Analytical Modeling of Shrouded Rotors in Hover with Experimental and Computational Validation

Rotors have been utilized for aircraft propulsion since the dawn of aviation, but their performance can degrade significantly if not properly designed. This study focuses on developing an accurate design tool and model validation for shrouded rotors. An experimental test rig was designed and manufactured to measure the rotor thrust and total thrust separately as well as the rotor torque. A key aspect was to account for the impact of a test rig on experimental results using computational simulations for the shrouded rotor configuration with and without the test rig. The findings indicate that the effects of the test rig were minimal and could be neglected, ensuring the validity of the experimental data compared to the analytical model. The analytical model employs a hybrid approach combining blade element momentum theory (BEMT) and the sphere-cap model which are used in conjunction with the shrouded rotor inflow ratio, as well as post-stall and tip gap clearance models. BEMT is used to calculate rotor performance, while the sphere-cap model addresses the aerodynamic influence of the shroud. The results demonstrate that the analytical model predicts shrouded rotor performance with considerable accuracy, addressing both the rotor dynamics and the shroud’s contribution to performance.