Abstract
The turbine shared support structure is used widely in aeroengines, but theoretical and experimental research on a rotor-bearing system containing a shared turbine support structure is lacking. This paper reports research into the coupling vibration response of a squeeze-film-damper rotor-bearing system that has two spools with different rotation speeds and is supported by a turbine shared support structure. The problem is addressed by means of experimental tests and the finite-element method. Based on the features of a turboshaft engine with a turbine shared support structure, a rotor-bearing test system with a shared support structure and squeeze film damper is designed, and a finite-element model of the test system is built based on Timoshenko beam elements. The experimental and simulation results indicate that the unbalanced response of the rotor-bearing system with a shared support structure may involve either the sum or difference of the fundamental frequencies of the rotors of the gas generator and power turbine. The simulations show that the unbalance of the power turbine rotor, the radial and bending stiffnesses of the shared support structure, and the radial clearances of squeeze film dampers at the shared support structure of the rotor-bearing system all affect the coupling response. The amplitude of the coupling response can be suppressed effectively by (i) selecting reasonable parameter values for the turbine shared support structure and (ii) exerting strict control over the spool unbalance.
Highlights
The core components of an aeroengine are its rotor-bearing systems, and the vibration characteristics of the latter determine directly whether the engine can work in harsh environments with high temperatures, pressures, speeds, and high loads, the vibration condition which has a critical influence on the overall performance of the engine
Vibration research; the analysis nodes selected in this work are the nodes at disk 5 on the gas generator (GG) rotor and the rightmost node on the power turbine (PT) rotor, which correspond to the measurement points of the outer rotor and the inner rotor in Figure 2(a), respectively
We studied how the unbalance of the PT rotor, the radial and bending stiffnesses of the shared support structure (SSS), and the radius clearances of the squeeze film dampers (SFDs) at the SSS affected the coupling vibration response of the rotor-bearing system, and the main conclusions are as follows: (1) In this paper, the experiment and simulation analysis of the SSS rotor-bearing system with SFDs have been carried out for the first time; the reliability of the modeling method in this article is verified through experiments and comparison with ANSYS
Summary
The core components of an aeroengine are its rotor-bearing systems, and the vibration characteristics of the latter determine directly whether the engine can work in harsh environments with high temperatures, pressures, speeds, and high loads, the vibration condition which has a critical influence on the overall performance of the engine. That literature concerns mainly the coupling vibrations of rotor-bearing and whole-engine systems containing intermediate bearings, with the main modeling approaches involving Newton’s second law, the Lagrange equations, and the finite-element (FE) method. Using beam elements to simulate the rotating shaft when establishing an analysis model of a rotor-bearing system of an aeroengine dates back to the 1970s [15,16,17]; the shaft was simulated as a Timoshenko beam, the dynamic model of the dual-rotor-bearing system containing intermediate bearings was built by component mode synthesis, and the influence of modal truncation on the calculation results was studied. The FE modeling method using Timoshenko beam elements has developed into an effective method for establishing dynamic models of complex rotor-bearing and whole-engine systems in aeroengines with nonlinear characteristics.
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