Cavitation funnel effect: Bio-inspired leading-edge tubercle application on ducted marine propeller blades

Stark, Callum; Shi, Weichao; Troll, Moritz

doi:10.1016/j.apor.2021.102864

Cited by 33 publications

(14 citation statements)

References 37 publications

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“…Tubercle-assisted propellers (TAPs), shown in (see Figure 9d) are a largely unproven technology of low maturity, but initial model-scale CFD has shown a maximum 6.5% improvement in propulsive efficiency in heavy-cavitating conditions, with a reduction in pressure pulse fluctuation and vibrations. Tubercles are inspired by the bumps on humpback whales and have shown a reduction of 50% in cavitation volume due to induced cavitation funnelling/fencing patterns because of the change in surface pressure distributions of the blade [100]. They can be applied to propellers as a retrofit or as a new design.…”

Section: Propeller and Hub Modificationsmentioning

confidence: 99%

“…The reduction in cavitation results in a reduction in the fluctuating thrust and torque from the propeller, which would be an extra benefit to the hydrogen drivetrain with a steadier load on the shaft compared to the baseline design, reducing negative impacts on the fuel cell. The TAPs have a wide range of applications, being applied to open propeller blades [101] as well as ducted propeller blades [100], with the possibility to provide benefits to various types of marine craft. Further research through model-scale test campaigns and numerical, full-scale investigations in the behind-hull condition is required to confirm the propulsive efficiency improvement and quantity the energy savings in a realistic setting.…”

Section: Propeller and Hub Modificationsmentioning

confidence: 99%

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Study on Applicability of Energy-Saving Devices to Hydrogen Fuel Cell-Powered Ships

Stark

Zhang

et al. 2022

JMSE

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The decarbonisation of waterborne transport is arguably the biggest challenge faced by the maritime industry presently. By 2050, the International Maritime Organization (IMO) aims to reduce greenhouse gas emissions from the shipping industry by 50% compared to 2008, with a vision to phase out fossil fuels by the end of the century as a matter of urgency. To meet such targets, action must be taken immediately to address the barriers to adopt the various clean shipping options currently at different technological maturity levels. Green hydrogen as an alternative fuel presents an attractive solution to meet future targets from international bodies and is seen as a viable contributor within a future clean shipping vision. The cost of hydrogen fuel—in the short-term at least—is higher compared to conventional fuel; therefore, energy-saving devices (ESDs) for ships are more important than ever, as implementation of rules and regulations restrict the use of fossil fuels while promoting zero-emission technology. However, existing and emerging ESDs in standalone/combination for traditional fossil fuel driven vessels have not been researched to assess their compatibility for hydrogen-powered ships, which present new challenges and considerations within their design and operation. Therefore, this review aims to bridge that gap by firstly identifying the new challenges that a hydrogen-powered propulsion system brings forth and then reviewing the quantitative energy saving capability and qualitive additional benefits of individual existing and emerging ESDs in standalone and combination, with recommendations for the most applicable ESD combinations with hydrogen-powered waterborne transport presented to maximise energy saving and minimise the negative impact on the propulsion system components. In summary, the most compatible combination ESDs for hydrogen will depend largely on factors such as vessel types, routes, propulsion, operation, etc. However, the mitigation of load fluctuations commonly encountered during a vessels operation was viewed to be a primary area of interest as it can have a negative impact on hydrogen propulsion system components such as the fuel cell; therefore, the ESD combination that can maximise energy savings as well as minimise the fluctuating loads experienced would be viewed as the most compatible with hydrogen-powered waterborne transport.

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Section: Propeller and Hub Modificationsmentioning

confidence: 99%

Section: Propeller and Hub Modificationsmentioning

confidence: 99%

Study on Applicability of Energy-Saving Devices to Hydrogen Fuel Cell-Powered Ships

Stark

Zhang

et al. 2022

JMSE

Self Cite

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“…The ZGB model is based on the assumption that the cavitation bubbles do not influence each other and that the vapor core density decreases with the increase in the vapor volume fraction. In Equation (8), m e and m c represent the source terms of vapor generation and condensation, respectively. The radius of the vapor core R B is 10 −6 m, the volume fraction α nuc at the nucleation location is 5 × 10 −4 , the evaporation coefficient F vap is 50, and the condensation coefficient F cond is 0.01.…”

Section: Cavitation Modelsmentioning

confidence: 99%

“…Vortex cavitation [1] is a common physical phenomenon in hydraulic machines, and it usually occurs at the inlet [2] and the draft tube [3,4] of the hydraulic machinery, and the tail of the blade, such as pump impeller [5] and marine propeller [6][7][8]. Cavitation could cause pressure fluctuation [9,10], uneven load distribution, hydrodynamic noise [11] and erosion [12], which seriously reduce the operation efficiency of the hydraulic machine.…”

Section: Introductionmentioning

confidence: 99%

Cavitation of Multiscale Vortices in Circular Cylinder Wake at Re = 9500

Huang

Stankovic

2021

JMSE

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Cavitation characteristics in the wake of a circular cylinder, which contains multiscale vortices, are numerically investigated via Large Eddy Simulation (LES) in this paper. The Reynolds number is 9500 based on the inlet velocity, the cylinder diameter and the kinematic viscosity of the noncavitation liquid. The Schneer–Sauer (SS) model is applied to cavitation simulation because it is more sensitive to vapor–liquid two-phase volume fraction than the Zwart–Gerber–Belamri (ZGB) model, according to theoretical analyses. The wake is quasiperiodic, with an approximate frequency of 0.2. It is found that the cavitation of vortices could inhibit the vortex shedding. Besides, the mutual aggregation of small-scale vortices in the vortex system or the continuous stripping of small-scale vortices at the edge of large-scale vortices could induce the merging or splitting of cavities in the wake.

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“…According to the investigations on the ducted propeller, the duct existence delays the wake constraction [27] and changes the tip vortex trajectory [28]. The bio-inspired blade also weakens the effects of low pressure in tip clearance leakage flow on the blade suction side [29]. For a propeller, the tip flow characterizes its wake topology.…”

Section: Introductionmentioning

confidence: 99%

Effects of Blade Number on the Propulsion and Vortical Structures of Pre-Swirl Stator Pump-Jet Propulsors

Han

Huang

Pan

et al. 2021

JMSE

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Reducing the noise of the underwater propulsor is gaining more and more attention in the marine industry. The pump-jet propulsor (PJP) is an extraordinary innovation in marine propulsion applications. This paper inspects the effects of blade number on a pre-swirl stator pump-jet propulsor (PJP) quantitatively and qualitatively. The numerical calculations are conducted by IDDES and ELES, where the ELES is only adopted to capture the vortical structures after refining the mesh. The numerical results show good agreement with the experiment. Detailed discussions of the propulsion, the features of thrust fluctuation in time and frequency domains, and the flow field are involved. Based on the ELES results, the vortices in the PJP flow field and the interactions between the vortices of the stator, rotor, and duct are presented. Results suggest that, though changing the blade number under a constant solidity does not affect the propulsion, it has considerable effects on the thrust fluctuation of PJP. The wakes of the stator and rotor are also notably changed. Increasing the stator blade numbers has significantly weakened the high-intensity vortices in the stator wake and, hence, the interaction with the rotor wake vortices. The hub vortices highly depend upon the wake vortices of the rotor. The hub vortices are considerably broken by upstream wake vortices when the load per rotor blade is high. In summary, the blade number is also vital for the further PJP design, particularly when the main concerns are exciting force and noise performance.

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Cavitation funnel effect: Bio-inspired leading-edge tubercle application on ducted marine propeller blades

Cited by 33 publications

References 37 publications

Study on Applicability of Energy-Saving Devices to Hydrogen Fuel Cell-Powered Ships

Study on Applicability of Energy-Saving Devices to Hydrogen Fuel Cell-Powered Ships

Cavitation of Multiscale Vortices in Circular Cylinder Wake at Re = 9500

Effects of Blade Number on the Propulsion and Vortical Structures of Pre-Swirl Stator Pump-Jet Propulsors

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