Vibration Characteristics of Low Aspect Ratio Compressor Blades

Abstract

This paper presents the results of a study of the vibration characteristics of low aspect ratio compressor blades. The treatment is based on thin shell theory and the Rayleigh-Ritz method is used to obtain the eigenvectors and eigenvalues. The object is to elucidate those characteristics which are inaccessible using beam theory. Results are presented which show the variation of the natural frequencies and mode shapes with angle of twist, aspect ratio, and angle of inclination of the base of the blade. A three-dimensional plot of the bending mode frequencies versus aspect ratio and twist angle is presented. Although the surfaces describing the variation of frequencies for specific modes do not intersect, there is a point of contact. This contact point is significant in the transition of mode shapes along the frequency surfaces. It is demonstrated that the “stiff-direction” or “in-plane” vibration of the untwisted plate evolves into coupled bending modes as the twist angle increases from zero and that the character of these modes changes in the vicinity of the contact point.

Transient Response of Rotating Laminated Plates With Interfacial Friction Under Accelerating Conditions

“…The application of plate theory to blade vibration problems has been considered by several authors which include Petricone and Sisto [1], Dokainish and Rawtani [2], MacBain [3], Gupta and Rao [4] amongst others. The steady state response and stability of rotating laminated plates is studied by Shiau et al [5].…”

A Mixed Shell Element for Cambered Helicoidal Blades and Dynamic Stresses due to Aerodynamic Excitation

“…A vast literature is available using classical shallow shell theories, e.g., the curved shell elements of Olson and Lindberg (1971). Ritz method is applied for rotating pre-twisted flat blades by Petricone and Sisto (1970), Gupta and Rao (1987), however, constant width, thickness and radius of curvature are assumed. A procedure for the rotating cambered helicoidal blades using curved shell element based on Mindlin (1951) shell theory is presented by Rao et al (1997).…”

Vibration Analysis of Rotating Cambered Helicoidal Turbomachine Blades

“…A vast literature is available using classical shallow shell theories, e.g., the curved shell elements of Olson and Lindberg (1971) and Walker (1978). Ritz method is applied for rotating pre-twisted flat blades by Petricone and Sisto (1970), Gupta and Rao (1987), however, constant width, thickness and radius of curvature are assumed. Here, a procedure for the rotating cambered helicoidal blades is given using curved shell element based on Mindlin (1951) shell theory.…”