Numerical Analyses of Aerodynamic and Aeroacoustic Interaction Characteristics of Rear-Mounted Propeller on Highspeed Helicopter

To study the interference effects of the fuselage/rear-mounted propeller on the aerodynamic and aeroacoustic characteristics at a forward speed of Ma = 0.323, a multi-component flowfield simulation and an aeroacoustic prediction method were employed. Firstly, hybrid grids were adopted in the embedded grid system, and a new boundary identification method was developed to address the overlap problem by adjusting the grid boundary based on entities. The simulations were based on the URANS and FW-H equations. The employed numerical analysis methods were validated through comparisons with experimental data. Then, the aerodynamic and aeroacoustic characteristics of the propeller were analyzed, and the interference of the fuselage with the propeller was discussed in detail. Key findings included the following. Under fuselage interference, the sound pressure level (SPL) of the propeller at those observers near the forward flight direction increased dramatically, by more than 10 dB, especially in the range of two to six times the fundamental frequency. A downward vertical velocity reduced the SPLs beneath the fuselage, while an upward one had the opposite effect. The flat/vertical tails’ deceleration effect caused a thrust surge in the propeller, with most magnitudes around 20%. At different forward speeds, the thrust surge and SPL changes were similar.