Inventors:
William H. Brown - Marietta GA
Krishan K. Ahuia - Atlanta GA
Assignee:
Lockheed Corporation - Burbank CA
International Classification:
G01L 1100, G01L 2300
Abstract:
A probe (P) capable of sensing acoustic and hydrodynamic pressures in a heated flow field and an associated apparatus for acoustically exciting the heat flow (35), for positioning the probe (P) within the flow field and fro acquiring data. The probe (P) consists of a miniature microphone (10) mounted in an assembly which provides direct water cooling to the microphone body and which, by means of a bullet nosed extension (23, 24) with lateral ports (25), protects the microphone element (10) from direct impingement of the flow (35). Acoustic excitation of the flow (35) is introduced upstream of the nozzle (34) through a tube (37) from an externally mounted acoustic driver (36) which responds to the amplified output of a signal generator (38); the signal generator (38) and the amplifier (39) are adjusted to control the frequency and amplitude of the excitation. A traversing mechanism (32), capable of movement in three orthogonal directions is used to position the probe (P) within the flow (35). Signals from an acoustic excitation sensor (47) and from the probe (P) are amplified to convenient levels and processed by a two-channel Fast Fourier analyzer (40) which produces the transfer function correlograms and spectra of the input signal individually and jointly displayed on a recorder/indicator (41).