scholarly journals Numerical Simulation Studies on Stall Suppression of a NACA0015 Airfoil

2021 ◽  
Vol 6 ◽  
pp. 23-31
Author(s):  
Biswash Shrestha ◽  
Nawraj Bhattarai
Keyword(s):  
Reynolds Number ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Constant Width ◽  
Low Reynolds Number ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Ansys Fluent ◽  
Control Plate ◽  
Low Reynolds

This study aims to achieve an improved airfoil performance at low Reynolds number, and to determine the optimum position and size of rectangular cross-section burst control plate (BCP) to suppress stall in airfoil. The type of airfoil used in the present study is NACA0015 (National Advisory Committee for Aeronautics) airfoil with 200 mm of chord (c) length. Here, rectangular cross-section burst control plates with different sizes and at different locations are investigated numerically at the low Reynolds number of 1.6×105. Total of three positions (0.05c, 0.1c and 0.2c from the leading edge of airfoil), and four sizes (with heights 0.3 mm, 0.7mm, 1mm and 1.5 mm, and constant width 4 mm) of rectangular BCPs are simulated in ANSYS Fluent software using Transition SST model. The results indicate that the rectangular cross-section burst control plate is an effective device in the suppression of airfoil stall. For 0.7 mm and 1 mm height BCPs, the stall angle is postponed by 2° for all positions, while for 0.3 mm and 1.5 mm height BCPs, the reduction in sudden fall of lift can be observed but at the cost of reduction in maximum lift coefficient. Among various configurations, the 1mm height BCP located at 0.2c position is found to be most effective in the suppression of stall.

Novel Tubercle Design for a Wind Turbine Blade Operating at Low Reynolds Number

2019 ◽  
Author(s):  
R. Deeksha ◽  
Mahesh K. Varpe
Keyword(s):  
Reynolds Number ◽  
Wind Turbine ◽  
Amplitude Ratio ◽  
Low Reynolds Number ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Operating Condition ◽  
Low Reynolds

Abstract Wind energy has become one of the vital sustainable energy resources and a leading contender to the renewable resources race. The need of extending the aerodynamic performance of a wind turbine paved the way for radical approaches in the design of wind turbine blades. One such promising technique is the adoption of passive flow controls like leading edge protuberance or tubercles. In this paper the aerodynamic performance of NACA0009 (baseline) superimposed with a leading edge protuberance is numerically investigated in the post-stall operating conditions. The investigation objective was to identify the optimum pitch to amplitude ratio of the protuberance in the post stall operating condition for a low Reynolds number of 5 × 104. Computational fluid dynamics computations were performed using κ-ω SST turbulence model. The optimum pitch to amplitude ratio was found to be 6 which enhanced the aerodynamic lift coefficient by 42% in the post stall operating condition. The lift is reduced at lower AOA but gets complement in the post stall operating conditions.

3D Flow Dynamics in a Patterned Round Microchannel

2009 ◽  
Author(s):  
Huihe Qiu ◽  
Peng Zhang
Keyword(s):  
Reynolds Number ◽  
Surface Modification ◽  
Flow Pattern ◽  
Cross Section ◽  
Low Reynolds Number ◽  
The Other ◽  
Surface Charges ◽  
Patterned Surface ◽  
Zeta Potentials ◽  
Low Reynolds

The development of MEMS requires deliberate designs for controlling fluids in the low Reynolds number regime. Arranging surface charges in rectangular channels to obtain in-plane or out-of-plane vortices have been studied by previous researchers. However, previous surface modification techniques require different signs of zeta potentials from the other wall surfaces which made it difficult in selecting and coating microchannels. Previously, the opposite polarities are usually adjusted by changing the pH value of the solution with acid chemicals in other researches which made the solution complicated and difficult to simulate a real application. Meanwhile the acid chemicals may also destroy the coating. It is convenient to use same polarity patches if a vortex flow can also be generated. However, it is not clear if the patterned surface charges have the same polarity of zeta potentials as the other walls, what kind flow pattern will be generated and what mechanism behind the flow pattern. Furthermore, the cross-section of previously studied microchannels is usually limited to a rectangular shape. Therefore, the surface charge patterns are usually in 2D since the sidewalls of the rectangular microchannels are difficult to be patterned. However, a channel with round cross-section has better leak-proof performance of the membrane valve. Furthermore, a round channel is also advantageous in mimicking the human vein when a vascular structure is needed in tissue scaffolding, the round microfluidic channel is considered as a good candidate for an artificial capillary vessel. It is anticipated that there will be no stagnation occurs at the corner edges, which occurs at the corners of a rectangular channel, for a round microchannel owing to the perfectly symmetrical velocity profile. This is important when the microfluidic chip is subjected to a separation process such as liquid chromatography. In this paper, effects of patterned surface modification on 3D vortex flows generation in a micro capillary tube under very low Reynolds number have been investigated. Microfabrication technology was successfully employed to pattern surface charges on inner surfaces of round capillary tubes, which form non-uniform zeta-potentials. This technique extends the heterogeneous surfaces from flat surface to curved surface. 3D vortices are visualized and measured at the vicinity of tube walls when an electric field is applied across the surfaces utilizing micro resolution PIV. It demonstrated that 3D vortices can also be generated by the patterned surface charges with a same polarity. Experimental results have been compared with the numerical simulations using CFD-ACE+.

Numerical Study of Winglet Cant Angle Effect on Wing Performance at Low Reynolds Number

2013 ◽  
Vol 393 ◽  
pp. 366-371
Author(s):  
C.F. Mat Taib ◽  
Abdul Aziz Jaafar ◽  
Salmiah Kasolang
Keyword(s):  
Reynolds Number ◽  
Numerical Analysis ◽  
Numerical Study ◽  
Low Reynolds Number ◽  
Lift Coefficient ◽  
Wing Model ◽  
Low Reynolds ◽  
Wing Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The study on the effect of winglet shape in wing design has been a focus of many researchers. Nevertheless, the effect of cant angle on the wing performances at low Reynolds number has not been fully explored. This paper describes the effect of a single semi-circular shaped winglet attached with a rectangular wing model to lower the drag without increasing the span of the wing. Aerodynamic characteristics for the rectangular wing (NACA 65-3-218) with and without semi-circular winglets have been studied using STAR CCM+ 4.0. This numerical analysis is based on Finite Volume Approach. Simulations were carried out on the rectangular wing model with and without winglet at aspect ratio of 2.73 and Reynolds number of 0.16 x 10 6 for various angles of attack. From the numerical analysis, wing performance characteristics in terms of lift coefficient CL, drag coefficient CD, and lift-to-drag ratio, CL/CD were obtained. It was found that the addition of a semi-circular winglet has resulted in a larger lift curve slope and higher Lift-to-Drag ratio in comparison with the case of a wing without winglet. Further investigation has revealed that a wing with semi-circular winglet with cant angle of 45 degree has produced the best Lift-to-Drag ratio, CL/CD.

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