Numerical analysis of broadband noise reduction with wavy leading edge

Tong, Fan; Qiao, Weiyang; Chen, Weijie; Cheng, Hao-Yi; Wei, Renke; Wang, Xunnian

doi:10.1016/j.cja.2018.03.020

Cited by 32 publications

(19 citation statements)

References 29 publications

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“…In separate reviews of tubercle applications [3,39], tubercled leading edges were found to reduce unsteady fluctuations and tonal noise, thereby improving efficiency. In a numerical study using an upstream cylinder to generate turbulence, Tong et al [49] discovered tubercled leading edges provided a substantial reduction in lift and drag fluctuations. Considering the humpback whale, it makes sense their fins are designed to extract as much power as possible during a maneuver, optimizing stability amidst turbulent flow.…”

Section: Plos Onementioning

confidence: 99%

Performance evaluation of humpback whale-inspired shortboard surfing fins based on ocean wave fieldwork

Shormann

Panhuis

2020

PLoS ONE

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We present field results revealing improved surfing performance when a novel approach ("Real Whale", RW) is used for applying several of the humpback whale's passive flow control mechanisms, including tubercles, to surfboard fins. It is also the first study presenting evidence of dynamic performance of tubercled designs rotating on all three axes. We evaluated low aspect ratio, thruster-style 3-fin configurations used in high-performance surfing. Fieldwork involved surfing almost 2,000 ocean waves from around the world, comparing standard commercial fins with straight leading edges to RW fins. We collected surfing data from instrumentation attached to surfboards, including GPS and 9-axis motion sensors. Eighteen turn performance values were measured and calculated, including novel, surfingspecific rotational power coefficients. ANOVA revealed surfers using RW fins showed significant improvements in power generation compared to when they used standard commercial fins. Turn rates using RW fins also improved, although not significantly. We found using RW fins allowed a skilled surfer to improve their surfing performance relative to a professionally ranked surfer.

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Section: Plos Onementioning

confidence: 99%

Performance evaluation of humpback whale-inspired shortboard surfing fins based on ocean wave fieldwork

Shormann

Panhuis

2020

PLoS ONE

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“…Zhang & Frendi [36] used numerical simulations to investigate the influence of LE tubercles on the noise from an aerofoil in the wake of a cylinder, showing that the near-field sound pressure level was found to be between 4 and 10 dB lower for the wavy LE aerofoil depending on location. Tong et al [37] used LES to show that LE tubercle-modified aerofoil could reduce the far-field noise by an average of 9.5 dB at the azimuthal angle of 90°when compared to the reference design. In maritime applications, there is a lot of potential to implement LE tubercles for noise reduction purposes.…”

Section: Introductionmentioning

confidence: 99%

“…Tong et al . [ 37 ] used LES to show that LE tubercle-modified aerofoil could reduce the far-field noise by an average of 9.5 dB at the azimuthal angle of 90° when compared to the reference design. In maritime applications, there is a lot of potential to implement LE tubercles for noise reduction purposes.…”

Section: Introductionmentioning

confidence: 99%

Hydroacoustic and hydrodynamic investigation of bio-inspired leading-edge tubercles on marine-ducted thrusters

Stark

Shi

2021

R. Soc. open sci.

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Underwater radiated noise (URN) has a negative impact on the marine acoustic environment where it can disrupt marine creature's basic living functions such as navigation and communication. To control the ambient ocean noise levels due to human activities, international governing bodies such as the International Maritime Organization (IMO) have issued non-mandatory guidelines to address this issue. Under such framework, the hydroacoustic performance of marine vehicles has become a critical factor to be evaluated and controlled throughout the vehicles' service life in order to mitigate the URN level and the role humankind plays in the ocean. This study aims to apply leading-edge (LE) tubercles of the humpback whales’ pectoral fins to a benchmark ducted propeller to investigate its potential in noise mitigation. This was conducted using CFD, where the high-fidelity improved delayed detached eddy simulations (IDDES) in combination with the porous Ffowcs-Williams Hawkings (FW-H) acoustic analogy was used to solve the hydrodynamic flow field and propagate the generated noise to the far-field. It has been found that the LE tubercles have shown promising noise mitigation capabilities in the far-field, where the OASPL at J = 0.1 was reduced to a maximum of 3.4 dB with a maximum of 11 dB reduction in certain frequency ranges at other operating conditions. Based on detailed flow analysis researching the fundamental vortex dynamics, this noise reduction is shown to be due to the disruption of the coherent turbulent wake structure in the propeller slipstream causing the acceleration in the dissipation of turbulence and vorticity-induced noise.

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“…The wavy leading edge shows enhancement in the lift to drag ratio with suppressed fluctuations. This is because of the generation of vortex pair from the peak (Tong et al , 2018; Rostamzadeh et al , 2013). The wavy design increases the aerodynamic efficiency (lift increases and drag decreases) at high angles (Kobæk and Hansen, 2016; Colpitts et al , 2020).…”

Section: Introductionmentioning

confidence: 99%

Flow separation control using a bio-inspired nose for NACA 4 and 6 series airfoils

Mohamed

Yadav

Güven

2021

AEAT

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Purpose This paper aims to achieve an optimum flow separation control over the airfoil using a passive flow control method by introducing a bio-inspired nose near the leading edge of the National Advisory Committee for Aeronautics (NACA) 4 and 6 series airfoil. In addition, to find the optimised leading edge nose design for NACA 4 and 6 series airfoils for flow separation control. Design/methodology/approach Different bio-inspired noses that are inspired by the cetacean species have been analysed for different NACA 4 and 6 series airfoils. Bio-inspired nose with different nose length, nose depth and nose circle diameter have been analysed on airfoils with different thicknesses, camber and camber locations to understand the aerodynamic flow properties such as vortex formation, flow separation, aerodynamic efficiency and moment. Findings The porpoise nose design that has a leading edge with depth = 2.25% of chord, length = 0.75% of chord and nose diameter = 2% of chord, delays the flow separation and improves the aerodynamic efficiency. Average increments of 5.5% to 6° in the lift values and decrements in parasitic drag (without affecting the pitching moment) for all the NACA 4 and 6 series airfoils were observed irrespective of airfoil geometry such as different thicknesses, camber and camber location. Research limitations/implications The two-dimensional computational analysis is done for different NACA 4 and 6 series airfoils at low subsonic speed. Practical implications This design improves aerodynamic performance and increases the structural strength of the aircraft wing compared to other conventional high lift devices and flow control devices. This universal leading edge flow control device can be adapted to aircraft wings incorporated with any NACA 4 and 6 series airfoil. Social implications The results would be of significant interest in the fields of aircraft design and wind turbine design, lowering the cost of energy and air travel for social benefits. Originality/value Different bio-inspired nose designs that are inspired by the cetacean species have been analysed for NACA 4 and 6 series airfoils and universal optimum nose design (porpoise airfoil) is found for NACA 4 and 6 series airfoils.

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Numerical analysis of broadband noise reduction with wavy leading edge

Cited by 32 publications

References 29 publications

Performance evaluation of humpback whale-inspired shortboard surfing fins based on ocean wave fieldwork

Performance evaluation of humpback whale-inspired shortboard surfing fins based on ocean wave fieldwork

Hydroacoustic and hydrodynamic investigation of bio-inspired leading-edge tubercles on marine-ducted thrusters

Flow separation control using a bio-inspired nose for NACA 4 and 6 series airfoils

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