To see the other types of publications on this topic, follow the link: Humpback whale flipper.
Journal articles on the topic 'Humpback whale flipper'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 29 journal articles for your research on the topic 'Humpback whale flipper.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Fish, Franke E., and Juliann M. Battle. "Hydrodynamic design of the humpback whale flipper." Journal of Morphology 225, no. 1 (July 1995): 51–60. http://dx.doi.org/10.1002/jmor.1052250105.
Full text
2
Fish, Frank E., Paul W. Weber, Mark M. Murray, and Laurens E. Howle. "Marine Applications of the Biomimetic Humpback Whale Flipper." Marine Technology Society Journal 45, no. 4 (July 1, 2011): 198–207. http://dx.doi.org/10.4031/mtsj.45.4.1.
Full textAbstract:
AbstractThe biomimetic approach seeks technological advancement through a transfer of technology from natural technologies to engineered systems. The morphology of the wing-like flipper of the humpback whale has potential for marine applications. As opposed to the straight leading edge of conventional hydrofoils, the humpback whale flipper has a number of sinusoid-like rounded bumps, called tubercles, which are arranged periodically along the leading edge. The presence of the tubercles modifies the water flow over the wing-like surface, creating regions of vortex generation between the tubercles. These vortices interact with the flow over the tubercle and accelerate that flow, helping to maintain a partially attached boundary layer. This hydrodynamic effect can delay stall to higher angles of attack, increases lift, and reduces drag compared to the post-stall condition of conventional wings. As the humpback whale functions in the marine environment in a Reynolds regime similar to some engineered marine systems, the use of tubercles has the potential to enhance the performance of wing-like structures. Specific applications of the tubercles for marine technology include sailboat masts, fans, propellers, turbines, and control surfaces, such as rudders, dive planes, stabilizers, spoilers, and keels.
3
Versiani, Leonardo Leão, and Cristiano Schetini Azevedo. "Surface activity of Humpback whales Megaptera novaeangliae (Cetacea, Mysticeti) on the northern coast of Bahia, Brazil." Revista Brasileira de Zoociências 21, no. 1 (July 29, 2020): 1–12. http://dx.doi.org/10.34019/2596-3325.2020.v21.29788.
Full textAbstract:
Surface activities of humpback whale groups were studied during the reproductive seasons of 2008, 2009 and 2010 on the northern coast of Bahia State, Brazil, near the district of Praia do Forte. The level of surface activity exhibited by 342 groups of whales was evaluated according to the sea state (measured on the Beaufort scale) and cloud coverage. Five behaviours were recorded: breaching, head slapping, tail slapping, pectoral flipper slapping and tail breaching. Most of the sightings occurred with a sea state classified on the Beaufort scale as 2, and with a cloud coverage of 26 to 50%. The most recorded level of surface activity was pectoral flipper slapping. The results showed that humpback whale behaviours do not seem to be influenced by the sea state or by cloud coverage.
4
Silber, Gregory K. "The relationship of social vocalizations to surface behavior and aggression in the Hawaiian humpback whale (Megaptera novaeangliae)." Canadian Journal of Zoology 64, no. 10 (October 1, 1986): 2075–80. http://dx.doi.org/10.1139/z86-316.
Full textAbstract:
Humpback whale (Megaptera novaeangliae) social vocalizations (nonsong sounds) were clearly related to whale group size and surface activity. Social sounds occurred almost exclusively in groups containing three or more whales and were rarely heard near single whales, pairs, or cow–calf groups. Large groups (3 to 20 individuals) vocalized at an overall mean rate of 43.1 ± 55.52 sounds per whale/h. Group size changed frequently and a dramatic increase in vocalization rate resulted when a new whale entered a group. Large groups engaged in flurries of surface activity, such as breaching, flipper- and tail-slapping, and underwater bubbling. Aggressive encounters resulted from male–male interaction. Social sounds probably acted to demonstrate aggression or agitation as adult males competed for temporary social dominance within the group and for proximity to the female. Likewise, visual displays may have been used as threats in close quarters and were apparently produced in conjunction with sounds to convey levels of aggression. Although other studies suggested that surface activity increased with group size, I found a negative correlation between activity and group size, both in the group as a whole and per individual. In contrast, social vocalizations per group increased with group size while the vocalization rate per individual did not vary significantly with increasing group size.
5
Arrondeau, Benjamin, and Zeeshan A. Rana. "Computational Aerodynamics Analysis of Non-Symmetric Multi-Element Wing in Ground Effect with Humpback Whale Flipper Tubercles." Fluids 5, no. 4 (December 17, 2020): 247. http://dx.doi.org/10.3390/fluids5040247.
Full textAbstract:
The humpback whale flipper tubercles have been shown to improve the aerodynamic coefficients of a wing, especially in stall conditions, where the flow is almost fully detached. In this work, these tubercles were implemented on a F1 front-wing geometry, very close to a Tyrrell wing. Numerical simulations were carried out employing the k−ω SST turbulence model and the overall effects of the tubercles on the flow behavior were analyzed. The optimal amplitude and number of tubercles was determined in this study for this front wing where an improvement of 22.6% and 9.4% is achieved, respectively, on the lift and the L/D ratio. On the main element, the stall was delayed by 167.7%. On the flap, the flow is either fully detached, in the large circulation zone, or fully attached. Overall, in stall conditions, tubercles improve the downforce generation but at the cost of increased drag. Furthermore, as the tubercles are case-dependent, an optimal configuration for tubercles implementation also exists for any geometry.
6
Kumar, Vivek V., and Dilip A. Shah. "Application of Tubercles in Wind Turbine Blades: A Review." Applied Mechanics and Materials 867 (July 2017): 254–60. http://dx.doi.org/10.4028/www.scientific.net/amm.867.254.
Full textAbstract:
Due to the rapid depletion of conventional energy resources like fossil fuels and their harmful effects on the environment, there is an urgent need to seek alternative and sustainable energy sources. Wind energy is considered as one of the efficient source of energy which can be converted to useful form of energy like electrical energy. Though the field of wind engineering has developed in the recent era there is still scope for improvement in the effective utilization of energy. Energy efficiency in wind turbine is largely determined by the aerodynamics of the turbine blades and the characteristics of the turbulent fluid flow. The objective of this paper is to have a review on the improvement of Horizontal Axis Wind Turbine (HAWT) blade design by incorporating biomimetics into blades. Biomimetics is the field of science in which we adapt designs from nature to solve modern problems. The morphology of the wing-like flipper of the humpback whale (Megaptera novaeangliae) has potential for aerodynamic applications. Instead of straight leading edges like that of conventional hydrofoils, the humpback whale flipper has a number of sinusoidal rounded bumps, called tubercles arranged periodically along the leading edge. The presence of tubercles modifies the flow over the blade surface, creating vortices between the tubercles. These vortices interact with the flow over the tubercle and accelerate that flow, helping to maintain a partially attached boundary layer. This aerodynamic effect can delay stall to higher angles of attack, increase lift and reduce drag compared to the post-stall condition of conventional airfoils. The modified airfoil is characterized by a superior lift/drag ratio (L/D ratio) due to greater boundary layer attachment from vortices energizing the boundary layer.
7
Papadopoulos, Charalampos, Vasilis Katsiadramis, and Kyros Yakinthos. "Numerical 3D study on the influence of spanwise distribution of tubercles on wings for UAV applications." MATEC Web of Conferences 304 (2019): 02014. http://dx.doi.org/10.1051/matecconf/201930402014.
Full textAbstract:
In this work, a 3D numerical study on the influence of the spanwise distribution of tubercles for UAV applications is presented. The idea of using tubercles in aeronautics comes from the humpback whale (Megaptera novaeangliae) which has a characteristic flipper, with a spanwise scalloped leading edge, creating an almost sinusoidal shape, consisting of bumps called tubercles. Early experimental research showed a great potential in enhancing the 3D aerodynamic characteristics of a wing. Most of the existing experimental results concern infinite wings (2D) models and are accompanied with substantial loss in lift and increase in drag in pre–stall region. On the other hand, finite models (3D) have displayed a better overall aerodynamic performance (increased lift and moment, but also decreased drag). At a range of Reynolds number between 500,000 and 1,000,000 (based on the mean chord of the flipper), tubercles act as virtual fences, introducing a pair of counter rotating vortices that delays the stall of the flipper, a phenomenon that the whales use to perform sharp turns and catch their prey. The aforementioned Reynolds number range is the same as the operational Reynolds number for typical Unmanned Aerial Vehicles (UAV). To assess the influence of the tubercles installation on UAV wings, a full 3D computational study is carried-out, with the use of CFD tools that at a first phase are validated and calibrated with available in the literature experimental data. Then, computations are performed, for different spanwise tubercles distributions. The results show that there is a noticeable potential on controlling the flow on the wings of a UAV operating in a Reynolds number range between 500,000 and 1,000,000 (based on UAV’s wing mean chord), which can lead to an aerodynamic performance and efficiency increase.
8
Li, Bowen, Xiaojun Li, Xiaoqi Jia, Feng Chen, and Hua Fang. "The Role of Blade Sinusoidal Tubercle Trailing Edge in a Centrifugal Pump with Low Specific Speed." Processes 7, no. 9 (September 17, 2019): 625. http://dx.doi.org/10.3390/pr7090625.
Full textAbstract:
Pressure pulsations may cause high-amplitude vibrations during the process of a centrifugal pump. The trailing edge shape of the blade has a critical influence on the pump’s pressure fluctuation and hydraulic characterization. In this paper, inspired by the humpback whale flipper, the authors research the impact of applying the sinusoidal tubercles to the blade suction side of the trailing edge. Numerical calculation and experiments are carried out to investigate the impact of the trailing edge shape on the pressure pulsations and performance of a centrifugal pump with low specific speed. Two designed impellers are tested, one is a sinusoidal tubercle trailing edge (STTE) impeller and the other is the original trailing edge (OTE) prototype. The detailed study indicates that the sinusoidal tubercle trailing edge (STTE) reduces pressure pulsation and enhances hydraulic performance. In the volute tongue region, the pressure pulsation amplitudes of STTE at fBPF decrease significantly. The STTE impeller also effectively changes the vortex structure and intensity in the blade trailing edge area. This investigation will be of great benefit to the optimal design of pumps.
9
Segre, Paolo S., S. Mduduzi Seakamela, Michael A. Meÿer, Ken P. Findlay, and Jeremy A. Goldbogen. "A hydrodynamically active flipper-stroke in humpback whales." Current Biology 27, no. 13 (July 2017): R636—R637. http://dx.doi.org/10.1016/j.cub.2017.05.063.
Full text
10
Brown, Alan S. "From Whales to Fans." Mechanical Engineering 133, no. 05 (May 1, 2011): 24–29. http://dx.doi.org/10.1115/1.2011-may-1.
Full textAbstract:
This article discusses a story about a man named Fish who noticed something unusual about whale flippers and who, after nearly 30 years, turned it into a technology platform. This technology takes its inspiration from the natural design of the bumps, or tubercles, on humpback whale flippers. The 24-foot-diameter fans, based on tubercle technology, use half the number of blades and move 25% more air and consume 25% less power than fans with conventional blades turning at the same speed. After thousands of years of hiding in plain sight, tubercles are emerging as a real, if limited, technology platform. Research has shown tubercles work only on thick, tapered wings operating in a very narrow laminar-to-turbulent transition regime. Whale-inspired fans are already available, and wind and tidal power blades could be the next.
11
Kosma, Madison M., Alexander J. Werth, Andrew R. Szabo, and Janice M. Straley. "Pectoral herding: an innovative tactic for humpback whale foraging." Royal Society Open Science 6, no. 10 (October 2019): 191104. http://dx.doi.org/10.1098/rsos.191104.
Full textAbstract:
Humpback whales ( Megaptera novaeangliae ) have exceptionally long pectorals (i.e. flippers) that aid in shallow water navigation, rapid acceleration and increased manoeuvrability. The use of pectorals to herd or manipulate prey has been hypothesized since the 1930s. We combined new technology and a unique viewing platform to document the additional use of pectorals to aggregate prey during foraging events. Here, we provide a description of ‘pectoral herding’ and explore the conditions that may promote this innovative foraging behaviour. Specifically, we analysed aerial videos and photographic sequences to assess the function of pectorals during feeding events near salmon hatchery release sites in Southeast Alaska (2016–2018). We observed the use of solo bubble-nets to initially corral prey, followed by calculated movements to establish a secondary boundary with the pectorals—further condensing prey and increasing foraging efficiency. We found three ways in which humpback whales use pectorals to herd prey: (i) create a physical barrier to prevent evasion, (ii) cause water motion to guide prey towards the mouth, and (iii) position the ventral side to reflect light and alter prey movement. Our findings suggest that behavioural plasticity may aid foraging in changing environments and shifts in prey availability. Further study would clarify if ‘pectoral herding’ is used as a principal foraging tool by the broader humpback whale population and the conditions that promote its use.
12
Miklosovic, D. S., M. M. Murray, L. E. Howle, and F. E. Fish. "Leading-edge tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers." Physics of Fluids 16, no. 5 (May 2004): L39—L42. http://dx.doi.org/10.1063/1.1688341.
Full text
13
Fish, F. E., P. W. Weber, M. M. Murray, and L. E. Howle. "The Tubercles on Humpback Whales' Flippers: Application of Bio-Inspired Technology." Integrative and Comparative Biology 51, no. 1 (May 15, 2011): 203–13. http://dx.doi.org/10.1093/icb/icr016.
Full text
14
Sisinni, Giuseppe, Domenico Pietrogiacomi, and Giovanni Paolo Romano. "Biomimetic Wings." Advances in Science and Technology 84 (September 2012): 72–77. http://dx.doi.org/10.4028/www.scientific.net/ast.84.72.
Full textAbstract:
An experimental analysis is performed in a wind tunnel on wings with wavy leading edge derived from humpback whale flippers. The major peculiarity of such flippers is given by the presence of several bumps placed along the leading edge, called tubercles, giving rise to a sort of wing with irregular wavy leading edge. Specifically, the important question to be solved is if the tubercles are able to delay wing stall and to attain higher lift in comparison to a standard wing without them. The present investigations employ different measurement techniques in order to evaluate the amount of possible gain, the potential drawbacks and the physics under such a phenomenon.
15
ZHANG, Yang, Xu ZHANG, Yi LI, Min CHANG, and Jiakuan XU. "Aerodynamic performance of a low-Reynolds UAV with leading-edge protuberances inspired by humpback whale flippers." Chinese Journal of Aeronautics 34, no. 5 (May 2021): 415–24. http://dx.doi.org/10.1016/j.cja.2020.11.004.
Full text
16
Favier, Julien, Alfredo Pinelli, and Ugo Piomelli. "Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers." Comptes Rendus Mécanique 340, no. 1-2 (January 2012): 107–14. http://dx.doi.org/10.1016/j.crme.2011.11.004.
Full text
17
Weber, Paul W., Laurens E. Howle, and Mark M. Murray. "Lift, Drag, and Cavitation Onset On Rudders With Leading-edge Tubercles." Marine Technology and SNAME News 47, no. 01 (January 1, 2010): 27–36. http://dx.doi.org/10.5957/mtsn.2010.47.1.27.
Full textAbstract:
This paper presents the experimental measurement of lift and drag as well as the determination of the onset of cavitation on rudders with leading-edge protuberances (tubercles) that are operating at low to moderate Reynolds Numbers in water. The leading-edge shape used for the rudders in this study is derived from our earlier work concerning the analysis of the leading-edge morphology found on the pectoral flippers of humpback whales. While humpback whales do not swim at speeds that induce cavitation, engineered control surfaces based on this bio-inspired control surface modification might operate in cavitation conditions. This point motivates our present work to investigate the onset of cavitation on small aspect ratio rudders with tubercles. Our findings are that (i) the presence of leading-edge tubercles accelerates the onset of cavitation, (ii) the tubercles can modify the location of the onset of cavitation, (iii) the tubercle geometry has an influence on the rudder's hydrodynamic performance, (iv) for the lower Reynolds Numbers considered in this paper, the tubercles decrease lift and increase drag for angles of attack between 15 and 22 deg, (v) for angles above 22 deg, rudders with tubercles generate more lift than smooth rudders, and (vi) for the higher Reynolds Numbers investigated, the difference in performance between the smooth and tubercled rudders diminishes, suggesting the existence of a critical Reynolds Number for a given tubercle geometry beyond which tubercles have no significant effect on hydrodynamic performance.
18
Aftab, Syed Mohammed Aminuddin, and Kamarul Arifin Ahmad. "NACA 4415 Wing Modification Using Tubercles - A Numerical Analysis." Applied Mechanics and Materials 629 (October 2014): 30–35. http://dx.doi.org/10.4028/www.scientific.net/amm.629.30.
Full textAbstract:
In this work, the characteristic design of the humpback whale flippers is incorporated and investigated on NACA 4415 airfoil at very low Mach number. The effect of Tubercle Leading Edge on NACA4415 airfoil has been studied. This novel study attempts to mimic the effect of tubercles on the airfoil wing to improve lift and delay stall. The results showed significant improvement in aerodynamic performance of TLE when compared to CW. TLE, in comparison to wing with vortex generators, performed better. An improvement in lift by about 13.6% was obtained contrary to only 6.3% increase in case of VG under same Reynolds number. In addition, it was also observed that incorporation of tubercles further delayed stall and continued to produce lift at high angle of attacks.
19
Asli, Majid, Behnam Mashhadi Gholamali, and Abolghasem Mesgarpour Tousi. "Numerical Analysis of Wind Turbine Airfoil Aerodynamic Performance with Leading Edge Bump." Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/493253.
Full textAbstract:
Aerodynamic performance improvement of wind turbine blade is the key process to improve wind turbine performance in electricity generated and energy conversion in renewable energy sources concept. The flow behavior on wind turbine blades profile and the relevant phenomena like stall can be improved by some modifications. In the present paper, Humpback Whales flippers leading edge protuberances model as a novel passive stall control method was investigated on S809 as a thick airfoil. The airfoil was numerically analyzed by CFD method in Reynolds number of 106and aerodynamic coefficients in static angle of attacks were validated with the experimental data reported by Somers in NREL. Therefore, computational results for modified airfoil with sinusoidal wavy leading edge were presented. The results revealed that, at low angles of attacks before the stall region, lift coefficient decreases slightly rather than baseline model. However, the modified airfoil has a smooth stall trend while baseline airfoil lift coefficient decreases sharply due to the separation which occurred on suction side. According to the flow physics over the airfoils, leading edge bumps act as vortex generator so vortices containing high level of momentum make the flow remain attached to the surface of the airfoil at high angle of attack and prevent it from having a deep stall.
20
Taheri, Arash. "HYDRODYNAMIC ANALYSIS OF BIONIC CHIMERICAL WING PLANFORMS INSPIRED BY MANTA RAY EIDONOMY." Indonesian Journal of Engineering and Science 2, no. 3 (September 8, 2021): 011–29. http://dx.doi.org/10.51630/ijes.v2i3.25.
Full textAbstract:
In this paper, inspired by the external morphology of a manta ray (Mobula alfredi), four chimerical wing planforms are designed to assess its gliding performance. The planforms possess an arbitrary combination of extra hydrodynamic features like tubercles at the leading edge (L.E.) and trailing edge (T.E.) inspired by humpback whale's flippers and flukes, respectively, as longitudinal ridges inspired by whale shark's economy. In addition, another planform is designed to investigate the possible effects of manta ray's injuries (geometric deficiency) generated by predator's attacks or boat strikes on its locomotion (gliding) performance. In this regard, turbulent flow physics involved in the problem is numerically simulated at different angles of attack (AoA). High Reynolds number, 106, corresponding to the swimming of a juvenile manta ray at an average speed equals one m/s. The results show that the manta ray-inspired planform with L.E. undulations exhibits a superior performance at high AoAs than its other counterpart variants. In addition, the results demonstrate that injuries on the manta ray's body can noticeably modify hydrodynamics and, as a result corresponding hydrodynamical forces and moments acting on the swimming animal in the gliding phase.
21
Zhang, Man, and Abdelkader Frendi. "Effect of airfoil leading edge waviness on flow structures and noise." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 6 (August 1, 2016): 1821–42. http://dx.doi.org/10.1108/hff-04-2015-0143.
Full textAbstract:
Purpose – The tubercles at the leading edge of Humpback Whale flippers have been shown to increase aerodynamic efficiency. The purpose of this paper is to compute the flow structures and noise signature of a NACA0012 airfoil with and without leading edge waviness, and located in the wake of a cylinder using the hybrid RANS-LES method. Design/methodology/approach – The mean flow Mach number is 0.2 and the angle of attack used is 2°. After benchmarking the method using existing experimental results, unsteady computations were then carried-out on both airfoil geometries and for a 2° angle of attack. Findings – Results from these computations confirmed the aerodynamic benefits of the leading edge waviness. Moreover, the wavy leading edge airfoil was found to be at least 4 dB quieter than its non-wavy counterpart. In-depth analysis of the computational results revealed that the wavy leading edge airfoil breaks up the large coherent structures which are then convected at higher speeds down the trough region of the waviness in agreement with previous experimental observations. This result is supported by both the two-point and space-time correlations of the wall pressure. Research limitations/implications – The limitations of the current findings reside in the fact that both the Reynolds number and the flow Mach number are low, therefore not applicable to aircrafts. In order to extend the study to practical aircrafts one needs huge grids and large computational resources. Practical implications – The results obtained here could have a huge implications on the design of future aircrafts and spacecrafts. More specifically, the biggest benefit from such redesign is the reduction of acoustic signature as well as increased efficiency in fuel consumption. Social implications – Reducing acoustic signature from aircrafts has been a major research thrust for NASA and Federal Aviation Administration. The social impact of such reduction would be improved quality of life in airport communities. For military aircrafts, this could results in reduced detectability and hence saving lives. Originality/value – Humpback Whales have been studied by various researchers to understand the effects of leading edge “tubercles” on flow structures. What is new in this study is the numerical confirmation of the effects of the tubercles on the flow structures and the resulting noise radiations. It is shown through the use of two-point correlations and space-time correlations that the flow structures in the trough area are indeed vortex tubes.
22
Serson, Douglas, Julio R. Meneghini, and Spencer J. Sherwin. "Direct numerical simulations of the flow around wings with spanwise waviness." Journal of Fluid Mechanics 826 (August 10, 2017): 714–31. http://dx.doi.org/10.1017/jfm.2017.475.
Full textAbstract:
The use of spanwise waviness in wings has been proposed in the literature as a possible mechanism for obtaining improved aerodynamic characteristics, motivated by the tubercles that cover the leading edge of the pectoral flippers of the humpback whale. We investigate the effect of this type of waviness on the incompressible flow around infinite wings with a NACA0012 profile, using direct numerical simulations employing the spectral/hp method. Simulations were performed for Reynolds numbers of $Re=10\,000$ and $Re=50\,000$, considering different angles of attack in both the pre-stall and post-stall regimes. The results show that the waviness can either increase or decrease the lift coefficient, depending on the particular $Re$ and flow regime. We observe that the flow around the wavy wing exhibits a tendency to remain attached behind the waviness peak, with separation restricted to the troughs, which is consistent with results from the literature. Then, we identify three important physical mechanisms in this flow. The first mechanism is the weakening of the suction peak on the sections corresponding to the waviness peaks. This characteristic had been observed in a previous investigation for a very low Reynolds number of $Re=1000$, and we show that this is still important even at $Re=50\,000$. As a second mechanism, the waviness has a significant effect on the stability of the separated shear layers, with transition occurring earlier for the wavy wing. In the pre-stall regime, for $Re=10\,000$, the flow around the baseline wing is completely laminar, and the earlier transition leads to a large increase in the lift coefficient, while for $Re=50\,000$, the earlier transition leads to a shortening of the separation bubble which does not lead to an increased lift coefficient. The last mechanism corresponds to a sub-harmonic behaviour, with the flow being notably different between subsequent wavelengths. This allows the wing to maintain higher lift coefficients in some portions of the span.
23
Chen, Shuling, Yan Liu, Changzhi Han, Shiqiang Yan, and Zhichao Hong. "Numerical Investigation of Turbine Blades with Leading-Edge Tubercles in Uniform Current." Water 13, no. 16 (August 13, 2021): 2205. http://dx.doi.org/10.3390/w13162205.
Full textAbstract:
Inspired by the tubercles on humpback whale flippers, leading-edge tubercles have been incorporated into the design of wings and turbine blades in an attempt to improve their hydrodynamic performance. Although promising improvements, especially in terms of the stall performance, have been demonstrated in the limited research that exists to date, the effectiveness of the leading-edge tubercles seems to be influenced by the base blade. This paper focuses on the introduction of sinusoidal leading-edge tubercles to a base blade developed from the classic NACA0018 airfoil, and numerically investigates the effectiveness of leading-edge tubercles on the hydrodynamics associated with the blade in uniform current with different attack angles. Both the macroscopic parameters, such as the lift and drag forces, and the micro-scale flow characteristics, including the vortex and flow separation, are analyzed. The results indicate that the leading-edge tubercles brings a significant influence on the hydrodynamic forces acting on the blade when subjected to an attack angle greater than 15°. This study also reveals the important role of the turbulence and flow separation on hydrodynamic loading on the blade and the considerable influence of the tubercles on such micro-scale flow characteristics. Although the conditions applied in this work are relatively ideal (e.g., the blade is fixed in a uniform flow and the end effect is ignored), the satisfactory agreement between the numerical and corresponding experimental data implies that the results are acceptable. This work builds a good reference for our future work on the hydrodynamic performance of tidal turbines which adopt this kind of blade for operating in both uniform and shearing currents.
24
Papadopoulos, Charalampos, Vasilis Katsiadramis, and Kyros Yakinthos. "Influence of tubercles’ spanwise distribution on swept wings for unmanned aerial vehicles." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, April 16, 2020, 095441002091958. http://dx.doi.org/10.1177/0954410020919583.
Full textAbstract:
In this work, a 3D numerical study on the influence of the spanwise distribution of tubercles on a unmanned aerial vehicle wing is presented. The idea of using tubercles in aeronautics comes from the humpback whale (Megaptera novaeangliae) which has a characteristic flipper, with a spanwise scalloped leading edge, creating an almost sinusoidal shape, consisting of bumps called tubercles. The whale uses this layout in order to achieve high underwater maneuverability. Early experimental research showed a great potential in enhancing the 3D aerodynamic characteristics of a wing. Most of the existing experimental results concern infinite wings (2D) models and are accompanied with substantial loss in lift and increase in drag in pre-stall region. On the other hand, 3D finite models have displayed a better overall aerodynamic performance (increased lift and moment, but also, decreased drag). At a range of Reynolds number between 500,000 and 1,000,000 (based on the mean chord of the flipper), tubercles act as virtual fences, introducing a pair of counter rotating vortices that delays the stall of the flipper, a phenomenon that the whales exploit to perform sharp turns and catch their prey. The aforementioned Reynolds number range is the same as the operational Reynolds number for typical unmanned aerial vehicles. To assess the influence of the tubercles installation on UAV wings, a full 3D computational study is carried-out with the use of CFD tools which at a first phase are validated and calibrated with the available literature experimental data. Then, computations are performed for different spanwise tubercles distributions. The results show that there is a noticeable potential on controlling the flow on the wings of a UAV operating in a Reynolds number range between 500,000 and 1,000,000 (based on UAV’s wing mean chord), which can lead to an aerodynamic performance and efficiency increase.
25
Gopinathan, VT, and J. Bruce Ralphin Rose. "Aerodynamics with state-of-the-art bioinspired technology: Tubercles of humpback whale." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, March 27, 2021, 095441002110015. http://dx.doi.org/10.1177/09544100211001501.
Full textAbstract:
Bioinspired aerodynamics is an emerging subject in the design of advanced flight vehicles with superior performance and minimum fuel consumption. In the present review article, a comprehensive evaluation is focused on previous studies and investigations toward the performance enhancement of aerodynamic surfaces with leading-edge (LE) tubercles. The implementation of tubercles has been biologically imitated from humpback whale (HW) flippers. Particularly, aerodynamicists are much interested in this bioinspired technology because of the exclusive maneuvering and flow control potential of HW flippers. LE protuberances are considered as a passive flow control method to improve the aerodynamic performance in various applications like aviation, marine, and wind energy. The aerodynamic and hydrodynamic performance variations caused by specific tubercles amplitude and wavelength are also compared through numerical and wind tunnel testing. The prospective utilization of tubercles on boundary layer flow control is measured with regard to conventional and swept-back wing designs. Flow control mechanisms of tubercles are outlined with several interesting facts in addition to the outcomes of various bioinspired aerodynamic investigations in the recent years.
26
Zheng, Tan, Xiaoqing Qiang, Jinfang Teng, and Jinzhang Feng. "Investigation of Leading Edge Tubercles with Different Wavelengths in an Annular Compressor Cascade." International Journal of Turbo & Jet-Engines, February 9, 2018. http://dx.doi.org/10.1515/tjj-2017-0064.
Full textAbstract:
Abstract Humpback whales possess bumpy tubercles on the leading edge of their flippers. Due to these leading edge tubercles, whales are able to produce high degree of maneuverability. Inspired by the flippers, this paper applies sinusoidal-like tubercles to the leading edge of blades in an annular compressor cascade, and presents a numerical investigation to explore the effects of tubercles with the aim of controlling the corner separation and reducing losses. Steady 3D RANS simulations are performed to investigate the aerodynamic performance and behavior of the corner separation in compressor cascades with and without leading edge tubercles. A crucial geometry parameter of the tubercles, wavelength, is varied to obtain different configurations. Results show that a smaller wavelength (more wave number) corresponds to a larger loss reduction and the maximum loss reduction reaches to 46.0%. Also, it is found that leading edge tubercles result in a stall delay and the maximum stall angle improvement reaches to 28.1%. Flow visualizations show that leading edge tubercles could induce the formation of counter-rotating streamwise vortices. The interaction between the streamwise vortices and corner separation is thought to be the primary flow mechanism generated by leading edge tubercles in an annular compressor cascade.
27
Río, Santiago Bernal-del, and Gilberto Osorio-Gómez. "Experimental Comparison of Energy Generation between Conventional and Wavy Leading Edge Blades in HAWT." International Journal of Electrical and Electronic Engineering & Telecommunications, 2020, 441–46. http://dx.doi.org/10.18178/ijeetc.9.6.441-446.
Full textAbstract:
Horizontal Axis Wind Turbine (HAWT) is one of the most important devices for electricity generation from Wind Energy, and design of new blades has become a fundamental research field to improve the efficiency and to reduce cost of this system. This article presents a preliminary comparison between two micro Wind Turbines (WT), one with standard blades and another one with Wavy Leading Edge (WLE) morphology, inspired by the flippers of the humpback whale, to work at low-speed wind conditions. To perform a correct validation, the authors propose a four steps approach for the design, manufacture and test of a WT. First, the design of the blade, followed by the design of the Wind Turbine (WT). Next step is the manufacture of two functional models, one with WLE and another with standard blades, to make a relative comparison, and, finally, the acquisition of real-time data from these systems for the corresponding analysis in terms of energy generation. Results show that the WLE has an increase of over 20% in energy production in all the tests that were performed, with respect to the standard blade.
28
Tu, Baofeng, Hao Wang, and Jun Hu. "Investigation on the aerodynamic performance of high camber turning angle cascade with tubercle leading edge." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, January 21, 2020, 095765091990123. http://dx.doi.org/10.1177/0957650919901238.
Full textAbstract:
In order to improve the performance of high-loaded compressor stator with large camber turning angle, a stator cascade blade with tubercle leading edge was designed based on the wavy leading edge of humpback’s flipper, and computational fluid dynamics simulation was carried out. The results show that the tubercle leading edge can effectively improve the aerodynamic performance of the stator cascade at high attack angles, and the total pressure loss coefficient can be reduced by 26.46%. The main reason why the tubercle structure improves the performance is that it makes the radial displacement of airflow appear as a butterfly-like structure at the leading edge of the blade, which restrains the occurrence and development of airflow separation. By comparing the performance of the blades with full-span and part-span tubercle leading edges, it is considered that the tubercle leading edge of 80% blade height in the mainstream region can improve the aerodynamic performance of cascade better, while the one of 50% blade height has the worst effect.
29
Prabhu, S. Gowtham, Azhagarasan S., Pavithra K., and Sasi G. "Experimental Investigation of Propeller Performance with Propeller Surface Corrugations." Research Journal of Engineering and Technology, June 30, 2021, 39–43. http://dx.doi.org/10.52711/2321-581x.2021.00007.
Full textAbstract:
The propeller is the primary component of flying vehicles powered by electric motors, internal combustion engines, and turboprops for producing thrust. A propeller thrust is produced in the engine by effective spinning of the propeller through air for cost-effective and environmental friendly flight. Natural flyers like birds as well as aquatic animals like humpback whales effectively use its wings and flippers with its surface features for capturing its prey and escaping from their enemies. As part of this work, corrugations are established in the leading edges or in the suction surfaces of the propeller to modify the flow field prevailing over there. Because of the flow field, the surface corrugations or leading edge corrugations energize the boundary layer in the surfaces of the propeller by counter-rotating vortices which, in turn, delays the separation of the boundary layer from the surface. The performance parameters of the propeller such as thrust, torque, propeller efficiency, power consumption etc., are measured using propeller test rig. Depending on the location of surface or leading corrugations, the variations in the performance of the propeller are investigated for further optimization on the selection of better propeller to the applications of UAVs operating at low Reynolds No.