Simulation of Helicopter Shipboard Launch and Recovery with Time-Accurate Airwakes

Abstract

A simulation of the helicopter/ship dynamic interface has been developed and applied to simulate a UH-60A operating from an LHA class ship. Time accurate CFD solutions of the LHA airwake are interfaced with a flight dynamics simulation based on the GENHEL model. The flight dynamics model was updated to include improved inflow modeling and gust penetration effects of the ship airwake. A maneuver controller was used to simulate pilot control inputs for specified approach and departure trajectories. The CFD solutions show significant time varying flow effects in the airwake. Time histories of the aircraft angular rate and pilot control activity indicate that the time varying nature of the airwake has significant effect on aircraft response and pilot workload.

Shipboard Landing Challenges for Autonomous Parafoils

“…Characterization and visualization of the "airwake" of a ship underway as been the subject of some research, particularly for the application of helicopter operations; the article by Lee et al contains a survey. 6 These studies often rely on Computational Fluid Dynamics (CFD) in order to predict the flow field around the ship's superstructure; however, one recent research project at the U.S. Naval Academy is correlating CFD results with flow field data gathered in situ on a 33 m training vessel that has been modified to include a scale model flight deck aft of the superstructure.…”

An investigation of coupling ship/rotor flowfield using steady and unsteady rotor methods

“…The results illustrate that the RANS solver is capable of predicting the fundamental flow characteristics of ship airwake, although there are some deficiencies in detail simulations of turbulent fluctuation. One-way coupling calculations (Forrest, Owen, & Padfield, 2009;Forrest, Owen, Padfield, & Hodge, 2012;Lee, Sezeruzol, Horn, & Long, 2005;Roper, Owen, Padfield, & Hodge, 2006) refer to simulations that only assume the effect of the ship wake on the helicopter, as commonly used in previous analyses of shipboard landing. However, a large discrepancy has been found in the helicopter control inputs compared with the experimental data, due to the rotor-on-ship effect being ignored.…”

Reduced-Order Modeling of Rotor-Ship Interaction

“…The current NAVAIR approach is to adopt the advanced Computational Fluid Dynamics (CFD) method to compute the ship airwake offline [1][2][3] and then use the table lookup approach to include the CFD ship airwake solutions into the induced velocity fields, which are used in the blade element model in a real-time Manned Flight Simulator (MFS) [4]. The deficiency of this approach is that only the effects of unsteady ship airwake on the rotor induced flow field are considered but the effects of rotor induced flow on unsteady ship airwake are neglected.…”