Abstract
While linear scaling laws for swashplate axial piston pumps have previously demonstrated a predictive capacity for speed limitations in commercial units, experimental results in the literature show deviations with smaller displacement pumps, as well as scaled unit sets with a significant difference in displacement from the baseline. This paper presents a comparison and analysis of simulated cavitation-based phenomena from a baseline open-circuit axial piston pump and scaled versions of the unit. This investigation is implemented through a CFD (Computational Fluid Dynamics) model of the reference unit. Cavitation effects within fluid flow are applied through a simplified version of Singh’s Full Cavitation Model, with dissolved gas handled through an equilibrium analysis. By using published scaling laws to determine shaft rotational speeds corresponding to equivalent behavior in the scaled units across varying degrees of cavitating conditions, the cavitation phenomena results of each are analyzed in a normalized manner to assess the level of agreement within specific fluid volumes of interest. The analysis performed demonstrates that some averaged phenomena, such as reduced volumetric efficiency, can be predicted reliably with scaling laws, while the spatial distribution of some phenomena within chamber fluid volumes, such as vapor volumetric fraction, exhibit significant discrepancies across scaled units. Such results indicate that the eventual damage or other negative impacts of cavitation may not be accurately accounted for by published scaling laws, and that further considerations may need to be made when scaling units for applications where cavitation is high-risk.
