Open Rotor Propulsion System

Research Area: Aeromechanics & Elasticity

The open rotor propulsion system is being explored as a next-generation technology to improve fuel efficiency in aviation. Unlike conventional ducted fans used in modern turbofan engines, open rotor engines operate without engine nacelle/casing. This design allows for higher bypass ratios, meaning that a larger volume of air is moved by the fan compared to the air passing through the engine core, leading to significant improvements in fuel efficiency and weight reduction.

The Advanced Noise Control Fan (ANCF) facility was originally developed and used by NASA for the study of acoustic technology for turbofan engines. The facility, now operated by the University of Notre Dame, was recently converted to study Open Rotor (OR) configurations. The successful development of the un-ducted test article required (i) a low-cost, flexible test platform which allows rapid testing and evaluation of new open rotor design concepts (ii) a test bed for open rotor aeroacoustics and aeromechanic predictive codes (iii) answer fundamental research questions and provide operational experience with open rotor testing.

The design of the first OR-ANCF test article focused on testing conditions that align with flight take-off conditions. The aerodynamics design methodology iterated between simplified actuator disk theory, aerodynamic strip theory, and full 3D computational fluid dynamics. The hardware was machined, assembled, and successfully tested in November 2024. Ongoing activities include a number of new hardware configurations, and the use of neural-net based regression analysis to quantify both radiated sound and blade vibration.