Session: 24-01 Compressor aerodynamic damping

Paper Number: 82382

82382 - Preliminary Numerical Validation of the Frequency Response Method on the Study of Aero-Damping in a Linear Oscillating Compressor Cascade 

Flutter is a self-excited, self-sustained vibration phenomenon caused by the coupling interaction of aerodynamics and structural vibration, which is a major threat to the operation of aero engines and gas turbines. When flutter occurs, the aerodynamic damping is negative, indicating that the aerodynamic work inputs energy to the vibration system. In the study of flutter, the energy method is usually used based on Lane’s theorem. The traveling wave method (TWM) and the influence coefficient method (ICM) based on the superposition of small perturbation flow are widely used. The aeroelastic stability is judged by measuring the dynamic pressure data on the blade surface and calculating the aerodynamic work in one vibration cycle.

A test rig of linear oscillating compressor cascade is designed and built to understand the phenomenon of flutter and validate the research scheme. From the point of view of considering the vibration damping characteristics, the frequency-domain method (FDM) is used in this paper. In contrast with time-domain energy method, the frequency-domain method is not limited by the distribution of pressure taps on blade surface, and there is no error led by spatial interpolation and temporal integration of discrete pressure data. It can theoretically reflect the vibration features more accurately. In the experimental study, besides, it is more convenient to apply frequency-domain method to non-straight blade or study the aeroelasticity of three-dimensional modeled blades. The test rig consists of eight passages with seven controlled diffusion (CD) blades. The vibrating blade with two degrees of freedom is excited by an electromagnetic actuation system over a range of frequencies in a non-contact manner. The amplitude-frequency characteristics of controlled vibrating blades under different flow conditions can be used to deduce the change of aerodynamic damping, which is superimposed with structural damping (considered to be constant). Detailed aerodynamic and mechanical measurements are applied in the experiment. The time-domain energy method that collects dynamic pressure data is conducted for comparative verification. The corresponding CFD simulations are carried out. The feasibility of applying the influence coefficient method through the frequency domain is studied.

Presenting Author: Xin Tong Shanghai Jiao Tong University

Presenting Author Biography: Tong Xin, PhD student of School of Mechanical Engineering, Shanghai Jiao Tong University

Authors:

Xin Tong Shanghai Jiao Tong University
Fanfu Yin Shanghai Jiao Tong University
Xin Shen Shanghai Jiao Tong University
Xiaoqing Qiang Shanghai Jiao Tong University
Hua Ouyang Shanghai Jiao Tong University