Abstract
An acoustical method for temperature measurement of large-scale spaces in a wind field is described. The real-time thermometry in a long span of 100 m was realized by the adoption of a bidirectional sound probe as a temperature sensor and a wireless local area network for controlling sensors. The probe mainly consists of two loudspeakers and two microphones. An accurate mean spatial temperature was measured without the interference of the wind in the area by the bidirectional probe. We carried out numerical simulations to confirm the validity of our method. The mean temperature was satisfactorily measured by this principle under various distributions of wind velocity. In field measurements, mean spatial temperature along a 100-m-long baseline was measured by the system with a conventional thermometer as a reference. The temperature change over one hour at 30 s intervals was compared to the change in the reference temperature at the center of the baseline. The results indicated that the system recorded a long periodic change in air temperature without the effects of local turbulence and wind. The advantages of the proposed system compared to a conventional thermometer are real-time, wireless and noncontact measurements.