning “after” with tenning meaning “ignition.” It is used in Norwegian engineering and technical literature to describe related ignition phenomena, including pre-ignition and detonation, across different systems.