Vibration characteristics of turbopump rotor-graphite seal system

To study the contact friction problem of a turbopump rotor-graphite contact seal system in liquid rocket engines, a lateral-torsional coupling dynamic equation of a rotor-graphite seal system is established. The vibration resonance under unbalanced excitation is obtained by using the Runge-Kutta method and the influence of the pressing force on the rotor resonance is also studied. The frequency analysis results show that under graphite seal excitation, the rotor-graphite seal system with small unbalance exhibits obvious characteristics of lateral-torsional coupling vibration such as combination resonance and zero frequency vibration. With the increase in the pressing force, continuous spectra and zero frequency vibrations emerge in the frequency spectrum graph, and combination resonance exists in the whole frequency domain. The increases in the rotating speed and that of the pressing force can lead to low frequency vibration. The research results prove that the graphite contact seal can enhance the coupling effects of lateral and torsional vibration and may lead to instability.