🔍 Key Concepts

• Fuel atomization and how droplet size affects spray behavior • Role of air turbulence and swirl in diesel combustion • What is meant by penetration of the fuel spray in a cylinder or combustion chamber

💭 Think About

• Think about what happens to fuel droplets if they are made smaller versus larger—how does that change how far they travel into the air before burning? • Which factor mainly controls the distance the fuel spray travels: the motion of the air or the size/character of the droplets? • In a pre‑combustion chamber system, does fuel contact with air in the main cylinder completely stop, or is it just controlled differently?

✅ Before You Answer

• Be clear on the definition of spray penetration (distance fuel jet travels into the compressed air). • Compare how finer atomization changes surface area and evaporation rate, and how that would logically affect penetration distance. • Verify whether any system truly has no penetration into the main cylinder, or if that sounds absolute and therefore suspicious on an exam.