A Three Dimensional Vortex Particle-Panel Code For Modeling Propeller-Airframe Interaction

Abstract

Analysis of the aerodynamic effects of a propeller flowfield on bodies downstream of the propeller is a complex task. These interaction effects can have serious repercussions for many aspects of the vehicle, including drag changes resulting in larger power requirements, stability changes resulting in adjustments to stabilizer sizing, and lift changes requiring wing planform adjustments.Historically it has been difficult to accurately account for these effects at any stage during the design process. More recently methods using Euler solvers have been developed that capture interference effects well, although they don't provide an ideal tool for early stages of aircraft design, due to computational cost and the time and expense of setting up complex volume grids. This research proposes a method to fill the void of an interference model useful to the aircraft conceptual and preliminary designer.The proposed method combines a flexible and adaptable tool already familiar to the conceptual designer in the aerodynamic panel code, with a pseudo-steady slipstream model wherein rotational effects are discretized onto vortex particle point elements. The method maintains a freedom from volume grids that are so often necessary in the existing interference models. In addition to the lack of a volume grid, the relative computational simplicity allows the aircraft designer the freedom to rapidly test radically different configurations, including more unconventional designs like the channel wing, thereby providing a much broader design space than otherwise possible.Throughout the course of the research, verification and validation studies were conducted to ensure the most accurate model possible was being applied. Once the vortex particle scheme had been verified, and the ability to model an actuator disk with vortex particles had been validated, the overall product was compared against propeller-wing wind tunnel results conducted specifically as benchmarks for numerical methods.The method discussed in this work provides a glimpse into the possibility of pseudo-steady interference modeling using vortex particles. A great groundwork has been laid that already provides reasonable results, and many areas of interest have been discovered where future work could improve the method further. The current state of the method is demonstrated through simulations of several configurations including a wing and nacelle and a channel wing. iv ACKNOWLEDGMENTS My tenure at

Development of a Vortex Particle Code for the Modeling of Wake Interaction in Distributed Propulsion

“…Taking the curl over Eq. (2), and using the identity ∇ × (∇ 2 u) = ∇ 2 (∇ × u), the momentum equation is then transformed into its vorticty form…”

Influence analysis of propeller location parameters on wings using a panel/viscous vortex particle hybrid method

“…When the vortex particles are included, their influences can be accounted for by adding the induced velocities of all wake particles into the Neumann boundary condition. Therefore, the new source strength (23) of each panel can be rewritten as where is the induced velocity of the particle q, it can be obtained through the Biot-Savart law.…”

Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

“…Also, due to the vorticity representation of the flow by free vortex particles, they can move freely with local flow velocity, allowing a natural development of the wake and avoiding singularities due to intersections between wake and lifting surfaces. Additionally, the Viscous Vortex Particle method has been successfully applied in many studies involving rotors and propellers and their interaction with other lifting surfaces or propellers (58,60,59,61,62,63,64) .…”