One of the main problems in the development of the rocket engine is the vibration problem of the fuel turbopump(FTP). In this study, the nonstationary vibration during the fast acceleration of FTP is investigated. The rotordynamic fluid force, damping effect of the wire-mesh-damper at the support parts, and rotating cavitation force are considered in the modeling. The variation of the rotational speed and the cavitation number obtained in the experiment are used as the input for the theoretical model, and the variation of the vibration amplitude is calculated numerically. In the spectra of the experimental data, the super-harmonic components and the asynchronous components which are not proportional to the rotational speed are observed in addition to the synchronous component. Because the developed model considers only the synchronous vibration, the synchronous component is extracted from the experimental data and compared with the numerical simulation data. These experimental and numerical results agree quantitatively, and as a result, the developed theoretical model is validated.

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A floating ring seal(FRS)has been employed as a noncontact type seal, which seals in high-pressure liquid oxygen(LOX) for the rocket engine turbopump. However a dynamic behavior of FRS has rarely been focused on. The objectives of the present study are to evaluate the rotordynamic fluid forces of FRS experimentally. The axial force induced by differential pressure presses the floating-ring(FR) against the stationary housing. Because of the increasing friction force of the secondary contact surface, high axial load increases the radial force required to reposition the FR. Therefore, it is very important to investigate rotordynamic forces as tribological behavior.

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In order to analyze a stability of the balancing mechanism for the axial thrust force in turbo-pumps, the simplified model expressing the essentials of dynamic behavior is shown. By the examination on that model, the dynamic characteristics in several working conditions are considered, it is shown that what kind of conditions determine the response and stability of the balancing mechanism.

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