What causes detonation in SI engine?
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 is detonation how it can be controlled in Si engine?
Investigations indicate that detonation may be controlled by retarding the rate of combustion by chemicals added to the mixture, which serve to increase its specific heat and prevent excessive temperature, and by reducing the temperature of the walls of the combustion-chamber, so that the temperature of the charge …
What are the three causes of detonation?
What Causes Detonation Engine Knock?
- Bad Knock Sensor. Your engine has a sensor that is designed to detect when there is a detonation knock.
- Air-Heavy Mixture. Air and fuel combust together to create detonation in the cylinders.
- Low-Octane Fuel.
- Poor Engine Timing.
- Bonus Cause.
What is meant by abnormal combustion explain the phenomena of knock in SI engine?
Abnormal combustion for an SI engine is defined as that type of combustion process in which the heat is released at an abnormal rate than desired. The corresponding rise and fall of pressure with respect to crank angle does not remain smooth.
Which of the following factors increase detonation in the SI engine?
Knocking or detonation is due to the auto-ignition of the end portion of the unburned charge in the combustion chamber. Factors affecting knocking in SI engine: Compression ratio:- Higher compression ratio will result in the higher temperature of the charge, the tendency to knock will increase.
What are the 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.
What is the definition of a detonation?
Definition of detonation 1 : the action or process of detonating. 2 : rapid combustion in an internal combustion engine that results in knocking.
What is detonation What are the effects of detonation?
Unlike normal exhaust noise, detonation is a higher-pitched, raspy note that emanates from the engine compartment. When detonation occurs, serious internal damage may happen, including melted spark plug electrodes, cracked piston rings, melted or cracked pistons, hammered rod bearings, and blown head gaskets.
On what factor does detonation depend?
Mostly Detonation is occurred because of following reasons: Low Octane Fuel. High Compression engine. High Mileage engine.
What is the effect of detonation on engine performance?
The detonation has a bad impact on the overall engine. The lesser extent of detonation can cause the bushings and bearings to wear while long time detonation in ic engine results in the bending of the connecting rod, breakage of the piston, melting of valves as well as damage to the cylinder head.
How detonation or knocking affects the performance of SI engine?
The usage of hydrogen in compression ignition engine leads to production of knocking or detonation because of its lower ignition energy, wider flammability range, and shorter quenching distance. Knocking combustion causes major engine damage, and also reduces the efficiency.
What is detonation material?
Detonation—Is a propagating chemical reaction of a substance in which the reaction front advances into the unreacted substance at greater than sonic velocity in the unreacted material.
What are detonation waves?
Detonation waves are shock waves that are sustained by the energy of the chemical reaction that is initiated by the shock compression.
How do you test for detonation?
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 detonation process?
22.2. The detonation process is based on repetitive explosions or detonations of oxygen-fuel gas mixtures, rather than the continuous burning of a combustion flame, as in the HVOF process. Oxygen and acetylene are loaded into a long, water-cooled barrel with powder. The mixture is ignited and it explodes.
Is detonation and knocking same?
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.
What is difference between knocking and detonation?
Why is detonation called detonation in SI engines?
In SI engine, the charge that autoignites is homogeneous and therefore intensity of knocking or the rate of pressure rise at explosive autoignition is likely to be more than that in CI engines where the fuel and air are not homogeneously mixed even when explosive autoignition of charge occurs. Therefore, it is often called detonation in SI engines.
What is the difference between Knock and detonation in an engine?
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 is knocking in SI engines?
Knocking in SI engine occurs due to the pre-ignition of the air fuel mixture. This means the charge is already heated to the self ignition temperature of the fuel before the spark plug ignites the mixture by generating spark. Hence the power is generated before completion of the stroke.
How does deflagration work in an SI engine?
During normal deflagration combustion, in an SI engine, there is a laminar and controlled oxidization of the charge, with a succinct flame front. (Combustion in a CI engine combustion is via a diffusion flame, which is another matter for another time).