Temperature Field Reconstruction Based On Acoustic Tomography

Temperature is a physical quantity that characterizes the degree of coldness and hotness of an object.It is necessary to measure temperature in many fields such as biology,medicine,industry and energy.With the developement of society and the advancement of science and technology,various related fields have put forward high requirements for temperature measurement,such as wider range,more complex working conditions,and higher accuracy.The measurement results obtained by traditional contact temperature measurement methods such as thermal resistance and thermocouple temperature measurement,are realized through thermal equilibrium between the sensor and the object to be measured.This method can only measure the temperature of a single point,which has great limitations.For non-contact temperature measurement methods such as optical temperature measurement and thermal radiation temperature measurement,although direct contact with the measured object is not needed and the temperature of the area can be measured,they still have the disadvantages of being easily affected by the environment and high cost.Acoustic thermometry,as an emerging non-contact temperature measurement technology,has the advantages of high measurement accuracy,large measurement range,applicability to a variety of complex environments and low cost.Therefore,this thesis adopts the acoustic method for temperature measurement and temperature field reconstruction.This thesis analyzes and compares the existing acoustic temperature measurement algorithms,proposes a temperature field reconstruction algorithm based on ridge basis function,and designs and builds a complete acoustic temperature measurement platform to realize a complete acoustic temperature measurement process.The main work carried out in this thesis is summarized as follows:1.The historical development and research status of acoustic temperature measurement technology have been reviewed.The existing temperature measurement techniques and their pros and cons have been analyzed.The basic principles and influencing factors of acoustic temperature measurement technology have been presented in detail.2.The reconstruction accuracy of commonly used temperature field reconstruction algorithms such as the least squares method,the algebraic reconstruction technique.the simultaneous iterative reconstruction technique are compared and analyzed through simulation experiments.The simulation results show that the existing classic reconstruction algorithms generally have the disadvantages of weak noise immunity and low reconstruction accuracy.To solve the above problems,this thesis proposes a new two-dimensional temperature field reconstruction algorithm that combines singular value decomposition and ridge basis function,and conducts simulation experiments to compare the temperature field reconstruction results under several classical temperature distributions.Simulation experiments show that the algorithm has higher reconstruction accuracy and better anti-noise ability than other algorithms.3.An acoustic temperature measurement test rig was built,and a series of experiments was carried out.Cross-correlation algorithm is used to obtain the time-of-flight of the sound wave on 54 acoustic paths.The proposed algorithm is used to reconstruct the two-dimensional temperature field.The image and temperature value of the temperature field reconstruction result are displayed on the computer.A platinum resistance thermometer is used as a reference sensor.The reliability and practicability of the entire temperature measurement system and the effectiveness of the ridge basis function algorithm in the two-dimensional temperature field reconstruction are verified through the experiments.