Measurement of Gas Temperatures Using Acoustic Oscillators

The first three chapters of this thesis are devoted to a study of the measurement of gas temperature by utilisation of the relationship between the absolute temperature and the speed of sound in a gas. The advantages of self excited systems, or acoustic oscillators, over other systems are pointed out together with an appraisal of the various types of this device already in existence ie survey of previous work done on the Air Jet Generator indicates the possibility of its adaption for a temperature to frequency converter which would be particularly useful for the measurement of rapid temperature changes.
The fourth and subsequent chapters are an account of the work carried out by the author in order to assess the feasibility of the Air Jet Generator for both steady state and transient measurements including investigations into the effects of changes in geometry, pressure and gas properties. The apparatus and techniques which had to be specially developed for these investigations are described in detail.
The results show that the Air Jet Generator is a feasible proposition as a temperature sensor being inferior to thermocouple instruments such as the Sonic Suction Pyrometer for absolute temperature measurements but much superior from both the transient response and mechanical strength points of view.
As a result it could be a useful addition to the existing instrumentation used for such systems as gas turbines.