Review of aerodynamic and aeroacoustics characteristics of counter rotating propellers

Counter rotating propellers (CRPs) have recently attracted more attention due to their high thrust and aerodynamic efficiency. This article comprehensively reviews five aspects of coaxial CRPs: experimental research, aerodynamic performance evaluation, aerodynamic simulation, aeroacoustics prediction, and aerodynamic noise optimization design. Firstly, it summarizes the current domestic and international experimental achievements regarding the aerodynamics and aeroacoustics of CRPs. Next, it introduces the engineering methods for the aerodynamic force calculation of CRPs and elaborates on the strip theory developed by Lu Shijia Laboratory at Beihang University for the aerodynamic force evaluation of CRPs. Based on this, numerical simulation methods for CRPs are presented, and both frequency domain and time domain methods for predicting the aerodynamic noise of CRPs are discussed. Finally, it presents the current research achievements in the aerodynamic noise optimization design of CRPs.