Abstract
In view of improving the understanding of the loss mechanisms existing on a compact turbine driving a cryogenic engine turbo-pump for a satellite delivering rocket, a new perspective on how the aspect ratio of turbine blades affects the secondary and profile losses is presented. This perspective, originally based on published experimental data, is further developed by a series of back-to-back highly resolved computational fluid dynamics (CFD) numerical simulations, with the aim of acquiring further insight into the dynamics of the secondary vortices, and the intermediate boundary layer flow for varying blade heights. The main outcome redefines the extreme cases and the partition of losses between secondary and profile, and establishes a new critical ultra-low aspect ratio of 0.35 as a threshold distinguishing two different behaviors. The final venue of this new perspective is the possibility to further improve existing off-design turbine loss models, like those presented by Craig–Cox and Ainley–Mathieson.