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This study presents the development of computationally efficient coupling of NavierStokes Computational Fluid Dynamics (CFD) with a helicopter flight dynamics model with the ultimate goal of real-time simulation of airwake effects in the helicopter/ship Dynamic Interface (DI). The flight dynamics model is free to move within a computational domain, where the main rotor forces are converted to source terms in the momentum equations of the CFD solution using an actuator disk model. Simultaneously, the CFD solver calculates induced velocities that are fed back to the simulation and affect the aerodynamic loads in the flight dynamics. The CFD solver models the inflow, ground effect and interactional aerodynamics in the flight dynamics simulation, and these calculations can be coupled with the solution of the external flow (e.g., ship airwake effects). The simulation framework for fully-coupled pilot-in-the-loop (PIL) flight dynamics/CFD is demonstrated for a simplified shedding wake. Initial tests were performed with 0.38 million structured grid cells running on 352 processors and showed near-real-time performance. Improvements to the coupling interface are described that allow the simulation run at near-real-time execution speeds on currently available computing platforms. Improvements in computing hardware are expected to allow real-time simulations.

Accurate models for the prediction of ship airwake flowfields are critical to the development of realistic flight simulation tools for aircraft carrier launch and recovery operations. The accurate computation of the ship airwake can be very challenging due to the complexity of the ship geometry, the size of and difficulty in generating a suitable computational mesh, and the large range of length and time scales present in the unsteady flowfield. The present paper investigates the sensitivity of the airwake solution to several modeling parameters, including geometric complexity and the resolution of boundary layers, with the aim of determining the level of fidelity required to obtain an accurate solution.Results are compared to wind tunnel experimental measurements. The results of these studies show that, in general, a majority of the airwake flow features are characterized by bluff body shedding from the larger geometric entities that comprise the ship geometry. Depending on the requirements and intended use of the solution, a certain tradeoff can be reached between solution turn-around/grid generation time and solution accuracy.

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