Rotor-Airwake Aerodynamic Coupling in Real-Time Simulation
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This SBIR Phase I proposal will examine the feasibility of using the Vorcat implementation of the grid-free vortex method to provide accurate, real time simulations of helicopter aerodynamics in a landing environment. The project is motivated by the unique capabilities of the Vorcat code in efficiently capturing the physics of complex turbulent flows by using vortical elements to represent the vortices that lie at the heart of turbulent fluid motion.
The phase I study will be aimed at answering several questions that will establish the parameters controlling when and in what way helicopter rotor downwash and ship wake interactions affect rotor aerodynamics and consequently real time dynamic simulations. In particular, this study will investigate several approaches for modeling rotor downwash and will establish the optimal setup that provides rapid and accurate results. This, in turn, will be utilized for a rigorous analysis which will determine the flow parameters that dominate the dynamic simulation and help improve the current simulator by providing corrections to the aerodynamic data used currently and which does not account for complex wake interactions.
A successful simulation of the non-steady, turbulent flow associated with helicopters must well resolve the sources of vorticity at the moving rotors and other solid surfaces that ultimately determine the loading of vorticity in the flow field. Rotor flows may be very complicated owing to the presence of transition and non-steady interactions with previously shed vorticity or free stream turbulence. Of equal importance to the overall simulation is the problem of properly accounting for the wake vortices formed out of the shed vorticity after it leaves the rotor tip and other surfaces. An important part of this is not imposing unphysical diffusion upon the separated vorticity field that artificially erases and weakens its structure. In essence, the wake vortices need to be carefully tracked to accurately predict the inlet flow to the rotor plane as well as their interactions with the rotors, fuselage, empennage and ground surfaces that are especially important in the present context of the landing flow field.