An Improved System for Control and Measurement of Air Consumption of a Single Cylinder Engine 520261
A NEW system for measuring accurately the air consumption of single-cylinder test engines is described in this paper by two engineers who have sought to eliminate errors resulting from the pulsating airflow caused by piston movement and the opening of the intake valve.
The new technique utilizes the principle of critical or sonic flow of gas through a convergent nozzle to measure air consumption to an accuracy of 1% under all operating conditions, as compared with errors of as much as 20% resulting from the use of conventional orifice meters.
In addition the new system makes possible the maintenance of constant inlet air pressure, temperature, and humidity, independent of prevailing atmospheric conditions, whereas the conventional system fails to isolate the engine’s “breathing” from vagaries of atmospheric conditions.
The new technique is not needed for multicylinder engines inasmuch as they produce a “steady state” of airflow through conventional orifice meters.