Vortex control strategy for unsteady aerodynamic optimization of a plunging airfoil at a low Reynolds number

2021 ◽  
Vol 33 (11) ◽  
pp. 117110
Author(s):  
Lei Wang ◽  
Li-Hao Feng ◽  
Yan Liang ◽  
Yi-Long Chen ◽  
Zhen-Yao Li
Keyword(s):  
Reynolds Number ◽  
Control Strategy ◽  
Low Reynolds Number ◽  
Aerodynamic Optimization ◽  
Vortex Control ◽  
Unsteady Aerodynamic ◽  
Low Reynolds

scholarly journals FLAPPING WING DEVICES FOR MARS EXPLORATION

2011 ◽  
Author(s):  
Asier Ania ◽  
Dominique Poirel ◽  
Marie-Josée Potvin ◽  
Steeve Montminy
Keyword(s):  
Reynolds Number ◽  
Insect Flight ◽  
Low Reynolds Number ◽  
Flapping Wing ◽  
Low Density ◽  
Mars Exploration ◽  
Unsteady Aerodynamic ◽  
Aerial Vehicle ◽  
Low Reynolds

The use of an aerial vehicle would greatly enhance the domain of exploration on Mars. The main constraint in such a design would be the extreme Martian environment. The low-density atmosphere suggests the use of a low Reynolds number flight regime modeled after flapping wing insect flight. This flapping wing flight employs several unsteady aerodynamic mechanisms; delayed stall, wake capture, and rotational mechanisms. Two prototypes, a flapping wing and a rotary-flapping wing hybrid, have been built and will be tested in order to quantify the 'overall lift' generated and allow us to evaluate the efficacy of flapping wing flight on Mars.

Unsteady aerodynamic characteristics of a translating rigid wing at low Reynolds number

2015 ◽  
Vol 27 (12) ◽  
pp. 123102 ◽  
Author(s):  
Peter Mancini ◽  
Field Manar ◽  
Kenneth Granlund ◽  
Michael V. Ol ◽  
Anya R. Jones
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Aerodynamic Characteristics ◽  
Unsteady Aerodynamic ◽  
Low Reynolds ◽  
Rigid Wing

scholarly journals Simulation and feedback control of the Ahmed body flow exhibiting symmetry breaking behaviour

2017 ◽  
Vol 817 ◽  
Author(s):  
O. Evstafyeva ◽  
A. S. Morgans ◽  
L. Dalla Longa
Keyword(s):  
Reynolds Number ◽  
Feedback Control ◽  
Symmetry Breaking ◽  
Numerical Simulations ◽  
Control Strategy ◽  
Low Reynolds Number ◽  
Reynolds Numbers ◽  
Low Reynolds ◽  
Feedback Control Strategy ◽  
Ahmed Body

The present work considers the low-Reynolds-number wake flow behind a squareback Ahmed body, in close proximity to a ground. At low Reynolds numbers such wakes are known to undergo a series of bifurcations to a state that breaks reflectional symmetry. The symmetry breaking of the wake also persists at turbulent high Reynolds numbers, where it manifests as bi-modal behaviour with random switching between the asymmetric states. Thus far, it has only been possible to study the low-Reynolds-number sequence of bifurcations experimentally and mathematically. The present work presents the first numerical simulations capturing the sequence of symmetry breaking bifurcations that occur. A study of how the wake topology changes throughout suggests that interaction between the closer top/bottom pair of parallel shear layers can only dominate once there is sufficient underbody flow. When this occurs, the two main vortex structures in the wake switch from being horizontally to vertically aligned. A linear feedback control strategy, designed to attenuate base pressure force fluctuations, is then implemented. This causes an accompanying reduction in drag and re-symmetrisation of the wake. Analysis using the dynamic mode decomposition confirms that the wake shedding mode is re-symmetrised. This work motivates future attempts to capture wake symmetry breaking and bi-modality in numerical simulations, and application of a promising feedback control strategy at higher, turbulent Reynolds numbers.

scholarly journals Applications of an Improved Aerodynamic Optimization Method on a Low Reynolds Number Cascade

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1150 ◽  
Author(s):  
Shuyi Zhang ◽  
Bo Yang ◽  
Hong Xie ◽  
Moru Song
Keyword(s):  
Reynolds Number ◽  
Simulated Annealing Algorithm ◽  
Design Method ◽  
Incidence Angle ◽  
Thickness Distribution ◽  
Low Reynolds Number ◽  
Pressure Coefficient ◽  
Optimization Method ◽  
Aerodynamic Optimization ◽  
Low Reynolds

The effect of cascade aerodynamic optimization on turbomachinery design is very significant. However, for most traditional cascade optimization methods, aerodynamic parameters are considered as boundary conditions and rarely directly used as the optimization variables to realize optimization. Given this problem, this paper proposes an improved cascade aerodynamic optimization method in which an incidence angle and nine geometric parameters are used to parameterize the cascade and one modified optimization algorithm is adopted to find the cascade with the optimal aerodynamic performance. The improved parameterization approach is based on the Non-Uniform Rational B-Splines (NURBS) method, the camber line superposing thickness distribution molding (CLSTDM) method, and the plane cascade design method. To rapidly and effectively find the cascade with the largest average lift-drag ratio within a certain range of incidence angles, modified particle swarm optimization combined with the modified very fast simulated annealing algorithm (PSO-MVFSA) is adopted. To verify the feasibility of the method, a cascade with NACA4412 and a practical cascade are optimized. It is found that the average lift-drag ratios of two optimal performance cascades are respectively increased by 13.38% and 15.21% in comparison to those of two original cascades. Meanwhile, through optimizing the practical cascade of the Blade D500, under different volume flow rates, the pressure coefficient of the optimized cascade is increased by an average of more than 6.12% compared to that of the prototype, and the average efficiency is increased by 11.15%. Therefore, this improved aerodynamic optimization method is reliable and feasible for the performance improvement of cascades with a low Reynolds number.

The Effects of Flexible Deformation on an Oscillating Airfoil at Low Reynolds Number

2011 ◽  
Vol 117-119 ◽  
pp. 610-614
Author(s):  
Jiang Hao Wu ◽  
Chao Zhou ◽  
Yan Lai Zhang
Keyword(s):  
Reynolds Number ◽  
Phase Difference ◽  
Low Reynolds Number ◽  
Aerodynamic Performance ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic ◽  
Deformation Parameters ◽  
Low Reynolds ◽  
Time Courses ◽  
Flexible Deformation

The objective of investigation is to use numerical simulation obtain the effect of three different flexible deformation parameters (the maximum deforming amplitude, the phase difference between the plunging motion and the deformation motion and location of the maximum deforming) on unsteady aerodynamic performance of an airfoil with plunging and pitching motion. It is shown the effect of flexible deformation at low Reynolds number is obvious. The effect of the maximum deforming amplitude and the phase difference on aerodynamic forces is quite significant while the time courses of CL and CT don’t almost change with location of the maximum deforming. Different deforming amplitude and the phase difference may be advantageous or disadvantageous for averaged aerodynamic forces. Larger phase difference can produce more thrust and make the forward flight faster. Compared with the rigid airfoil, the appreciate combination of deformation parameters is beneficial in MAV design.

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