Axial-vortex stage application prospects in turbo-pumps of liquid propellant rocket engines

DOI: 10.34759/vst-2021-3-17-23

Аuthors

Ankudinov A. A.^*, Vashchenko A. V.^**

Kaluga branch of Moscow State Technical University named N. E. Bauman, 2, Bazhenov str., Kaluga, 248000, Russia

*e-mail: ankudinov051@yandex.ru
**e-mail: nastya.vashenko.97@mail.ru

Abstract

To improve centrifugal pumps cavitation qualities of turbopump units (TPU) of liquid-propellant rocket engines, a centrifugal impeller with increased throat area at the inlet is being developed, a booster pump with rotational speed lower than that of the main pump is being employed, an upstream axial wheel, i.e. a screw inducer, is being applied. This allows reducing the required cavitation margin. However, along with high cavitation qualities, the upstream inducer displays significant disadvantages. When the screw is operating at the inlet at feeding modes less than 0.5 of the optimal value, backflows are being formed, increasing with the feeding decrease. These backflows lead to the increased vibration, unstable operation, and low-frequency pressure pulsations of the self-oscillations nature. Cavitational self-oscillations attain a large amplitude and may lead to the pump and even the entire feeding system failure. One of the promising ways of the pump cavitation qualities improving, and reducing noise, vibration and low-frequency pressure and flow pulsations consists in the axial-vortex stage installing at the pump inlet. The axial-vortex stage (AVS) represents a pump consisting of an axial screw wheel and a fixed helical cascade on its periphery. The AVS advantages are being manifested most substantially at the flow rates less than the optimal one compared to the screw inducer. The axial-vortex stage (AVS) wields a higher pressure coefficient, better cavitation qualities, and ensures stable operation in the entire flow range and on the stalling branch of the cavitation characteristic. Further studies on the possibility of pressure pulsations, vibration and cavitation damage reduction while the AVS application are required.

Keywords:

screw inducer, axial-vortex stage, screw-centrifugal pump, cavitation margin, pressure pulsations

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