Research Of Data Acquisition System For Acoustic Temperature Field Measurement

Temperature field measurement based on acoustic tomography is a new technology developing in recent years. Abroad, it has been matured, and applied to industry furnace for temperature measurement online. This paper briefly introduces acoustic tomography technology, summarizes the research of acoustic pyrometer at home and abroad, expatiate the keystone of acoustic temperature field measurement, describes the whole scheme of temperature field measurement based on acoustic tomography, determines general cross correlation method to measure the time-of-flight (TOF) of sound wave, and discusses the hardware and software realization of data acquisition system for acoustic temperature measurement based on virtual instrument.In this paper, the estimation of TOF of sound wave between the sound emitter and receiver by cross-correlation method is investigated in MATLAB with a simulation swept sound signal. The anti-noise ability and the precision of sound TOF estimation between basic cross-correlation and general cross-correlation are compared in the condition of strong noise and serious signal attenuation. The research results indicate that, even in the condition of serious aberration of signal, general cross-correlation has strong anti-noise ability, while basis cross-correlation can not achieve good precision unless the aberration of signal is restrained by a pre-processing filter.The data acquisition system of acoustic temperature measurement based on virtual instrument is developed. The system uses LabVIEW as design flat of software, uses data acquisition module PMD1608, computer with sound card, sound transmitting circuit, receiving circuit as hardware system. The system can collect signals on the sound wave paths produced by 8 emitters/receivers around the field to be measured at scan mode, calculate the TOF of sound wave in each sound wave path with general cross-correlation method, and finally reconstruct the temperature field with pre-embedded reconstruction algorithm. The system is tested on the condition of room temperature in lab. The experiment results indicate that the system can measure the TOF of sound wave in all the 24 sound wave paths; the relationship between the TOF measurement value and the sound path length is linear as expected. Two-dimension temperature field reconstruction experiment is implemented in Lab, and the temperature reconstructed described the characteristic of real temperature field.