Vibration analysis of rotating pre-twisted curved blades under thermal environment

Vibration characteristics of rotating pre-twisted curved blades, made of INCONEL 718 and operating in thermal environment, are numerically investigated in this paper. Commercially available software ANSYS is used to perform combined steady state thermal and pre-stressed modal analysis. Analysis is performed for different blade taper ratios, pitch angles and rotating speed conditions. Both straight and curved blades, modelled as plates with clamped-free-free-free boundary conditions, and subjected to steady state thermal and pre-stressed conditions are numerically analysed to determine their natural frequencies. Free vibration characteristics of straight and curved blades, having the same volume and material properties, are estimated to see the effect of changing the geometry from flat blades to curved ones. The effect of change in the temperature at different rotating speeds is also investigated.