Using Hydrodynamic Testing to Assess the Performance of Five Fouling Control Coatings Immersed at Two Field Sites along the East Coast of Florida

2017 ◽  
Author(s):  
J. Travis Hunsucker ◽  
Harrison Gardner ◽  
Geoffrey Swain
Keyword(s):  
High Speed ◽  
East Coast ◽  
Immersion Test ◽  
Fouling Control ◽  
Drag Forces ◽  
Fouling Release ◽  
Fouling Control Coatings ◽  
Fouling Organisms ◽  
Hydrodynamic Testing ◽  
Static Immersion

Static immersion studies are commonly used to assess the performance of fouling control coatings. While these tests provide valuable data, it is also of importance to understand the drag forces associated with the accrued fouling communities and the velocities required for fouling removal. Combining the measurements of hydrodynamic testing with those from static immersion testing can help in predicting the performance of coatings prior to their consideration for use on Navy vessels. Replicates of five commercially available coatings (three fouling release coatings and two biocide based coatings) were deployed at two static immersion test sites located along the east coast of Florida (Port Canaveral and Sebastian Inlet). After four months of immersion, the panels were removed, photographed, subjected to known water velocities in a high-speed boat modified for hydrodynamic testing. Each panel was run at 5 m/s for 10 minutes, photographed, and then run at 10 m/s for 10 minutes. The drag forces were measured at speeds of 3, 6, 8.8 and 10 m/s for 1 minute each. Photographs taken before, during, and after hydrodynamic testing were also visually analyzed. After testing adhesion measurements were taken to determine the attachment strength of any hard fouling organisms which remained on the panels. The data collected from this series of tests, enabled the fouling control and fouling release properties of each coating to be characterized.

A High Speed Boat for the Hydrodynamic Testing of Fouling Control Coatings

2017 ◽  
Author(s):  
J. Travis Hunsucker ◽  
Harrison Gardner ◽  
Geoffrey Swain
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Load Cell ◽  
Structure Characterization ◽  
Hydrodynamic Drag ◽  
Experimental Uncertainty ◽  
High Definition ◽  
Fouling Control ◽  
Drag Forces ◽  
Fouling Control Coatings

An 8.2 m high speed boat was modified to measure the drag and to provide real time video of ship hull fouling control coatings under boundary layer conditions that developed at speeds up to 15 m/s. It consists of a through hull Hydrodynamic Drag Meter (HDM) placed in a wet-well built into the aft section of the boat. The HDM consists of a load cell attached to a floating element balance and a high definition video camera to observe fouling. Test panels are attached to the load cell such that they remain flush with the hull. Fouled test panels are placed in the facility to observe the velocities required for fouling removal and changes in drag forces associated with different fouling community structure. Characterization studies of the HDM were undertaken to understand the overall accuracy of the novel testing system. These experiments included 1) Smooth acrylic drag measurement with the HDM and a Preston tube and 2) Drag measurements with the HDM on panels with 60- grit and 220-grit sandpaper. Smooth panel wall shear stress values obtained using the HDM were within experimental uncertainties of results from Preston tube. Roughness function values for 60-grit and 220-grit sandpaper agree within the experimental uncertainty of the Nikuradse-type roughness function for uniform roughness. Skin friction coefficients of a smooth panel determined on the HDM had an experimental uncertainty of around 5% for Froude numbers greater than 1. Roughness function values for a 220-grit and 60-grit sandpaper surface had maximum uncertainties of 11% and 13% respectively.

scholarly journals Using hydrodynamic testing to assess the performance of fouling control coatings

2019 ◽  
Vol 194 ◽  
pp. 106677 ◽  
Author(s):  
Kelli Z. Hunsucker ◽  
Harrison Gardner ◽  
Kody Lieberman ◽  
Geoff Swain
Keyword(s):  
Fouling Control ◽  
Fouling Control Coatings ◽  
Hydrodynamic Testing

scholarly journals Marine biofilms on different fouling control coating types reveal differences in microbial community composition and abundance

2021 ◽  
Author(s):  
Maria Papadatou ◽  
Samuel Robson ◽  
Sergey Dobretsov ◽  
Joy E. M. Watts ◽  
Jennifer Longyear ◽  
...  
Keyword(s):  
Protective Coatings ◽  
Microbial Community Composition ◽  
Rrna Gene ◽  
Shipping Industry ◽  
Fouling Control ◽  
Coating Type ◽  
Fouling Release ◽  
Marine Applications ◽  
Fouling Control Coatings ◽  
Inert Surfaces

Marine biofouling imposes serious environmental and economic impacts on marine applications, especially in the shipping industry. To combat biofouling, protective coatings are applied on vessel hulls which are divided into two major groups: biocidal and non-toxic fouling-release. The aim of the current study was to explore the effect of coating type on microbial biofilm community profiles to better understand the differences between the communities developed on fouling control biocidal antifouling and biocidal-free coatings. Biocidal (Intersmooth(R) 7460HS SPC), fouling-release (Intersleek(R) 900), and inert surfaces were deployed in the marine environment for 4 months and the biofilms that developed on these surfaces were investigated using Illumina NGS sequencing, targeting the prokaryotic 16S rRNA gene. The results confirmed differences in the community profiles between coating types. The biocidal coating supported communities dominated by Alphaproteobacteria (Loktanella, Sphingorhabdus, Erythrobacter) and Bacteroidetes (Gilvibacter), whilst other taxa such as Portibacter and Sva0996 marine group, proliferated on the fouling-release surface. Knowledge of these marine biofilm components on fouling control coatings will serve as a guide for future investigations of marine microfouling as well as informing the coatings industry of potential microbial targets for robust coating formulations.

scholarly journals Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 559
Author(s):  
Lakshminath Kundanati ◽  
Prashant Das ◽  
Nicola M. Pugno
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Speed ◽  
Prey Capture ◽  
High Speed Photography ◽  
Sensory Organs ◽  
Dragonfly Nymph ◽  
Drag Forces ◽  
Predatory Insects ◽  
Dragonfly Nymphs

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

Prediction of drag and lift forces of a high-speed vessel at full scale by CFD-based GEOSIM method

2022 ◽  
pp. 147509022110707
Author(s):  
Ugur Can ◽  
Sakir Bal
Keyword(s):  
High Speed ◽  
Full Scale ◽  
Navier Stokes ◽  
Drag Forces ◽  
Fluid Body ◽  
Unsteady Rans ◽  
Lift Forces ◽  
Drag And Lift ◽  
Lift And Drag ◽  
Model Family

In this study, it was aimed to obtain an accurate extrapolation method to compute lift and drag forces of high-speed vessels at full-scale by using CFD (Computational Fluid Dynamics) based GEOSIM (GEOmetrically SIMilar) method which is valid for both fully planing and semi-planing regimes. Athena R/V 5365 bare hull form with a skeg which is a semi-displacement type of high-speed vessel was selected with a model family for hydrodynamic analyses under captive and free to sinkage/trim conditions. Total drag and lift forces have been computed for a generated GEOSIM family of this form at three different model scales and full-scale for Fr = 0.8 by an unsteady RANS (Reynolds Averaged Navier–Stokes) solver. k–ε turbulence model was used to simulate the turbulent flow around the hulls, and both DFBI (Dynamic Fluid Body Interaction) and overset mesh technique were carried out to model the heave and pitch motions under free to sinkage/trim condition. The computational results of the model family were used to get “drag-lift ratio curve” for Athena hull at a fixed Fr number and so the corresponding results at full scale were predicted by extrapolating those of model scales in the form of a non-dimensional ratios of drag-lift forces. Then the extrapolated full-scale results calculated by modified GEOSIM method were compared with those of full-scale CFD and obtained by Froude extrapolation technique. The modified GEOSIM method has been found to be successful to compute the main forces (lift and drag) acting on high-speed vessels as a single coefficient at full scale. The method also works accurately both under fully and semi-planing conditions.

Effects of Dissolved Gas on Unsteady Cavitating Flow Around a Clark Y-11.7% Hydrofoil

2015 ◽  
Author(s):  
Haruki Daido ◽  
Satoshi Watanabe ◽  
Shin-ichi Tsuda
Keyword(s):  
High Speed ◽  
Cavitating Flow ◽  
Gas Content ◽  
Dissolved Gas ◽  
Drag Forces ◽  
Cavitation Behavior ◽  
Lift And Drag ◽  
Super Cavity ◽  
Unsteady Cavitating Flow ◽  
Low Do

In the present study, the effects of dissolved gas content on the unsteady cavitating flow around a Clark Y-11.7% hydrofoil are investigated in a cavitation tunnel. Lift and drag forces in various cavitating conditions are directly measured by strain gauges attached on the cantilever supporting the hydrofoil. In addition, the cavitating flow is filmed from the top and the side simultaneously using two high speed video cameras. The high (roughly 6–8ppm) and low (1–2ppm) DO conditions are examined to obtain the qualitative tendencies of the effects of dissolved gas on unsteady cavitation behavior and lift/drag characteristics. It is found that that the relationship between the cavitation behavior and the lift/drag fluctuations does not qualitatively differ in the two different DO conditions, while the amplitude is slightly larger in the low DO condition. At transitional cavity oscillation, in the both DO conditions, the lift/drag coefficients increase during the growth stage of sheet/bubble cavities on the hydrofoil and they decrease when the developed super-cavity disappears. Moreover, it seems that the amplitude of the lift/drag forces in the low DO condition is larger than in the high DO condition but the frequency of lift force fluctuation is not very different.

Preparation and Characterization of a Novel Hydrogel-Based Fouling Release Coating

2017 ◽  
Vol 898 ◽  
pp. 1539-1544
Author(s):  
Lin Liu ◽  
Zi Jie Li ◽  
Sen Sun ◽  
Ting You ◽  
Xiao Tong Qi ◽  
...  
Keyword(s):  
Surface Tension ◽  
Rapid Development ◽  
Salt Spray ◽  
Immersion Test ◽  
Salt Spray Test ◽  
Transportation Industry ◽  
Water Contact ◽  
Marine System ◽  
Fouling Release

With the rapid development of marine transportation industry, biological fouling not only affects the speed of navigation but also highly increases fuel consumption. In the paper, a novel hydrogel-based fouling release coating is developed to address the issue by a combination of non-stick property with a low surface tension of the coating. A hydrogel-based silicone fouling release coating was synthesized and two kinds of different intermediate coatings were studied to give a proper match as the tie layer between the substrate coated with primer and the hydrogel silicone on the surface. The adhesion strength, surface tension as well as surface topography of the fouling release coating were studied. The corrosion resistance and anti-fouling performance of the substrates sprayed with the coating were characterized by salt spray test and immersion test in a simulated marine system. The results show that the adhesion between the substrate and the fouling release coating is grade two measured by grid test. The water contact angle of the coating is 104.8o and Rz of the coating is 10.71μm. The specimen is intact after 1000 hours under salt spray test. No diatom was found settled on the specimens in a simulated static marine system while a little diatom was observed on the specimens in a simulated dynamic marine system. It has been found that the intermediate coating comprising of epoxy resin gives proper match between the primer and the fouling release coating consisting of PDMS resin. The coating exhibits superior anti-fouling performance under stationary state.

scholarly journals Mechanical models of sandfish locomotion reveal principles of high performance subsurface sand-swimming

2011 ◽  
Vol 8 (62) ◽  
pp. 1332-1345 ◽  
Author(s):  
Ryan D. Maladen ◽  
Yang Ding ◽  
Paul B. Umbanhowar ◽  
Adam Kamor ◽  
Daniel I. Goldman
Keyword(s):  
High Speed ◽  
High Performance ◽  
Granular Media ◽  
The Body ◽  
Physical Models ◽  
Particle Simulation ◽  
Sinusoidal Wave ◽  
Drag Forces ◽  
Single Period ◽  
Discrete Particle Simulation

We integrate biological experiment, empirical theory, numerical simulation and a physical model to reveal principles of undulatory locomotion in granular media. High-speed X-ray imaging of the sandfish lizard, Scincus scincus , in 3 mm glass particles shows that it swims within the medium without using its limbs by propagating a single-period travelling sinusoidal wave down its body, resulting in a wave efficiency, η , the ratio of its average forward speed to the wave speed, of approximately 0.5. A resistive force theory (RFT) that balances granular thrust and drag forces along the body predicts η close to the observed value. We test this prediction against two other more detailed modelling approaches: a numerical model of the sandfish coupled to a discrete particle simulation of the granular medium, and an undulatory robot that swims within granular media. Using these models and analytical solutions of the RFT, we vary the ratio of undulation amplitude to wavelength ( A / λ ) and demonstrate an optimal condition for sand-swimming, which for a given A results from the competition between η and λ . The RFT, in agreement with the simulated and physical models, predicts that for a single-period sinusoidal wave, maximal speed occurs for A / λ ≈ 0.2, the same kinematics used by the sandfish.

Sign in / Sign up

Export Citation Format

Share Document