Automated High-Temperature Pressure Sensor Verification and Characterization

Sammanfattning: Gas turbines are widely used in power generation. Monitoring pressure variations in the combustion chamber allows for real-time assessment of the turbines performance, and can be used to optimize combustion processes, leading to reduced emissions. By analyzing pressure, patterns, potential faults or degradation in critical components can be identified, enhancing the safety and reliability of the gas turbine. Measurements close to the combustion flame put high demands on the pressure sensors and their verification method. The aim of this thesis is thus to create an automated pressure sensor verification prototype capable of operating at elevated temperature.  With the intention of increasing knowledge of how high temperature influences piezoelectric dynamic pressure sensor readings, this thesis inherits and updates an existing pressure sensor verification device. A design of thermal management system for the device is presented together with a CFD model analysis for the cooling cycle, while the heating cycle and its control algorithm is studied experimentally. This thesis also focuses on sinusoidal pressure wave generation methods used in the existing verification device to achieve reliable signals at low frequencies. An experimental study to evaluate the signal quality is performed. The results propose a feasible prototype design for automated pressure sensor verification at elevated temperature. It provides insight on how the separate parts of the thermal management system could be implemented with a PID regulator. It is concluded that air heating, even with to some extent varying mass flow, can be controlled with a PID regulator. It is also concluded that stable sinusoidal pressure waves can be generated at as low as 1Hz with the gear wheel method used in the previous verification device.