One estimation approach utilizes CFD under inviscid approximations where the net body force should be equal to the induced drag and, in the context of inviscid assumptions, provides an estimate of the inviscid drag behavior. Navier–Stokes-based CFD methods directly include induced-drag contributions, but identifying each component is not straightforward due to the underlying formulation approach. Both authors explored identifying drag-elements in viscous flows using potential flow models. Chu, “ How does a gurney flap enhance the aerodynamics forces?” AIAA J. Chang, “ Potential flow and forces for incompressible viscous flow,” Proc. Other force-decomposition approaches include the works of Chang 7 7. A key attribute to potential flow methods is its foundation upon elementary functions that can be superimposed, which enables the direct assessment of induced and profile drag. to solve for the corresponding adjusted profile drag and provide an estimate to the total drag distribution. Thwaites, “ Approximate calculation of the laminar boundary layer,” Aeronaut. Stewartson, “ Further solutions of the Falkner-Skan equation,” Math. Gersten, Boundary-Layer Theory ( Springer, 2016). These methods are also coupled to integral-boundary-layer solvers 4–6 4. These methods provide fidelity to address how shed vorticity interacts with the circulation about lifting surfaces and enables the calculation of induced effects. Bramesfeld, “ Higher-order free-wake method for propeller–wing systems,” J. James, “ On the remarkable accuracy of the vortex lattice method,” Comput. lifting surface methods to vortex lattice methods. Anderson, Jr., A History of Aerodynamics: And its Impact on Flying Machines ( Cambridge University Press, 1998), Vol. These range from low order analytical models such as Prandtl’s Lifting Line Theory (LLT) and 1 1. In the context of numerical methods, potential flow methods serve as an excellent, computationally inexpensive option for estimating induced drag effects. This study aims at closing that gap through a semi-analytical method to directly compute induced and profile drag components on wings through viscous CFD simulations.Ī plethora of methods exists to estimate individual drag contributions. This presents a gap for CFD simulations in the inability to isolate effects of cross-sectional shape and planform shape that are critical in the design of wings. However, in the context of CFD, such decoupling is non-trivial. In classical aerodynamics, it is conventional to decompose the two-dimensional, airfoil, forces from the three-dimensional, induced, effects. These pressure and viscous forces can readily be computed from Computational Fluid Dynamics (CFD) simulations at a discrete level, where surface integration provides the bulk aerodynamic forces. A prime example of this is the finite wing, which experiences a combination of viscous and inviscid drag. It is of interest to engineers to identify individual contributions of drag to an arbitrary body because specific design changes can be applied to lower these individual aerodynamic losses. Results indicate a novel and efficient method to extract induced drag from CFD models. The results from the approach indicate accuracy in the method as displayed with good correlation to predictions from analytical and potential flow methods for a variety of wing planforms. In addition, the results indicate an interesting character in the development of energy losses in the context of induced drag associated with flow reorganization into a tip vortex. We find that the energy equation provides the necessary means for the closure of quantifying induced drag within the context of minor assumptions. The present approach builds on mass, momentum, and energy equation control volume analysis performed within the CFD results. Isolating induced drag from aerodynamic drag is not well developed using CFD, leading to the present effort that derives a mathematical framework to extract induced drag from CFD model results. It does so using surface integration of pressure and viscous forces, which does not readily enable conventional separation of profile and induced drag. The more recent evolution of Navier–Stokes-based Computational Fluid Dynamics (CFD) methods typically directly computes aerodynamic forces. Early aerodynamic mathematical methods rely on potential flow concepts that formally isolate aerodynamic drag into a profile and an induced drag component.
0 kommentar(er)
