Study on Wing Aspect Ratio on the Performance of a Gliding Robotic Fish

2015 ◽  
Vol 786 ◽  
pp. 248-253 ◽  
Author(s):  
Javaid Muhammad Yasar ◽  
Ovinis Mark ◽  
T. Nagarajan ◽  
Syed Saad Azhar Ali ◽  
Ullah Barkat
Keyword(s):  
Aspect Ratio ◽  
Angle Of Attack ◽  
Robotic Fish ◽  
Michigan State University ◽  
State University ◽  
High Lift ◽  
Aspect Ratios ◽  
Drag And Lift ◽  
Lift And Drag ◽  
Wing Aspect Ratio

In this paper, the performance of a gliding robotic fish with different wing aspect ratio is investigated. The gliding robotic fish, developed by Michigan State University, has the energy efficient locomotion of an underwater glider and high maneuverability of a robotic fish. ANSYS Computational Fluid Dynamics turbulence model was used to determine lift and drag coefficients for various wing aspect ratios at different angle of attack. Subsequently, the corresponding glide angle and velocity were determined analytically based on its dynamic model. The simulation results compare well with published experimental data and shows that the drag and lift coefficients are inversely proportional to the wing aspect ratio. As such, a gliding robotic fish with a low wing aspect ratio is suitable for shallow waters only, due to the high lift forces generated for a given angle of attack, requiring greater energy to sustain the glide velocity and vice versa.

scholarly journals Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio

2015 ◽  
Vol 12 (105) ◽  
pp. 20150051 ◽  
Author(s):  
Jan W. Kruyt ◽  
GertJan F. van Heijst ◽  
Douglas L. Altshuler ◽  
David Lentink
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Angle Of Attack ◽  
Radial Distance ◽  
Leading Edge ◽  
High Angle ◽  
High Angle Of Attack ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Low Aspect Ratio Wings

Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack and vice versa at high angle of attack.

Cross-Wind Influence on Low Aspect Ratio Wings at Low Reynolds Numbers

2013 ◽  
Author(s):  
Amir Karimi Noughabi ◽  
Mehran Tadjfar
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Lift And Drag ◽  
Lift And Drag Coefficient

The aerodynamics of the low aspect ratio (LAR) wings is of outmost importance in the performance of the fixed-wing micro air vehicles (MAVs). The flow around these wings is widely influenced by three dimensional (3D) phenomena: including wing-tip vortices, formation of laminar bubble, flow separation and reattachment, laminar to turbulent transition or any combination of these phenomena. All the recent studies consider the aerodynamic characteristics of the LAR wings under the effect of the direct wind. Here we focus on the numerical study of the influence of cross-wind on flow over the inverse Zimmerman wings with the aspect ratios (AR) between 1 and 2 at Reynolds numbers between 6×104 and 105. We have considered cross-wind’s angles from 0° to 40° and angle of attack from 0° to 12°. The results show that lift and drag coefficient generally decrease when the angle of the cross-wind is increased.

Bat wing airfoil and planform structures relating to aerodynamic cleanliness

2007 ◽  
Vol 55 (4) ◽  
pp. 237 ◽  
Author(s):  
R. D. Bullen ◽  
N. L. McKenzie
Keyword(s):  
Aspect Ratio ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Foraging Strategy ◽  
High Lift ◽  
Minimum Drag ◽  
Wing Chord ◽  
Lift And Drag ◽  
Lift And Drag Coefficient ◽  
Bat Wing

In this paper we examine 12 species of Western Australian bat for anatomical and morphometric attributes related to wing lift and drag characteristics. We present values for bat wing camber (typically 6.5–9%) and its location, measurements of wing planform and tip shape (typically elliptical but with two different tip designs), dimensions of wing leading-edge flaps (typically 8–10.5% of hand wing chord but with some species having much larger flaps up to 18%) and then discuss several features related to airflow separation control. All species assessed had thin, low-camber airfoil sections, an optimisation appropriate to the range of Reynolds Numbers in which bats fly. Wing relative cleanliness was consistent with, and functionally appropriate to, species foraging strategy. The interceptors had the point of maximum camber well forward and no trailing edge wing fences, optimisations for minimum drag generation. The air-superiority bats had leading-edge fences optimised for maximum lift generation while maintaining low drag. Surface bats were characterised by their low-aspect-ratio wingtips and the absence of optimisations for either low section drag or high lift. The frugivore and the carnivore appear to be discrete optimisations while the emballinurid had a long and broad leading edge flap in combination with a high-aspect-ratio tip. We propose a range of lift and drag coefficient values for use in models of metabolic power output.

scholarly journals Numerical Computations for Flow Patterns and Force Statistics of Three Rectangular Cylinders

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hamid Rahman ◽  
Shams-ul-Islam ◽  
Waqas Sarwar Abbasi ◽  
Raheela Manzoor ◽  
Fazle Amin ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Vortex Shedding ◽  
Lift Coefficient ◽  
Flow Characteristics ◽  
Drag And Lift Coefficients ◽  
Aspect Ratios ◽  
Spacing Ratio ◽  
Drag And Lift ◽  
Rectangular Cylinders

In this work, numerical simulations are performed in order to study the effects of aspect ratio (AR) and Reynolds number (Re) on flow characteristics of three side-by-side rectangular cylinders for fixed spacing ratio ( g ), using the lattice Boltzmann method (LBM). The Reynolds number varies within the range 60 ≤ Re ≤ 180, aspect ratio is between 0.25 and 4, and spacing ratio is fixed at g  = 1.5. The flow structure mechanism behind the cylinders is analyzed in terms of vorticity contour visualization, time-trace analysis of drag and lift coefficients, power spectrum analysis of lift coefficient and variations of mean drag coefficient, and Strouhal number. For different combinations of AR and Re, the flow is characterized into regular, irregular, and symmetric vortex shedding. In regular and symmetric vortex shedding the drag and lift coefficients vary smoothly while reverse trend occurs in irregular vortex shedding. At small AR, each cylinder experiences higher magnitude drag force as compared to intermediate and large aspect ratios. The vortex shedding frequency was found to be smaller at smaller AR and increased with increment in AR.

scholarly journals Optimizing Effect of Wavy Leading Edge (WLE) in Rectangular Wing and Taper Wing

2021 ◽  
Vol 1 (2) ◽  
pp. 56-68
Author(s):  
Iis Rohmawati ◽  
Hiroshi Arai ◽  
Hidemi Mutsuda ◽  
Takuji Nakashima ◽  
Rizal Mahmud
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Wing Shape ◽  
Aspect Ratios ◽  
Impressive Result ◽  
Rectangular Form ◽  
Numerical Research ◽  
Wing Aspect Ratio

Experimental and numerical research have been performed to investigate the Wavy Leading Edge (WLE) effect on the rectangular wing. The WLE is inspired by humpback whale flipper morphology which is blunt and rounded in certain form pattern. This flipper shape plays an important role for its behaviour specially capturing their prey. This advantage could be applied to other systems such as fin stabilizers or wind turbines. Steady cases in various aspect ratios were conducted to find out the optimum effect of WLE with baseline NACA 0018 profile at Reynolds number 1.4 x 105. The chord length of the wing (c) was 125 mm. The WLE shape defined as wavelength (W) 8% of c and amplitude (d) is 5% of c. The aspect ratio (AR) variations were 1.6; 3.9; 5.1; 7.9 and 9.6.  A simple rectangular form of the wing was selected to analysis the WLE effect on the various ARs. The taper wing shape is applied to find out the WLE effect at the AR 7.9. three types of taper ratio (TR) are 0.1; 0.3 and 0.5. The results show that the WLE on the taper wing has better advantage to control the stall in steady case. Another impressive result was the WLE wing with AR 7.9 and TR 0.3 has the best lift coefficient and pressure distribution.Keywords: stall, wavy leading edge, steady case, rectangle wing, taper wing, aspect ratio. 

Ultrastructural Studies of Bovine Respiratory Disease Complex

1975 ◽  
Vol 33 ◽  
pp. 428-429
Author(s):  
James C.S. Kim
Keyword(s):  
Michigan State University ◽  
State University ◽  
Diagnostic Laboratory ◽  
Ultrastructural Studies ◽  
Bovine Respiratory Diseases ◽  
Etiologic Agents ◽  
Diagnostic Difficulties ◽  
The Subject ◽  
Capillary Walls ◽  
Alveolar Capillary

Bovine respiratory diseases cause serious economic loses and present diagnostic difficulties due to the variety of etiologic agents, predisposing conditions, parasites, viruses, bacteria and mycoplasma, and may be multiple or complicated. Several agents which have been isolated from the abnormal lungs are still the subject of controversy and uncertainty. These include adenoviruses, rhinoviruses, syncytial viruses, herpesviruses, picornaviruses, mycoplasma, chlamydiae and Haemophilus somnus.Previously, we have studied four typical cases of bovine pneumonia obtained from the Michigan State University Veterinary Diagnostic Laboratory to elucidate this complex syndrome by electron microscopy. More recently, additional cases examined reveal electron opaque immune deposits which were demonstrable on the alveolar capillary walls, laminae of alveolar capillaries, subenthothelium and interstitium in four out of 10 cases. In other tissue collected, unlike other previous studies, bacterial organisms have been found in association with acute suppurative bronchopneumonia.

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