Mechanical Engineering - Automobile Engineering - Discussion

The correct answer is it measures delay period. Now the reason is that knocking in engine is dependent on delay period. In order to avoid detonation or knocking in SI engine the delay period should be long.

But in CI engines the knocking happens before combustion (in SI-after (end) of combustion) the delay period the delay period should be less. If delay period is longer the fuel injected and accumulated in cylinder more and very high temp and pressure is generated inside cylinder.

So for CI engine alpha methyl naphthalene has very long delay while for cetane its very less. So given answer is correct.

No, delay period is D right answer, ignition quality is measure by octane number.

It measures ignition quality.

The cetane rating of diesel fuel refers to it's ability to "light on contact". So therefore, the answer I believe is "ignition quality".

Its correct is ignition quality and cetane no is increased then the quality is improved.

Cetane number is a measure by ignition quality of diesel fuel.

Cetane number is a measure of ignition quality of diesel fuel.

Cetane number or CN is a measure of a fuel's ignition delay, the time period between the start of injection and the first identifiable pressure increase during combustion of the fuel. In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower cetane fuels. Cetane numbers are only used for the relatively light distillate diesel oils.

It is measurement of ignition quality of fuel.

No.It is used for volatility of fuel.