Atmospheric Humidity and Engine Performance 290033

SO-CALLED correction factors to compensate for variations in atmospheric temperature and pressure have been in practical use in connection with engine testing; but the influence of the varying amount of aqueous vapor present in the atmosphere has not had sufficient consideration. The author submits brief test-data indicative of the effect of humidity on some factors of engine performance and of the feasibility of using rational power-correction factors. By assigning due importance to the effect of humidity, he believes that a more satisfactory analysis of car and of engine performance can be obtained.
Using a single-cylinder engine operated at full throttle and 1000 r.p.m. under stabilized conditions, tests were made observing maximum power, air-flow, fuel-flow, detonation and spark-advance requirements over a wide range of relative humidity for an air-intake temperature of 100 deg. fahr. Curves made from the data obtained are given and discussed.
In conclusion, the author says the data show that humidity should be taken into consideration in engine and automobile test-work because of its relatively important effect on maximum power, spark-advance requirements, carbureter metering-characteristics and radiator performance, and its lesser but measurable effect on detonation. Further, he asserts that the tests reasonably substantiate rational power-correction factors.
As stated by one discusser, the importance of the paper lies in the fact that it has taught something definite and not because it has raised the question whether corrections should be made for the effect of moisture. Another states that his company has found that data check very much closer from day to day when the humidity is taken into account. The effect of the moisture in the air is analyzed by a third, and a fourth says Mr. Gardiner's data furnish ample justification for adopting his correction factors officially.


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