Puissance = couple Ă vitesse angulaireP: W; pair: N·m ; Ï: rad/s.
Use when: Mechanical relation P = CÏ for a rotating shaft.
The four-stroke engine
Understand the mechanical cycle and distinguish the succession of times from the ideal thermodynamic model.
What is happening?
Admission, compression, combustionâexpansion and exhaust follow one another in two revolutions of the crankshaft. The connecting rod transforms the movement of the piston into rotation while the distribution controls the valves.
The ideal Otto cycle represents certain transformations of a spark ignition engine. The real engine undergoes thermal losses, friction, gas renewal and combustion of finite duration.
The formulas, with their conditions.
ηOtto = 1 â 1/r^(Îłâ1)η: ideal yield; r: compression ratio; Îł = câ/cᔄ.
Use when: Otto cycle with ideal gas and constant thermal capacities; no real return guaranteed.
Where is this principle used?
Engine factory and automobile workshop
Assemble, control and diagnose organs.
Generator
Transform the energy of fuel into work then into electricity.
What to observe in the experiment
Scroll through the assembly and identify the valve positions at each of the four strokes. Count the crankshaft revolutions per cycle.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian