This is a exam of probability. It includes 12 questions and every question requires detailed answer steps. It needs to be finished as PDF file.

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Discussion Questions: 1

Explain why the engine power and torque characteristic curves peak and then drop off with engine speed

Answer: The torque reduces due to the air flow losses in the valves and mechanical losses which dominate at higher speeds. … As the rpm of an engine increases, the torque reduces due to low volumetric efficiency. Due to less air-fuel mixture being burned, power is also reduced.

2. Explain why the brake specific fuel consumption characteristic curve decreases and then increases with engine speed.

Answer: Brake-specific fuel consumption (BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft power. It is typically used for comparing the efficiency of internal combustion engines with a shaft output.

It is the rate of fuel consumption divided by the power produced. It may also be thought of as power-specific fuel consumption, for this reason. BSFC allows the fuel efficiency of different engines to be directly compared.