Theoretical evaluation of the amplitudes of pogo vibrations in liquid propellant launch vehicles

1Pilipenko, VV, 1Dovgot'ko, NI, 2Dolgopolov, SI, 2Nikolaev, AD, 1Serenko, VA, 2Khoryak, NV
1Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and State Space Agency of Ukraine, Dnipropetrovsk, Ukraine
2Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, Dnipropetrovsk, Ukraine
Kosm. nauka tehnol. 1999, 5 ;(1):90–96
https://doi.org/10.15407/knit1999.01.090
Section: Space-Rocket Vehicles
Publication Language: Russian
Abstract: 
Theoretical determination of the amplitudes of longitudinal vibrations in launcher structure is a most burning problem in providing POGO-stabilit of liquid propellant launchersy. Development of a mathematical model of the nonlinear nonsteady-state structural and liquid-propulsion system holds central position in the solution of the above problem. The model provides a rather comprehensive descrip­tion and a high degree of authenticity. The present paper gives approach to a mathematical simulation of the closed structural and liquid-propulsion system whose parameters vary with flight time. The distinctive feature of the given approach is allowance for dynamics of cavitation phenomena in inducer-type centrifugal pumps at the dynamic mathematical model of liquid propellent rocket engine which is of fundamental importance for increasing the authenticity of theoretical determination of the amplitudes of the longitudinal vibration of the launcher structure. Analytical description of dynamics is done on the basis of a hydrodynamic model cavitational self-excited oscillations in the LPRE feedline system developed by the authors. Nonlinearities that are due to cavitation in LPRE pumps and have a determining effect on restriction of longitudinal vibration amplitudes of the structure are described. Calculation results for determining amplitudes of the longitudinal vibrations of specific launchers are presented. Authenticity of theoretical results is validated by the flight test data for these launchers.
Keywords: flight test, liquid propellant launch vehicles, mathematical simulation
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