Influence of Characteristic Parameter on Extrusion Stress with Working Surface of the Zigzag-shroud Blade

Abstract

Taking a high aspect ratio and low-pressure turbine blade as an example, the research on the influence of zigzag-shroud characteristic parameters on the circumferential tightness and extrusion stress of the working surface, the comprehensive influence law of the zigzag-shroud key parameters on blades strength can be obtained to reduce the zigzag-shroud stress level to the allowable range. It is found that the engagement angle (β) and pre-torsion angle (△β) are the two key parameters to determine the tightness of the contact surface. When the engagement angle is 40.9°, the extrusion strength of the zigzag-shroud working surface is the highest. At the same time, it is found that the pre-torsion angle and circumferential degree (△S) are proportional to the extrusion stress of the working surface, and there is an “optimal window” for both circumferential degree and pre-torsion angle. The best circumferential degree is 0.22 mm, and the optimal pre-torsion angle range is from 30’ to 1° by the calculation model.