State any TWO ways by which air turbulence can be improved during the intake stroke on a direct injection diesel engine.

• A points to the device that injects fuel into the chamber.
• B points to the heating element used for cold starts.
• C points to the moving part that compresses the air.
• D points to the enclosed space where initial combustion occurs, separate from the main cylinder.
• E points to the narrow opening connecting the pre-combustion chamber to the main cylinder.

The chamber labelled D is a compact, often spherical or pear-shaped, chamber connected to the main cylinder by a narrow passage (E). This design promotes a swirling motion of air, which is characteristic of a swirl chamber.

Indirect combustion chambers are designs where combustion begins in a separate chamber before expanding into the main cylinder. Common types include the swirl chamber and the air cell chamber.

6.4.1)
A: Fuel injector
B: Glow plug
C: Piston
D: Pre-combustion chamber
E: Throat / Passage

6.4.2)
This is a swirl chamber.

6.5)
Two types of indirect combustion chambers are:

• Swirl chamber
• Air cell chamber