Modeling and analysis of hose-drogue aerial refueling docking process based on fluid-solid coupling simulation

The hose-drogue aerial refueling process involves the complex coupling of aerodynamic force, fuel flow, and flexible structure deformation. Solving these interactions requires advanced simulation techniques and significant computational resources, which posed challenges to the accuracy and safety of practical implementations. A novel fluid-solid coupling model and methodology integrating aerodynamic loads, wake vortex effects, hose flexibility, airflow and internal fuel flow were developed to analyze structural deformation of hose-drogue assembly during docking and fuel transfer phases, overcoming limitations of traditional kinetic equation modeling. The aerodynamic forces of the paradrogue were obtained by performing separate CFD modeling on the paradrogue and conducting steady-state calculations. Meanwhile, the stabilizing moment of the paradrogue was equivalently converted into the lateral and rotational boundary condition at the center point of the paradrogue. Subsequently, based on the Hallock-Burnham model, the analytical expressions of the aerodynamic loads on the hose-drogue assembly under the action of the wake vortex alone were derived, and the aerodynamic loads were applied to hose-drogue assembly by ABAQUS subroutine. With the proposed model, the multi-stage operational processes of hose-drogue aerial refueling including steady-state, docking-state and refueling-state were calculated. Fluid-solid coupling simulations, which were conducted through co-simulation, demonstrated excellent agreement with experimental data, particularly under the steady-state. Furthermore, the influence of fuel flow characteristics, docking parameters and flight parameters were systematically identified. The results show that the matching relationship between the docking speed and retracting acceleration is the main influencing factor of whiplash load, and the retracting acceleration is positively correlated with the magnitude of the optimally matched docking velocity. In addition, the flight parameters are the secondary influencing factors. When the fuel flow is not considered, it is established at each altitude that the higher the flight speed, the lower the whiplash load. Fuel flow dynamics acts as a disturbing factor that partially perturbs the established relationship between whiplash loads and key operational parameters. However, these disturbances do not fundamentally alter the overall trend, and therefore, analyses under specific conditions are imperative to account for the effects of the fuel flow in different situations.