Describe piston stroke, swept volume, clearance volume and compression ratio for a diesel engine with a suitable diagram?
Short answer
| Term | Definition | Formula |
|---|---|---|
| Piston Stroke | Distance between TDC and BDC | L |
| Swept Volume | Volume displaced by piston | Vs = (π/4) × D² × L |
| Clearance Volume | Volume at TDC | Vc |
| Compression Ratio | Ratio of total to clearance volume | r = (Vs + Vc) / Vc |
- Piston Stroke: Linear distance between top dead centre (TDC) and bottom dead centre (BDC)
- Swept Volume: Volume displaced by piston, Vs = (π/4) × bore² × stroke
- Clearance Volume: Volume remaining in cylinder at TDC (combustion chamber + piston bowl)
- Compression Ratio: r = (Vs + Vc) / Vc, typical 14.5:1–20:1 for marine diesel engines
- Diagram: Cylinder cross-section showing TDC/BDC positions and volume labels
Full answer
The full answer explains each point step by step, with the regulations and figures behind it and the discussion from other candidates. It is in the MEO Class IV section of the Marine One forum, open to members enrolled for the MEO Class IV exam.