In S.I. engines detonation is caused by
the auto-ignition of end gas towards the end of combustion
whereas knocking in CI engines is due to auto-ignition of the first charge at the start of combustion.
What causes detonation in aircraft?
During detonation, the fuel/air charge (or pockets within the charge) explodes rather than burning smoothly. … Other causes of detonation are improper ignition timing,
high inlet air temperature, engine overheating, oil in the combustion chamber
, or a carbon build up in the combustion chamber.
Which of the following can cause detonation?
Causes of detonation are limited to
excessive heat and low octane
. Excessive heat can come from improper cooling, high compression from excessive combustion chamber deposits, lean mixture, advanced timing and more.
What causes detonation in a two stroke engine?
Compression causes heat.
If the air/fuel mixture is compressed too much
, it can detonate. Low coolant or a bad water pump can cause the engine to overheat. Too much heat can cause the air/fuel in the chamber to detonate.
Does pre ignition cause detonation?
Pre-ignition is combustion inside the cylinder BEFORE the spark plug fires. It is
similar to Detonation
, but it is different. When pre-ignition happens, something ignites the Air/Fuel Mixture during the Compression Stroke.
How is detonation diagnosed?
The best way to diagnose detonation in this situation is to
install a wide-band oxygen sensor and monitor it during periods of high engine load
. A lean condition under full throttle can induce knock at ratios as low as 13:1, and that should tell you not enough fuel is reaching the cylinder.
What is effect of detonation?
Answer: Effects of detonation (1)
Noise
– As intensity of detonation increases, the sound intensity increases & it is harmful. (2) Mechanical damage – shock waves are so violent that it may cause mechanical damage like breaking of piston. It increases the rate of wear erosion of piston.
Can too much fuel cause detonation?
Detonation is generally caused by
excessive heat
, excessive cylinder pressure, improper ignition timing, inadequate fuel octane or a combination of these. … For engines that are experiencing detonation problems, the primary options are the use of ignition/timing retard systems, higher octane fuel, or intercooling.
What is difference between knocking and detonation?
Knocking vs Detonation
Knocking is the making sharp sounds due to uneven combustion of fuel in the cylinder of a vehicle engine. Detonation is the process of pre-ignition or auto-ignition of a fuel in an engine’s combustion chamber.
How do you prevent engine detonation?
- #1. Up Your Octane. …
- #2. Keep Compression Reasonable. …
- #3. Check Your Timing. …
- #4. Manage Your Boost. …
- #5. Monitor the Mixture. …
- #6. Blow out the Carbon. …
- #7. Examine Your Knock Sensor. …
- #8. Read Your Spark Plugs.
Can spark plugs cause detonation?
The wrong spark plugs can cause
detonation.
Spark plugs with the wrong heat range (too hot) can cause detonation as well as preignition.
Can bad spark plugs cause detonation?
A reading over about 3% to 4% oxygen would indicate a lean fuel condition. Spark Plug Too Hot:
The wrong heat range plug can cause detonation
as well as pre-ignition. Copper core plugs are less likely to cause detonation than standard spark plugs.
What is fuel detonation?
Detonation is
the abrupt combustion or explosion of the fuel charge inside the cylinder
. During normal combustion, the spark plugs ignite the fuel charge and the fuel has a consistent and even burn as the piston moves through the power stroke and chemical energy is efficiently converted to mechanical.
What does pre detonation look like?
Typically, with pre-ignition, you will see
holes melted in pistons
, spark plugs melted away, and engine failure happens pretty much immediately.
How can we prevent fuel detonation in aircraft engines?
Fuel with a higher octane rating will
reduce detonation. Having said that, if you use a low octane fuel and start using a high octane fuel without changing anything else, you will increase the safety margin before detonation will occur. By itself, using a higher octane fuel will not increase the power of an engine.
How pre-ignition can be detected?
To detect the onset of pre-ignition an in-cylinder pressure transducer 60 can be used to detect the occurrence of heat release before the intended spark event. This can be performed on all cylinders of the engine 100 and on a cycle-by-cycle basis. … By
calculating heat release rates
it is possible to detect pre-ignition.
