Lift and Drag Characteristics of an Airfoil and Feedback Flow Control by Flap Actuators in the Low Reynolds Number Region

2015 ◽  
Author(s):  
Toshiki Mori ◽  
Masashi Yamaguchi ◽  
Kyoji Inaoka ◽  
Mamoru Senda
Keyword(s):  
Reynolds Number ◽  
Wind Speed ◽  
Unsteady Flow ◽  
Flow Control ◽  
Flow Condition ◽  
Low Reynolds Number ◽  
High Lift ◽  
Unsteady Flow Condition ◽  
Lift And Drag ◽  
Drag Ratio

The present paper describes the applicability of the flow control device, mini actuators attached on the leading edge of an airfoil, for the flow separation control under unsteady flow condition in the low Reynolds number region. Lift and drag have been measured for a wide variety of the wind speeds (Reynolds numbers) and the angles of attack. Then, effects of simple feedback flow control, where the time-dependent signal of the lift-drag ratio has been used as an input to detect the stall and served as a trigger to start the actuation, have been explored under the unsteady flow condition for evading the stall. For every Reynolds number from 30,000 to 80,000, the actuators worked quite well to delay the stall, increasing both in the lift and the stall angle of attack. Then, threshold value of the lift-drag ratio was determined to detect the stall. Effectiveness of the feedback control of the actuation was demonstrated under the condition of the wind speed decrease which would lead to the stall if no-actuation. Immediately after the velocity decrease, the decrease in the lift-drag ratio below the threshold were detected and the dynamic actuations were started, resulting in evading the stall and keeping high lift. The additional operation of the feedback, stopping the actuation when the lift-drag ratio showed lower than the second threshold, was revealed effective to keep the high lift force under the condition combined with the wind speed increase and decrease.

420 Aerodynamic Characteristics and Flow Field of High Lift-to-drag Ratio Airfoils in Low Reynolds Number

2015 ◽  
Vol 2015.68 (0) ◽  
pp. 167-168 ◽  
Author(s):  
Takahiro MAKIZONO ◽  
Gaku SASAKI ◽  
Hiroshi OCHI ◽  
Takaaki MATSUMOTO ◽  
Koichi YONEMOTO
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Low Reynolds Number ◽  
Aerodynamic Characteristics ◽  
High Lift ◽  
Low Reynolds ◽  
Drag Ratio ◽  
Lift To Drag Ratio

805 Characteristics of High Lift-to-Drag Ratio Low Reynolds Number Airfoil for Mars Exploration Aircraft Using Towing Equipment

2014 ◽  
Vol 2014.67 (0) ◽  
pp. _805-1_-_805-2_
Author(s):  
Hidemasa SAITO ◽  
Itaru TAMAI ◽  
Gaku SASAKI ◽  
Koichi YONEMOTO ◽  
Takaaki MATSUMOTO
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Mars Exploration ◽  
High Lift ◽  
Low Reynolds ◽  
Low Reynolds Number Airfoil ◽  
Drag Ratio ◽  
Lift To Drag Ratio

807 Cluster Analysis of Shape Parameters of High Lift-to-Drag Ratio Low Reynolds Number Airfoils

2014 ◽  
Vol 2014.67 (0) ◽  
pp. _807-1_-_807-2_
Author(s):  
Shintaro SHIGEOKA ◽  
Gaku SASAKI ◽  
Takaaki MATSUMOTO ◽  
Koichi YONEMOTO
Keyword(s):  
Cluster Analysis ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Shape Parameters ◽  
High Lift ◽  
Low Reynolds ◽  
Drag Ratio ◽  
Lift To Drag Ratio

scholarly journals A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 828
Author(s):  
Igor Rodriguez-Eguia ◽  
Iñigo Errasti ◽  
Unai Fernandez-Gamiz ◽  
Jesús María Blanco ◽  
Ekaitz Zulueta ◽  
...  
Keyword(s):  
Aerodynamic Coefficients ◽  
Trailing Edge ◽  
High Lift ◽  
Trailing Edge Flaps ◽  
Artificial Neural Network Ann ◽  
Lift And Drag ◽  
Artificial Neuronal Network ◽  
Naca 0012 ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

Investigation of Aerodynamics and Heat Transfer of a Highly Loaded Turbine Blade Using the Universal Intermittency Function

2017 ◽  
Author(s):  
A. Nikparto ◽  
M. T. Schobeiri
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Gas Turbine ◽  
Flow Condition ◽  
Computational Results ◽  
Turbine Engine ◽  
Low Pressure Turbine ◽  
Unsteady Flow Condition ◽  
Highly Loaded

Efficiency and performance of gas turbine engines are affected by the flow field around the blades. The flow field inside a gas turbine engine is very complex. One of the characteristics of the flow inside an engine is existence of periodic unsteady wakes, originating from the upstream stator blades. The unsteady wakes, with their highly vortical core, impinge on the downstream blade surfaces and cause an intermittent transition of the flow regime from laminar to turbulent. This study aims at investigating and modeling the behavior and development of the boundary layer along the suction surface of a highly loaded low-pressure turbine blade under steady and unsteady inlet flow condition. The current paper includes results of a computational work substantiated by the experimental verifications. For the experimental investigations, the linear cascade facility in Turbomachinery Performance and Flow research Lab (TPFL) at Texas A&M University was used to simulate the periodic unsteady flow condition inside gas turbine engine. Moving wakes, originating from upstream blades, were simulated in this facility by moving rods attached to two parallel timing belts. Measurements and calculations were conducted at Reynolds number of 110,000. This Reynolds number pertains to cruise condition of a low-pressure turbine. At this Reynolds number, the flow around the blades is transitional and highly susceptible to flow separation. Aerodynamics experiments include measuring the boundary layer, locating its transition, separation and finally re-attachment using miniature hot wire probes. Heat transfer measurements along the suction and pressure surfaces were conducted utilizing a specially designed heat transfer blade that was instrumented with liquid crystal coating. To numerically simulate the transitional behavior of the boundary layer under periodic unsteady flow condition, a new intermittency function is developed which is based on the universal intermittency function developed by Chakka and Schobeiri [1]. Accurate prediction of the boundary layer behavior under the above conditions requires minimum and the maximum intermittency functions. These functions were developed inductively using the experimental results that were obtained in the absence of flow separation. In the current investigation the impact of the separation on the minimum and maximum intermittency are accounted for. The enhanced minimum and maximum intermittency functions along with the universal intermittency are implemented in a RANS based solver for computational simulation. The computational results are compared with (a) experimental ones and (b) with the computational results from RANS that involves Langtry-Menter [2, 3] method.

scholarly journals Passive flow control strategies for low Reynolds number airfoils

2020 ◽  
Vol 954 ◽  
pp. 012002
Author(s):  
T Rajesh Senthil Kumar ◽  
Mohini Priya Kolluri ◽  
V R Gopal Subramaniyan ◽  
A D Sripathi
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Control Strategies ◽  
Low Reynolds Number ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Low Reynolds
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