scholarly journals Low Reynolds number proprotor aerodynamic performance improvement using the continuous surface curvature design approach

2018 ◽  
Vol 123 (1259) ◽  
pp. 20-38
Author(s):  
E. J. Avital ◽  
T. Korakianitis ◽  
F. Motallebi
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Surface Curvature ◽  
Design Approach ◽  
Space Applications ◽  
Continuous Surface ◽  
Low Reynolds ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
High Angles Of Attack

ABSTRACTLow Reynolds number blade profiles of ReC=105–2×105 as based on the chord length and used for small unnamed air vehicles, and near space applications are investigated for single and counter-rotating (co-axial) proprotors, i.e. acting as rotors or propellers. Such profiles are prone for early stall, significantly reducing their maximum lift to drag ratio. Two profiles previously designed by our continuous surface curvature design approach named as CIRCLE are investigated in order to improve the performance of the proprotors. The profiles are redesigns of the common symmetric NACA0012 and asymmetric E387 profiles. Using general arguments based on composite efficiency and rotor’s lift to drag ratio, the performance envelope is noticeably increased when using the redesigned profiles for high angles of attack due to stall delay.A new approach is derived to account for the distance between the rotors of a co-axial proprotor. It is coupled with a blade element method and is verified against experimental results. Single and co-axial CIRCLE-based proprotors are investigated against the corresponding non-CIRCLE-based proprotors at hover and axial translation. Noticeable improvements are observed in thrust increase and power reduction at high angles of attack of the blade’s profiles, particularly for the co-axial configuration. Plots of thrust, torque, power, composite efficiency and aerodynamic efficiency distributions are given and analysed.

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

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.

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

Steric scattering of rod-like swimmers in low Reynolds number environments

Soft Matter ◽  
2021 ◽  
Author(s):  
Kentaro Hoeger ◽  
Tristan Ursell
Keyword(s):  
Reynolds Number ◽  
Cell Size ◽  
Low Reynolds Number ◽  
Surface Curvature ◽  
Natural Environments ◽  
Solid Objects ◽  
Low Reynolds

While navigating natural environments, interactions with cell-size solid objects alter paths of swimming microbes. We characterized such ‘scattering’ from synthetic objects of controlled surface curvature. A sterics-only model agrees well with the data.

scholarly journals Aerodynamic and Vibration Characteristics of the Micro-Octocopter at Low Reynolds Number

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohua Zou ◽  
Mingsheng Ling ◽  
Wenzheng Zhai
Keyword(s):  
Reynolds Number ◽  
Load Capacity ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Vibration Characteristics ◽  
Low Reynolds ◽  
Vibration Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

With the development of flight technology, the need for stable aerodynamic and vibration performance of the aircraft in the civil and military fields has gradually increased. In this case, the requirements for aerodynamic and vibration characteristics of the aircraft have also been strengthened. The existing four-rotor aircraft carries limited airborne equipment and payload, while the current eight-rotor aircraft adopts a plane layout. The size of the propeller is generally fixed, including the load capacity. The upper and lower tower layout analyzed in this paper can effectively solve the problems of insufficient four-axis load and unstable aerodynamic and vibration performance of the existing eight-axis aircraft. This paper takes the miniature octorotor as the research object and studies the aerodynamic characteristics of the miniature octorotor at different low Reynolds numbers, different air pressures and thicknesses, and the lift coefficient and lift-to-drag ratio, as well as the vibration under different elastic moduli and air pressure characteristics. The research algorithm adopted in this paper is the numerical method of fluid-solid cohesion and the control equation of flow field analysis. The research results show that, with the increase in the Reynolds number within a certain range, the aerodynamic characteristics of the miniature octorotor gradually become better. When the elastic modulus is 2.5 E, the aircraft’s specific performance is that the lift increases, the critical angle of attack increases, the drag decreases, the lift-to-drag ratio increases significantly, and the angle of attack decreases. However, the transition position of the flow around the airfoil surface is getting closer to the leading edge, and its state is more likely to transition from laminar flow to turbulent flow. When the unidirectional carbon fiber-reinforced thickness is 0.2 mm and the thin arc-shaped airfoil with the convex structure has a uniform thickness of 2.5% and a uniform curvature of 4.5%, the aerodynamic and vibration characteristics of the octorotor aircraft are most beneficial to flight.

423 Performance Evaluation of High loft-to-Drag Ratio Airfoil at Low Reynolds Number Using Variable Pressure Wind Tunnel

2015 ◽  
Vol 2015.68 (0) ◽  
pp. 173-174
Author(s):  
Yu FUKUSHIMA ◽  
Takahiro MAKIZONO ◽  
Gaku SASAKI ◽  
Hiroshi OCHI ◽  
Takaaki MATSUMOTO ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Performance Evaluation ◽  
Wind Tunnel ◽  
Low Reynolds Number ◽  
Variable Pressure ◽  
Low Reynolds ◽  
Drag Ratio

scholarly journals Surface curvature effects on the tonal noise performance of a low Reynolds number aerofoil

2017 ◽  
Vol 125 ◽  
pp. 34-40 ◽  
Author(s):  
Xiang Shen ◽  
Eldad Avital ◽  
Qinghe Zhao ◽  
Junhui Gao ◽  
Xiaodong Li ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Surface Curvature ◽  
Noise Performance ◽  
Tonal Noise ◽  
Curvature Effects ◽  
Low Reynolds

Calculation of low Reynolds number flows at high angles of attack

1991 ◽  
Vol 28 (4) ◽  
pp. 246-252 ◽  
Author(s):  
T. Cebeci ◽  
M. McIlvaine ◽  
H. H. Chen ◽  
R. H. Liebeck
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Low Reynolds Number Flows ◽  
Low Reynolds ◽  
Reynolds Number Flows ◽  
High Angles Of Attack
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