The Contra-Rotating Open Rotor (CROR) system has promising environmental benefits due to its ultra-high bypass ratio and high propulsive efficiency. The reduced fuel burn and emissions of the CROR compared to an equivalent thrust turbofan make it a viable economic and environmentally friendly propulsion alternative to traditional ducted systems. However, in the absence of a noise-conditioning duct, aerodynamic interactions within the CROR system as well as between the system and surrounding installation components like the engine pylon may result in noise penalties. If the system configuration is not optimized, the added effect of flow asymmetry to the aerodynamic interactions could potentially result in severe noise penalties, making the CROR system infeasible for the use in the aircraft industry. The proposed work will perform a sensitivity study on the design parameters of a CROR-pylon configuration. This study will leverage knowledge from past efforts with this type of configuration in order to narrow down the space of design parameters High-fidelity computational aeroacoustics analyses will be carried out in order to generate the accurate data necessary to analyze the effect of each of the chosen parameters on noise generation. This research is intended to provide both the FAA and industry with key insights necessary for design optimization of the CROR system in the future.
A major challenge in meeting noise targets is assessing and reducing noise sources while dealing with multiple design constraints. Therefore, there is a need to quantify the impact of design parameters on noise. Based on the literature review, key CROR system design parameters will be chosen to perform the parametric study for the noise sensitivity. The analysis will identify the trends that can aid further research and provide manufacturers with the ability to assess design tradeoffs. Without this research, there will be insufficient information for FAA and industry stakeholders to judge whether CROR technology is feasible to achieve a step change in fuel burn reduction while also addressing noise constraints.