Aerothermoelastic flutter analysis of pre-twisted thin-walled rotating blades reinforced with functionally graded carbon nanotubes

Abstract

In this study, the aerothermoelastic flutter analysis of pre-twisted tapered rotating blades reinforced with functionally graded carbon nanotubes (FG-CNTs) under supersonic flow is investigated. Based on the thin-walled Timoshenko beam theory and quasi-steady supersonic linear piston theory, the dynamic model of the supersonic rotating blades reinforced with FG-CNTs has been developed. The CNTs are considered to be either uniformly or non-uniformly distributed in the matrix along the thickness direction. Three various CNTs distribution patterns namely, UD, FG-X and FG-O have been assumed. The properties of CNTs and polymer matrix are considered to be temperature-dependent. Based on the extended Hamilton's principle, the equations of motion as a system of coupled linear partial deferential equations are found. The extended Galerkin method (EGM) is utilized to transform these coupled partial deferential equations to a set of coupled ordinary deferential equations. The influences of rotating speed, CNTs distribution, CNTs weight fraction, temperature, pre-twist and pre-setting angels, hub radius ratio, taper ratios and Mach number on the aerothermoelastic flutter responses of the system have been analyzed. The results indicate that the FG-X distribution pattern have predicted more strengthening the total bending of blade and the greatest flutter frequency for the composite blades. Furthermore, the pre-twist and pre-setting angles as well as taper ratio have significant effects on the flutter frequency of the thin-walled blade reinforced with CNTs.