Laser-based Acoustic Sensing for Noise Measurement in Wind Tunnel

AeroMancer Technologies proposes a Laser Rayleigh Aeroacoustic Density Sensor (LRADS) for the measurement of aeroacoustic density perturbations in anechoic wind tunnels using Rayleigh scattering of laser radiation by air molecules. The relative acoustic density perturbations are directly proportional to the ratio of fluctuations of the intensity of the light received by the detector to the mean light intensity. In Phase I, AeroMancer refined the instrument requirements, developed a simulation of its performance; built and tested a breadboard instrument for validating the performance simulation; and conducted an error analysis to determine the dominant sources of measurement uncertainty. Using these results, AeroMancer developed the preliminary design of a prototype LRADS system that is based on a lidar configuration that can provide range resolved aeroacoustic density measurements along the laser beam to >1 KHz. In Phase II, AeroMancer proposes to finalize the LRADS prototype design; develop a noise and vibration enclosure to isolation the laser and sensitive optics from wind tunnel noise and vibration; fabricate and assemble the prototype; and test, validate and calibrate the system both in the laboratory and operationally in the 40x80 wind tunnel.