scholarly journals Study of Flow by Varying the Position of Maximum Chamber Thickness on Aerofoil

2021 ◽  
Vol 1 (2) ◽  
pp. 69-75
Author(s):  
Jithendra Sai Raja Chada ◽  
◽  
Ganesh Nathipam ◽  
Sri Ram Deepak Akella ◽  
Phani Bhaskar Anusuri ◽  
...  
Keyword(s):  
Flow Separation ◽  
Angle Of Attack ◽  
Surface Modifications ◽  
Current Work

Aerofoil is a design with a curved exterior that gives the most commendable ratio of lift to drag. The aerofoil which allows for the flow at a margin range of angle has a more remarkable impact on the power spawning from the turbine. The conception and examination for the airfoil Structure have been implemented in the current work to raise the behavior of the flow with a commendatory condition by varying the position of maximum chamber thickness position thereby varying the angle of attack with 5 degrees interval from 0-25 degrees. The best model is studied with surface modifications to increase the flow separation and efficiency of lift.

Soaring and Gliding Flight of the Black Vulture

1958 ◽  
Vol 35 (2) ◽  
pp. 280-285
Author(s):  
B. G. NEWMAN
Keyword(s):  
Flow Separation ◽  
Angle Of Attack ◽  
High Angle ◽  
High Angle Of Attack ◽  
Wing Area ◽  
Wing Span ◽  
Gliding Flight ◽  
Black Vulture ◽  
Wing Geometry

1. The soaring and gliding performance of the black vulture has been analysed and the following conclusions are drawn. 2. The wing span of the bird is altered in flight so that it may perform two tasks efficiently. First, that it may soar in rising currents of air for which a low sinking speed and thus a large wing span are required. Secondly, that it may penetrate into wind without undue loss of height for which a reduced wing area is desirable. Adjustment of the wing geometry towards the optimum soaring configuration is achieved by bending forward and opening the primary tip feathers. 3. Since the airflow readily separates from the flat primary feathers at high angle of attack, these feathers, which are emarginated, are parted to form slots. The alula also presumably assists in delaying the flow separation over the primaries. 4. It is unlikely that the opening of the primaries reduces the vortex drag.

scholarly journals Methods for selecting the supporting curve for the model of hysteresis loop

2018 ◽  
Vol 18 ◽  
pp. 01003
Author(s):  
O.N. Korsun ◽  
A.V. Stulovskii
Keyword(s):  
Hysteresis Loop ◽  
Test Data ◽  
Flow Separation ◽  
Physical Interpretation ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Flight Test ◽  
Separation Point ◽  
Aerodynamic Coefficients

The article deals with a model describing the dependence of aerodynamic coefficients on the angle of attack for post-stall conditions. This paper also discusses the choice of parameters for the calculating the lift coefficient in such cases. In addition, it also considers some methods used to choose the shape of a supporting curve. The article also provides arguments concerning the physical interpretation of the coordinate of flow separation point in the implementation of the model. The examples of processing the flight test data are presented.

Heat Transfer from a Plate Elevated above a Host Surface and Washed by a Separated Flow Induced by the Elevation Step

1981 ◽  
Vol 103 (3) ◽  
pp. 441-447 ◽  
Author(s):  
E. M. Sparrow ◽  
F. Samie ◽  
S. C. Lau
Keyword(s):  
Heat Transfer ◽  
Flow Separation ◽  
Angle Of Attack ◽  
Separated Flow ◽  
Active Surface ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Reynolds Number Flow ◽  
Heat Transfer Coefficients ◽  
High Reynolds

Wind tunnel experiments were performed to determine heat transfer coefficients and fluid flow patterns for a thermally active surface elevated above a parallel host surface. The step-like blockage associated with the elevation causes flow separation and recirculation on the forward portion of the thermally active surface. Four parameters were varied during the course of the experiments, including the angle of attack of the oncoming airflow relative to the surface, the step height, the extent of the host surface which frames the active surface (i.e., the skirt width), and the Reynolds number. Flow visualization studies, performed with the oil-lampblack technique, showed that the streamwise extent of the separation zone increases with decreasing angle of attack, with larger step heights and skirt widths, and at higher Reynolds numbers. At larger angles of attack, separation does not occur. The experimentally determined heat transfer coefficients were found to increase markedly due to the flow separation, and separation-related enhancements as large as a factor of two were encountered. The enhancement was accentuated at small angles of attack, at large step heights and skirt widths, and at high Reynolds numbers. A main finding of the study is that the separation-affected heat transfer coefficients are generally greater than those for no separation, so that the use of the latter may underestimate the heat transfer rates. For an application such as a retrofit solar collector, such an underestimation of the wind-related heat loss would yield an optimistic prediction of the collector efficiency.

Numerical study of turbulent flow over an S-shaped hydrofoil

2008 ◽  
Vol 222 (9) ◽  
pp. 1717-1734 ◽  
Author(s):  
T Micha Prem Kumar ◽  
Dhiman Chatterjee
Keyword(s):  
Shear Stress ◽  
Turbulent Flow ◽  
Flow Separation ◽  
Numerical Study ◽  
Angle Of Attack ◽  
Turbulence Models ◽  
Pressure Gradients ◽  
Convex Surfaces ◽  
Shear Stress Transport ◽  
Formidable Challenge

In this paper, a numerical study of turbulent flow over the S-shaped hydrofoil at 0° angle of attack has been reported. Here, the flow takes place over concave and convex surfaces and is accompanied by the favourable and adverse pressure gradients and flow separation. Modelling such a flow poses a formidable challenge. In the present work four turbulence models, namely, k–∊ realizable, k–ω shear stress transport

A Study of Pulsed Blowing Effect on Flow Separation Over Flap

2014 ◽  
Author(s):  
Ping Zhou ◽  
Yankui Wang ◽  
Dejian Zhao
Keyword(s):  
Numerical Simulation ◽  
Flow Separation ◽  
Deflection Angle ◽  
Angle Of Attack ◽  
Simulation Method ◽  
Control Effect ◽  
Momentum Coefficient ◽  
Numerical Simulation Method

A model with main wing and flap which is based on NACA0025 airfoil is used in this paper to study the pulsed blowing effect on flow separation over flap. The effects of average blowing momentum coefficient and Stroul number on flow separation over the flap have been discussed at first. Furthermore, thecontrol effect of this pulsed blowing technique under different deflection angle of flap isdiscussed to make sure whether the control effect of pulsed blowing can meet the needs under different deflection angle of flap. All the research works have been finished by numerical simulation method under conditions of 0deg angle of attack of the main wing.

Flow separation control of NACA-2412 airfoil with bio-inspired nose

2019 ◽  
Vol 91 (7) ◽  
pp. 1058-1066 ◽  
Author(s):  
Mohamed Arif Raj Mohamed ◽  
Ugur Guven ◽  
Rajesh Yadav
Keyword(s):  
Flow Control ◽  
Flow Separation ◽  
Control Method ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Separation Control ◽  
Cetacean Species ◽  
Aerodynamic Efficiency ◽  
Content Type ◽  
Flow Separation Control

Purpose The purpose of this paper is to achieve an optimum flow separation control over the airfoil using passive flow control method by introducing bio-inspired nose near the leading edge of the NACA 2412 airfoil. Design/methodology/approach Two distinguished methods have been implemented on the leading edge of the airfoil: forward facing step, which induces multiple accelerations at low angle of attack, and cavity/backward facing step, which creates recirculating region (axial vortices) at high angle of attack. Findings The porpoise airfoil (optimum bio-inspired nose airfoil) delays the flow separation and improves the aerodynamic efficiency by increasing the lift and decreasing the parasitic drag. The maximum increase in aerodynamic efficiency is 22.4 per cent, with an average increase of 8.6 per cent at all angles of attack. Research limitations/implications The computational analysis has been done for NACA 2412 airfoil at low subsonic speed. Practical implications This design improves the aerodynamic performance and increases structural strength of the aircraft wing compared to other conventional high-lift devices and flow-control devices. Originality/value Different bio-inspired nose designs which are inspired by the cetacean species have been analysed for NACA 2412 airfoil, and optimum nose design (porpoise airfoil) has been found.

Experimental Flow Visualization Study of Flow Separation Control With High-Frequency Translational Surface Actuation

2020 ◽  
Author(s):  
Kenechukwu Okoye ◽  
Wing Lai ◽  
Taiho Yeom
Keyword(s):  
Flow Separation ◽  
High Frequency ◽  
High Speed ◽  
Free Stream ◽  
Separation Bubble ◽  
Angle Of Attack ◽  
Small Displacement ◽  
Peak Displacement ◽  
Flow Separation Control ◽  
Translational Surface

Abstract Flow separation causes aircraft to experience an increase in drag degrading their aviation performance. The current study aims to delay flow separation on an airfoil by embedding a high-frequency translational piezoelectric actuator along the surface of the airfoil. The actuators with two actuation surfaces were embedded on the suction surface of an Eppler 862 airfoil model and placed in a low-speed wind tunnel. Consecutive pictures of the flow fields with dry ice fogs around the airfoil were taken using a high speed camera in order to observe the flow separation phenomenon before and after turning on the high-frequency translational surface actuation. The effects of the actuation on the flow separation were observed at various actuation displacements, angles of attack, and free stream velocities. The operating frequency of the surface actuation was 565 Hz. The measured actuation mean-to-peak displacement ranged up to 0.12 mm at the maximum applied voltage of 150 V. The angle of attack of the airfoil varied from 6° to 24°. The chord Reynolds number was increased up to around 262,000. It was confirmed that the actuation had a very strong influence on the flow separation even at a very small displacement of 0.024 mm remaining significantly reduced separation bubble compared to the one before activating the actuators at 4.3 m/s of velocity and 14° of angle of attack. The flow separation was completely suppressed when the actuation displacement reached around 0.082 mm under the same conditions of flow velocity and angle of attack. This implied that the actuation should generate a strong enough momentum relative to the free stream in order to completely suppress the flow separation. In summary, the study confirmed that the employed high-frequency translational surface actuation had the obvious control authority on delaying or suppressing the flow separation over the airfoil depending on the parameters changed.

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