Ground Effect Aerodynamics of a Flapping Airfoil in Hover

Qu, Qiulin; Zheng, Yunlong; Liu, Peiqing; Qin, Ying-zhi; Agarwal, Ramesh K.

doi:10.2514/6.2017-3408

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…The capability of the FLUENT for the simulations of an insect flight has been shown and validated in several relevant studies. 27,30,31 Additionally, the newly introduced overset grid technology accelerates the simulation of any moving object including flapping wings and/or the forward motion.…”

Section: Cfd Solvermentioning

confidence: 99%

Multi-physics simulation of an insect with flapping wings

Bakhshaei

MoradiMaryamnegari

SalavatiDezfouli

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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In this paper, the unsteady aerodynamic of an insect’s forward flight has been carried out with a novel approach. In order to fully utilize the available powerful solvers, an innovative intermediary MATLAB code has been written for the high-fidelity time-resolved multi-physics problems involving fluid flow and multi-body simulations. For simulating the insect’s flight, the FLUENT solver has been utilized to determine aerodynamic forces and moments of the wings and main body while ADAMS software has been employed to calculate translational and angular velocities. Overset grid technology accompanied with dynamic mesh method have been implemented for the movement of the insect. The code is responsible for the synchronization of the solvers at the end of each time step as well as the integration of the solutions. Three different simulations are done for two different insects’ geometries. For the first and second simulations, a simplified geometry of an insect is selected, due to the ease of manufacturing and testing. At first, all rotational and translational degrees of freedom are considered to be free. The motion path history shows the instability due to an inappropriate location of the center of gravity. Hence, in the second case, it is assumed that the insect’s main body is limited to the vertical motion. In the final simulation, a complicated model of a bee with exact geometry and wings kinematics extracts from the experimental data with the free translational degrees of freedom. According to the results, combining multiple software in which they can interact with each other at each time step, is the most accurate way for doing precise multi-physics simulations.

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Section: Cfd Solvermentioning

confidence: 99%

Multi-physics simulation of an insect with flapping wings

Bakhshaei

MoradiMaryamnegari

SalavatiDezfouli

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

View full text Add to dashboard Cite

show abstract

“…The effects of ground proximity on the force generation and vortex structures have been discussed in the past. 30,31 However, the present study has not considered the ground, as the wing kinematics measured during take-off from a platform of very small length. 29 From the literature, we note that most previous studies have focused on the aerodynamic performance of hovering dragonflies.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the aerodynamic performance of dragonfly-like flapping foil in take-off flight

Shanmugam¹,

Sohn

2019

Proceedings of the Institution of Mechanical Engineers, Part G:

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In this study, the aerodynamic performance of a dragonfly-like flapping foil is investigated in take-off flight using two-dimensional numerical simulations. Two parameters, foil spacing L * ( L/c) and the phase shift between forefoil and hindfoil ψ, which characterize the flow in the tandem configuration, are varied to explore their impact on the resulting aerodynamic performance. Both the vertical and thrust forces generated in one cycle are found to be strongly dependent on ψ and relatively weakly dependent on L *. The tandem configuration is beneficial for the vertical force generation in the range of 0° ≤ ψ ≤ 30°, and further, it aids the thrust force generation for 40° ≤ ψ ≤ 110°. The flow interactions between the forefoil and hindfoil can increase the vertical force generated in a cycle by a maximum of ∼1.2 times when ψ is close to 0° relative to the no foil–foil interaction case (additive effect of two single foils). These interactions can also increase the thrust force generated in a cycle by a maximum of ∼2.8 times when ψ is close to 80°. The vortex structures reveal that the enhancement in thrust force mainly depends on the timing of interactions and how the hindfoil utilizes the vortex detached from the forefoil to benefit from it. Further, we find that dragonflies use in-phase stroking pattern ( ψ = 0 °) with a large downstroke angle of attack, α D ( α D = 86 °), in the initial phase of take-off as it aids in generating additional vertical force. Our findings can significantly contribute to the design of micro aerial vehicles.

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Effect of Gurney flap on the aerodynamic behavior of an airfoil in mutational ground effect

Roozitalab

Kharati-Koopaee

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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In this research, the effect of Gurney flap on the aerodynamic behavior of an airfoil in mutational ground effect is investigated. To perform this, lift and drag coefficients of NACA 4412 airfoil section in the presence and absence of Gurney flap in mutational ground effect are evaluated and compared. To provide a better illustration of the effect of Gurney flap on the aerodynamic behavior of the airfoil section in the mutational ground effect, results are obtained during the takeoff and landing processes. Validation of the used numerical model is also performed by comparison of the obtained results with those of other works and reasonable agreements were seen. Results show that inclusion of Gurney flap to the airfoil leads to higher variations of lift and drag coefficients during takeoff and landing process. During the takeoff process, the flapped airfoil results in a higher lift decrement and drag increment although an increase in distance of airfoil from the ground or angle of attack causes the lift decrement of the flapped airfoil to get close to that of clean airfoil. It is shown that during takeoff process, downwash is generated around the airfoil as the airfoil leaves the step and as the airfoil gets away from the step, the generated downwash decreases. During the landing process, at each distance of airfoil form the ground and angle of attack, the lift decrement and drag increment of the flapped airfoil are significant compared to that of the clean airfoil. Results exhibit that during landing process, upwash is generated around the airfoil as the airfoil reaches the step and further airfoil move on the step leads to the decrease in the upwash. The decrement in lift coefficient and also the increment in drag coefficient during landing process are more remarkable than those in takeoff process.

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Ground Effect Aerodynamics of a Flapping Airfoil in Hover

Cited by 4 publications

References 17 publications

Multi-physics simulation of an insect with flapping wings

Multi-physics simulation of an insect with flapping wings

Numerical investigation of the aerodynamic performance of dragonfly-like flapping foil in take-off flight

Effect of Gurney flap on the aerodynamic behavior of an airfoil in mutational ground effect

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