Cavitation-Free Properties Of LH2 Axial Pumps

*† ‡ § ** his paper considers the problems of achieving high cavitation-free operation in axial LH2 pumps. The possibility of pump operation at the boiling point (two-phase fluid) hydrogen is considered in this paper. The peculiarities of axial pump operation at stationary, quasi-stationary and non-stationary modes are reviewed. Special attention has been given to the experimental investigations of LH2 axial pump cavitationfree properties. It has been shown that the new method of cavitation test performance. This paper presents a quantitative description of a new method of cavitation testing. The algorithm developed allows performance of computer simulation of the test process. The developed approach also provides quantitative planning of experiment performance, and automatic real time control during performance of experimental testing. Elimination of the need for LH2 tank pressurization is one of the most expedient design solutions to increase the vehicle technical, operational, and efficiency capabilities, for example, for exploration of the solar system planets. Eliminating the need for fuel tank pressurization significantly simplifies the vehicle by eliminating the components needed to pressurize the tank and reduced the volume by eliminating the fuel ullage volume; however the main benefit comes from the ability to use the two-phase hydrogen remaining in the tank. For application of this technical solution it is necessary to increase the cavitation-free characteristics of the hydrogen supply system in engines up to the level at which the system maintains operability even with a high volumetric content of gaseous hydrogen at the pump inlet duct. The possibility of operating the pump with two-phase hydrogen is controlled by the thermodynamic effect of cavitation suppression. This effect is related to the cooling of vaporizing liquid adjacent to the cavitation cells located at the pump impeller blade leading edge. Quantitatively, the thermodynamic effect of cavitation suppression is expressed by the value of the vapor pressure decrease in the cavitation cell, in comparison with the saturated vapor pressure for liquid in the non-boiling state . In the literature, this value is designated as thermodynamic correction of NPSP [1] SK p S p