What are the stages of combustion?

What are the stages of combustion?

Based on the experimental results the combustion in SI engines takes place in three stages as follows:

• Period of ignition Lag Or preparation phase.
• Flame propagation phase.
• after burning or flame termination phase.

What is abnormal combustion?

The Abnormal Combustion:- ➢ When the combustion gets deviated from the normal behavior resulting loss of performance or damage to the engine. ➢It is happened when the charge inside the cylinder may be ignite before the flame front reach it.

What are the two types of abnormal combustion?

There are three forms of abnormal combustion: Detonation, Pre-Ignition and Detonation of fuel before Ignition or (Pre-Ignition due to Detonation). The process of burning the fuel in the combustion chamber has always been the most misunderstood concept by people who modify engines and tune engines.

What are the factors affecting abnormal combustion?

The most important factors are explained below.

• Molecular structure of fuel.
• Temperature of self ignition.
• Affect of high temperature and pressure after compression.
• Temperature of combustion wall chamber.
• Rate of burning.
• Spark timing.
• Spark intensity and duration.
• Air-fuel ratio.

What causes abnormal combustion?

Abnormal combustion. When unburned fuel/air mixture beyond the boundary of the flame front is subjected to a combination of heat and pressure for a certain duration (beyond the delay period of the fuel used), detonation may occur.

What is normal and abnormal combustion?

Under normal operating conditions, combustion is initiated towards the end of the compression stroke at the spark plug by an electric discharge. Abnormal combustion in spark ignition engine majorly occurs as knock and surface ignition.

What is abnormal combustion in CI engine?

Controlled combustion is shown between ‘c’ to ‘d’ and during this phase maximum of heat gets evolved in controlled manner. Combustion generally becomes abnormal combustion in CI engines when the ignition delay is too large resulting into large uncontrolled combustion and zig-zag pressure rise.

How abnormal combustion processes can be avoided in CI engines?

Methods to avoid abnormal combustion in SI engines : Using fuel having high octane number. Retarding the MBT timing of spark. Reducing intake temperature and pressure.

Does flame front exist in CI engine?

In C.I engines, during the suction stroke the air alone is taken in and the fuel is injected over a period of time at the end of the compression stroke. When the fuel combustion takes place, it happens so, not at a particular point but at several locations resulting in multiple flame fronts.

What are the stages of combustion in CI engine?

4 Stages of combustion in CI engine

• Ignition Delay Period.
• Period of Uncontrolled Combustion.
• Period of Controlled Combustion.
• After Burning.

What are the factors that affect flame propagation during combustion in a CI engine?

What Are the Various Factors Influencing Flame Propagation?

• Abnormality in SI engine like detonation is depends on the rate of pressure rise in the combustion chamber.
• Compression ratio.
• Intake temperature and pressure.
• Turbulence.
• Engine speed.
• Engine size.
• Engine load/ engine output.

What is the following two stage of combustion of SI engine?

The second phase i.e. flame propagation phase starts when the pressure in the combustion chamber starts rising at point B and the phase ends when the highest pressure is achieved in the cylinder at point C on ( P – θ ) diagram.

What are the three factors of engine good combustion?

Three things are required in proper combination before ignition and combustion can take place—Heat, Oxygen and Fuel.

• There must be Fuel to burn.
• There must be Air to supply oxygen.
• There must be Heat (ignition temperature) to start and continue the combustion process.

What are the factors affecting engine performance?

(i) The working media is not air but mixture of air and fuel in case of actual engine. (ii) The chemical composition of working media changes during combustion. (Hi) The process of combustion is never at constant volume or at constant pressure. (iv) The process of compression and expansion are not adiabatic.

How do you read engine performance?

Engine horsepower is measured using a dynamometer, but what the dynamometer really does is measure the torque output of the engine, as well as the RPM – or “revolutions per minute”. These numbers are plugged into a formula (torque x RPM / 5,252) to determine the horsepower.

What is a good amount of horsepower for a car?

Right between 200 and 300 horsepower is the sweet spot for many drivers. Be cautious with models that approach 300 horsepower, unless the vehicle is a heavy truck or another large model.

Does higher BHP mean faster car?

The Brake Horse Power is the unit of power of an engine without any losses like heat and noise. The BHP determines the acceleration and top speed of a vehicle. Often fast and quick vehicles will focus more on the BHP than the torque.

Which is better cc or BHP?

CC merely determines how much volume of air-fuel mix the engine can burn whereas BHP is a measure of how much mechanical energy the engine can extract by burning the air-fuel mix. So in general larger the CC larger the BHP by virtue of the fact that more CC = more fuel burnt and hence more energy extracted.