Session: 22-02 Compressor Aerodamping, Forced Response, and Mistuning

Paper Number: 152296

Impact of Rotor-Rotor Interaction on the Mistuned Forced Response Prediction of an Embedded Compressor Rotor: Effect of Sideband Travelling Wave Excitations and Random Mistuning 

This paper describes the aeromechanical aspects of multi-row forced response in embedded compressor rotors building upon previous research by the authors. Forced response is turbomachinery compressor is one of the grand challenge topics and has received a lot of attention in literature recently. The current paper fills a gap in literature by the authors. Previously, the multi-row analysis presented by the authors utilized the time transformation (TT) method within CFX to reduce the number of passages in each row to a specific count. This enabled significant savings in computational resources but did not capture the rotor-rotor interaction accurately in computational space. The current paper fills that gap and models full wheel domains which indeed does capture the wave reflection, circumferential variation in pressure field, rotor-rotor interaction and its impact on mistuned forced response. Mistuning in this paper is modeled from a random mistuning standpoint—as a result of frequency variations due to manufacturing. The computational results are validated with data from the Purdue 3.5stage compressor rig. : The first part talks briefly about the unsteady CFD computational approach utilized to obtain the modal force values for each of the multi-row cases. These modal forces were utilized to obtain the mistuned forced response predictions. The second part describes in detail the method used to quantify blade responses and goes onto account for a few discrepancies in the mistuned forced response predictions. The last part addresses the cause for these discrepancies and the authors conduct sensitivity studies to justify the anomaly. Some of the conclusions drawn from this study were 1) The rotor-rotor interaction was captured well by numerical methods and in-line with system ID data 2) The response was more localized at the -11ND computationally as against experimental data, which included significant responses at other ND’s although the -11ND content dominated. 3)Including the sidebands in the mistuning model from CFD predictions helped improve the mistuned blade response predictions significantly, in-line with data

Keywords: Compressor, Forced Response, Multi-Row, Mistuning, FMM, CMM, Disc Modes, Sidebands

Presenting Author: Shreyas Hegde Pratt&Whitney

Presenting Author Biography: Shreyas is a senior engineer, compressor system aerodynamics at Pratt&Whitney

Authors:

Shreyas Hegde Pratt&Whitney
Huan-Min Shang Pratt&Whitney