Tomographic Measurement of Vortex Air Flow Field Using Multichannel Transmission and Reception of Coded Acoustic Wave Signals

An acoustic travel time tomography system for the monitoring of the vortex wind flow velocity profile has been studied, where multichannel parallel acoustic transmitter/receiver pairs are placed along opposite sides of the monitoring region. Thus far, to prevent cross-talk between the elements, travel time collections must be made successively for every single transducer element. Hence, it is difficult to achieve real-time observation while maintaining the temporal variation in the air flow field. To realize simultaneous multichannel travel time collections, a coded modulation method is introduced using the Kasami sequence. To verify the validity of the method, basic examinations of both simulation and experiment data are carried out. (C) 2011 The Japan Society of Applied Physics