Abstract: The tenon tooth structure of the moving blades in a newly designed flue gas expander fails to meet the strength margin requirements. To further investigate the stress characteristics of the flue gas expander tenon teeth and optimize the structural design, this paper systematically analyzes the specific effects of factors such as tenon tooth axial width, rotational speed, tenon tooth geometric parameters and aerodynamic forces on the strength of the tenon tooth region based on the stress distribution of the rotor blade tenon teeth of the flue gas expander under actual operating conditions as calculated by ANSYS software. Particular attention is paid to investigate the stress concentration phenomenon in the tenon tooth region. The results show that reducing the rotational speed, increasing the tooth tip inclination angle β and increasing the tenon tooth fillet radius R can significantly reduce the maximum concentrated stress in the tenon tooth, while the tenon tooth axial width L and the tooth base inclination angle γ have no significant effect on the maximum concentrated stress. Optimizing the load-bearing state of the tenon teeth by considering maximum concentrated stress as well as four stress indicators including tensile, bending, compressive and shear stress can provide technical support for reliability analysis in the design of rotor blades for flue gas expander.

Key words: flue gas expander, tenon teeth, stress concentration