Can the ground enhance vertical force for inclined stroke plane flapping wing?

Shanmugam, Deepthi; Vengadesan, S.

doi:10.1088/1748-3190/abce4c

Cited by 8 publications

(6 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The stroke plane angle was found to change the dipole jet characteristics (Deepthi and Vengadesan 2020) and the jet characteristics were found to explain the vertical force trends in hovering conditions. Further, vertical force enhancement due to the ground effect for intermediate heights could also be explained by the dipole jet patterns (Deepthi and Vengadesan 2021). This calls for understanding the effect of dipole jet on the tandem wing configuration and their role in vertical force enhancement.…”

Section: Introductionmentioning

confidence: 94%

Vortex dynamics and on the mechanism of vertical force enhancement in inclined stroke flapping wings

Shanmugam,

Vengadesan

2023

Eng. Res. Express

Self Cite

View full text Add to dashboard Cite

The rigorous numerical investigation of the class of inclined stroke plane flapping wings has brought to light the vertical force enhancement due to dipole jet interaction. In this study, the class of inclined stroke plane flapping wings with varying inter-plane distances and stroke inclinations are studied for vertical force generation. The configurations with stroke plane angles of 60° and 75° are found to produce significantly high vertical forces. Further, wake structures of the tandem flapping wing in an inclined stroke plane show various types of dipole vortex shedding and dipole jet interactions. The identified types of dipole jet interactions help in the understanding of vertical force trends of the forewing, hindwing, and hence the tandem wing configuration as a whole. It reveals the potential dipole jet interaction producing the highest vertical force in tandem wing configurations. In all, the study can classify the flows of the tandem wing configurations based on vortex shedding during hovering conditions and understand its vertical force enhancements. This not only helps in getting physical insights into the vortex dynamics of inclined stroke plane flapping wings but also in the design optimisation of the tandem wing configurations in biomimetic Micro Air vehicles (MAVs).

show abstract

Section: Introductionmentioning

confidence: 94%

Vortex dynamics and on the mechanism of vertical force enhancement in inclined stroke flapping wings

Shanmugam,

Vengadesan

2023

Eng. Res. Express

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, it is important to note that the 'air cushion' underneath the body is created by the downwash from the flapping wings. Different from these effects which is caused by the downwash [50] or happened simultaneously with the vortex wake in inclined stroke plane [48,49], our present work shows that this 'ramming effect' also exists for the insect flapping wing in ground effect when the wing flaps in a horizontal plane without any vortex wake (or downwash).…”

Section: Ramming Effectmentioning

confidence: 46%

“…This effect has been identified as the dominant factor of the ground effect on a flapping bird [47]. Studies on flapping wings with inclined stroke plane angle in ground effect also showed the ramming effect on the wings, where it is also referred as 'cushion effect' [48,49]. This air cushion effect was also found to enhance the lift on the insect body when the fruit fly model hovered above the ground [50].…”

Section: Ramming Effectmentioning

confidence: 95%

Very low Reynolds number causes a monotonic force enhancement trend for a three-dimensional hovering wing in ground effect

Meng¹,

Ghaffar²,

Zhang³

et al. 2021

Bioinspir. Biomim.

View full text Add to dashboard Cite

This research reports the numerical results of the ground effect trend for a three-dimensional flapping insect wing at a very low Reynolds number (Re = 10). It demonstrates that the ground effect trend at this Re has a ‘single force regime,’ i.e. the forces only enhance as the ground distance decreases. This phenomenon is unlike the widely expected non-monotonic trend publicized in previous studies for higher Reynolds numbers, that shows ‘three force regimes,’ i.e. the forces reduce, recover, and also enhance as the ground distance decreases. The force trend in the ground effect correlates to a similar trend in wing–wake interaction or the downwash strength on the wing’s head. At very low Re (10), the very large viscosity causes diffused vortices and less advected vortex wake, while at relatively high Re, the vortices are easily separated from the wing and then advected downwards. This different development of the vortex wake caused different force trends for the flapping wing in the ground effect. Furthermore, by examining only the first stroke when there is no vortex wake, we found that the ‘ramming effect’ enhances the forces on the wing. This effect increases the pressure of the lower wing surface due to the squeezed air between the wing and the ground. The ‘ramming effect’, combined with the reduced downwash (or wing–wake interaction) effect, causes the force enhancement of the wing near the ground’s vicinity. It is further comprehended that the trend is dependent on Re. As the Re is increased, the trend becomes non-monotonic. The effect of varying angles of attack, flapping amplitude and wing planform at very low Re does not change this trend. This ground effect might help insects by enhancing their lift while they hover above the surface. This finding might prove beneficial for developing micro air vehicles.

show abstract

“…This low-pressure region acts as a sink flow, drawing fluid between the two vortices. This combination of source flow and sink flow forms a dipole jet that is characteristic of counter-rotating vortices (Drucker & Lauder 2000; Deepthi & Vengadesan 2021). The schematic diagram in figure 10 illustrates the pitch-up motion of the wing and the resulting formation of the dipole jet.…”

Section: Resultsmentioning

confidence: 99%

“…They also observed that pitching near the ground generates a vortex pair instead of a vortex street, increasing the average thrust force. In another study, Deepthi & Vengadesan (2021) showed that an inclined flapping wing-in-ground effect experiences an enhanced vertical force at a stroke plane angle of due to the interaction of the recirculating jet with the wing. However, at other angles, the influence of the ground on the jet is minimal or non-existent, resulting in negligible changes in the force with varying ground height.…”

Section: Introductionmentioning

confidence: 99%

Rapidly pitching plates in decelerating motion near the ground

Adhikari,

Bhattacharya

2024

J. Fluid Mech.

View full text Add to dashboard Cite

Birds employ rapid pitch-up motions close to the ground for different purposes: perching birds use this motion to decelerate and come to a complete stop while hunting birds, such as bald eagles, employ it to catch prey and swiftly fly away. Motivated by these observations, our study investigates how natural flyers accomplish diverse flying objectives by rapidly pitching their wings while decelerating near ground. We conducted experimental and analytical investigations focusing on rapidly pitching plates during deceleration in close proximity to the ground to explore the impact of ground proximity on the unsteady dynamics. Initially, we executed synchronous pitch-up motion, where both pitching and deceleration have the same motion duration, at different ground heights. Experimental results demonstrate that as the pitching wing approaches the ground, the instantaneous lift increases by approximately $38\,\%$ compared with a far-from-ground case, while the initial peak drag force remains relatively unchanged. Our analytical model conforms to this trend, predicting an increase in lift force as the wing approaches the ground, indicating enhanced added mass and circulatory lift force due to the ground effect. Next, we examined asynchronous pitch-up motion cases, where rapid pitching motions were initiated at different stages of deceleration. The results reveal that initiating the wing pitch early in the deceleration leads to the formation of larger counter-rotating vortices at the early stage of the manoeuvre. These vortices generate stronger dipole jets that orient backward in the later stages of the manoeuvre after impinging with the ground surface, which hunting birds utilize to accelerate after catching prey. Conversely, when the wing pitch is delayed, smaller vortices form, but their growth is postponed until late in the manoeuvre. This delayed vortex growth produces lift and drag force at the end phase of the manoeuvre that facilitates a smooth landing or perching. Thus, through strategic tuning of a rapid pitch-up motion with deceleration, natural flyers, such as birds, achieve diverse flying objectives.

show abstract

Can the ground enhance vertical force for inclined stroke plane flapping wing?

Cited by 8 publications

References 17 publications

Vortex dynamics and on the mechanism of vertical force enhancement in inclined stroke flapping wings

Vortex dynamics and on the mechanism of vertical force enhancement in inclined stroke flapping wings

Very low Reynolds number causes a monotonic force enhancement trend for a three-dimensional hovering wing in ground effect

Rapidly pitching plates in decelerating motion near the ground

Contact Info

Product

Resources

About