The present study concerns validation of data-driven modeling for ship dynamics from free-running model test results, in terms estimation hydrodynamic force and moment, maneuvering coefficients, maneuver simulation results. An method the moment acceleration a surface combatant is suggested compared with conventional modeling. hull relates motion developed by optimizing coefficients which leads to minimum loss function criteria. system-based model. Lastly, results are adequately predicts...

In the present study, we conducted resistance test, propeller open water test and self-propulsion for a ship's propulsion performance, using computational fluid dynamics techniques, where Reynolds-averaged Navier-Stokes equations solver was employed. For convenience of mesh generation, unstructured meshes were used in bow stern region ship, hull shape is formed delicate curved surfaces. On other hand, structured generated middle part rest domain, i.e., relatively simple geometry. To...

The resistance and seakeeping performance of a high-speed monohull vessel were investigated through series model tests in towing tank. hull had slender wave-piercing bow, round bilge, small deadrise angle on stern. Tests the bare calm water first conducted spray rails followed. designed to control flow direction induce hydrodynamic lift force bottom reduce trim increase rise hull. maximum was 4.65° at speed, but optimum location reduced by 0.97°. ship motion head seas examined after tests....

The present study concerns an open water performance of a partially submerged propeller. To investigate the free surface effects on propulsion performance, force and moment were measured, ventilation phenomena visualized with respect to submergence ratios advance coefficients. thrust loss in heavy load conditions due at suction side propeller blade was observed. extent ring-shaped increased as coefficients decreased, resulting loss. Using underwater camera fast Fourier transform results...

The present study concerns a feasibility for applying principal component analysis to ship dynamics in maneuver. Using the four degrees of freedom standard modular model maneuver simulations large angle zigzag tests with rudder deflection variations are conducted. datasets motion, hydrodynamic force, and moment during acquired identify modes. covariance matrix obtained variables shows strong linear correlation between moment, except surge force. Four eigenvectors selected as modes dynamics....

Tip Vortex Cavitation (TVC) is a major issue in design and operation of axial hydraulic machines. We investigate the capacity flexible trailing thread alleviating TVC by analyzing flow-induced motion. For this purpose, nylon with three diameters cut various lengths attached to tip an elliptical hydrofoil. The selected threads are enough become unstable start flutter under almost all tested flow conditions. Due vortical flow, oscillating forced spiral around vortex axis. resulting rotational...

One of the most critical issues for ship owners, shipbuilders, and insurance companies is operational safety. In particular, keeping damaged ships stable in waves great interest, because more nonconventional hull forms are being introduced military passenger vessels while international rules regulations becoming stricter. However, stability quite different from that intact as assessment very complicated difficult due to highly nonlinear behavior. Computational fluid dynamics (CFD) methods...

The present study aimed to identify significant design parameters on the propeller open water efficiency and characteristics of wake field a with propeller-boss-cap-fins (PBCFs), special attention hub vortex dynamics. A towed underwater stereoscopic particle image velocimetry system was used measure near fields five-bladed PBCF model. Through model tests, it confirmed that disappearance low-pressure area behind boss cap, i.e., reduction vortex, dominant contribution gains from rather than...

This study aimed to clarify the cause of quality reduction in Korean sourdough after successive back-slopping.We investigated dynamic changes lactic acid bacteria during back-slopping process using genetic fingerprinting techniques. During initial propagation phases, dominant were Fructilactobacillus sanfranciscensis (<5 log CFU per g sourdough), Latilactobacillus curvatus (9·5 sourdough) and Levilactobacillus brevis (6·5 sourdough). However, 11th propagation, F. became more prominent (>9·0...

The present study aims to assess test uncertainty assessment method of nominal wake field measurement by a Stereoscopic Particle Image Velocimetry (SPIV) system in towing tank. systematic the SPIV was estimated from repeated uniform flow measurements. In case, time interval between image frames and speed were varied examine effects particle displacement around on standard uncertainty. random assessed repeating measurements compared with that laser Doppler velocimetry. applied tests very...

Techniques of the design experiments (DOE) and computational fluid dynamics (CFD) were applied for improving bow shape a tanker hull. Through this, hull that could reduce added resistance in waves was derived. The key elements selected as parameters optimization short-wavelength region interpreted through CFD considering operational condition full scale ship. For parameter changes, number analyses minimized by applying DOE. regression equation calculating derived using bow-shape response...

The present study is about the application of a four-degree-of-freedom (4DOF) maneuvering mathematical model based on Abkowitz’s for assessing damaged ship maneuverability with initial asymmetry. A scaled Office Naval Research Tumblehome hull compartment was used as test model. Based survivability regulations naval vessels, designed and located near bow, such that it had an heel trim. Static dynamic captive tests were performed to determine coefficients Maneuvering simulations carried out...

This article introduces the process of identifying dynamics models a combatant in intact and damaged condition based on measured data from free running model tests. The applied system identification method is an Estimation-Before-Modeling approach, which estimates state variables parameters separately. After estimating states, tendency hydrodynamic force acting conditions compared. modeling performed estimated tendency. Then, results derivatives constituting modeled are described....

In the present study, we conducted resistance test, propeller open water test and self-propulsion for a ship's propulsion performance, using computational fluid dynamics techniques, where Reynolds-averaged Navier-Stokes equations solver was employed. For convenience of mesh generation, unstructured meshes were used in bow stern region ship, hull shape is formed delicate curved surfaces. On other hand, structured generated middle part rest domain, i.e., relatively simple geometry. To...

The present study concerns reduced order modeling of a marine diesel engine, which can be used for outlier detection in status monitoring and carbon intensity index calculation. Principal Component Analysis (PCA) is introduced the modeling, focusing on feasibility detecting treating nonlinear variables. By cross-correlation, it found that there are seven non-linear data channels among 23 channels, i.e., fuel mode, exhaust gas temperature after turbocharger, cylinder coolant temperatures....

In the present study, a towed underwater particle image velocimetry (PIV) system was validated in uniform flow and used to investigate free-surface effects on turbulent wake of simple surface-piercing body. The selected test model cylindrical geometry formed by extruding Wigley hull's waterplane shape vertical direction. Due constraints two-dimensional (2D) PIV for velocity field measurements were done separately horizontal planes. Using measured data at several different locations, it...