FREQUENCY EVALUATION FOR MECHANICAL INTEGRATION OF SHROUDED HP ROTOR BLADES IN AN AIRCRAFT ENGINE COMPRESSOR

Abstract

Frequency evaluation in rotary engine blade design is an important research area because of its critical applications in aircraft engines and land-based gas engines. A compressor blade plays an important role in increasing pressure and velocity of the fluid, which influences the efficiency of gas turbines. Due to peak centrifugal stresses, gas bending loads and vibratory stresses, flow-induced blade vibrations occur leading to blade catastrophe. The airfoil is expected to prove not only the mechanical efficiency but also mechanical integrity for a desired life. The present research focuses on the study of the vibrational behaviour of an Axial HP Shrouded Compressor blade for in-service conditions. A Computational Fluid Dynamics based model is generated with reference to NACA 65-series, to analyse the flow behaviour through a linear cascade of axial compressor blades, followed by mechanical integrity stress checks to take it further with root attachment design. The present work demonstrates the need for shrouds in compressor rotor blades for stiffening the blade to avoid resonance. The positioning of the shroud is a challenge across the blade height by achieving Frequency Separation Margins using Campbell Diagram, an industry best practice.

Keywords

• Blade vibrations
• Campbell diagram
• Frequency evaluation
• Mechanical integrity
• Shrouded compressor