Evaluating the adequacy of dynamic pressure remote sensing method in a model gas turbine combustor

Abstract

Direct measurement of dynamic pressure in a combustor using a flush sensor mounting generally shortens the lifetime and lowers the measurement accuracy of the sensor due to its direct exposure to hot-burnt gases. Thus, indirect remote sensing methods are typically employed in combustion systems; however, the measurements may contain errors. Therefore, in this study, the feasibility of a remote sensing method for measuring dynamic pressure is verified by conducting an acoustic forcing experiment in a model gas turbine combustor. Sensing performance of the sensor adapters are evaluated based on their measurement locations for a driving frequency of 50–5000 Hz. In an experiment with different measurement locations, mode shapes corresponding to a resonant frequency of 160 Hz are clearly observed. Furthermore, in a sensor-adapter performance experiment, the effects of hole-size and length of a dynamic pressure propagation tube on the sensing characteristics are investigated and the optimum design shape is obtained. The results indicate an increase in the accuracy of dynamic pressure measurements and a subsequent decrease in the risk of combustion instability accidents. Therefore, the findings of this study and optimal design methodology for remote sensing equipment could positively contribute to the safe operation of gas turbines.

Keywords

• Gas turbine combustor
• Dynamic pressure measurement
• Combustion instability
• Remote sensing
• Dynamic pressure propagation tube