Performance of S-Cambered Profiles With Cut-Off Trailing Edges

1994 ◽  
Vol 116 (3) ◽  
pp. 522-527 ◽  
Author(s):  
Baby Chacko ◽  
V. Balabaskaran ◽  
E. G. Tulapurkara ◽  
H. C. Radha Krishna
Keyword(s):  
Lift Coefficient ◽  
Forward Direction ◽  
Aerodynamic Characteristics ◽  
Reverse Direction ◽  
Flow Conditions ◽  
Reversed Flow ◽  
Trailing Edge ◽  
Reverse Mode ◽  
Trailing Edges

The aerodynamic characteristics of an S-cambered profile are studied under forward and reversed flow conditions. The profile chord is cut by 3, 6, and 9 percent of the chord at the sharp trailing edge end and the performances of these profiles are compared. It is found that with increase in length of cutting the lift coefficient increases in forward direction and decreases in reverse direction of flow. Cutting off the sharp trailing edge improves the lift-drag characteristics in forward mode and deteriorates in the reverse mode.

Computational Study of the Risø-B1-18 Airfoil with a Hinged Flap Providing Variable Trailing Edge Geometry

2005 ◽  
Vol 29 (2) ◽  
pp. 89-113 ◽  
Author(s):  
Niels Troldborg
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Computational Study ◽  
Turbine Blades ◽  
Aerodynamic Characteristics ◽  
Flow Conditions ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Edge Geometry ◽  
Fully Developed Turbulent Flow

A comprehensive computational study, in both steady and unsteady flow conditions, has been carried out to investigate the aerodynamic characteristics of the Risø-B1-18 airfoil equipped with variable trailing edge geometry as produced by a hinged flap. The function of such flaps should be to decrease fatigue-inducing oscillations on the blades. The computations were conducted using a 2D incompressible RANS solver with a k-w turbulence model under the assumption of a fully developed turbulent flow. The investigations were conducted at a Reynolds number of Re = 1.6 · 106. Calculations conducted on the baseline airfoil showed excellent agreement with measurements on the same airfoil with the same specified conditions. Furthermore, a more widespread comparison with an advanced potential theory code is presented. The influence of various key parameters, such as flap shape, flap size and oscillating frequencies, was investigated so that an optimum design can be suggested for application with wind turbine blades. It is concluded that a moderately curved flap with flap chord to airfoil curve ratio between 0.05 and 0.10 would be an optimum choice.

Lift Control Using MEMS-Based Moving Trailing-Edge Tabs

2002 ◽  
Author(s):  
C. P. van Dam ◽  
C. Bauer ◽  
D. T. Yen Nakafuji
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Trailing Edge ◽  
Aircraft Wings ◽  
Lifting Surface ◽  
Lifting Surfaces ◽  
Lift Control

Micro-electro-mechanical (MEM) translational tabs are introduced for active lift control on aircraft. These tabs are mounted near the trailing edge of lifting surfaces such as aircraft wings and tails, deploy approximately normal to the surface, and have a maximum deployment height on the order of one percent of the section chord. Deployment of the tab effectively changes the sectional camber, thereby changing the aerodynamic characteristics of a lifting surface. Tabs with said deployment height generate a change in the section lift coefficient of approximately ±0.3. The microtab design and the techniques used to fabricate and test the tabs are presented.

Unsteady aerodynamic characteristics of a morphing wing

2018 ◽  
Vol 91 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jinwu Xiang ◽  
Kai Liu ◽  
Daochun Li ◽  
Chunxiao Cheng ◽  
Enlai Sha
Keyword(s):  
Lift Coefficient ◽  
Angle Of Attack ◽  
Large Angle ◽  
Unsteady Aerodynamics ◽  
Aerodynamic Characteristics ◽  
Static Case ◽  
Morphing Wing ◽  
Trailing Edge ◽  
Content Type ◽  
Unsteady Aerodynamic

Purpose The purpose of this paper is to investigate the unsteady aerodynamic characteristics in the deflection process of a morphing wing with flexible trailing edge, which is based on time-accurate solutions. The dynamic effect of deflection process on the aerodynamics of morphing wing was studied. Design/methodology/approach The computational fluid dynamic method and dynamic mesh combined with user-defined functions were used to simulate the continuous morphing of the flexible trailing edge. The steady aerodynamic characteristics of the morphing deflection and the conventional deflection were studied first. Then, the unsteady aerodynamic characteristics of the morphing wing were investigated as the trailing edge deflects at different rates. Findings The numerical results show that the transient lift coefficient in the deflection process is higher than that of the static case one in large angle of attack. The larger the deflection frequency is, the higher the transient lift coefficient will become. However, the situations are contrary in a small angle of attack. The periodic morphing of the trailing edge with small amplitude and high frequency can increase the lift coefficient after the stall angle. Practical implications The investigation can afford accurate aerodynamic information for the design of aircraft with the morphing wing technology, which has significant advantages in aerodynamic efficiency and control performance. Originality/value The dynamic effects of the deflection process of the morphing trailing edge on aerodynamics were studied. Furthermore, time-accurate solutions can fully explore the unsteady aerodynamics and pressure distribution of the morphing wing.

Non-Deterministic CFD Simulations on the Effect of Uncertain Tip Clearance on an Axial Rotor Performance

2013 ◽  
Vol 860-863 ◽  
pp. 1499-1505
Author(s):  
Zhi Yi Liu ◽  
Xiao Dong Wang ◽  
Shun Kang
Keyword(s):  
Mass Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
High Mass ◽  
Separation Flow ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Trailing Edge ◽  
Trailing Edges ◽  
Main Factor

In the present paper, the non-intrusive Probabilistic Collocation (NIRPC) method is introduced in detail and used to simulate the effects of tip clearance uncertainty on the aerodynamic performance of NASA Rotor 37, which is combined with a commercial CFD software. The tip clearance height is supposed to be a stochastic variable in Beta distribution with four schemes of uncertainty in the random height of the plain tip clearance, the leading edge, the trailing edge and both the leading and trailing edges, respectively. The statistical properties of total performance of the rotor and flow structure within the blade passage in different flow conditions are analyzed. The results show that the Std. of total performances caused by the uncertain plain tip clearance decreases with reducing of the outlet pressure. The maximum of the standard deviation of Mach number appears in the regions where the leakage flow, the shock wave and the separation flow locate, which decreases from the tip to the hub. When the tip clearance is linear distributed, the uncertainty of tip clearance height at the leading edge is the main factor under high mass flow conditions. With the mass flow reaches to choking point, the Std. of total performances caused by the uncertainty of tip clearance height at the trailing edge drops sharply.

Flow Separation and Stall Characteristics of Plane, Constant-Section Wings in Subcritical Flow

1968 ◽  
Vol 72 (685) ◽  
pp. 82-90 ◽  
Author(s):  
P. D. Chappell
Keyword(s):  
Flow Separation ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Empirical Correlations ◽  
Trailing Edge ◽  
Subcritical Flow ◽  
Mach Numbers ◽  
Wing Tip ◽  
Constant Section

Summary This paper discusses the various aspects of flow separation on wings and aerofoils at subcritical Mach numbers. It is shown that in general the onset of non-linearities in the aerodynamic characteristics, for plane constant-section wings, can be related to the initiation of regions of flow separation somewhere on the wing and often near the wing tip. Empirical correlations are produced, tor plane wings of constant symmetrical section, enabling estimates to be made of the lift coefficient for onset of separation at either the leading or trailing edge of the wing. A correlation of stall types on aerofoils, due to Gault, is extended in application to the estimation of initial stall and separation types for plane wings of constant symmetrical section. Suggestions for extending the application of this correlation to the estimation of section stall type for cambered, twisted and non-constant section wings are made.

Research on Wind Turbine Airfoils Aerodynamic Performance of Trailing Edge Modification

2015 ◽  
Vol 741 ◽  
pp. 554-557
Author(s):  
Shang Ke Yuan ◽  
Zi Qin Zhao
Keyword(s):  
Pressure Distribution ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Trailing Edge ◽  
Airfoil Surface ◽  
Computation Result ◽  
Surface Pressure Distribution ◽  
Gurney Flap ◽  
Aerodynamic Performances ◽  
Turbine Airfoils

The airfoil commonly employed in wind turbines is modified by attaching a Gurney flap with length of 2% chord at its trailing edge and its remodeled form as well,but it showed special aerodynamic characteristics.The software FLUENT are respectively used to carry out numerical computation of aerodynamic performances of above-mentioned three airfoils, so that their aerodynamic characteristics, surface pressure distribution, and streamline around them are obtained for different angles of attack. It is shown by the computation result that the modified airfoils will result in such a strong downwash effect and the pressure distribution on airfoil surface is remarkably altered, the lift coefficient, and meantime the airfoil stalling is greatly postponed,but the airfoil of Gurney flap shown the characteristics of opposite.

scholarly journals The aerodynamics of the wavy blade under the effect of fluctuated wind flow

2021 ◽  
Vol 49 (3) ◽  
pp. 704-710
Author(s):  
Basim Al-Bakri ◽  
Radwan Aljuhashy
Keyword(s):  
Experimental Data ◽  
Unsteady Flow ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Wind Flow ◽  
Flow Conditions ◽  
Ansys Fluent ◽  
Turbulent Wind ◽  
Flow Case

In the present study, the influence of the wavy edge blade on aerodynamic characteristics for the flow of blades at Reynolds number (Re) of 8×105 is numerically investigated based on the unsteady wind flow. Aerodynamic characteristics of a (sinusoidal leading edge) wavy NACA0015 aerofoil blade are carried out using ICEM 19.1 and ANSYS fluent. The numerical simulation is conducted then validated by experimental data with steady wind flow. This is conducted by employing the same Reynold's number in the experimental work. While, the unsteady flow was numerically performed at 1 Hz frequency of wind flow conditions. The main findings from this work show that the wavy blade can behave better in turbulent wind conditions with the maximum lift coefficient of 0.73 compared to 0.621 for the normal blade. However, the findings declare that the wavy blade stalled earlier than the normal one in the unsteady flow case. Similarly, it stalled at 12° angle of attack earlier than the normal one which was stalled at 14° in the steady flow case.

Analysis Influence of Trailing Edge Modification on Aerodynamic Performance of Airfoils for Wind Turbine

2012 ◽  
Vol 220-223 ◽  
pp. 900-904 ◽  
Author(s):  
Shang Ke Yuan ◽  
Ren Nian Li
Keyword(s):  
Pressure Distribution ◽  
Characteristic Curve ◽  
Lift Coefficient ◽  
Simple Algorithm ◽  
Aerodynamic Characteristics ◽  
Trailing Edge ◽  
Airfoil Surface ◽  
Gurney Flap ◽  
Aerodynamic Performances ◽  
Volume Method

The airfoil NACA 4412 commonly employed in wind turbines is modified by attaching a Gurney flap with length of 2% chord at its trailing edge and its remodeled form as well. The SIMPLE algorithm of finite volume method and software FLUENT are respectively used to carry out numerical computation of aerodynamic performances of above-mentioned three airfoils (including the un-modified one), so that their aerodynamic characteristics, pressure distribution on their surface, and streamline around them are obtained for different angles of attack. It is shown by the computation result that the modified airfoils will result in such a strong downwash effect that the pressure distribution on airfoil surface is remarkably altered, the lift coefficient and as well as the slope of lift-drag characteristic curve are increased, and meantime the airfoil stalling is greatly postponed.

Design and simulation research of the double-spin folding mechanism based on a suspended missile

2021 ◽  
pp. 154851292110231
Author(s):  
ZH Yuan ◽  
SY Guo ◽  
SN Zhang ◽  
JQ Zhao ◽  
WJ Lu ◽  
...  
Keyword(s):  
High Reliability ◽  
Lift Coefficient ◽  
Great Influence ◽  
Reference Value ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Simulation Research ◽  
Double Spin ◽  
Locking Mechanism

Based on the suspension of a missile using folding rotary wings and airbags, in order to improve the basic parameters and motion characteristics of the rotor during the unfolding process and analyze the aerodynamic characteristics of the entire device in the suspension state, after proposing a scheme of double-spin mechanism, the main folding and unfolding mechanism, initial driving device, rotating driving device, and locking mechanism were designed, and the simulation research is studied by the Automatic Dynamic Analysis of Mechanical System and Ansys Fluent Fluid Simulation software, respectively. The results show that the rotation rate was controlled at 41.8 mm/s, the various motion parameters are reasonable, and the operation process is relatively smooth, with high reliability. The speed and pressure value at the tip of the rotor are higher and the aerodynamic disturbance is obvious, which has a great influence on the aerodynamic performance. The speed and pressure distribution of the surrounding flow field is stable, the lift provided is 46 N, and the lift coefficient is 0.55, which can ensure the long-time suspension state of the missile. This paper puts forward a valuable design idea and has practical reference value for the research of the suspended missile.

Effect of trailing edge dual synthesis jets actuator on aerodynamic characteristics of a straight-bladed vertical axis wind turbine

Energy ◽  
2022 ◽  
Vol 238 ◽  
pp. 121792
Author(s):  
Peilin Wang ◽  
Qingsong Liu ◽  
Chun Li ◽  
Weipao Miao ◽  
Shuai Luo ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Aerodynamic Characteristics ◽  
Vertical Axis Wind Turbine ◽  
Trailing Edge
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