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In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
LSPI events are random and infrequent, and their effects on impacted vehicles can include very high-pressure spikes, loud knocking noises and sometimes catastrophic engine damage. [4] It's commonly known as "Detonation or Knock". Engine management systems can overcome pre ignition by the means of a knock or detonation sensor.
Higher compression ratios can make gasoline (petrol) engines subject to engine knocking (also known as "detonation", "pre-ignition", or "pinging") if lower octane-rated fuel is used. [5] This can reduce efficiency or damage the engine if knock sensors are not present to modify the ignition timing.
In a reciprocating engine, the use of water injection, also called anti-detonation injection or ADI, is used to prevent engine knocking also known as "detonation". [3] Commonly found on large radial engines with pressure carburetors , it is a mixture of water and alcohol injected into the carburetor at high power settings.
Unintentional detonation when deflagration is desired is a problem in some devices. In Otto cycle, or gasoline engines it is called engine knocking or pinging, and it causes a loss of power. It can also cause excessive heating, and harsh mechanical shock that can result in eventual engine failure. [29]
Axi-symmetric stall, more commonly known as compressor surge; or pressure surge, is a complete breakdown in compression resulting in a reversal of flow and the violent expulsion of previously compressed air out through the engine intake, due to the compressor's inability to continue working against the already-compressed air behind it.
The basic concept of an RDE is a detonation wave that travels around a circular channel (annulus). Fuel and oxidizer are injected into the channel, normally through small holes or slits. A detonation is initiated in the fuel/oxidizer mixture by some form of igniter. After the engine is started, the detonations are self-sustaining.
The engine's tune especially in computer controlled applications can have a dramatic effect on durability, [citation needed] the aggressiveness of the tune puts the engine at risk of detonation which can be catastrophic to all rotating assembly components. Modern (roughly 1988+) DOHC, SOHC flat 4, flat 6, flat 8, and flat-plane V8 have no need ...