Journal articles: 'Towing Tank Test'

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Mori, Takayuki. "Hydrodynamic Test Facilities in Naval Systems Research Center- Large Towing Tank, High Speed Towing Tank and Flow Noise Simulator." Marine Engineering 56, no. 6 (November 1, 2021): 867–71. http://dx.doi.org/10.5988/jime.56.867.

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Tsai, Jing-Fa, and Chi-Chuan Chen. "Boundary Layer Mixture Model for a Microbubble Drag Reduction Technique." ISRN Mechanical Engineering 2011 (July 14, 2011): 1–9. http://dx.doi.org/10.5402/2011/405701.

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The boundary mixture model is derived to predict the performance of the microbubble drag reduction technique for a flat plate. The flat plate with a porous material microbubble injecting system and resistance-measuring system are set up to measure the frictional resistance of the flat plate without and with injected microbubbles. The tests are conducted in a water tunnel and a towing tank. The test results show that the boundary mixture model predicts the drag reduction well for the flat plate when testing with injected microbubbles in the water tunnel. However, the boundary mixture model overestimates the drag reduction effect for the flat plate tested in the towing tank. The possible mechanism for the overestimation of drag reduction effect in the towing tank may be due to the different behaviors of microbubbles in the velocity gradient of boundary layer.

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Syamsuar, Sayuti. "Gaya Hambat Saat Hidro Planing dan Gaya Angkat Aerodinamika Saat Cruise di Efek Permukaan pada Pesawat Wing in Surface Effect." WARTA ARDHIA 42, no. 2 (September 22, 2017): 71. http://dx.doi.org/10.25104/wa.v42i2.237.71-78.

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Perhitungan komputasional dinamika fluida pada model 3 Dimensi pada pesawat Wung In Surface Effect sangat penting untuk mengetahui data hasil uji towing tank dan uji terbang. Konfigurasi Lippisch mempunyai sayap berbentuk inverse delta dan punuk di atasnya menggunakan airfoil jenis Clark Y yang telah dirancang untuk memenuhi karakteristik efek permukaan. Piranti lunak pertama Maxsurf digunakan untuk membandingkan hasil uji model towing tank saat fase hydro planing. Piranti lunak kedua ANSYS CFX digunakan untuk menghitung gaya hambat air dan gaya angkat aerodinamika dari pesawat Wing In Surface Effect kapasitas 8 orang model 3 Dimensi dengan konfigurasi Berat Maksimum saat take off sebesar 32000 Newton pada kecepatan cruise 80 knots pada ketinggian terbang 2.5 meter. Aspek eksperimen pada uji model towing tank dan data uji terbang pada prototipe pesawat Wing In Surface Effect kapasitas (1-2) orang saat hydro planing dijelaskan dengan menggunakan teori gelombang hidrodinamika dan porpoising efek. [The Hump Drags During Hydro planing and Aerodynamic Lift During Cruise in Surface Effect Altitude Of Wing in Surface Effect Craft] The computational fluid dynamics of 3 Dimensions model of Wing in Surface Effect craft is very important to proof the model towing test and flight testing data. The inverse delta wing and shoulder airfoil is by using Clark Y of Lippisch configurations have been designed for the surface effect characteristics. The first Maxsurf software are used to compared the towing test results during hydro planing phase. The second ANSYS CFX software is used to calculate the hump drags and aerodynamic lift of Wing In Surface Effect craft 8 seaters 3 Dimensions model to verified the Design Requirement and Objectives. The forces equilibrium on the body axis during hydro planing are very important to fulfill the take off phase on the water surface. And, the aerodynamic lift for Maximum Take off Weight of 8 seaters configuration is 32000 Newton during cruise speed at 80 knots on the 2.5 meter altitude. The experimental aspects of towing tank test model and Wing In Surface Effect craft (1-2) seaters prototype during hydro planing test have been proposed by using the hydrodynamic wave and porpoising effect theory.

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Longo, Joe, and Fred Stern. "Uncertainty Assessment for Towing Tank Tests With Example for Surface Combatant DTMB Model 5415." Journal of Ship Research 49, no. 01 (March 1, 2005): 55–68. http://dx.doi.org/10.5957/jsr.2005.49.1.55.

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Uncertainty assessment methodology, procedures, and results are presented for most typical towing tank tests using a 3.048 m geosym of naval combatant DTMB model 5415, which is an established benchmark for computational fluid dynamics validation. The tests include resistance, sinkage and trim, wave profile, wave elevations, and nominal wake. The procedures are summarized and follow International Towing Tank Conference Quality Manual Procedures. The facility and measurement systems are briefly described, and detailed uncertainty assessment examples for each test are provided with descriptions of bias and precision limits and total uncertainties.

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Hiltabrand, Robert R., and Gail S. Roderick. "Fire-Resistant Booms: From Testing to Operations1." International Oil Spill Conference Proceedings 1999, no. 1 (March 1, 1999): 535–39. http://dx.doi.org/10.7901/2169-3358-1999-1-535.

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ABSTRACT A great deal of concern and effort has gone into testing various fire resistant booms since the 1993 Newfoundland Offshore Burn Experiment (NOBE), when it became apparent that there were potential limitations in the performance of commercially manufactured fire booms. One of the major questions that arose after this experiment was the capability of fire booms to adequately support real in situ burn operations. Towing experiments on selected booms both at sea and in test tanks, coupled with data from burn tests based on proposed ASTM-F20 Standards, have begun to new reveal facts about the performance of these booms. Results of the at-sea towing tests indicate that, in general, booms with higher buoyancy-to-weight ratios attained higher critical tow speeds, sustained higher towing tensions, and maintained better wave conformance. Results of towing tests of booms containing oil at the OHMSETT test tank facility suggest that fire booms should perform successfully when tow speeds of less than 1.0 knot is maintained. Burn tests at the U.S. Coast Guard Fire and Test Detachment revealed that fire booms could be expected to maintain some structural stability and freeboard for at least three 1-hour burns during a deployment.

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Li, Guang Nian, and Xin Guo. "Design on the Testing System of the Towing Tank." Advanced Materials Research 217-218 (March 2011): 1026–31. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.1026.

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Considering the requirement of testing on ship powering performance, and the actual situation of the towing tank, a system, which contains the testing module of resistance performance, propeller on open water, self-propulsion and calibration, was designed. And a system software used for measuring ,controlling and analyzing date was written as well. Every modules’ main functions, test requirements and the realization forms were also put forward in this paper. Considering it not only meets the need of the model test mentioned already, but also fits the function expanding in the future, this system was designed to be modularized and scalable. I hope that it could give technical support to the researchers in ship performance and ship construction enterprises.

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Kang, Jung-Min, Yeong-Ho Lee, and Kyu-Chan Lee. "A Comparative Performance Test for Turbine in Wind Tunnel and Towing Tank." Journal of The korean society for new and renewable energy 7, no. 4 (December 25, 2011): 42–49. http://dx.doi.org/10.7849/ksnre.2011.7.4.042.

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Chen, Jeng-Horng, and Che-Chun Chang. "A moving PIV system for ship model test in a towing tank." Ocean Engineering 33, no. 14-15 (October 2006): 2025–46. http://dx.doi.org/10.1016/j.oceaneng.2005.09.011.

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Sverchkov, А. V., and M. V. Galushina. "Transom interceptor for towing resistance reduction of fast displacement ships." Transactions of the Krylov State Research Centre 4, no. 402 (October 14, 2022): 75–84. http://dx.doi.org/10.24937/2542-2324-2022-4-402-85-100.

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Object and purpose of research. This paper discusses three models of fast monohull displacement ships of various purpose and one model of fast passenger catamaran. The purpose of the study was to experimentally verify the efficiency of transom interceptor in towing resistance reduction. Subject matter and methods. The study was based on the test results available with Krylov State Research Centre Deepwater Towing Tank. Main results. This study was performed on four models and showed how their towing resistance depended on interceptor advance and static trim angle. Conclusion. The tests have confirmed the efficiency of transom interceptor in towing resistance reduction of fast displacement monohulls and catamarans with operational speeds corresponding to Froude numbers 0,4–0,6. Transom interceptor reduces towing resistance by 4,5–6,5 %.

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Ying, Zong Quan, Lin Wang Su, and Mei Hong Lin. "A Scale Model Test on Hydraulic Resistance of Tunnel Elements during Floating Transportation." Advanced Materials Research 919-921 (April 2014): 841–45. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.841.

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The transportation of tunnel elements is one of the most important procedures of immersed tunnel construction. To investigate the hydraulic resistance of tunnel elements during transportation, hydrodynamic scale model tests of the were carried out in a towing tank for the tunnel element transportation under wave action. The test results show that the hydraulic resistance is linear to the square of towing speed basically. The drag coefficients of the element under different water depths and dragging angles are calculated. The dragging coefficient decreases with the increase of water depth, and increases with the increase of the dragging angle. Finally, the influence of the wave is also discussed for the tunnel dragged in the open sea.

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Zen, Hardi, Indra Ranu Kusuma, and Endang Widjiati. "Robust Laboratory Scale Seakeeping Test Wave Measurement Method Use Ultrasonic Sensor." IOP Conference Series: Earth and Environmental Science 1081, no. 1 (September 1, 2022): 012042. http://dx.doi.org/10.1088/1755-1315/1081/1/012042.

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Abstract The seakeeping test is one of the tests done in the Indonesia Hydrodynamic Laboratory (IHL) test tank on a model ship or floating unit. In the test tank, a wave can be generated by using electric and mechanic wave flaps that are pre-programmed on a certain condition of the wave, i.e. different frequencies and amplitude. To measure waves, produced by a wave generator, a wave measuring instrument is needed that can measure changes in water level in the test tank. The current wave measuring instrument is in the form of a 600 mm twin wire wave probe. This instrument is can be used to measure waves in the test tank but has limitations because it is only placed in one location without being moved. Another method is developed to be used in making alternative measuring instruments using ultrasonic sensors. In this paper, this alternative wave measuring instrument shows that measuring waves even when moving the measurement point to a new point location or following a towing carriage can be done and gives better measurement results. Based on these results, this new measuring instrument can be used in a more complex configuration test in the tank.

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More, R. R., Piyush Adhav, K. Senthilkumar, and M. W. Trikande. "Stability and Drag Analysis of Wheeled Amphibious Vehicle Using CFD and Model Testing Techniques." Applied Mechanics and Materials 592-594 (July 2014): 1210–19. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1210.

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Amphibious design of combat vehicle has become a challenging task in the context of increase in Gross Vehicle weight (GVW) of present generation combat vehicles due to demand for high protection levels and higher capacity engine and transmission, incorporation of multiple weapon systems, increased ammunition storage and larger addition of electrical and electronic items. Development of combat vehicles is complex and very expensive, and normally limited with less number of prototypes. The scale modeling and CFD analysis offers a viable solution to accomplish the amphibian design of a combat vehicle with adequate confidence before manufacturing the actual prototype. In the present work, an approach involving experimental towing test using scaled model and CFD simulation has been used to carry out the amphibious design of an 8X8, wheeled, combat vehicle with GVW of 22 ton. In this work, a 1/5thscaled model of the vehicle was manufactured and tested in the towing tank at different test speeds for drag and stability analysis. CFD analysis was carried out on the full scale model to gain adequate details about the dynamics of vehicle in the water in addition to drag estimation. Good correlation has been found in drag values and the flow patterns obtained from towing tank tests and CFD simulations.

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Tun, Thu Han, and Ye Thet Htun. "THE EXPERIMENTAL METHOD AND CFD STUDY OF THE BARE HULL FORM OF UNDERWATER VEHICLE AT NEAR SURFACE CONDITION." ASEAN Engineering Journal 11, no. 1 (March 16, 2021): 24–33. http://dx.doi.org/10.11113/aej.v11.16664.

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Hull form selection, resistance and powering are important in designing underwater vehicle. An underwater vehicle bare hull form is based on the five parameters due to the interaction between the propeller and the hull. When they are running on the surface condition, there will be problems likely as surface vessel, but the main hull of the underwater vehicle is below the waterline with low freeboard. The underwater vehicles are operating with high speed at a high Froude Number. Therefore, the wave making component becomes important in surface resistance. The wave making resistance of the underwater vehicle model at surface condition is analyzed by using CFD tools. Friction component of resistance is calculated by using ITTC’57 correlation line. The flow around the ship’s hull is complicated, so that model experiments are still the most reliable data source on ship resistance determination. The bare hull form of underwater vehicle resistance is based on the model experiments and CFD results. The towing mechanism arrangement should be considered at model. Therefore, towing mechanism is designed for model testing. This paper discusses the towing method and result between model test and CFD. This paper also makes comparison of wave formation Towing tank test and CFD at various speeds. The model was tested with bare hull form of underwater vehicle in the Ship Model Towing Tank at Marine Hydrodynamics Centre, Myanmar Maritime University. CFD analysis is also carried out and the results are compared for surface condition. The three software packages XFLOW, XMESH and XPAN are used for CFD simulations. The comparison of results shows that the coefficient differences are less staggered based on the speed.

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Dai, Kun, and Yunbo Li. "Manoeuvring Prediction of KVLCC2 with Hydrodynamic Derivatives Generated by a Virtual Captive Model Test." Polish Maritime Research 26, no. 4 (December 1, 2019): 16–26. http://dx.doi.org/10.2478/pomr-2019-0062.

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Abstract This paper describes the application of computational fluid dynamics rather than a towing tank test for the prediction of hydrodynamic derivatives using a RANS-based solver. Virtual captive model tests are conducted, including an oblique towing test and circular motion test for a bare model scale KVLCC2 hull, to obtain linear and nonlinear hydrodynamic derivatives in the 3rd-order MMG model. A static drift test is used in a convergence study to verify the numerical accuracy. The computed hydrodynamic forces and derivatives are compared with the available captive model test data, showing good agreement overall. Simulations of standard turning and zigzag manoeuvres are carried out with the computed hydrodynamic derivatives and are compared with available experimental data. The results show an acceptable level of prediction accuracy, indicating that the proposed method is capable of predicting manoeuvring motions.

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Van Dyck, Robert L., and Michael S. Bruno. "EFFECT OF WAVES ON CONTAINMENT BOOM RESPONSE." International Oil Spill Conference Proceedings 1995, no. 1 (February 1, 1995): 880–81. http://dx.doi.org/10.7901/2169-3358-1995-1-880.

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ABSTRACT A series of generic model booms were developed, built, and tested in the Stevens towing tank. Precise measurements were made of heave response to waves for catenary tows. Drag force was also measured. Test variables included model size, buoyancy I weight ratio, speed, wave size and gap/length ratio.

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Purnamasari, Dian, I. Ketut Aria Pria Utama, and Ketut Suastika. "Benchmark Study of Ship Model Resistance Test." Applied Mechanics and Materials 874 (January 2018): 114–20. http://dx.doi.org/10.4028/www.scientific.net/amm.874.114.

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A benchmark test will insure that the equipment, procedures, and uncertainty estimates are adequate. The experiments of a well-known bulk carrier bare hull shape (the model LHI-007) has been set up and conducted at towing tank Indonesian Hydrodynamic Labotatory. The aim of the present study is to contribute data of the surface ship resistance model-scale database in calm water on one hand, and on the other – reliable Experimental Fluid Dynamics (EFD) data, as part of an internal benchmark test. Conclusions are made with regard to the available data and past uses and recommendations are provided for future uses of the available data and future data procurement.

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Doctors, Lawrence J., Alexander H. Day, and David Clelland. "Unsteady Effects During Resistance Tests on a Ship Model in a Towing Tank." Journal of Ship Research 52, no. 04 (December 1, 2008): 263–73. http://dx.doi.org/10.5957/jsr.2008.52.4.263.

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It is known that there are oscillations in the wave resistance during the constant-velocity phase of a towing-tank resistance test on a ship model. In this work, the unsteady thin-ship resistance theory has been applied to this case. The results have been compared with experiment data obtained using a towing carriage the velocity history of which can be programmed. It is demonstrated here that generally excellent correlation exists between the theory and the experiments. In particular, one can predict the influence of Froude number, rate of acceleration, and type of smoothing of the acceleration on the characteristics of the oscillations. These characteristics include the amplitude, rate of decay, frequency, and phasing of the oscillations in the curve of wave resistance versus time.

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Nugroho, W. H., NJH Purnomo, RK Priohutomo, and E. Suwarni. "Experimental Evaluation of Structural Hull Damping Coefficient of a Hydro-Elastic Segmented Submarine Model." IOP Conference Series: Earth and Environmental Science 972, no. 1 (January 1, 2022): 012008. http://dx.doi.org/10.1088/1755-1315/972/1/012008.

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Abstract This paper presents an experimental study of determining structural damping ratio of the hydro-elastic submarine model. The model test of a hydro-elastic submarine model was conducted at the Towing Tank facility of the Indonesian Hydrodynamic Laboratory (BTH-BPPT). To investigate the effect of the wet and dry damping ratio the vibration tests were performed in both air and water. The experiments in wet and dry condition were undertaken to investigate the influences of the damping ratio at zero forward speed. Vibration tests were also conducted in the Towing Tank at speed in calm water to explore the effect of the forward speed on both fixed and free pitch conditions on the damping ratio. From these experiments it has been found the damping ratios of wet condition are greater than the dry one. The damping ratios increased also as the submarine model speeds forward, whereas both the fixed and free pitch showed an increase in the damping ratio with increase forward speed.

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Karimi, Mohammad Hosein, Mohammad Saeed Seif, and Madjid Abbaspoor. "An experimental study of interceptor’s effectiveness on hydrodynamic performance of high-speed planing crafts." Polish Maritime Research 20, no. 2 (April 1, 2013): 21–29. http://dx.doi.org/10.2478/pomr-2013-0013.

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Abstract Trim control mechanisms such as interceptors and trim flaps have been widely used in recent years in highspeed crafts for ride and trim control. In spite of their extensive application, a few studies investigating the impact of interceptors on planing craft performance, have been published. In the present study, the impact of interceptors on planing crafts hydrodynamic quality is investigated through application of an experimental method. Two scaled-down models of high-speed planing mono-hull and catamaran are tested with and without interceptors in calm water at different heights of the interceptors to investigate the effect of interceptors on drag reduction of the models. The first one is a scaled-down model of 11 m planing mono-hull boat and the test was conducted at the towing tank of Sharif University of Technology, Iran. The second one is a scaled-down model of 18 m planing catamaran boat and the test was conducted at the towing tank of Krylov Shipbuilding Research Institute (KSRI), Russia. The experimental results show a remarkable drag reduction of up to 15% for mono-hull model and up to 12% for catamaran model over the wide speed range of the models.

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Doctors, Lawrence J., Alexander H. Day, and David Clelland. "Resistance of a Ship Undergoing Oscillatory Motion." Journal of Ship Research 54, no. 02 (June 1, 2010): 120–32. http://dx.doi.org/10.5957/jsr.2010.54.2.120.

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In this paper, we describe extensions to the research of Doctors et al. (Doctors, L. J., Day, A. H., and Clelland, D., 2008, Unsteady effects during resistance tests on a ship model in a towing tank, Journal of Ship Research, 52, 4, 263–273) and Day et al. (Day, A. H., Clelland, D., and Doctors, L. J., 2009, Unsteady finite-depth effects during resistance tests in a towing tank, Journal of Marine Science and Technology, 14, 3, 387–397) in which the oscillations in the wave resistance during the constant-velocity phase of a towing-tank resistance test on a ship model were measured and predicted, in the cases of relatively deep and relatively shallow water. In the current study, the ship model was towed with a harmonic velocity component superimposed on the usual constant forward velocity. This work constitutes a first step in the understanding of the unsteady hydrodynamics of a racing shell (rowing boat). We show here that the unsteady wave resistance varies considerably from the traditional (steady) average value. Indeed, the wave resistance is frequently negative during part of the oscillatory cycle. However, the general effect is an increase in the temporal mean value of the wave resistance; this suggests that every effort should be made to reduce the unsteadiness of the motion. We also demonstrate that the unsteady wave-resistance theory provides an excellent prediction of the measured effects summarized here. These predictions are often within a few percent of the measured values of the resistance.

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Bin Tofa, Mohammad Mobassher, Adi Maimun, Yasser Mohamed Ahmed, Saeed Jamei, Ab Saman Kader, and Hassan Abyn. "Two Degree of Freedom Vortex Induced Vibration Tests of a Riser Model Using Spring Bars." Applied Mechanics and Materials 465-466 (December 2013): 1339–46. http://dx.doi.org/10.4028/www.scientific.net/amm.465-466.1339.

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Tests have been performed on a riser model with low mass ratio subjected to uniform flows in a towing tank at subcritical Reynolds numbers. Qualisys video motion capture system was used to measure VIV and Spring bars are used instead of commonly used parallel linkage mechanism for this kind of test. The circular cylinder of 100 mm in diameter and 1.5 m in length was towed vertically at constant speeds through the towing tank to simulate uniform current condition. Some key VIV parameters such as amplitude over diameter, lift and drag coefficients are presented against a non dimensional parameter known as reduced velocity to understand the effects of VIV on two degree of freedom system.The relative magnitude of the super-upper response branch vibration amplitudes are emphasised in this particular study. Results of this paper can be used as validation materials for CFD analysis that is very important to design riser system for oil and gas industry, also mentioned experiment procedure can be treated as a guide for future endeavour to perform similar kind of tests.

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KIM, JOON-YOUNG, YUN-HAE KIM, HYEUNG-SIK CHOI, JINHO BAE, CHONG HYUN LEE, IL-HYOUNG CHO, and HYEOK-JUN KOH. "DYNAMIC MODELING AND STRUCTURAL ANALYSIS OF MANTA-TYPE UUV." International Journal of Modern Physics B 25, no. 31 (December 20, 2011): 4319–22. http://dx.doi.org/10.1142/s0217979211066866.

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This paper describes the dynamic modeling, structural analysis, implementation and experimental test of a Manta-type Unmanned Underwater Vehicle (MUUV). Various controllers such as PID, Sliding mode, and Fuzzy and H∞ controllers are designed for depth and heading control in order to compare the performance of each controller based on simulation. In addition, experimental tests are carried out in a towing tank for depth keeping and heading angle tracking.

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Dymarski, Czesław, Paweł Dymarski, and Wojciech Litwin. "Novel Design of an Ocean Wave Power Device." Key Engineering Materials 490 (September 2011): 206–15. http://dx.doi.org/10.4028/www.scientific.net/kem.490.206.

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The paper presents a novel device for capturing the energy of sea-waves and the construction of its model for conducting test in a towing-tank. The paper also presents the research program and general analyses on selecting the hull form and systems of anchoring and propulsion. In addition, it includes remarks and observations gathered following initial tests and measurements of the device operating in regular wave conditions.

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Zhang, Jia Ning, Yu Chen Shang, and Lei Zhang. "Ice Resistance Model Test Technology for 110K Tanker Adopting FSICR Ice Class IA." Advanced Materials Research 779-780 (September 2013): 1117–23. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1117.

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Ship model test in ice towing tank is one of the key technologies for the design of ice-strengthened ship, and is the primary measure of determining the ship required minimum engine output power in ice navigation and checking whether satisfies the requirements of ice class rules. Researched the relevant requirements of 1A ice-strengthened ship based on the Finnish-Swedish ice class rules (FSICR), which is minimum engine output power according to the forward form of hull line and according to standard formulas. Studied the technical requirements of ice model test. Determined the minimum engine output power for 110k oil tanker with ice class 1A based on ice model test.

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Karczewski, Artur, and Janusz Kozak. "Comparison of Selected Parametric Methods for Prediction of Inland Waterways Ship Hull Resistance in Towing Tank Test." Polish Maritime Research 25, s1 (May 1, 2018): 63–67. http://dx.doi.org/10.2478/pomr-2018-0024.

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Abstract In the paper selected approximate methods for calculation of inland waterways ship resistance and their verification by towing tests, compared on the example of a small urban ferry, are presented. The test results are made for both the bare hull and the hull with appendages (skeg, azimuthal propeller). Significant differences between results of the theoretical methods and experimental ones, especially in the case of the model with skegs and propulsion, are pointed out. The purposefulness of using several parametric methods and the use of average results at the preliminary design stage were also discussed.

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Savitsky, Daniel. "Direct Measure of Rigid Body Accelerations for Wave Impact of a Planing Hull." Journal of Ship Production and Design 32, no. 04 (November 1, 2016): 235–44. http://dx.doi.org/10.5957/jspd.2016.32.4.235.

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Measurements of accelerations during wave impact of a planing hull are usually contaminated by nonhydrodynamic disturbances inherent in full-scale tests and by vibrations induced by the test model and towing carriage in towing tank tests. As a consequence, researchers have resorted to the use of electronic filters to extract rigid body hydrodynamic impact accelerations. This article first calculates the rigid body impact acceleration time histories of 2dimensional deadrise wedges impacting on a level water surface as a function of initial contact velocity, deadrise angle, and unit drop weight. It also calculates the spectral content of these time histories. It then demonstrates how the time histories, time to peak, and spectral content of these 2D wedges are distorted by the use of standard "one-way" electronic filters when processing the data. In a sense, this section of the article can be taken as a simple tutorial on the impact process. The Davidson Laboratory suggests and demonstrates the use of a rigid "free-running" model that is not rigidly connected to the towing carriage and is thus devoid of carriage-induced disturbances. This obviates the use of filters in processing the recorded data. Hence, the directly measured impact accelerations are thus rigid body hydrodynamic accelerations. These are compared with measurements made with the model rigidly attached to the carriage to demonstrate its effect on contaminating the recorded hydrodynamic signal. It is recommended that other towing tanks consider the use of this or other "free-model" test procedures to identify the possible contamination of the recorded acceleration time histories introduced by their carriage and model disturbances. It is also recommended that for those full-scale tests, where the "Standard G" method of data reduction has been applied, that a model be built and tested using the "free-model" test procedure suggested in this article. This will compare the derived rigid body accelerations with the true hydrodynamic impact accelerations as obtained in these free-model tests.

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Schmitt, Pál, Song Fu, Ian Benson, Gavin Lavery, Stephanie Ordoñez-Sanchez, Carwyn Frost, Cameron Johnstone, and Louise Kregting. "A Comparison of Tidal Turbine Characteristics Obtained from Field and Laboratory Testing." Journal of Marine Science and Engineering 10, no. 9 (August 24, 2022): 1182. http://dx.doi.org/10.3390/jmse10091182.

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Experimental testing of physical turbines, often at a smaller scale, is an essential tool for engineers to investigate fundamental design parameters such as power output and efficiency. Despite issues with scaling and blockage which are caused by limitations in size and flow velocity of the test facilities, experimental tank testing in laboratory environments is often perceived as offering more control and thus trustworthier results than field testing. This paper presents field tests of a tidal turbine, performed using a self-propelled barge in real tidal flow and still water conditions, that are compared to a towing tank test. Factors influencing the performance characteristics, such as the choice of velocity sensor, vessel handling and data processing techniques are investigated in this paper. Direct comparison with test results of the exact same turbine obtained in an experimental test facility further confirms that field testing with robust data analysis capabilities is a viable, time and cost efficient alternative to characterise tidal turbines.

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Azarsina, Farhood, and Christopher D. Williams. "Nomoto Indices for Constant-Depth Zigzag Manoeuvres of an Autonomous Underwater Vehicle." ISRN Oceanography 2013 (December 19, 2013): 1–8. http://dx.doi.org/10.5402/2013/219545.

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A two-dimensional simulation code is used to study the characteristics of constant-depth zigzag manoeuvres of the axisymmetric autonomous underwater vehicle (AUV) MUN Explorer. Sea trials data for several manoeuvres with the AUV have been reported during the past four years; however, to obtain a more complete understanding of the vehicle's hydrodynamics, additional towing tank tests and computer simulation were performed. The present work, based on the towing tank test results and sea-trials data, utilizes computer simulations to predict the performance of the MUN Explorer AUV during horizontal zigzag manoeuvres. Next, the Nomoto indices for this AUV during constant-depth zigzag manoeuvres are estimated using the simulation results, and, then, Nomoto's first-order model for the rate of turn of the vehicle during horizontal zigzag manoeuvres in response to a square-wave input for the rudder deflection angle is analytically solved. The paper investigates the validity of the simplified yaw equation to predict a zigzag manoeuvre. Results of this research are a first step to understand the details of zigzag manoeuvres of an AUV such as duration of the first execute, yaw-checking ability, and duration of the overshoot.

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Irvine, Martin. "Pitch and Heave Tests and Uncertainty Assessment for a Surface Combatant in Regular Head Waves." Journal of Ship Research 52, no. 02 (June 1, 2008): 146–63. http://dx.doi.org/10.5957/jsr.2008.52.2.146.

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Towing-tank experiments of coupled pitch and heave motions are presented for a surface combatant advancing in regular head waves. The data include ballasting parameters, time histories, fast Fourier transform (FFT), Fourier series amplitudes, and pitch and heave transfer functions and phases for a range of speeds, wave steepnesses, and wave frequencies. The geometry is David Taylor Model Basin (DTMB) model 5512, which is a 1/46.6 scale geosim of DTMB model 5415 (DDG-51) with Lpp = 3.048 m. The experiments are performed in a 3.048 × 3.048 × 100 m towing tank equipped with a plunger-type wave maker. The test program is undertaken to provide a validation data set for unsteady Reynolds-averaged Navier-Stokes and other computational fluid dynamics (CFD) codes, including rigorous uncertainty assessment of the experimental results following standard procedures. Results indicate that the regular head waves are linear with second- and third-order magnitudes consistent with third-order Stokes waves. Pitch and heave responses and phases show expected trends for long and short wavelengths and are linear or Ak independent for all test conditions. Maximum response occurs for frequency of encounter equal to pitch and heave natural frequencies and Lpp / λ = 0.75. Under these conditions, an equation is derived that predicts the Froude number for maximum response as a function of ship geometrical coefficients.

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Fujiwara, Toshifumi, Tadashi Nimura, Yoshimasa Minami, Noriyuki Sasaki, and Ken Takagi. "Free running model test on a large container ship under wind and waves at towing tank." Journal of the Japan Society of Naval Architects and Ocean Engineers 8 (2008): 155–62. http://dx.doi.org/10.2534/jjasnaoe.8.155.

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Jung, Jae-Sang, Young-guk Lee, Min-guk Seo, In-Bo Park, Jin-ha Kim, and Dong-bae Kang. "Study on Extension of the 6-DOF Measurement Area for a Model Ship by Developing Auto-tracking Technology for Towing Carriage in Deep Ocean Engineering Tank." Journal of Ocean Engineering and Technology 36, no. 1 (February 28, 2022): 50–60. http://dx.doi.org/10.26748/ksoe.2021.066.

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The deep ocean engineering basin (DOEB) of the Korea Research Institute of Ship and Ocean Engineering (KRISO) is equipped with an extreme-environment reproduction facility that can analyze the motion characteristics of offshore structures and ships. In recent years, there have been requirements for a wide range of six-degree-of-freedom (6-DOF) motion measurements for performing maneuvering tests and free-running tests of target objects (offshore structures or ships). This study introduces the process of developing a wide-area motion measurement technology by incorporating the auto-tracking technology of the towing carriage system to overcome the existing 6-DOF motion measurement limitation. To realize a wide range of motion measurements, the automatic tracking control system of the towing carriage in the DOEB was designed as a speed control method. To verify the control performance, the characteristics of the towing carriage according to the variation in control gain were analyzed. Finally, a wide range of motions was tested using a model test object (a remotely operated vehicle (ROV)), and the wide-area motion measurement technology was implemented using an automatic tracking control system for a towing carriage.

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Sugianto, Erik, and Hendika Puji Haditama. "PENGGUNAAN METODE KOMPUTERISASI DALAM PENENTUAN TAHANAN KAPAL TANKER." ROTOR 10, no. 2 (November 1, 2017): 54. http://dx.doi.org/10.19184/rotor.v10i2.6392.

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The ship resistance is influential to choose the ship's main engine, especially tankers that have large block coefficients. In general, ship resistance was obtained by modeling the vessel on a certain scale and then testing on the experimental tank. However, this test requires high funding, because testing requires special places such as towing tanks that have expensive operating costs. This research is intended to get ship prisoner with computerized method for tanker ship. Then the result is validated by Holtrop mathematical approximation method. The result of computerized method for speed 11.4 knots got the value of ship resistance is 86.2 KN. While the method of mathematical approach generated ship resistance is 74.38 KN. So the ship's resistance used to determine the tanker machine is 86.2 KN. Keywords: Ship resistance, tanker, computerized

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33

Shi, Sheng-zhe, Ting Jiang, Fan Wang, and Xiao-long Zheng. "Research on Direct Measurement to Spray Resistance Test of Prismatic Planing Hull." Journal of Physics: Conference Series 2419, no. 1 (January 1, 2023): 012001. http://dx.doi.org/10.1088/1742-6596/2419/1/012001.

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Abstract To obtain spray resistance directly, a prismatic planing hull test was conducted in a towing tank in static water. The characteristic angles of the standing line and leading edge line of the spray zone were obtained through the fixed flight test of the whole prismatic planing hull. The prismatic planing hull was divided into front and rear parts along the standing line, and then the fixed flight state test of the split planing hull was carried out, and the spray resistance was directly measured by the front planing hull. The results show that the percentage of splash resistance in the total resistance is from 15.83 % to 30.10 % under the condition of high-speed planing; Split planing hull model test is an effective method for direct measurement of spray resistance.

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Nurhadi, Nurhadi, Mochammad Nasir, Chandra Permana, and Endah Suwarni. "Design and Manufacture of 6 Axis Force and Moments Transducers for Seaplane Floaters Test in Towing Tank." EPI International Journal of Engineering 3, no. 1 (September 1, 2020): 84–89. http://dx.doi.org/10.25042/epi-ije.022020.12.

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To develop seaplanes as a means of inter-island transportation, it is necessary to have a simulation, testing, and analysis of force measurements that work so that the aircraft can be designed optimally in terms of function and safety. To fulfill one type of test, the seaplane floater model is pulled in the Towing Tank to determine the hydrodynamic forces acting on the floater which include resistance (Fx), side force (Fy), lift force (Fz), and moments in all three axes. A method of measuring the force of 6 axis force and moment or 6 degrees of freedom (6 Degree of Freedom, 6 DOF) was built and designed by combining several single load cells so that these forces can be known optimally. From the results of the 6 DOF transducer design, it is proven that it can be used well in measuring 6 forces and moments with force measurement errors ranging from 1.38%. The distance between the 6 DOF transducer capture point and the floater force capture point will affect the measured moment transformation.

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Sugalski, Karol. "Influence of the Symmetry Plane Boundary Condition on the Planing Multihull Calm Water Resistance Test. CFD to Towing Tank Comparison." New Trends in Production Engineering 1, no. 1 (October 1, 2018): 385–91. http://dx.doi.org/10.2478/ntpe-2018-0048.

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Abstract This article present results of the comparison between numerical simulation (utilising Computational Fluid Dynamics) and towing tank experiment of the multihull vessel. Effect of the symmetry plane boundary condition on the resistance has been investigated. Reynolds-Averaged Navier Stokes equations with k-ω turbulence model has been used to calculate resistance of the hull with two degrees of freedom (2-DOF). Calculation has been done using OpenFOAM software package. Governing equations of fluid motion, together with the concept of the mesh and boundary condition has been presented in the first section of this work. Conclusion about calculating resistance of the multihull vessels has been made, after short presentation of the results.

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Purnamasari, Dian, AAB Dinariyana, and Meitha Soetardjo. "Analisa Ketidakpastian Pengujian Resistance Model Kapal LCT 1000 DWT." Wave: Jurnal Ilmiah Teknologi Maritim 4, no. 1 (May 20, 2019): 21. http://dx.doi.org/10.29122/jurnalwave.v4i1.3537.

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Uji tahanan yang dilakukan di tangki tarik memiliki kesalahan (ketidakpastian) pada hasil. Analisa ketidakpastian dapat digunakan untuk mengevaluasi kualitas data percobaan dan menyediakan perkiraan kuantitatif kesalahan percobaan. Metodologi analisa ketidakpastian, prosedur, dan hasil disajikan untuk uji tahanan model kapal LCT 1000 DWT skala (λ) 15 dengan ukuran model kapal L = 3,997 M, B = 1000 M, T = 0,167 M, WSA = 4,089 M2, Prosedur dirangkum dan mengikuti International Towing Tank Conference (ITTC) Kualitas Manual Prosedur. Hasil penelitian menunjukkan nilai ketidakpastian sebesar 1,27% dari kecepatan 1,3271 m/s dan nilai ketidakpastian sebesar 4,79% dari tahanan 1,2771 kg.Keywords : Uncertainty analysis, Procedures, Ship model test.

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Casalone, Pietro, Oronzo Dell’Edera, Beatrice Fenu, Giuseppe Giorgi, Sergej Antonello Sirigu, and Giuliana Mattiazzo. "Unsteady RANS CFD Simulations of Sailboat’s Hull and Comparison with Full-Scale Test." Journal of Marine Science and Engineering 8, no. 6 (May 29, 2020): 394. http://dx.doi.org/10.3390/jmse8060394.

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The hydrodynamic investigation of a hull’s performance is a key aspect when designing a new prototype, especially when it comes to a competitive/racing environment. This paper purports to perform a fully nonlinear unsteady Reynolds Averaged Navier-Stokes (RANS) simulation to predict the motion and hydrodynamic resistance of a sailboat, thus creating a reliable tool for designing a new hull or refining the design of an existing one. A comprehensive range of speeds is explored, and results are validated with hydrodynamic full-scale tests, conducted in the towing tank facility at University of Naples Federico II, Italy. In particular, this work deals with numerical ventilation, which is a typical issue occurring when modeling a hull; a simple and effective solution is here proposed and investigated, based on the phase-interaction substitution procedure. Results of the computational fluid dynamic (CFD) campaign agree with the experimental fluid dynamic (EFD) within a 2% margin.

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Indiaryanto, Mahendra, Mohammad Ridwan Utina, Nurwidhi Asrowibowo, and Siti Sadiah. "Design and Hydrodynamic Model Test of Mini Submarine Propeller with High Efficiency and Low Cavitation." EPI International Journal of Engineering 1, no. 2 (November 20, 2018): 59–64. http://dx.doi.org/10.25042/epi-ije.082018.09.

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Design and development of propellers for submarines are in some ways different from propellers for surface vessels. The most important demand is low acoustic signature and propeller efficiency. The design for the propulsor for submarine is a specialist task of a later stage of design. The propulsive efficiency has essensially three parts in the traditional method of approach. The first and major part is the efficiency of the propeller it self as a divice which may develop to overcome the resistance to motion the vessel. The aim of this research is to design a mini submarine propeller and obtain high efficiency and low cavitation. To reach this aim, model tests were performed both in Towing Tank and Cavitation Tunnel. From the propeller model tests, the result shows a good efficiency and low cavitation. Keywords: Submarine , Propeller , Efficiency, Cavitation

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39

Schultz, Michael P. "Frictional Resistance of Antifouling Coating Systems." Journal of Fluids Engineering 126, no. 6 (November 1, 2004): 1039–47. http://dx.doi.org/10.1115/1.1845552.

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An experimental study has been made to compare the frictional resistance of several ship hull coatings in the unfouled, fouled, and cleaned conditions. Hydrodynamic tests were completed in a towing tank using a flat plate test fixture towed at a Reynolds number ReL range of 2.8×106-5.5×106 based on the plate length and towing velocity. The results indicate little difference in frictional resistance coefficient CF among the coatings in the unfouled condition. Significant differences were observed after 287 days of marine exposure, with the silicone antifouling coatings showing the largest increases in CF. While several of the surfaces returned to near their unfouled resistance after cleaning, coating damage led to significant increases in CF for other coatings. The roughness function ΔU+ for the unfouled coatings showed reasonable collapse to a Colebrook-type roughness function when the centerline average height k=0.17Ra was used as the roughness length scale. Excellent collapse of the roughness function for the barnacle fouled surfaces was obtained using a new roughness length scale based on the barnacle height and percent coverage.

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Widodo, Agoes Santoso, Erwandi, and Achmad Baidowi. "Form Factor Prediction Based on Ship Model Test Data by Statistical Method." IOP Conference Series: Earth and Environmental Science 1081, no. 1 (September 1, 2022): 012017. http://dx.doi.org/10.1088/1755-1315/1081/1/012017.

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Abstract The ship model resistance test is carried out on the towing tank with a certain scale to get the total resistance coefficient of the ship model. The value of the ship’s form factor is needed in extrapolation calculations to get the coefficient and total resistance value of a full-scale ship. The form factor can be obtained using the traditional method, namely testing the resistance of the ship model with a Froude Number between 0.1 – 0.2. This method is known as the Prohaska method. Another method or a more modern method is to use multiple linear regression statistics based on the ship model test. We used data from 41 displacement ship model tests conducted at the Hydrodynamics Technology Laboratory (LTH)-National Agency for Research & Innovation (BRIN). Data processing is done through statistical software using the OLS or Robust method which was previously done by transforming predictor variables to enlarge the variety of variables so that a good regression equation is obtained. The resulting form factor regression is a useful tool for predicting the ship’s Effective Power value.

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Du, Lei, Zhuang Lin, Yi Jiang, Ping Li, and Yue Dong. "Numerical Investigation on the Scale Effect of a Stepped Planing Hull." Journal of Marine Science and Engineering 7, no. 11 (November 5, 2019): 392. http://dx.doi.org/10.3390/jmse7110392.

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This article discusses the scale effects on a planing boat, utilizing the computational fluid dynamics method. The simulation is compared with a tank test for verification and validation. The planing boat sails use both aerodynamics and hydrodynamics. Studying the performances and wave patterns of different dimensions of the models is the best way to investigate the scale effect without using experimental data. The resistance is discussed in two parts, namely residuary resistance and friction resistance, and is compared to the calculated data using the international towing tank conference (ITTC) formula. The computational fluid dynamics (CFD) calculations of the model are increased by 4.77% on average, and the boat computations are also increased by 3.57%. The computation shows the scale effect in detail. The residuary resistance coefficients at different scales are approximately equal, and the friction resistance coefficients show the scale effect. The scale effect for longitudinal steadiness is also captured for the period of the porpoising behavior. The rational for the full-scaled boat oscillation period and the model is the root of the scales.

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Sumarsono, Beny Cahyono, Erwandi, B. Ali, and A. Baidowi. "Experimental Study of the Effect of Bilge Keels Position as Roll Damping Devices on the Resistance of LCU Vessels." IOP Conference Series: Earth and Environmental Science 1081, no. 1 (September 1, 2022): 012016. http://dx.doi.org/10.1088/1755-1315/1081/1/012016.

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Abstract Landing Craft Utility (LCU) is one type of ship whose role is to transport combat equipment vehicles and amphibious troops to make landings on the beach. On the ship, bilge keels were installed. However, the installation of bilge keels on the surface of the ship’s hull will add resistance to the ship’s speed. To find out the effect of placing bilge keels on the additional ship speed resistance, a towing test experiment was carried out in the towing tank using the LCU ship model. Two bilge keels were manufactured in 4 (four) different positions, called A, B, C, and D positions. From the results of the study, it is known that the average value of the addition to the total resistance is; at A position there is an increase in ship speed resistance of 3.22%, at B position by 3.36%, at C position by 2.67%, and at D position by 1.83% of the total resistance in bare hull conditions. The results of this study indicate that the placement of bilge keels with the same shape and dimensions can add to different total resistances.

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Lee, Jun-Hee, Kwang-Jun Paik, Soon-Hyun Lee, Jun Hwangbo, and Tae-Hyu Ha. "Experimental and Numerical Study on the Characteristics of Motion and Load for a Floating Solar Power Farm under Regular Waves." Journal of Marine Science and Engineering 10, no. 5 (April 21, 2022): 565. http://dx.doi.org/10.3390/jmse10050565.

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Recently, the demand for floating solar power farms in lakes and coasts (rather than on land) has been increasing rapidly. It is important to develop a numerical analysis technique that considers environmental conditions to predict structural stability and accurate motion response while designing a floating solar power farm. In this study, we performed a comparison under conditions similar to those of the Inha University towing tank (IUTT) model test to verify the numerical analysis method. The results revealed that heave and pitch movements were dominant under head sea conditions. Relative behavior occurred because of the hinge connection of each unit, and complex motion characteristics appeared depending on the wave conditions. The numerical method was verified based on the motion response and load of the floating solar farm. The validity of the results was also confirmed.

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Wu, Tiecheng, Wanzhen Luo, Dapeng Jiang, Rui Deng, and Shuo Huang. "Numerical Study on Wave-Ice Interaction in the Marginal Ice Zone." Journal of Marine Science and Engineering 9, no. 1 (December 22, 2020): 4. http://dx.doi.org/10.3390/jmse9010004.

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The effect of waves on ice sheet is critical in the marginal ice zone (MIZ). Waves break large sea ice into small pieces and cause them to collide with each other. Simultaneously, the interaction between sea ice and waves attenuates these waves. In this study, a numerical research is conducted based on a computational fluid dynamics (CFD) method to investigate the response of single ice floe to wave action. The obtained results demonstrate that the sea ice has a violent six degree of freedom (6DoF) motion in waves. Ice floes with different sizes, thicknesses, and shapes exhibit different 6DoF motions under the action of waves. The heave and surge response amplitude operator (RAO) of the sea ice are related to wavelength. Furthermore, the overwash phenomenon can be observed in the simulation. The obtained results are compared with the model test in the towing tank based on artificial ice, and they agree well with test results.

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Ma, Weijia, D. Hanbing Sun, D. Huawei Sun, D. Jin Zou, and Jiayuan Zhuang. "Test Studies of the Resistance and Seakeeping Performance of a Trimaran Planing Hull." Polish Maritime Research 22, no. 1 (January 1, 2015): 22–27. http://dx.doi.org/10.1515/pomr-2015-0004.

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Abstract Towing tank tests in calm water were performed on a trimaran planing hull to verify its navigational properties with different displacements and centres of gravity, as well as to assess the effects of air jets and bilge keels on the hull’s planing capabilities, and to increase the longitudinal stability of the hull. Hydrostatic roll tests, zero speed tests, and sea trials in the presence of regular waves were conducted to investigate the hull’s seakeeping ability. The test results indicate that the influence of the location of the centre of gravity on the hull resistance is similar to that of a normal trimaran planing hull; namely, moving the centre of gravity backward will reduce the resistance but lower the stability. Bilge keels improve the longitudinal stability but slightly affect the resistance, and the presence of air jets in the hull’s channels decreases the trim angle and increases heaving but has little effect on the resistance. Frequent small-angle rolling occurs in waves. The heaving and pitching motions peak at the encounter frequency of , and the peaks increase with velocity and move towards greater encounter frequencies. When the encounter frequency exceeds, the hull motion decreases, which leads to changes in the navigation speed and frequency.

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46

Reichel, Maciej. "Manoeuvring forces on azimuthing podded propulsor model." Polish Maritime Research 14, no. 2 (April 1, 2007): 3–8. http://dx.doi.org/10.2478/v10012-007-0006-0.

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Manoeuvring forces on azimuthing podded propulsor model This paper presents the preliminary part of comprehensive manoeuvring open-water tests of a gas carrier model. The paper focuses on open water experiments with an azimuthing podded propulsor. The test program was carried out in the cavitation tunnel and the large towing tank of Ship Hydromechanics Division, Ship Design and Research Centre, Gdańsk. The pod was tested as a pushing unit with a 161.3 mm diameter propeller. Steering forces were measured in the range of advance coefficient from 0.0 to 0.8 combined with the range of deflection angles from -45° up to +45°. Measurements on the pod without propeller were also performed. The experiment results are presented in the form of non-dimensional coefficients in function of advance coefficient and deflection angle. Analysis of the experimental results and the conclusions are presented.

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47

Bugalski, Tomasz, Heinrich Streckwall, and Jan A. Szantyr. "Critical review of propeller performance scaling methods, based on model experiments and numerical calculations." Polish Maritime Research 20, no. 4 (December 1, 2013): 71–79. http://dx.doi.org/10.2478/pomr-2013-0043.

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ABSTRACT The article presents the results of experimental and numerical investigation of propeller scale effects, undertaken in co-operation of the Hamburg Ship Model Basin (HSVA), Germany, and Ship Design and Research Centre (CTO SA), Poland. The objective of the investigation was to test the adequacy of the methods currently used to account for the propeller scale effect and to develop possible improvement of the methods. HSVA has conducted model experiments in the large cavitation tunnel together with panel method and CFD calculations. CTO SA has performed model experiments in the towing tank, together with lifting surface and CFD calculations. Both institutions have suggested different new approaches to the problem and different new procedures to account for the propeller scale effects. In the article the procedures are presented together with the description of the underlying experimental and theoretical research.

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Schultz, Michael P. "The Relationship Between Frictional Resistance and Roughness for Surfaces Smoothed by Sanding." Journal of Fluids Engineering 124, no. 2 (May 28, 2002): 492–99. http://dx.doi.org/10.1115/1.1459073.

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An experimental investigation has been carried out to document and relate the frictional resistance and roughness texture of painted surfaces smoothed by sanding. Hydrodynamic tests were carried out in a towing tank using a flat plate test fixture towed at a Reynolds number ReL range of 2.8×106−5.5×106 based on the plate length and freestream velocity. Results indicate an increase in frictional resistance coefficient CF of up to 7.3% for an unsanded, as-sprayed paint surface compared to a sanded, polished surface. Significant increases in CF were also noted on surfaces sanded with sandpaper as fine as 600-grit as compared to the polished surface. The results show that, for the present surfaces, the centerline average height Ra is sufficient to explain a large majority of the variance in the roughness function ΔU+ in this Reynolds number range.

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Ma, Leixin, Ke Hu, Shixiao Fu, Torgeir Moan, and Runpei Li. "A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System." Journal of Ship Research 60, no. 01 (March 1, 2016): 14–29. http://dx.doi.org/10.5957/jsr.2016.60.1.14.

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Because of scale effects and inappropriate hydrodynamic models, the nonlinear hydroelastic response of net cages used for fish-farming cannot be analyzed precisely with traditional model testing or combinations of finite element methods (FEMs) and load models. In this study, an innovative hybrid method is proposed to determine the hydroelastic response of full-scale floater-and-net systems more accurately. In this method, the net for the fish cage was vertically and peripherally divided into similar interconnected sections with different hydrodynamic parameters, which were assumed to be uniformly distributed over each section. A model of a typical section was subjected to various towing velocities, oscillation periods, and amplitudes in a towing tank to simulate the potential motions of all sections in the net under various currents, waves, and floater movements. By analyzing the measured hydrodynamic force from this test section, a hydrodynamic force database for a typical net section under various currents, waves, and floater motions was built. Finally, based on an FEM, the modified Morison equation and the hydrodynamic force database, the hydroelastic behavior of the full-scale fish cage was calculated with an iterative scheme. It is demonstrated that this hybrid method is able to produce correct hydroelastic response for both steady and oscillatory flows. The hydroelastic response of a two-dimensional example of a full-length net panel with steady currents and floater oscillations was studied in detail.

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Tian, Ying Yuan, Yun Hai Zhang, and Xu Jun Wang. "Solution of Energy Supply for Deep Ocean Installations: Design and Testing of a Micro-Fluid Turbine." Applied Mechanics and Materials 472 (January 2014): 247–53. http://dx.doi.org/10.4028/www.scientific.net/amm.472.247.

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A micro-fluid turbine has been successfully tested in the laboratory and towing tank. This 2m diametral device is designed to operate in flows with velocity from 0.1m/s to 1m/s. The designed output power varies from 0.3W to 200W. In this design, the low density ocean current energy in deep-sea stored as mechanical energy in plane roll-up spring first. When the spring has enough potential energy, it drives the generator to generate electricity. Through this assistant start approach, the turbine can work in ultra-low-speed current. On the other hand, the non-contact transmission remarkably reduced the drag torque of hubcap. Besides these approaches, some other advanced technologies, such as self-adaptive platform, high efficiency energy storage, and intelligent control, are applied in this turbine. Test results show that the micro-fluid turbine has potential to provide power for instruments and equipment in deep-sea environment.

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Journal articles on the topic 'Towing Tank Test'

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