Research Of Acoustic Temperature Field Measurement System And Acoustic Travel-time Measurement Method

Temperature field measurement based on acoustic travel- time tomography is a typical application in computerized tomography. Compared with traditional temperature measurement technology, acoustic method has many advantages such as non-contact, wide temperature range, wide measuring range, high-precision, real-time, easy maintenance and so on. Temperature field reconstruction is a typical inverse problem. Very small acoustic travel-time measurement errors could result large reconstruction errors. The key for acoustic temperature field measurement is to measure acoustic travel-time accurately.This paper briefly introduces the acoustic temperature measurement basic principle, summarizes the applied present situation and important meaning of acoustic tomography technology at home and on abroad. Design an eight synchronous data acquisition system for acoustic temperature field measurement based on virtual instrument technology. The system uses LabVIEW as software platform, using data acquisition module PMD1608, computer with sound card, sound transmitting circuits, receiving circuits as hardware system. The system can collect signals on the sound wave paths produced by 8 emitters/receivers around the field to be measured in scan mode, calculating the travel-time of sound wave in each sound wave path with general cross-correlation method, and finally reconstruct the temperature field with pre-embedded reconstruction algorithm. This paper introduces the acoustic temperature field measurement system from software and hardware design.To overcome the large sample interval, low sample rate and other restrict problem, a new method based on combing fast correlation and up-sampling is proposed. Use up-sampling method to reduce sample interval. Simulation research in MATLAB and experimental data both show that fast correlation combining up-sampling method has higher travel-time estimation accuracy, lower fluctuationUse the acoustic temperature field measurement system designed in this paper to do the uniform temperature field reconstruction experiment in the laboratory. The experimental result confirmed that using the travel-time estimate values by the new method to reconstruct, the reconstruct temperature field error is lower than using the travel-time estimate values by fast- correlation to reconstruct. The feasibility on acoustic temperature field measurement system and the effectiveness of new travel-time estimation method are both further verified.