The Challenges in Measuring Air Mass Flow Rate inside a Gas Turbine Duct

As opposed to gas and oil industries, where gases and fluids flow in round, symmetrical pipes, inlet air flows into the gas turbines through sometimes rather short, irregular inlet ducts. As a result, the flow does not become fully developed within the duct, and the flow distribution is irregular and does not show a pattern. Because of these complexities, a pitot tube approach is not a viable option for measuring inlet flow rate. Other approaches are also ineffective, and would cause significant pressure drop that decrease the efficiency of the compressor.

AirSonic™ is our Unique and Proprietary Ultrasonic Air Mass Flow Rate measurement technology. It is specifically engineered to work over the entire operational range of large complex industrial ducts for gas turbines, compressors, and coal plants. AirSonic™ is accurate, reliable, and industrially robust, giving you confidence in its results and its operational safety.

AirSonic™ consists of four to sixteen high frequency ultrasonic probes installed on opposite walls of the inlet duct of the gas turbine. These probes are designed to handle large amounts of vibration and ultrasonic noise typically found near high speed rotating compressor blades.

AirSonic™ gives highly accurate flow readings down to within 1% systematic uncertainty. The level of accuracy is due to the nature of the ultrasonic sound pulse which integrates the velocity profile along the duct. In addition, the geometry of each inlet duct is analysed and studied by our engineers to identify how our measurements relate to the overall flow velocity in the duct. This meticulous analysis allows us to offer the greatest accuracy in flow measurement.