Propeller tip vortex mitigation by roughness application

Asnaghi, Abolfazl; Svennberg, Urban; Gustafsson, Robert; Bensow, Rickard

doi:10.1016/j.apor.2020.102449

Cited by 23 publications

(8 citation statements)

References 30 publications

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“…Based on our previous studies for mitigation of back side tip vortices [34,47], the tip region of the refined blade, Figure 3, is considered the starting point to investigate the roughness impact on for wider operating conditions.…”

Section: Case Descriptionmentioning

confidence: 99%

“…The summary of evaluated roughness patterns and arrangements are presented in Table 2. Following our previous studies [34,47], all of the analysis is performed by considering a fixed value for the roughness height, K s =250 µm in model scale condition; this corresponds to K + s = 35. The roughness height is extended into the full scale condition by considering the geometrical scale ratio.…”

Section: Case Descriptionmentioning

confidence: 99%

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Propeller Tip Vortex Mitigation By Roughness Application

Asnaghi¹,

Svennberg²,

Gustafsson³

et al. 2020

Preprint

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In this study, the application of surface roughness on model and full scale marine propellers in order to mitigate tip vortex cavitation is evaluated. To model the turbulence, SST k − ω model along with a curvature correction is employed to simulate the flow on an appropriate grid resolution for tip vortex propagation, at least 32 cells per vortex diameter according to our previous guidelines. The effect of roughness is modelled by modified wall functions.The analysis focuses on two types of vortices appearing on marine propellers: tip vortices developing in lower advance ratio numbers and leading edge tip vortices developing in higher advance ratio numbers. It is shown that as the origin and formation of these two types of vortices differ, different roughness patterns are needed to mitigate them with respect to performance degradation of propeller performance. Our findings clarify that the combination of having roughness on the blade tip and a limited area on the leading edge is the optimum roughness pattern where a reasonable balance between tip vortex cavitation mitigation and performance degradation can be achieved. This pattern in model scale condition leads to an average TVC mitigation of 37% with an average performance degradation of 1.8% while in full scale condition an average TVC mitigation of 22% and performance degradation of 1.4% are obtained.

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Section: Case Descriptionmentioning

confidence: 99%

Section: Case Descriptionmentioning

confidence: 99%

Propeller Tip Vortex Mitigation By Roughness Application

Asnaghi¹,

Svennberg²,

Gustafsson³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…On the other hand, most other noise mitigation strategies are focused on the cavitating propeller, such as pressure pore technology and the roughness application to unload the propeller tip and reduce tip vortex cavitation [ 10 , 11 ]. This does come at the cost of hydrodynamic performance, therefore highlighting the challenge within the maritime industry, maintaining hydrodynamic performance while simultaneously reducing the URN or vice-versa.…”

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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“…In addition to this, the inclusion of additional geometry at the propeller blade tips, drilling holes and application of extra roughness on the propeller blades can be considered as alternative passive TVC mitigation methods (e.g., A. Feizi Chekab et al, 2013;Aktas et al, 2020;Asnaghi et al, 2020a;Asnaghi et al, 2020b). Amongst the different passive methods, the application of roughness on the propeller blades, which is the main interest of this study, becomes an appealing and suitable method to reduce the cavitation, hence propeller URN, particularly for retrofitting projects.…”

Section: Introductionmentioning

confidence: 99%

“…less than 2%). Following this study, the authors extended their investigation for Influence of roughness on propeller performance with a view to mitigating tip vortex cavitation the marine propellers using CFD (Asnaghi et al, 2020b). The authors achieved the suppression of TVC considerably by keeping the efficiency loss as small as possible both in the model and full-scale propeller with the application of roughness on the strategic areas at the blade surfaces under the uniform flow conditions.…”

Section: Introductionmentioning

confidence: 99%