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Journal ArticleDOI

Aerodynamic and experimental investigation on a delta wing incorporated with winglets at different angles

TL;DR: In this article , a flat delta wing with and without winglets at different angles of attack under low Reynolds numbers is analyzed and simulations are carried out to draw comparisons between the winglets on the basis of span-wise flow velocity vectors.
Abstract: Delta wing has numerous applications across aerospace vehicles. Highly inclined and variable swept back wings have a lot of added advantages in maneuverable fighter airplanes, supersonic cruise airliner; and modern unmanned aerial vehicles that have been equipped with and have deployed low swept back delta wings. Vortex flow across these delta wings is dominant for micro aerial vehicles and mini unmanned aerial vehicles flying at a low speed Reynolds number regime. Many experiments were carried out to study and analyze the aerodynamic flow parameters of delta wings wherein vortex sheet flow patterns were observed and studied at different angles of attack and flow parameters. In this paper we are plotting lift co-efficient and drag coefficient for a flat delta wing with and without winglets at different angles of attack under low Reynolds numbers. Furthermore, simulations are carried out to draw comparisons between the winglets on the basis of span-wise flow velocity vectors.

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Journal ArticleDOI
TL;DR: In this article, the authors present an application of this technique to triangular wings having leading edge separation, which leads to nonlinear lift curves with lift greater than that obtained from potential flow theory.
Abstract: There are a large class of important fluid flows which involve the effects of fluid viscosity and yet do not constitute flows having restrictive amounts of viscous dissipation. Examples of such flows are the flow over slender bodies in which vortex shedding occurs, swept wings having separated leading edges and-so forth. The important feature of these flows is the production of free vortex sheets in which large dissipation ultimately occurs but only at great distances downstream of the generating body; hence, these flow fields may be approximated by potential flow solutions. The present paper presents an application of this technique to slender triangular wings having leading edge separation. Curves are presented showing the lift versus angle of attack, pressure distributions, and integrated span loadings. I t is shown that leading edge separation leads to nonlinear lift curves with lift greater than that obtained from potential flow theory. Comparison of lift curve with experiment is made.

219 citations

Journal ArticleDOI
TL;DR: The classical view of these vortices is sketched in Fig. la and has been discussed by Hoerner and Borst among others as discussed by the authors, with a sharp leading edge at an angle of attack a, the flow is separated along the entire leading edge forming a strong shear layer.
Abstract: Introduction: The Classical View T HE flow over delta wings at an angle of attack is dominated by two large bound vortices that result from the flow separation at the leading edge. The classical view of these vortices is sketched in Fig. la and has been discussed by Hoerner and Borst among others. With a sharp leading edge at an angle of attack a, the flow is separated along the entire leading edge forming a strong shear layer. The shear layer is wrapped up in a spiral fashion, resulting in the large bound vortex as sketched. These vortices appear on the suction surface and increase in intensity downstream. The low pressure associated with the vortices produces an additional lift on the wing, often called nonlinear or vortex lift, which is particularly important at large angles of attack. As sketched in Fig. la, small secondary vortices also appear on the wing near the points of reattachment as a result of the strong lateral flow toward the leading edge.

167 citations

Journal ArticleDOI
TL;DR: In this paper, the flow fields around two pitching delta wings with apex angles of 90 and 60 degrees were visualized in a towing tank at chord Reynolds numbers up to 3.5 xlO.
Abstract: Delta wings in steady flow can provide high lift at large angles of attack and are therefore used on many highperformance aircrafts. However, the unsteady aerodynamic properties of a delta wing are practically unknown, although vital for operating and designing airplanes for poststall and other maneuvering. In this study, the flowfields around two pitching delta wings with apex angles of 90 and 60 deg were visualized in a towing tank at chord Reynolds numbers up to 3.5 xlO. The reduced frequency was varied in the range 0.05-3. The leadingedge separation vortex went through a growth-decay cycle with hysteresis during a pitching period. A distinct change of the separated flow was observed at a reduced frequency around ir.

118 citations

01 Jan 2019
TL;DR: In this article, a straight tapered flying wing Biomimetic Aircraft was used for the initial aircraft geometry and several relationships between aircraft geometries and proverse yaw control power were determined.
Abstract: Recent developments in the bell-shaped spanload have shown the existence of proverse yaw control power via induced thrust at the wingtips. With no need for vertical control surfaces, new types of aircraft designs are possible. Via the use of traditional roll and proverse yaw control power, a lateral directional control space can be created for flying wings where no sweep is required for lateral directional stability and control. These straight tapered flying wings have increased efficiency and performance compared to traditional aircraft. In order to maintain stability and control, straight tapered flying wings require adequate proverse yaw control power. This paper investigated the connection between aircraft geometry and proverse yaw control power while applying the bell spanload. A straight tapered flying wing Biomimetic Aircraft was used for the initial aircraft geometry. By varying taper ratio, wing chord, wing length, twist distribution, and outboard wing control surface (OWCS) size, several relationships between aircraft geometry and proverse yaw control power are determined. Proverse yaw control power is a function of the change in lift over a region of upwash as well as the change in localized downwash. As the OWCS area increases due to larger chord lengths, proverse yaw control power increases. Additionally, increasing the region of upwash via a longer wingspan or twist distribution leads to improved proverse yaw control power. However, increasing the span fraction of the OWCS does not necessarily result in increased proverse yaw control power as it is tied to localized downwash. Varying the lift distribution due to an OWCS deflection can positively affect this downwash decreasing proverse yaw control power. The Biomimetic Aircraft with 10% more span and 10% more twist at the wingtips has 16 times more proverse yaw control power than the original Biomimetic Vehicle. With this increase in proverse yaw control power, straight tapered flying wings are controllable through all necessary flight regimes.

5 citations

Journal ArticleDOI
01 Jun 2021
TL;DR: In this paper, a review sheds light on the traits behind an albatross's aerodynamic efficiency such as dynamic soaring, bell shaped lift distribution and provides insights into its hereditary posed encodings and evolutions.
Abstract: The aerodynamic efficiency of the albatross has always fascinated researchers and the designing of drones mimicking the albatross's aerodynamic traits have been a major area of interest for the aerospace industry. This review sheds light on the traits behind an albatross's aerodynamic efficiency such as dynamic soaring, bell shaped lift distribution and provides insights into its hereditary posed encodings and evolutions. The soaring techniques have been introduced and discussed along with the albatross's morphology and structure which is responsible for its efficiency. In addition, the albatross's navigational and foraging strategies are briefly discussed to provide a better understanding of the effects of atmospheric conditions on the albatross's flight characteristics and the limitations.

2 citations