Kash_
6th August 2006, 02:04 PM
I was just browsing the web and came across a few good points on what detonation is and how it occurs in Rotary engines. I thought this would be a good sticky for people such as myself who are new to rotary engines....
1. By running too lean, there is less fuel in the combustion chamber than needed to control the proper timing of the air/fuel charge being ignited by the spark of the ignition system, as opposed to just the compression of the rotor (the more you compress something the higher the temperature) or a "hot spot " (high temp area of the combustion chamber or anything in it). So basically the charge is being ignited before its suppose to which would put stress on all the components in the engine including the e-shaft and the apex seals which maintain the integrity of the combustion chamber compression.
2. An engine cannot run at stoich ("lean", but air is just = with fuel by the req'd ratios) as the combustion happens far too quickly: it explodes rather than burns. When running at a healthy ratio (which means more fuel than stoich, but not "rich") the fuel and air combine slowly in a controlled reaction, with a distinct flame front, forcing the rotor around as the combustion both heats the gas and increases the number of molecules, increasing the pressure in the combustion chamber driving the output shaft around, rather than a sudden BLAST jarring the whole motor.
3. With an improper amount of fuel in the mix, the air molecules can be compressed to a point where they can ignite just from the heat of compression causing a premature ignition or "detonation". This can also happen from "overheating" or a "hot spot". It's this violent, untimely explosion when the rotor is not in an optimum position to properly take advantage of the combustion vs. a relatively "controlled" burn of a proper air/fuel mixture at the right time, that causes stress and in severe cases, serious engine damage.
4. Detonation is caused because part of the fuel mixture fires before the spark plug fires and cause damage to the parts because of the conficting flame front. the reason for more fuel is because the fuel and air need to be correct so that the fuel burns in the right ratio to oxygen. when you dont have enough fuel that extra oxygen burns and cause damage to the engine by creating too much heat. The fuel helps to keep the combustion chamber at the correct temp, that is best for the engine combustion. You can make more power with less fuel by slowing down the flame front. which is one of the reasons we are able to make more power using less gas in newer cars.
5. Alot of times people call it detonation when the timing is off. but detonation has to do with where the flame front starts at. In a perfect world we would have is start a one end of the combustion chamber in a rotary and go to the other side with out any trouble. because there is a thing such as pre ingition that is not detonation. pre ingition start from having a hot spot ingite the fuel/air mixture. There is then the detonation which is caused buy not a correct air to fuel mixture.
1. By running too lean, there is less fuel in the combustion chamber than needed to control the proper timing of the air/fuel charge being ignited by the spark of the ignition system, as opposed to just the compression of the rotor (the more you compress something the higher the temperature) or a "hot spot " (high temp area of the combustion chamber or anything in it). So basically the charge is being ignited before its suppose to which would put stress on all the components in the engine including the e-shaft and the apex seals which maintain the integrity of the combustion chamber compression.
2. An engine cannot run at stoich ("lean", but air is just = with fuel by the req'd ratios) as the combustion happens far too quickly: it explodes rather than burns. When running at a healthy ratio (which means more fuel than stoich, but not "rich") the fuel and air combine slowly in a controlled reaction, with a distinct flame front, forcing the rotor around as the combustion both heats the gas and increases the number of molecules, increasing the pressure in the combustion chamber driving the output shaft around, rather than a sudden BLAST jarring the whole motor.
3. With an improper amount of fuel in the mix, the air molecules can be compressed to a point where they can ignite just from the heat of compression causing a premature ignition or "detonation". This can also happen from "overheating" or a "hot spot". It's this violent, untimely explosion when the rotor is not in an optimum position to properly take advantage of the combustion vs. a relatively "controlled" burn of a proper air/fuel mixture at the right time, that causes stress and in severe cases, serious engine damage.
4. Detonation is caused because part of the fuel mixture fires before the spark plug fires and cause damage to the parts because of the conficting flame front. the reason for more fuel is because the fuel and air need to be correct so that the fuel burns in the right ratio to oxygen. when you dont have enough fuel that extra oxygen burns and cause damage to the engine by creating too much heat. The fuel helps to keep the combustion chamber at the correct temp, that is best for the engine combustion. You can make more power with less fuel by slowing down the flame front. which is one of the reasons we are able to make more power using less gas in newer cars.
5. Alot of times people call it detonation when the timing is off. but detonation has to do with where the flame front starts at. In a perfect world we would have is start a one end of the combustion chamber in a rotary and go to the other side with out any trouble. because there is a thing such as pre ingition that is not detonation. pre ingition start from having a hot spot ingite the fuel/air mixture. There is then the detonation which is caused buy not a correct air to fuel mixture.