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How do air swirl and squish improve combustion in a diesel engine?
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diesel engine
Diesel engine equipped with a precombustion chamber.
In a diesel engine, air swirl and squish are critical techniques used to improve combustion by ensuring fuel and oxygen mix efficiently.1
When mechanical fuel nozzles replaced high-pressure air injection, the fuel struggled to find oxygen atoms, leading to improper burning and smoke. To solve this, engineers introduced additional motion to the air within the cylinder:1
- Air Swirl: This is an induction-produced rotational movement of the air. It is designed to move the entrapped air continuously from one fuel spray to the next during the injection period.1
- Squish: This refers to a radial movement of the air from the outer edge of the piston toward the center.1
By combining these motions, the engine ensures that fuel particles are thoroughly diffused throughout the air. Optimal performance is achieved when the rotational velocity of the air swirl is carefully balanced with the fuel-injection rate, allowing the fuel to effectively encounter the oxygen necessary for complete combustion.1