Willan's line (steam engine): straight-line relation Willan's line for a steam engine is an approximately straight-line plot between steam consumption per hour and which output measure? Choose the correct option.

ConceptFor steam engines, Willan's line plots steam consumption rate vs. indicated power; its intercept estimates the no-load steam consumption (friction/standby losses) and the slope gives steam rate per kW indicated. (For IC engines, an analogous Willan's line is often shown for fuel vs. brake power.)

Final AnswerIndicated power