Blades are twisted under load due to the aerodynamic pressure.  The effect is more pronounced on long blades such as fan blades.  Sudden untwist of a blade during operation of turbomachinery can be the sign of an upcoming stall or surge event.  Real-time measurement of blade twist and untwist is therefore an important parameter to monitor.

Measuring Blade Twist With FOCISTM

Blade twist measurement is performed by placing several optical sensors along the blade and timing the difference of time of arrival between the sensors.

Blade Twist Measurement

Blade Twist Measurement with FOCIS system

 

More Information on the FOCIS™ System