|Abstract:||The study involves a tiltrotor’s wing/rotor configuration design to properly test the model in both hover flight condition and crosswind condition replicated in the wind tunnel. To record data, a subsonic wind tunnel was utilized to test the wing/rotor configuration in different conditions of freestream velocity of V_∞=10, 15, and 20 m/s, the blade pitch angle of θ=5°, 10°, and 15°, and across a range of crosswind angles of β= 0°-90°. Post-processing of the obtained data was performed to interpret flow interactions between the rotor and wing in crosswind flight conditions and influences on the fountain effect. Further, a CFD simulation tool was used for comparison to these experiments. Also, a PIV experiment was performed to visualize the fountain effect’s flow structure, which occurred on the wing in the hover flight condition.
A series of wind tunnel tests performed indicated that lift coefficients of the wind tunnel tests and CFD results closely replicate each other’s results for crosswind angles lower than 60°. Therefore, it can be stated that the URANS-based CFD methodology can simulate the tiltrotor’s wing/rotor configuration performance for flight conditions of lower crosswind angles, ideally from 0° to 45° for this particular study.
Performing flow visualizations for crosswind flight conditions of lower crosswind angles indicated that the fountain effect is present in the hover flight condition. Then, the effect diminishes in the freestream flight condition. No significant change for thrust coefficient occurs. An induced flow beneath the rotor on the downstream side was observed to occur. Consequently, the thrust coefficient drops, indicating a performance decrease in higher crosswind angles.