Work

Experimental Investigation of Snow Cloud Evolution During Helicopter Operations over Snow-Covered Surfaces

Year: 2026

Type: article

Abstract: Helicopter operations over snow-covered surfaces are susceptible to whiteout conditions, which can severely degrade pilot visibility and threaten flight safety. To investigate the evolution characteristics and formation mechanisms of rotor-induced snow clouds during near-ground operations, a series of field experiments were conducted using an unmanned helicopter with a rotor diameter of 2.2 m under natural winter conditions. Image-processing techniques based on grayscale-difference analysis were employed to quantify snow cloud area and concentration, while planar laser qualitative flow visualization was used to examine snow particle motion and flow structures. The rotor-induced downwash is considered a dominant influencing factor affecting snow cloud formation and evolution under the present experimental conditions. During takeoff and landing, the proximity of the rotor to the ground strengthens the interaction between the downwash flow and the snow surface, resulting in enhanced snow particle entrainment and larger snow cloud areas. Increasing collective pitch tends to intensify the rotor-induced downwash, which may contribute to greater snow cloud extent and higher snow concentrations. The experiments also reveal that snow cloud evolution is characterized by a coupled process involving particle entrainment, suspension, recirculation, and deposition rather than simple transient dispersion. Flow visualization results indicate that rotor downwash initially generates a high-speed radial wall jet that mobilizes surface snow particles. Rotor tip vortices subsequently capture and transport these particles upward, promoting snow cloud growth and recirculation. The present study provides experimental insights into the physical mechanisms of helicopter-induced snow clouds and offers a basis for the assessment and mitigation of whiteout hazards during helicopter operations in snow-covered environments.

Source: Aerospace

DOI: 10.3390/aerospace13090772

Authors: Tianshuang Shao, Wenkai Yu, Xiangnan Liu, Shi Liu, Zheng Yang, Yuntong Li

Institutions: Northwestern Polytechnical University, AviChina Industry & Technology (China)

Language: English

Topic: Particle Dynamics in Fluid Flows

Subfield: Fluid Flow and Transfer Processes

Field: Chemical Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,896

Funder: Chinese Aeronautical Establishment