Aerodynamic Performance of Unmanned Aerial Vehicles in Ground Effect

The aerodynamic performance of unmanned aerial vehicles (UAVs) operating in close proximity to the ground is profoundly altered by the so-called ground effect. When a rotor or propeller approaches a planar surface, the induced downwash is partially obstructed, leading to a rise in static pressure beneath the lifting surfaces and a consequent increase in thrust and lift with reduced power requirement. This phenomenon influences vehicle stability, control effort and energy efficiency during critical phases such as vertical take-off, landing and low-altitude inspection missions. The complex interaction between rotor wakes and the ground plane can give rise to unsteady vortex structures, modified inflow distribution and fluctuation in aerodynamic loads, presenting both challenges and opportunities for flight control and mission planning. Advances in experimental wind-tunnel testing, high-fidelity computational fluid dynamics (CFD) and analytical modelling have deepened our understanding of thrust augmentation, wake re-ingestion and acoustic signatures in ground effect. Practical applications range from precision agriculture and urban air mobility to search and rescue in confined environments. Designers increasingly integrate ground-effect considerations into rotor geometry, control algorithms and noise-mitigation strategies to harness performance benefits while ensuring flight safety and regulatory compliance.

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Aerodynamic Performance of Unmanned Aerial Vehicles in Ground Effect publication trend

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Technical terms

Ground effect: The increase in lift and reduction in induced drag experienced by a rotor or wing operating close to a surface due to altered airflow and pressure distribution.

Wake interference: Interaction between rotor wakes or between a rotor wake and nearby surfaces, which can modify thrust, induce unsteady forces and affect control.

Computational fluid dynamics (CFD): A numerical simulation method that solves the governing equations of fluid flow to predict aerodynamic behaviour and wake structures.

Thrust coefficient: A dimensionless parameter expressing the ratio of generated thrust to dynamic pressure and rotor disk area, used to compare rotor performance under varying conditions.

Rotor-wake re-ingestion: Phenomenon whereby accelerated airflow from a rotor’s wake returns to the rotor plane, causing fluctuations in lift and torque.

References

1. Investigating UAV Propellers Performances Near Moving Obstacles: CFD Study, Thrust Control, and Battery Energy Management. IEEE Open Journal of Vehicular Technology (2023).
2. Ground Effect on the Thrust Performance of Staggered Rotor System. Drones (2024).
3. Experimental investigation of propeller noise in ground effect. Journal of Sound and Vibration (2023).