Abstract
In this paper, a comprehensive computational modeling study of the unsteady aerodynamic environment around a warship with a helicopter is performed. An experimental validation exercise is also conducted, comparing computational fluid dynamics (CFD) results of the airwake calculated for a reduced-scale model of the isolated Landing Helicopter Assault (LHA) model with high-quality particle image velocimetry experimental data provided by the NASA AMES Research Center. Comparisons of the results generally obtain agreement, indicating that the CFD numerical method is able to resolve the large-scale turbulent airflow. Building on this, a numerical simulation of a real Robin helicopter, immersed in the unsteady airwakes of a full-scale Amphibious Assault Ship (AAS), is performed. The aerodynamic simulation of the influence on the coupled airflow of warship–helicopter is explored and compared with that of the solitary ship airflow field and the superposition airwakes, where the vortex patterns and pressure on the ship surface, as well as the velocity distribution, are circumvented. As a further step, dynamic landing analysis of the airflow field for a shipborne helicopter is implemented at an important location through the landing path for headwind. The aerodynamic characteristics of a helicopter during a flight deck landing are also explored for the unsteady ship airwakes impacting on rotor force during shipboard landings. In addition, different shipboard landing paths of the helicopter are comparatively investigated for obtaining an optimal landing path decision. The present study demonstrates an effective aerodynamic analysis and robust numerical approach, which creates a solid foundation supporting further alternative evaluations of ship airflow fields.
Highlights
Shipboard operations are challenging and polytropic for helicopter pilots, as the launch and recovery of fixed or rotary wing aircraft suffer during unsteady ship airwakes or pseudo-random motion in the six-degree freedom of ships
Afterwards, the numerical computation method as well as the mesh technique proposed is applied to the aerodynamic simulation of the coupled airwakes of a full scale warship–helicopter in Section 4; the numerical comparison of coupled airwakes and the solitary ship airflow field for the flight deck dynamic landing analysis, as well as the comparative investigation of different shipboard landing paths for the helicopter, are carried out
This paper presents a comprehensive computational modeling study of the unsteady aerodynamic characteristics of warship–helicopter airwakes
Summary
Shipboard operations are challenging and polytropic for helicopter pilots, as the launch and recovery of fixed or rotary wing aircraft suffer during unsteady ship airwakes or pseudo-random motion in the six-degree freedom of ships. A bluff body flowing separation exists and the unstable sheared layers and vortices interact, bringing about time-varying turbulent structures with a significant increase in turbulence intensity and velocity gradients, which in turn put pressure on stability and controllability for the helicopter pilots performing the launch and landing maneuvers It is important for risk reduction in helicopter operations over the platform on a ship’s deck to understand real ship–helicopter dynamic airwakes in full scale. Afterwards, the numerical computation method as well as the mesh technique proposed is applied to the aerodynamic simulation of the coupled airwakes of a full scale warship–helicopter in Section 4; the numerical comparison of coupled airwakes and the solitary ship airflow field for the flight deck dynamic landing analysis, as well as the comparative investigation of different shipboard landing paths for the helicopter, are carried out. Ghalandari et al, 2019; Salih et al, 2019), which will be adopted for the current CFD model
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