2017 Volume 60 Issue 2 Pages 77-84
Considering the coupling interaction between oxidant system and fuel system in liquid-propellant rockets, the modeling and stability problem of Pogo vibration in liquid-propellant rockets with a two-propellant system are investigated. Firstly, the differential equations of the two-propellant equivalent system are derived through the physical characteristics and coupling mechanism of the basic elements in a propulsion system based on reasonable assumptions and simplification. Next, the dynamic equations of the Pogo analysis model are established by coupling a longitudinal structure mode and the two-propellant equivalent equations using the dimensionless methods. It is indicated that the simplified system contains 10 dimensionless parameters expressed by the combination of all physical factors. Furthermore, the critical parameter equation of this system is then explicitly formulated using Hurwitz criterion based on the characteristic equation of the Pogo analysis model. Moreover, the numerical solutions of the boundary surface of this system stability are extensively studied. The results show the effects of dimensionless and original parameters on Pogo stability. Finally, the correctness of the simplified Pogo stability analysis is confirmed using the simulation results of a certain type of Long March rocket.
