Calibration of a high temperature and pressure ejector facility with back pressure effects

An experiment has been designed to measure directly the effect of the length of a mixing duct on the pumping performance of a high temperature, high pressure ejector. The parameters of most importance to the tests are the mass flows of the primary and entrained air streams. The experiments are designed to measure these parameters by means of a venturi meter and a bellmouth inlet, respectively. The present report describes the calibration of both metering devices against a venturi that had earlier been calibrated by the National Bureau of Standards. Tests were conducted at primary reservoir pressures up to 6.6 atmospheres and temperatures up to 1000 F. Both the primary venturi meter and the bellmouth inlet demonstrated sensitivity to high temperatures, above 500 F, for example. The thermal effects were, however, capable of correlation and suitable coefficients evolved for each device. During the course of the experiments, measurements of the effect of back pressure on performance were made. Increasing back pressure reduced entrainment as predicted by an elementary analysis.