Similarity Study of Lightly Loaded Shrouded Rotors for Distributed Propulsion

Reaching the American and European long-term air transport emission reduction goals imposes to consider shifting by 2050 toward hybridation/electrification of airplanes. This implies development of distributed propulsion systems through the multiplication of low-diameter lightly-loaded shrouded rotors, operating at high rotational speed and moderate flight Mach number. A specific characteristic map for these kind of system is developed in this paper. It is based over an integrative approach that takes advantage of both internal and external flow formalisms. It outlines the main parameters representing the shrouded rotors performance and the parameters that drive them in a self-similar way. This is done by a dimensional analysis taking into account the geometric and operating parameters of both the rotor and the shroud and their combined variables. The self-similarity property of the characterization is validated with potential flow and RANS computations which proves it a powerful tool for scaling the shrouded rotors at iso-performance.