Gas Temperature Measurement Using Ultrasonic Waves
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概要
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If there occurs a rapid temperature change in the gas while constant frequency sound waves are passing through the gas, the waves undergo frequency change after passing through the gas. That is, the receiver receives the sound waves with a frequency different from that of the sound source. Here, the mathematical relations between the frequency change of the sound waves and the temperature change dT/dt (T : absolute temperature of gas, t ; time) of the gas are derived and by integrating these relations the relations between the frequency change of the sound waves and the gas temperature T are obtained. From these relations, using the obtained data of the frequency change of the sound waves, it is possible to measure the temperature T and the temperature change dT/dt of the gas. The experiments are successfully done with the polytropically compressed air in a rapid compression machine equipped with sound source and receiver using ultrasonic waves. The measured temperature based on this principle is coincident with the temperature calculated from measured pressure volume relations assuming polytropic change of the air in the machine. The maximum temperature change attained in the measurement is about several tens of thousands degrees centrigrade/second. From this fact it is surely expected that this method will be applicable for the measurement of instantaneous gas temperatures in reciprocating engines.
- 一般社団法人日本機械学会の論文