What are the effects of ignition delay?

The shorter ignition delay affects the combustion performance of an engine. Ignition delay of the CI engine fuel is inversely proportional to its cetane number. Hence, optimization of ignition delay will improve the performance of the engine.

What causes ignition lag?

The longer ignition delay can be caused by a number of factors including: lower intake air temperature, lower boost pressure due to turbocharger lag, lower combustion chamber wall temperature and more advanced dynamic injection timing.

What are the factors affecting ignition timing?

The right time to ignite the fuel is affected by various factors such as the engine displacement, octane rating of the fuel, engine compression ratio, condition of the spark plugs and intake pressure of the engine. Typically, the ignition timing is adjusted when any changes or upgrades are made to the engine.

What is ignition lag engine?

[ig′nish·ən ‚lag] (mechanical engineering) In the internal combustion engine, the time interval between the passage of the spark and the inflammation of the air-fuel mixture. Also known as ignition delay.

What is the effect of engine variables on flame propagation?

EFFECT OF ENGINE VARIABLES ON FLAME PROPAGATION Rate of flame propagation affects the combustion process in SI engines. Higher combustion efficiency and fuel economy can be achieved by higher flame propagation velocities. Unfortunately flame velocities for most of fuel range between 10 to 30 m/second.

What is ignition lag what all parameters it depends on?

9.9. Ignition delay is calculated as the period from the start of injection to the start of combustion in terms of the crank angle. It depends on the factors like compression ratio, inlet pressure, injection parameters, and the properties of fuels used.

What is ignition lag and delay period?

The ignition delay in a diesel engine is defined as the time interval between the start of injection and the start of combustion. This delay period consists of (a) physical delay, wherein atomisation, vaporization and mixing of air fuel occur and (b) of chemical delay attributed to pre-combustion reactions.

What is delay period and what are the factors that affect the delay period?

I C ENGINES – II Air Motion & Combustion •Factors Affecting the Delay Period : – Intake temperature and pressure : Increase in intake temp. increases compressed air temp. resulting in reduced delay period. Preheating may not be desirable as it reduces density of air affecting volumetric efficiency and power.

Is ignition delay and ignition lag is same?

Ignition lag or ignition delay as the name suggests is the time interval between the passage of spark and the ignition of the fuel-air mixture.

What is the ignition lag or ignition delay period?

Ignition lag (the time lag between first ignition of fuel and the commencement of the main phase of combustion) is not a period of inactivity but is a chemical process. The ignition lag in terms of crank angles is 10° to 20° and in terms of time, 0.0015 seconds.

What is ignition lag discuss the effect of engine variables on ignition lag in case of SI engines?

Effect of Engine Variables on Ignition Lag in SI Engines: Fuel: Since ignition lag is primarily chemical phenomenon the fuel quality—especially its self-ignition temperature has important bearing on ignition lag. The higher the self-ignition temperature of the fuel longer will be the ignition delay.

What are engine variables?

The following engine variables were investigated: air-fuel ratio, power output, engine speed, spark timing, exhaust back pressure, valve overlap, combustion chamber deposits, and intake manifold pressure.

What are the factors that can cause ignition lag?

*air fuel ratio-if the mixture is too rich i.e have more fuel wil suffer ignition lag leading to blowpast. *speed or load- if the engine works at very low load for longer period it will suffer ignition lag. *coolant temperature-if the coolant temperature decreases too much then due to overcooling of body.it will undergo late ignition.

What are the factors that influence ignition delay in diesel engine?

Factors that influence ignition delay in diesel engine (Compression Ignition or ‘CI’ engine) are 1. Compression ratio: With the increase in compression ratio reduces ignition lag, a higher pressure increases density resulting in closer contact of the molecules which reduce the time of action when fuel is injected.

What are the conditions necessary for combustion in spark ignition engines?

Conditions necessary for combustion in Spark Ignition engines are: Stabilization and propagation of flame in the combustion chamber SI engine combustible mixture supplied by carburetor and combustion initiated by an electric spark If temperature of burnt gases exceeds approximately 1500 K ,then flame will propagate.

What is the effect of pre-ignition on the performance of engine?

This adds to negative work by the piston. Pre-ignition is also reduces the efficiency of engine because if pre-ignition occurs during the compression stroke of the engine then the energy produced because of pre-ignition will oppose the compression stroke and thus reducing the effi­ciency of the engine.