بالبداية لازم نعرف شو يعني ال octan no.و بعدين بنحكي عن التعاريف الي طلبتها
The octane quality of a gasoline is its ability to resist detonation, a form of abnormal combustion. Detonation occurs when the air-fuel mixture reaches a temperature and/or pressure at which it can no longer keep from self igniting. Two types of abnormal combustion are common: the first is detonation as previously mentioned and the other is preignition.
Detonation occurs after the spark plug has ignited the air-fuel mixture and the flame front is moving smoothly across the combustion chamber. If, during this burning process, the unburned air-fuel mixture reaches a temperature and/or pressure at which it is no longer stable, it burns very rapidly causing a new flame front to collide with the one that originated at the spark plug. Maximum pressure in the cylinder occurs before the piston reaches top dead center (TDC) and that pressure try's to push the piston down before it is ready to go down. Piston burning and rod bearing damage are the result.
Preignition is the other bad actor and is usually started by a hot spot in the combustion chamber which causes the mixture to ignite before the plug fires. Under wide open throttle conditions, preignition will destroy pistons in seconds.
Research Octane Number (RON)
RON is determined in a single cylinder variable compression ratio engine that operates at 600 rpm with a 125 degree inlet air temperature at standard barometric pressure. Spark advance is fixed at 13 degrees btdc. In a real world engine, RON is necessary to satisfy part throttle knock problems.
A good quality racing gasoline has a RON in the range of 110 to 115. The difference in the spread of RON is not very important to racing engines.
The test and hardware were originally developed in 1931. The hardware was revised in 1946 with procedural changes made until the late 1960's.
Motor Octane Number (MON)
MON is determined in a single cylinder engine similar to the RON engine with a few changes that make operating conditions more severe and therefore the octane numbers are lower. The MON engine runs at 900 rpm with a 300 degree mixture temperature. Spark advance varies with compression ratio. In a real world engine, MON is necessary to satisfy octane demands at wide open throttle. This is a very important number for racing engines since they spend a high percentage of their lives under high speed and high load conditions. Racing engines cannot afford to be short on octane quality, since detonation or preignition will quickly reduce a racing engine to junk
و بالنسبة لل knocking no معلوماتي مش كتير واضحة عنه بس الي بعرفه انه لازم يكون الغازولين اله antiknock no. اعلى حتى يكون افضل.
بتمنى اكون افدتك باجابتي!!!