Investigation Of POGO Vibration Performance For Liquid Rocket With Stability Theory

The liquid fuels have been constantly consumed during the flight and launch of the large liquid rocket, the violent vibration caused by the rest of the fuel is happened in pipe section of the rocket. The vibration frequency of the rocket longitudinal shell is decreased by the vibration of fuel, and then, both will achieve resonance. The phenomenon of fluid-structure interaction is called the POGO vibration of large liquid rocket. It not only damage the performance of the equipment carried by the rocket, but also harm the health of the astronauts.In this paper, the main content: firstly, base on the law of conversation of mass, Newton’s second law and the conversation of momentum, nonlinear dynamic model of the POGO vibration of large liquid rocket is set up. Storage tank, pipeline system, pump system accumulator and combustor constitute large liquid rocket and their models are established respectively according to their own features and the above theory. The separate parts of the rocket are connected by the three joint and bellows. In the process of rocket flight, the forces of the rocket shell is the largest by the combustor. The forces act on the rocket shell from other components can be ignored under the precondition of not harming the veracity of the model. The vibration of liquid rocket is delivered by the rocket shall through the combustor, similarly, The vibration of the rocket shall can be transmitted to the liquid rocket. So, the phenomenon of fluid-structure interaction is formed. Next, the dimension of the rocket is reduced by centre manifold theory and plural normal form, so, the stability and the Hopf bifurcation of the system are studied. Base on the plus or minus of the eigenvalues of the parameter matrix, system stability is studied. when the eigenvalues of the parameter matrix are pure imaginary number and negative real component of the plural, system stability is decided by the pure imaginary number. Jordan matrix can be worked out through the plural regular type. In addition to, the exponential of the system is reduced by Poincare-Burke hoff paradigm and the characteristics of Hopf is studied. According to reduce evolution equations of the center manifold, dimension can be reduced. Base on the normal form, the third order model equation can be studied through by coefficient of the reduce evolution equations. The bifurcation characteristics of the system stability can be studied by the theorem of the Hopf bifurcation, with the transformation of the polar coordinates.