| Résumé | In order to measure air mass flow rates through the 86 duct in No. 4 test cell of the Engine Laboratory, an average total head is obtained from a 25-point rake, and an average static head from four wall taps. A graph, based on compressible flow theory, facilitates the conversion from dynamic head to air mass flow rates. While this measuring arrangement has given very good results with the mass flow rates encountered in the past (approximately 75 to 350 lbm/sec), it was felt that its accuracy and readability would be questionable for the mass flow range of the forthcoming icing program. The maximum combined air flow rate for the engine and a blower providing spillage flow has been estimated to be about 85 lbm/sec; the minimum flow rate would be about 27 lbm/sec.
A fluidic anemometer, similar to one developed by J. Tanney, Low Speed Aerodynamics Section, has been designed by the Engine Laboratory Design Office and built by the Experimental Work Shops. This anemometer is based on the principle of fluidic amplification where a primary, constant, air jet is deflected by the secondary flow to be measured. It lends itself especially to low velocity flows and is capable of measuring air velocities from 0 to 50 ft/sec. with an accuracy within 1%. |
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