Question

A high flame speed is obtained in diesel engine when air fuel ratio is ____________

(a) uniform throughout the mixture

(b) chemically correct mixture

(c) about 3-5% rich mixture

(d) about 10% rich mixture

This question was addressed to me in a national level competition.

My doubt stems from Air Fuel Mixtures in division Carburetion of IC Engine

Answer 1

The correct choice is (d) about 10% rich mixture

Easiest explanation: When air fuel ratio is about 10% rich mixture, then a high flame speed is obtained in diesel engine.