Entropy production by dissipation effects and characteristic vortex evolution in a rocket turbopump

Abstract

The relationship between entropy production and vortex evolution involves the efficiency and stability of rotating machinery. This study investigates the energy characteristics of a rocket turbopump, revealing the correlated mechanisms of the entropy production rate using dissipation effects and characteristic vortex evolution. Direct and turbulent dissipations and rigid and shear vorticity decomposition methods are utilized to analyze the correlation analysis of flow loss and characteristic vorticities in rotating machinery for the first time. With an increase in flow rate, the hydraulic loss of the dissipation effects and wall decrease by 60% and 38.3%, and proportions to the input energy decrease (from 13% to 8%) and remain stable (8%), respectively. The local entropy production rate using direct dissipation (EPDD) in the inducer-impeller is strongly related to shear entropy, and the correlated effect of total enstrophy on EPDD is weaker than that of shear vorticity, indicating that rigid enstrophy suppresses direct dissipation. The correlation between turbulent dissipation and rigid enstrophy is significantly weaker in the static flow passage of a turbopump owing to a weak rigid rotational effect. The correlation between the rigid enstrophy and local entropy production rate using turbulent dissipation (EPTD) gradually increases with increasing flow rate, reaching a medium correlation (the maximal correlated degree in the turbopump) and exhibiting rigid rotation effects on hydraulic loss. Moreover, the flow rate significantly affects the correlation (except for the diffuser) and the two characteristic vorticities reach the maximum at the designed flow rate owing to optimal efficiency and minimum hydraulic loss.