What Causes Detonation?

What causes detonation in aircraft engines?

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..

What does detonation feel like?

When detonation happens, some of the air/fuel ignites before the normal burn can get to it. This causes a brief, but intense, spike in cylinder pressure. Detonation is also called an “Engine Knock”, “Knocking”, or “Pinging” because of the sound it makes.

What is difference between knocking and detonation?

Detonation is an uncontrolled combustion event which occurs after the spark event. Pre-ignition is an uncontrolled combustion event which occurs before the spark event. Knock (pinging) is the actual noise that can be audibly heard if detonation is bad enough.

What is anti knocking?

An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel’s octane rating by raising the temperature and pressure at which auto-ignition occurs.

What do you mean by detonation?

Detonation (from Latin detonare, meaning ‘to thunder down/forth’) is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it.

What causes pre ignition knocking?

The most common causes of pre-ignition are the overheating of a spark plug electrode (using a spark plug that has a heat rating that is too high for your application and intended use) and excessive build-up of carbon in the cylinder.

What is fuel detonation?

Detonation — generally caused by fuel with a low octane rating — is the tendency for the fuel to pre-ignite or auto-ignite in an engine’s combustion chamber. … Prolonged and intense knocking can break the piston or the engine, though it is can also endure this slight issue for thousands of miles.

What does detonation look like on a spark plug?

With the early signs of detonation, the shock-wave will also rattle rings causing the tiny amounts of oil that now gets by rings, to be fused to the white porcelain as tiny black specks, also fused as specks are soot that was clinging to clearance volume surfaces in the relatively “still-air” of the boundary layer.

How do you stop engine knocking?

Tips for Preventing Engine KnockAlways fuel from a reputable gas station with good fuel quality.Change your spark plugs as often as required and not just when they are worn out.Reduce the throttle immediately you hear any engine knocking or pinging.Use high-quality fuel additives to minimize carbon build-up.More items…•

Can you hear engine detonation?

Detonation Knock: Too Low Octane. … When your engine is running smoothly, the air/fuel mixture burns up in a single, controlled detonation inside each cylinder. Detonation knock is a knocking noise that you’ll hear when the air fuel mixture in the cylinders is detonating in more than once place at a time.

How do I fix pinging noise when accelerating?

It can be fixed by fixing/improving/modifying the engines cooling system and use coolent if possible. 4. Due to the low speed of engine: Due to low engine speed, there is a sufficient ignition lag, which gives enough time for a secondary flame front to get formed leading to the knocking.

What is a deflagration explosive?

Deflagration (Lat: de + flagrare, “to burn down”) is subsonic combustion propagating through heat transfer; hot burning material heats the next layer of cold material and ignites it. Most “fires” found in daily life, from flames to explosions such as that of black powder, are deflagrations.

How do you fix detonation?

Detonation Elimination: 9 Ways to Prevent Engine Detonation#1. Up Your Octane.#2. Keep Compression Reasonable.#3. Check Your Timing.#5. Monitor the Mixture.#6. Blow out the Carbon.#7. Examine Your Knock Sensor.#8. Read Your Spark Plugs.#9. Consider Your Cooling System.

What is the effect of detonation?

when detonation occurs, the fuel charge ignites quickly in an uncontrolled explosion, causing a pounding or hammering force on the piston rather than a steady push. Moderate to severe detonation could be noticed as engine roughness, vibration or loss of power and eventually engine damage.

Can you drive with a knocking engine?

While we prefer the latter, some times the simplicity of changing the way you drive and maintain your car can help. Engine knocking is nothing to ignore. … Run your car for very long with this kind of problem, and it can cause serious engine damage.

Can bad spark plugs cause detonation?

If the heat range is correctly matched to the engine application, the plug will run hot enough under normal driving conditions to burn off fouling deposits before they can cause problems. Likewise, the plug won’t get too hot and become a source of ignition causing engine-damaging preignition and detonation.

What happens if ignition timing is too advanced?

If ignition timing is too far advanced, it will cause the fuel-and-air mixture to ignite too early in the combustion cycle. This can cause the amount of heat generated by the combustion process to increase and lead to overheating of the engine.

How do you check for detonation in an engine?

Moderate to severe detonation could be noticed as engine roughness, vibration or loss of power and eventually engine damage. A pilot should always be looking for unexpectedly high Cylinder Head Temperatures (CHTs) or Exhaust Gas Temperatures (EGTs) which may be a sign that detonation is occurring.

What is the difference between pre ignition and detonation?

Detonation: Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. … Pre-ignition: Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing.

How do you fix pre detonation?

Try a higher octane fuel. … Check for loss of EGR. … Keep compression within reasonable limits. … Check for over-advanced ignition timing. … Check for a defective knock sensor. … “Read” your spark plugs. … Check for engine overheating. … Check the operation of the heated air intake system.More items…