Experimental study on the effect of cryogenic two-phase flow inlet conditions on the suction capacity of a high speed centrifugal pump equipped with an inducer: first results on saturated pure liquid
Creators: name:  D. DURI 
name:   R. GAUTHIER 
name:   S. FRANCOIS 
name:   S. FAMMERY 
name:   Y. CUDENNEC 
name:   B. ROSSOW 
name:   E. ROULAND 
name:   S. LE MARTELOT 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: PROPULSION PHYSICS
NOZZLE
TURBOPUMPS

description: High performance cryogenic propulsion systems typically used in launcher upper stages must handle low boiling fluids such as oxygen, methane or hydrogen and require the use of high speed centrifugal pumps with low net positive suction head performance in conjunction with slightly pressurized tanks. Propellant and tank pressure management and the implementation of margins with respect to the tanks stratification and saturated flow characteristics are also included in the functional design process of the launcher stage contributing to assure a smooth pump behavior in the entire performance domain. New trends requiring a larger degree of versatility to the upper stage (i.e. re-ignitable engines in microgravity environment, thrust variations...) and new applications for earth-bound propulsive systems (i.e. for cryogenically stored liquid hydrogen powered low emission passenger aircrafts; ships and trains) impose the development of pumping systems capable to deal with a broader range of inlet conditions with respect to the current state of the art. Higher void of fraction values at the pump inlet level are imposed by the operational constraints and the so-called zero-tank NPSP handling capabilities may be also required. The consequence is that the design, the development and testing of centrifugal pumps must cope with non-null void of fraction inlet flows as long as with the presence of non-condensable gas bubbles whilst delivering with reliability the same pressure head. In order to contribute to the fundamental understanding of these issues and to contribute to the design, verification and validation process of high performance centrifugal pumps a dedicated experimental test campaign has been carried out by ArianeGroup and CNES at AREELIS Technologies in liquid nitrogen. A specific test setup has been integrated, coupling a state-of-the art centrifugal pump equipped with an inducer and an unshrouded impeller with an in-line, low disturbance and high dynamic response void of fraction capacitive sensor at the inlet. The aim is to measure the effect of a broad range of inlet conditions under a reasonably controlled cryogenic two-phase flow on the pump performance. In this article the experimental cryogenic setup layout will be presented and detailed as long as the void of fraction measurement system. Preliminary results obtained on the centrifugal pump performance with pure liquid nitrogen flow at subcooled and saturated inlet conditions will be presented and discussed. Tests carried out by injecting a finite amount of non-condensable gas (helium) were also performed in order to identify the different behavior induced by the accumulation of the non-condensable within the pressure and velocity field of the pump elements. Qualitative and quantitative comparison of the results with available references will be detailed and experimental perspectives and opportunities will be also highlighted.