Selecting pitot probes for gas turbine combustion chamber testing requires balancing high-temperature resistance, measurement accuracy, and structural stability, as the environment here is characterized by temperatures exceeding 1000°C, high turbulence, and potential corrosion from combustion by-products.5-Hole Pitotwelcome to click on the website to learn more!
Key considerations include material selection: Inconel 718 is suitable for temperatures up to 800°C, but for higher ranges (800-1200°C), Haynes 282 or ceramic matrix composites (CMCs) are better choices. In one test, an Inconel 718 probe showed signs of creep after 500 hours at 900°C, while a CMC probe maintained stability for over 1000 hours.
Structural design also matters. The probe head should be streamlined to minimize airflow disturbance, with a thickness of at least 1.2mm to resist thermal stress. Holes must be laser-drilled to ensure precision, as even a 0.02mm deviation can cause a 3% error in pressure readings.
Calibration is critical too. High-temperature probes require in-situ calibration using a reference thermocouple and pressure sensor, as laboratory calibration at room temperature may not account for thermal expansion effects. A power plant test found that uncalibrated probes overestimated total pressure by 5% in the combustion zone.
When comparing options, CMC probes offer superior temperature resistance but come at 3-4 times the cost of Inconel models, making them ideal for long-term, high-temperature applications. For intermittent testing below 800°C, Inconel 718 remains a cost-effective choice.