Measuring and testing – Test stand – For engine
Patent
1987-07-20
1989-05-16
Woodiel, Donald O.
Measuring and testing
Test stand
For engine
7386118, G01F 166, G01M 1500
Patent
active
048298131
ABSTRACT:
The Mach number M.sub.o of flow in the intake nozzle or bypass duct of a gas turbine aircraft engine is determined from the acoustic impedance of a Helmholtz resonator to an engine fan-stator sound source. Pressure measurements P.sub.1 (t) and P.sub.2 (t), made nonintrusively at the duct wall surface and resonator cavity bottom are subjected to Fourier analysis to give P.sub.1 (f) and P.sub.2 (f), and acoustic impedance for the flow is determined from a complex transfer function H.sub.12. Flow Mach number is then established using known acoustic impedance/Mach number correlation relationships or a stored look-up table. An alternative embodiment, utilizes a sound source mounted in the Helmholtz resonator bottom and determines Mach number by pressure measurements made at spaced locations on the resonator chamber wall.
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General Electric Company
Herkamp Nathan D.
Lawrence Derek P.
Woodiel Donald O.
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