USCG Exam PracticeDiesel engine principles (motor propulsion)
Which of the following best describes 'scavenging' as it applies to a two-stroke diesel engine?
- A. The process of recovering exhaust energy to drive a turbocharger compressor
- ✓ Forcing fresh air into the cylinder to sweep out combustion products, since there is no separate intake or exhaust strokeCorrect
- C. Cooling the intake charge after it leaves the turbocharger compressor
- D. Metering the quantity of fuel delivered to each cylinder
Why B is correct
Because a two-stroke diesel has no separate intake or exhaust stroke, fresh air must be forced in to sweep out combustion products; this process is called scavenging and requires a blower or turbocharger to supply air above exhaust-manifold pressure. (DOE-HDBK-1018 Vol.1 §1-2)
Cited:DOE-HDBK-1018 Vol.1 §1-2