Imperfection Sizing Method of Turbine Straddle Tree Blade Roots Using Phased Array Ultrasonic Technology

This paper studied the imperfection sizing method using the advanced ultrasonic phased array inspection technology for the straddle tree blade roots. Indication length measurement was determined by comparing several conventional indication sizing methods, such as 6dB drop technique, 12dB drop technique, and complete drop technique. Appropriate indication height measurement was conducted by analyzing the characteristics of various indications with different heights.