Topic
Vortex lattice method
About: Vortex lattice method is a research topic. Over the lifetime, 779 publications have been published within this topic receiving 9242 citations.
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01 Jan 1978
TL;DR: In this article, a numerical method is developed to predict distributed and total aerodynamic characteristics for low aspect-ratio wings with partial leading-edge separation, where the flow is assumed to be steady and inviscid.
Abstract: A numerical method is developed to predict distributed and total aerodynamic characteristics for low aspect-ratio wings with partial leading-edge separation. The flow is assumed to be steady and inviscid. The wing boundary condition is formulated by the quasi-vortex-lattice method. The leading-edge separated vortices are represented by discrete free vortex elements which are aligned with the local velocity vector at mid-points to satisfy the force free condition. The wake behind the trailing-edge is also force free. The flow tangency boundary condition is satisfied on the wing, including the leading- and trailing-edges. Comparison of the predicted results with complete leading-edge separation has shown reasonably good agreement. For cases with partial leading-edge separation, the lift is found to be highly nonlinear with angle of attack.
16 citations
TL;DR: In this paper, the convergence characteristics of a vortex-lattice method for the high-angle-of-attack, nonlinear aerodynamics of aircraft and missile configurations are studied parametrically.
Abstract: The convergence characteristics of a vortex-lattice method for the high-angle-of-attack, nonlinear aerodynamics of aircraft and missile configurations are studied parametrically. The solution for the vortex intensities is determined by the tangency boundary condition on all of the configuration surfaces, including the three-dimensional, rolled-up wakes that characterize such flowfields. The a priori unknown position of the wake that renders this problem nonlinear is determined by an iterative process. Since there is no proof for the existence and uniqueness of this process, this paper investigates the effects of several geometrical and numerical parameters on the converged solution. It was found that the convergence of the iterative solution procedure is usually rapid and is not affected by initial conditions of the first iteration and by the integration method of the wake streamlines. Grid refinement leads to a converged solution, but its final values vary with wing surface paneling and wake discretization schemes within some range in the vicinity of the experimental data.
16 citations
TL;DR: In this paper, a quasi-steady approach for the analysis of aerodynamic interaction between a propeller and a wing has been developed, where the aerodynamic coupling is represented by periodic loads, which are decomposed into harmonics and the harmonic amplitudes are found iteratively.
Abstract: A quasi-steady scheme for the analysis of aerodynamic interaction between a propeller and a wing has been developed. The quasi-steady analysis uses a 3D steady vortex lattice method for the propeller and a 3D unsteady panel method for the wing. The aerodynamic coupling is represented by periodic loads, which are decomposed into harmonics and the harmonic amplitudes are found iteratively. Each stage of the iteration involves the solution of an isolated propeller or wing problem, the interaction being done through the Fourier transform of the induced velocity field. The propeller analysis code was validated by comparing the predicted velocity field about an isolated propeller with detailed laser Doppler velocimeter measurements, and the quasi-steady scheme by comparison with mean loads measured in a wing-propeller experiment. Comparisons have also been made among the fluctuating loads predicted by the present method, an unsteady panel scheme and a quasi-steady vortex lattice scheme
16 citations
TL;DR: In this article, the contraction effect of the three-dimensional propeller slipstream and its inµ uence on the aircraft moment performance was considered in the computation of a single and multiple propeller aircraft.
Abstract: The panel method was used for the numerical calculations in this study. The propeller vortex system rotating with its blades, and the steady horseshoe vortex system distributed on the aircraft surface were used as the mathematical model. Neumann boundary conditions were satis ed at the panel control points of the blade and the aircraft panel to achieve coupling of propeller slipstream with the whole ow eld of the aircraft. At each corresponding azimuth angle of the propeller, pressure coef cients and induced velocities by the two vortex systems at the panel control points were calculated; from this, the average aerodynamic characteristics of the aircraft in one revolution period were obtained. The contraction effect of the three-dimensional propeller slipstream and its in uence on the ow eld were considered in the computation. Results of numerical examples showed that the slipstream had a signi cant effect on aircraft lift characteristics such as ap de ecting, resulting in relatively large changes of the aircraft moment performance. Numerical results were in good agreement with the experimental data. The method presented here is suitable for both singleand multiple-propeller aircraft.
16 citations