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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2011, Vol. 32 ›› Issue (5): 822-832.doi: CNKI:11-1929/V.20110310.1709.000

• Solid Mechanics and Vehicle Conceptual Design • Previous Articles     Next Articles

Study on Coupling Stability and Mechanism Between Engine Harmonic Oscillation and Launch Vehicle’s Modes

LI Jiawen, LI Daokui, ZHOU Jianping   

  1. College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073,China
  • Received:2010-05-25 Revised:2010-08-23 Online:2011-05-25 Published:2011-05-19

Abstract: In consideration of the instability of attitude control system caused by coupling resonance between engine harmonic oscillation and launch vehicle’s elastic vibration, dynamic coupling stability and mechanism between engine harmonic oscillation and launch vehicle’s modes are studied, and the engine harmonic oscillation frequency boundary due to the instability of attitude control system is also computed. Firstly, the dynamics of engine oscillation is simplified as a second order system, and an attitude dynamic model of launch vehicle including engine oscillation equations is derived. Then, the influence of engine oscillation on launch vehicle’s modal frequency and damping is analyzed, and the mechanism of coupling resonance between engine oscillation and launch vehicle’s modes when the modal damping is negative is also analyzed theoretically. Based on this, the engine oscillation frequency boundary which leads to the instability of attitude control system is also computed. Finally, the analytical results are validated by time domain simulation. The results show that coupling resonance between engine harmonic oscillation and low order mode will arise when the the engine oscillation frequency is lower, at that time the phenomenon of attitude angle and attitude angular velocity’s oscillation and divergence will appear. The stability requires that engine harmonic oscillation frequency is higher than the maximum of the harmonic oscillation frequency boundary. The studies in this paper can provide some references for the design of attitude control system.

Key words: launch vehicles, engine harmonic oscillation, coupling resonance, launch vehicle’s modes, resonance frequency boundary

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