A generalized vortex lattice method for subsonic and supersonic flow applications

Source: NTRS


If the discrete vortex lattice is considered as an approximation to the surface-distributed vorticity, then the concept of the generalized principal part of an integral yields a residual term to the vorticity-induced velocity field. The proper incorporation of this term to the velocity field generated by the discrete vortex lines renders the present vortex lattice method valid for supersonic flow. Special techniques for simulating nonzero thickness lifting surfaces and fusiform bodies with vortex lattice elements are included. Thickness effects of wing-like components are simulated by a double (biplanar) vortex lattice layer, and fusiform bodies are represented by a vortex grid arranged on a series of concentrical cylindrical surfaces. The analysis of sideslip effects by the subject method is described. Numerical considerations peculiar to the application of these techniques are also discussed. The method has been implemented in a digital computer code. A users manual is included along with a complete FORTRAN compilation, an executed case, and conversion programs for transforming input for the NASA wave drag program.

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    • "However, the vortex-lattice method has been found to be a very useful preliminary design tool [5]. Comparison with the experimental data shows good agreement with the force and moment coefficients due to lift in a subsonic regime [5] [6] [7] [8]. Specifically, Tornado has been evaluated to estimate static stability derivates. "
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    ABSTRACT: A preliminary evaluation of the static stability and open-loop dynamic stability for the unpowered condition by inviscid computational fluid dynamics (CFD) for Unmanned Aerial Vehicle for Ecological Conservation (ANCE) has been reported. The Unmanned ANCE is a small, twin-boom, pusher-propeller airplane with a maximum takeoff mass of 182.055 kg, capable of carrying 40 kg of payload in the form of a high-technology camera to find oil leakages during daylight or at night. The static stability was evaluated using a vortex-lattice method code called Tornado and it has been evaluated to estimate static stability derivates. The static stability data obtained by the vortex-lattice method were used to determine the airplane dynamic stability response characteristic. The handling qualities for the short-period mode are adequate for the mission flight phase, except for the terminal flight phases. The handling qualities for the lateral-directional motion are excellent for the Dutch roll and roll modes for all flight phases. Copyright © 2009 by Elsa M. Cárdenas. Published by the American Institute of Aeronautics and Astronautics, Inc.
    Full-text · Article · Jul 2009 · Journal of Aircraft
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    • "The landing gear and the camera are not included in the paneled geometry formed by 1100 panels, due to the fact that the contribution of these components to induced drag is assumed negligible. The fuselage and booms were idealized with cruciform shapes [17]; this body simulation is highly computationally efficient for load distribution and induced drag data [18]. "
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    ABSTRACT: Recently published works predict that any planform shape may be optimized with twist to reduce the induced drag to an optimum value. When the twist is applied along the span of the airplane, the lift-drag ratio is lower than that with no twist. This can be corrected if twist is applied only in a specific portion of the span. The objective of this paper is to demonstrate that the local twist increases the lift-drag ratio using two different inviscid computational fluid dynamics codes and to describe the method employed to obtain the twist start line to increase the lift-drag ratio. The method was applied to an unmanned aerial vehicle designed for the early detection of oil leakages in the extraction areas, and a variation of 8 cm in the wing tip was obtained. The results show that the lift-drag ratio of the twisted wing is higher than that with no twist in conditions close to cruise flight. The lift-drag ratio increased 2.89 and 0.31%, estimated by Multbopp's method and by the vortex-lattice method, respectively. The results demonstrate that the local twist may increase the lift-drag ratio when it is applied in the way explained in the present paper.
    Full-text · Article · Jan 2008 · Journal of Aircraft
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    • "For this reason, physics-based programs were preferred. HASC95 is based on VORLAX, which itself is based on a vortex lattice/panel method [15] extended to supersonic speeds. However, HASC95 also includes semi-empirical methods to capture non-linear aerodynamic effects such as vortex lift and vortex burst. "
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    ABSTRACT: In current design practices, safety, operational and handling criteria are often overlooked until late design stages due to the difficulty in capturing such criteria early enough in the design cycle and in the presence of limited and uncertain knowledge. Virtual (flight) testing and evaluation, based on autonomous modeling and simulation, is proposed as a solution to this shortcoming. The methodology enables one to evaluate vehicle behavior in relatively complex situations through a series of specific flight scenarios. Bringing this methodology to conceptual design requires the creation of an automatic link between the design database and the autonomous flight simulation environment. This paper describes the creation of such a link and an implementation of the Virtual Testing and Evaluation methodology with the use of an advanced design concept.
    Full-text · Article · Apr 2002
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