Acoustic computer tomographic pyrometry for two-dimensional measurement of gases taking into account the effect of refraction of sound wave paths

Abstract

The algorithm which takes into account the effect of refraction of sound wave paths for acoustic computer tomography (CT) is developed. Incorporating the algorithm of refraction into ordinary CT algorithms which are based on Fourier transformation is very difficult. In this paper, the least-squares method, which is capable of considering the refraction effect, is employed to reconstruct the two-dimensional temperature distribution. The refraction effect is solved by writing a set of differential equations which is derived from Fermat's theorem and the calculus of variations. It is impossible to carry out refraction analysis and the reconstruction of temperature distribution simultaneously, so the problem is solved using the iteration method. The measurement field is assumed to take the shape of a circle and 16 speakers, also serving as the receivers, are set around it isometrically. The algorithm is checked through computer simulation with various kinds of temperature distributions. It is shown that the present method which takes into account the algorithm of the refraction effect can reconstruct temperature distributions with much greater accuracy than can methods which do not include the refraction effect.

Acoustic imaging for temperature distribution reconstruction

“…Considering the most conditions, the theory in ideal gas is described in detail. The relationship between acoustic velocity and temperature is described as [14][15][16] …”

A Review of Research on Acoustic Detection of Heat Exchanger Tube

“…Lu [40] They studied theoretically that the sound propagation path"bending effect" will affect the measurement result in the temperature gradient field. According to this research, they came up with a theory that sound propagation must be considered as"sound ray bending" to improve the accuracy of a real-time temperature field measurement.…”

“…The first one is passive technologies, relying on the source of the leak which produces acoustic signal to determine whether the pipeline leaks or not and determine the leak position. The other is active technologies, which rely on the physical factors (e.g., temperature variation, air bubbles or residue suspended) nearby the source of leak, by affecting the external acoustic signals to get tubes leakage signs and location, etc.The research and development situation of the theory of tube leak detection technology for the heat exchanger in boilers [38], [39], [40], [41], [42] are shown in the following Table 4.…”

Simulation of Temperature Field Reconstruction by Acoustic Based on Improved Landweber Method

“…Acoustic pyrometry technology is very important in many real industrial needs and applications because of the advantages as wide measuring range, easy for real time continuous measurement, convenient maintenance. For example, deep-sea hydrothermal temperature field measurement, industrial furnace combustion temperature field distribution for reconstruction and detection, atmospheric temperature field distribution measurement of the storage of grain temperature, and temperature field detection inside the microwave heating cavity [1][2][3][4][5].…”