Question

A single cylinder four-stroke diesel engine has an engine displacement volume of 9 L, the engine rotates at 2400 rpm and its volumetric efficiency is 88%. The actual air inducted into the cylinder in m$^3$ s$^{-1}$ is _____.

Hint:

For four-stroke engines, remember that the air intake occurs once every two revolutions. Volumetric efficiency corrects the theoretical intake volume.

Answer 1

Correct Answer: 0.157

First, convert the engine displacement volume to cubic meters: \[ V_{\text{displacement}} = 9 \, \text{L} = 9 \times 10^{-3} \, \text{m}^3. \] Since the engine is a four-stroke, it takes two revolutions to complete a full intake cycle, so the air intake per revolution is half the displacement volume: \[ \text{Air intake per revolution} = \frac{9 \times 10^{-3}}{2} = 4.5 \times 10^{-3} \, \text{m}^3. \] At 2400 rpm, the air intake per second is: \[ \text{Air intake per second} = \frac{2400}{60} \times 4.5 \times 10^{-3} = 0.18 \, \text{m}^3 \, \text{s}^{-1}. \] Considering the volumetric efficiency is 88%, the actual air inducted is: \[ \text{Actual air inducted} = 0.88 \times 0.18 = 0.1584 \, \text{m}^3 \, \text{s}^{-1}. \] Thus, the actual air inducted is approximately \(\boxed{0.158} \, \text{m}^3 \, \text{s}^{-1}\).