Topic
Starting vortex
About: Starting vortex is a research topic. Over the lifetime, 4785 publications have been published within this topic receiving 100419 citations.
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TL;DR: In this paper, the flow field around a symmetrical NACA airfoil in the uniform flow under generation of noise was numerically studied and the numerical simulation was carried out by a large-eddy simulation that employs a deductive dynamic model as the subgrid-scale model.
48 citations
TL;DR: In this article, an existing vortex-lattice method was modified to include the effects of leading-edge separation, and the modified version was then used to calculate the aerodynamic loads on a highly swept delta wing.
Abstract: Vortex-lattice methods have been used successfully to obtain the aerodynamic coefficients of lifting surfaces without leading-edge separation. It is shown how an existing vortex-lattice method can be modified to include the effects of leading-edge separation. The modified version is then used to calculate the aerodynamic loads on a highly swept delta wing. The results are compared with Peckham's (1958) experimental data.
48 citations
TL;DR: In this article, detailed characteristics of the horseshoe vortex system formed at the juncture of a wing and flat plate have been studied using flow visualization and image analysis techniques, which exhibited three distinct modes consisting of 1) steady vortex system, 2) oscillatory vortex motion, and 3) vortex shedding.
Abstract: Detailed characteristics of the horseshoe vortex system formed at the juncture of a wing and flat plate have been studied using flow visualization and image analysis techniques. With increasing Reynolds number the flowfield exhibited three distinct modes consisting of 1) steady vortex system, 2) oscillatory vortex motion, and 3) vortex shedding. Vortex splitting and subsequent reconnection phenomena were also observed. Different trends in the variation of characteristic frequency were observed when the flow switched from second mode to the third mode.
48 citations
TL;DR: In this paper, a numerical analysis of leading-edge vortex breakdown on a delta wing at high angles of attack is presented, where the analysis has been restricted to low-speed flows on a flat-plate wing with sharp leading edges.
Abstract: A numerical investigation of leading-edge vortex breakdown on a delta wing at high angles of attack is presented. The analysis has been restricted to low-speed flows on a flat-plate wing with sharp leading edges. Both Euler and Navier-Stokes (assuming fully laminar and turbulent flows) equations have been used in this study and the results are compared against experimental data. Predictions of vortex breakdown progression with angle of attack with both Euler and Navier-Stokes equations are shown to be consistent with the experimental data. However, the Navier-Stokes predictions show significant improvements in breakdown location at angles of attack where the vortex breakdown approaches the wing apex. The location of the primary vortex and the level of vorticity in the prebreakdown regions are affected very little by the viscous effects. In the postbreakdown regions, however, the levels of vorticity in the primary vortex have increased differences between the Euler and Navier-Stokes solutions. Navier-Stokes solutions indicate the presence of a secondary vortex even after the primary vortex is burst. The predicted trajectories of the primary vortex are in very good agreement with the test data with the laminar solutions providing the overall best comparison.
48 citations
01 Jul 1983
TL;DR: In this article, a simple method of introducing such disturbances has been implemented numerically in the well-known transonic small-disturbance code LTRAN2, and calculations have been performed for two important classes of current aerodynamic problems.
Abstract: Unsteady interactions of concentrated vortices and distributed free-stream gusts with a stationary airfoil have been analyzed in two-dimensional transonic flow. A simple method of introducing such disturbances has been implemented numerically in the well-known transonic small-disturbance code LTRAN2, and calculations have been performed for two important classes of current aerodynamic problems. The first, which demonstrates many of the essential features of the interactions between helicopter rotor blades and their trailing-vortex wakes, is that of a discrete potential vortex convecting past an airfoil. The second is the response of a transonic airfoil to a transverse periodic gust, with and without the alleviation that can be achieved by the proper active control motion of a trailing-edge flap. In both cases, unsteady effects are found to play important roles in the shock-wave motion, in the overall flow-field development, and consequently, in the air loads on the airfoil.
48 citations