Computational Investigation of Aeromechanical Hcf Effects in a Compressor Rotor

High-Cycle Fatigue is a major problem facing the gas turbine industry today. It has been investigated by many researchers, using many different methods. Due to its highly complex nature, designers still do not have adequate tools to accurately predict the onset of high-cycle fatigue. A three-dimensional Navier-Stokes program was used to perform a study of the unsteady aerodynamics on a compressor rotor. The effect of aerodynamic detuning on the forced response of a rotor blade was compared to a baseline tuned rotor case. Detuning consisted of a ten percent decrease in circumferential spacing between alternate pairs of blades. The high-cycle fatigue effects of this detuning were investigated by examining the unsteady forces and moments on the rotor blades and inlet guide vanes. Computations were performed using a three-dimensional NASA research code (ADPAC) on a cluster of five desktop PCs. Computational times were on the order of several days for a grid of approximately 500,000 cells. These computations showed that detuning of the rotor blade could result in a reduction in the forced response of the IGV and rotor blades. This reduction came without much loss in overall performance (less than ten percent) and therefore may be a viable option to reduce high-cycle fatigue.