A Quasi-Prescribed Vortex Wake Method Capturing Rotor Wake Distortion

Prescribed vortex wake methods have historically provided rapid analysis for modeling rotor performance with reasonable accuracy suitable to conceptual and preliminary design. However, determining an appropriate wake geometry requires accurate prescription functions, often relying on empirical data. For distributed electric propulsion (DEP) and electric vertical takeoff and landing (eVTOL) aircraft, interaction effects of installed multi-rotor and rotor-wing systems can introduce significant wake distortion and deflection, which is not captured by a rigid or prescribed wake model. Force-free wake methods can capture these wake interactions, but at significant computational cost. To maintain rapid analysis capabilities while capturing external wake interactions, we develop an approach for an adaptive quasi-prescribed vortex wake method. The proposed approach is developed using principles of potential flow theory and a relaxation procedure to include the mutual wake interaction between aircraft components. Applications to rotor-wing systems with coupling between the rotor wake and a vortex lattice method representation of the wing is explored. Results are compared with two additional methods that have been developed, a prescribed vortex wake and a free vortex wake. Validation against experimental measurements for a blown wing configuration is conducted, and the method's ability to more closely predict wake distortion of a tilt-rotor and wing system is also explored.