Ship Propeller Research Articles

Remote interactive platform for matching design of ship screw propeller and diesel engine based on Internet Plus

In order to meet the requirements of the remote ship propeller matching design, and can feed the measurement data to the offshore calculation model to guide the design of the ship propulsion system, this paper designed a screw propeller matching computing platform based on the internet. The platform was built on the B/S architecture, combined with MATLAB and C# for mixed programming, and used EasyUI plug-in set to design user interface. The open water characteristics of the ship were selected as the fundamental data of the whole process of matching calculation. The platform was tested by three parts: the preliminary matching, ultimate matching and cavitation checking. By comparison, the difference between calculated value and actual value is very small, which can meet the accuracy requirements. This platform can provide an engineering basis for the online working condition monitoring of the ship power system and the dynamic matching of the ship propeller in the 'Internet Plus' environment in future.

Modification of the average durability for CuSn12 bronze at cavitation erosion using volumetric treatments

The bronze CuSn is used sometimes for equipment components working in cavitation conditions, as for example ship propellers, bodies and other parts of valves. To increase the working time, in cavitation conditions, those elements can be subjected to volumetric thermal treatments. The present research is concerned with the increase of the mean durability , of the bronze CuSn12 by applying two volume treatments: quenching both at 700°C and 800°C, with tempering at 500°C. The cavitation erosion behavior was experimentally tested using the standard vibratory device of the Cavitation Laboratory of Timisoara Polytechnic University. Comparing the results we found that the durability, in both cases, is substantial increased, the better solution being the quenching with the lower temperature.

Automatic Docking for Underactuated Ships Based on Multi-Objective Nonlinear Model Predictive Control

Autonomous shipping refers to the ability of a ship to independently control its own actions while transporting cargo from one port to another, which places higher requirements on ship motion control methods. When a ship enters a port, it is important to ensure that the ship sails from the fairway area to the assigned position at the berth with a desirable speed and that it finally stops at the desired position. Ship docking is known as one of the most challenging tasks due to the non-linearity of low-speed ship movements and the high requirements on collision avoidance with the quayside. This paper proposes a nonlinear model predictive control (NMPC) -based approach for underactuated ships, providing optimal ship rudder angles and propeller revolution rate to automate the ship docking process. At each sampling instant, a finite horizon optimal control problem is formulated based on a nonlinear ship maneuverability model. A lexicographic multi-objective optimization strategy is proposed in the design of the NMPC controller, saving the efforts on control parameters tuning. Simulation experiments are carried out to evaluate the effectiveness of the proposed approach.

Remote interactive platform for matching design of ship screw propeller and diesel engine based on Internet Plus

In order to meet the requirements of the remote ship propeller matching design, and can feed the measurement data to the offshore calculation model to guide the design of the ship propulsion system...

Increased Corrosion Resistance On Cu35%Zn Surface By Shot Peening Process

Cu35Zn is a metal with a copper matrix that has the properties of forgings and has good corrosion resistance. Cu35Zn is commonly known as brass metal. Brass is widely used by industry to make various metal components. Brass for engine components must be able to withstand statistical and dynamic loads. One of these components is a ship propeller made of brass. These components must be able to withstand axial loads and have high corrosion resistance. To improve physical and mechanical properties, surface treatment needs to be done with the shot peening method. Shot peening is done with steel shot ball with a diameter of 0.5 mm with a hardness of 40-50 HRC. Shooting distance between nozzles and 100 mm specimens for 4, 6 and 8 minutes. The shot peening pressure varies 7, 8 and 9 bars. Corrosion tests according to the ASTM G5-94 standard are carried out in a 3.5% NaCl solution, instead of seawater. The results showed an increase in the best corrosion resistance of 0.028 mpy at 8 Bar shot pressure, which is 2.8 times compared to raw materials.

Topological optimization and manufacturing of vessel propeller via LMD-method

This article presents results of complex study based on new methods of designing and manufacturing of metal ship propellers. The original model of propeller was redesigned with help of topological optimization method. Using a static distribution of rated pressure, the parameters of the stress-strain state of the optimized version of the propeller were estimated by comparing its stress state with the initial cast version of the solid unit. The propeller with optimized structure has reliability characteristics close to the original solid version. Based on optimized 3-D model the controlling program for robotic LMD-method of manufacturing was created and propeller was built-up. The weight of optimized propeller is 20% less than original solid one. Control samples for destructive testing also were manufactured. The mechanical properties of samples are not lower than for cast and rolled metal. Based on the same conditions of manufacturing it could be supposed that strength properties of built-up propeller are almost the same to control sample.

Experimental investigation of the passive control of unsteady cloud cavitation using miniature vortex generators (MVGs)

The research is aimed at the study of a passive control method to control unsteady cloud cavitation that is characterized by regular shedding of large vapour structures from the solid surface of a cavitating immersible body. The unsteady cloud cavitation is an important subject of research because of its destructive impacts in various industrial applications, including ship propellers and rudders, pumping and hydraulic machinery systems. For this, we placed miniature vortex generators (MVGs) of a cylindrical type on the surface of a benchmark CAV2003 hydrofoil and investigated effects of these MVGs on the spatial structure of unsteady cavitation clouds. We analyzed the temporal and spatial cavity characteristics in comparison with those for the original hydrofoil (without MVGs) by means of high-speed imaging. In addition, we used a hydrophone to register the signal of pressure pulsations in time and thereby derive power spectra of the pressure pulsations. The results showed that the implemented cavitation control method is an effective tool to manage the unsteady behaviour of cloud cavitation and to mitigate the amplitude of pressure pulsations. It was revealed that, with this control approach, the large-scale cavitation clouds appear to be broken and only small-scale cavity structures are shed away from the hydrofoil surface. Moreover, a notable reduction in the cavitation-induced vibrations of the solid surface may be expected.

Composite methodology to prevent ship propeller erosion

The jet flow generated by manoeuvring ships nearby vertical structures is known to erode the seabed sediment but is still difficult to predict the effects of a particular ship operating in a harbour basin. This paper presents a methodology to quantify the scouring action generated by ship's propellers combining field and real data with a manoeuvre numerical simulator testing some of the most commonly used formulas for maximum scouring depth prediction. From the real manoeuvres, analysed through Automatic Identification System (AIS) data, the manoeuvre patterns are identified to be later reproduced at the simulator, thus obtaining the propulsion system behaviour to apply the formulae and to estimate the maximum erosion depth expected in a harbour basin. The obtained results are validated with field data from bathymetries and Acoustic Doppler Velocimeter (ADV). Results show the arrival and departure manoeuvre sections where the vessel is potentially harmful. The different formulae applied yielded results in accordance with the provided bathymetry of the study area in terms of maximum erosion depth. Also, the areas of maximum expected seabed velocity are coincident with the areas where the maximum scour is observed in the bathymetry.

Influence of EEDI (Energy Efficiency Design Index) on Ship–Engine–Propeller Matching

With the increasingly strict international GHG (greenhouse gas) emission regulations, higher requirements are placed on the propulsion system design of conventional ships. Playing an important role in ship design, construction and operation, ship–engine–propeller matching dominantly covers the CO2 emission of the entire ship. In this paper, firstly, a ship propulsion system matching platform based on the ship–engine–propeller matching principle and its application on WinGD 5X52 marine diesel engine have been investigated. Meeting the energy efficiency design index (EEDI) regulation used to calculate the ship CO2 emission is essential and ship–engine–propeller matching has to be carried out with EEDI into consideration. Consequently, a procedure is developed combining the system matching theory and EEDI calculation, which can provide the matching results as well as the corresponding EEDI value to study the relationship between EEDI and ship–engine–propeller matching. Furthermore, a comprehensive analysis is performed to obtain the relationship of EEDI and system matching parameters, such as ship speed, effective power and propeller diameter, reflecting the trend and extent of EEDI when changing these three parameters. The results of system matching parameters satisfying different EEDI phases indicate the initial value selection in matching process to provide reference for the design of ship, engine and propeller under the EEDI regulations.

Redesigning of 4 (Four) Blades Propeller Installed in a Wooden Fishing Boat in a Ship Yard in Tegal, Central Java Province

For design of marine propeller, the energy supply from marine engine to the propeller should be converted to thrust force with minimum losses. Furthermore, the unwanted vibration and cavitation due to the overlooking a detail calculation of the propeller should be prohibited for increasing the fuel efficiency and life-span of the propeller. In the last few decades, most of small and medium sized enterprises (SMEs) focusing their work on ship component industry in Central Java Province Indonesia provide the marine propeller to the ship manufacturer and ship repairmen in some shipyards in northern part of Central Java port. The design of the propeller is never been observed and optimized. The aim of the present work is to redesign the installed propeller on a wooden fishing boat with the new optimized design using B-Series propeller theory approach. The reverse engineering method uses three-dimensional scanner to obtain the geometrical data of the installed ship propeller. The new optimized propeller design is obtained from free software calculation based on the boat and engine specification. The comparison shows that the new optimized propeller design has a wider blade and larger pitch and increases 20% of the open water efficiency of the propeller performance at lower engine rotation.
 Keywords: B-series design, fishing boat, marine propeller, redesign, optimization

Additive Manufacturing Application to a Ship Propeller Model for Experimental Activity in the Cavitation Tunnel

Additive manufacturing (AM), or three dimensional printing, is a modern way to build objects with possibly a high degree of accuracy and favorable cost/benefit ratio. This approach is widely used by many manufacturing industries and a certain interest for this innovative production technology is also growing in the ship design and production field. To this regard, the experimental activity at the model scale is often necessary for the ship performance assessment in the design phase. In the article, preliminary results of a propeller model for the cavitation tunnel, built with additive technology, are presented, showing the strengths and weaknesses of the printed model. Moreover, as an introductive overview, different AM technologies are briefly described, with the aim to point out potential applicability to ships. 1. Introduction Additive Manufacturing (AM), also known as 3D printing, is a well-known process to shape objects by layering materials under numerical control until the completion of the work. It represents an innovative approach because it is based on the addition of material instead of carving material from a block (like CNC—Computer Numerical Control, i.e. a manufacturing approach relying on mills, drills, and other numerically controlled tools). AM is deemed as an outstanding flywheel for innovation in the productive world, and the shipbuilding industry seems to have started realizing the advantages of this technology, already largely used, e.g., in the automotive, aerospace, biomedical, and energy industries (Shahi 2016; Satish Prakasha et al. 2018). In this perspective, an introductive overview of different AM typologies is presented in the article, to possibly understand how it could be used to improve ship design and production. The overview includes the applicable technologies, focusing on the printing process, the materials, and the mechanical properties of the final printed object. A practical example of AM technology application is presented regarding the printing of the blades of a ship's propeller model for experiments in a cavitation tunnel.

ДОСЛІДЖЕННЯ ПРИЧИН ВТОМНОГО РУЙНУВАННЯ СУДНОВИХ ГРІБНИХ ВАЛІВ

The article summarizes the statistics on the causes of accidents of river and sea vessels, 50 % of which are loss of movement and loss of controllability. One of their main causes is damage to shafting of ships, which accounts for about 10 % of all causes of accidents. As a result of the analysis of the revealed damages, as well as metallographic studies, it was established that during operation the ship propellers are subjected to cyclic variable loads, and the resulting stresses that reach critical values, which can lead to microscopic defects in the metal. The accumulation of defects inside the metal leads to intergranular fracture, and as a result, the appearance of microcracks. When one or several cracks reach critical sizes, the shaft is destroyed. Considered the place, the stage of appearance and development of cracks. It was established that the transition zone of the cylindrical part of the shaft to the conical was the most dangerous place for fatigue damage in the shafts ships. Were tested shafts with a diameter of 70 mm, restored by surfacing, for fatigue failure under cyclic loads. The article presents photos of the fatigue destruction of shafts with the surfacing of three steel grades. After fatigue tests, the destroyed samples were examined on an electron scanning microscope. Electron microscopy showed the viscous nature of the intergranular destruction of the surface layer of the restored propeller shaft. According to the study, the main regularities in the appearance and development of cracks are highlighted: violation of technological processes of shaft repair, fatigue destruction of shaft material under the influence of variable cyclic loads, development of defects under the action of corrosive environment, poor quality centering of shaft lines and their significant transverse oscillations, asynchronous cyclic loads, temperature condition of the shafts and lubrication of friction units. Recommendations are given to increase the service life by diagnosing the percentage of shaft wear, detecting surface defects and eliminating them by restoring by welding surfacing.

An interactive machine learning toolkit for classifying impulsive signals in passive acoustic recordings

A typical wide-bandwidth passive acoustic seafloor sensor can record tens of millions of impulsive signals produced by biological, anthropogenic, and physical sources each year. Sources include echolocating toothed whales, snapping shrimp, ship propeller cavitation, echosounders, and weather. The volume and variety of detections make manual classification by human analysts unmanageable without in-depth knowledge of the overall acoustic context of each monitoring location. We describe an interactive machine learning toolkit in development for efficiently detecting and classifying short, highly variable impulsive signals in large passive acoustic datasets. Modules include a configurable event detector, an unsupervised clustering module for identifying dominant signal categories, a deep learning unit for learning and applying event classes, and a graphical user interface for viewing, correcting and evaluating detectors and classifiers. These tools are discussed and illustrated in the context of efforts to extract distinctive features of toothed whale clicks from towed array recordings collected by NOAA SEFSC and to use them to classify detections in unlabeled seafloor sensor recordings. The goal of the toolkit is to facilitate classification of individual signals to species in very large PAM datasets across sensor types and monitoring locations, and to improve quantitative assessment of these sources.

Automatic detection and classification of sounds generated by ocean vehicles via cyclic demodulation and beamformed coherence

Narrow-band tonal signals generated by ocean vessels are a dominant source of underwater sound, occurring at discrete frequencies ranging from several Hertz to several kiloHertz and continuously over long time intervals. Here we develop a two-stage approach for the automated passive acoustic detection and classification of underwater vehicles. The first stage utilizes the commonly used cyclic demodulation to extract the low frequency tonal sound modulated into high frequency noisy signal from which the fundamental frequency and blade pass frequency of ship propeller can be determined. The second applies magnitude-squared coherence to beamformed signals to directly extract tonal sounds spanning a wide range of frequencies from low (∼10 Hz) up to the array cutoff frequency and to estimate their bearings. Both the modulated and unmodulated tonal signals generated by a ship can be simultaneously determined using this two-stage approach leading to a more complete spectral characterization of the underwater sound radiated by an ocean vessel. Here, the approach is applied to analyze and characterize the underwater sound generated by research vessel RV Knorr, received on a large-aperture densely populated coherent hydrophone array.Narrow-band tonal signals generated by ocean vessels are a dominant source of underwater sound, occurring at discrete frequencies ranging from several Hertz to several kiloHertz and continuously over long time intervals. Here we develop a two-stage approach for the automated passive acoustic detection and classification of underwater vehicles. The first stage utilizes the commonly used cyclic demodulation to extract the low frequency tonal sound modulated into high frequency noisy signal from which the fundamental frequency and blade pass frequency of ship propeller can be determined. The second applies magnitude-squared coherence to beamformed signals to directly extract tonal sounds spanning a wide range of frequencies from low (∼10 Hz) up to the array cutoff frequency and to estimate their bearings. Both the modulated and unmodulated tonal signals generated by a ship can be simultaneously determined using this two-stage approach leading to a more complete spectral characterization of the underwater sou...

Non-linear noise from a ship propeller in open sea condition

In the present paper, we study the hydrodynamic noise generated by a ship propeller in open sea conditions. We use Large Eddy Simulation for the hydrodynamic field whereas the acoustic field is reconstructed by applying the advective form of the Ffowcs-Williams and Hawkings equation. A dynamic Lagrangian model is adopted for the closure of the subgrid-scale stresses and a wall-layer model allows to skip the resolution of the viscous sub-layer. The acoustic equation is formulated in the integral form and solved through direct integration of the volume terms. The propeller herein considered is a benchmark case, whose fluid dynamic data are available in the literature. A grid of about 3 ×106 cells is able to reproduce accurately both integral quantities like thrust and torque over the propeller, and turbulence propagating downstream in the wake.Different noise generation mechanisms are investigated separately. The linear terms give rise to a narrow-band noise spectrum, with a mean peak at the blade frequency and other peaks at frequencies multiple of the rotational one. The non-linear quadrupole term reveals a broad band noise spectrum; the shaft vortex provides the largest contribution to the non-linear part of the noise propagated in the far field.

A Flow Study by the Number of Wings at Ship Propeller

A Flow Study by the Number of Wings at Ship Propeller

CFD results on hydrodynamic performances of a marine propeller

In this work, the commercial Computational Fluid Dynamics (CFD), ANSYS-Fluent V.14.5 has been used to illustrate the effects of rudder and blade pitch on hydrodynamic performances of a propeller. At first, the characteristic curves of a container ship propeller are computed. Then, effects of rudder on hydrodynamic performances of the propeller in the both cases of the propeller with and without rudder have been investigated. The relationships between the blade pitch angle and the hydrodynamic performances of the selected referent propeller in this work having designed conditions as diameter of 3.65 m; speed of 200 rpm; average pitch of 2.459 m and the boss ratio of 0.1730. Using CFD, the characteristic curves of the marine propeller, pressure distribution, velocity distribution around propeller and the efficiency of the propeller have been shown. From the obtained results, the effects of rudder and blade pitch angle on hydrodynamic performances of the propeller have been evaluated.

MONITORING PROCESSES IN SHIP MACHINES THAT CHANGE RAPIDLY OVER TIME, WITH SUBSEQUENT ANALYSIS OF RESULTS

In a number of scientific and technical studies, it is necessary to analyze the processes occurring in the research object and quickly and dynamically change over time. Such processes can be the suddencollision of the object with a stationary obstacle, the analysis of the dynamics of processes occurring in the ship's body, propellers and screws in difficult conditions of navigation (storm, ice collision, etc.). An analysis of this process monitoring allows you to improve the engine parameters.The purpose of this work is to develop methods for monitoring processes in the ship's casing, propellers and screws under difficult conditions of navigation. The object of research is the processes that are rapidly changing in time. The subject of the study is monitoring methods based on measuring the frequency of output signals from sensors. Method. A method for monitoring processes that are rapidly changing over time using 8 sensors is proposed, which is based on measurement of the frequency of sensor output signals by a synchronous method with addition at the beginning and at the end of the survey period with discrete monitoring of not less than 8 ms.Results. The method of monitoring is developed, which allows simultaneously to receive informationfrom 8 sensors with frequency outputs with a discreteness of the study no more than 8 ms, with subsequent analysis of the results, which allows to study the dynamics of processes that are rapidly changing in time.Conclusions. The scientific and applied task of developing a method for monitoring the dynamics ofrapidly changing processes in time is solved. It allows monitoring of 8 sensors with a discreteness of at least 8 ms, with the storage of monitoring results in the form of a text file for the subsequent analysis of the dynamics of process flow in time

The Corrosion Erossion of Ship Propeller Al 7075 Produced by Gravity Sand Casting

Propeller is one of the important components of ships and boats that function as motor or boat propulsion. The mechanical properties required in propeller material are high toughness, easy to cast, and good engine capability, as well as good resistance to corrosion and erosion. One of the aluminum alloys that have been widely used in major vessels in propeller systems is the Nickel-aluminum-bronze (NAB) alloy because it has an excellent combination of mechanical properties and corrosion-erosion resistance. Another type of aluminum alloy that is widely used as a machining component is the Al 7075 T651 because it has the highest strength among other aluminum alloys. The mechanical properties of the Al 7075 T651 are directly proportional to the erosion resistance of the propeller which agrees with the pot tester porridge. The higher the value of the erosion propeller failure that occurs also increases with increasing testing rotational speed. For corrosion, a propeller with air testing media at a speed of 1000 rpm which results in significant corrosion products.
 Keywords: Al 7075 T651, Slurry Pot Tester, Corrosion Erosion

Three-dimensional analysis of local scouring induced by a rotating ship propeller

The jet induced by a rotating ship propeller can cause scouring of the seabed and consequent deposition of the scoured material nearby. Despite these effects are extremely important for the operability of a harbour, there is currently limited work concerning a detailed investigation of the three-dimensional (3D) characteristics of the bed topography changes induced by the ship propeller. Thus, this paper presents laboratory experiments with the aim of analysing the effects induced by a propeller on a mobile bed, in different conditions of submergence depth (h0) and rotational speed (n). The equilibrium bed surface topography was acquired with the photogrammetry technique combined with a 3D Terrestrial Laser Scanner (TLS), in order to analyse, for the first time, bed elevation data obtained from high-resolution Digital Elevation Models (DEMs). As a result, it was demonstrated that the swirling jet produced by a rotating propeller causes the development of a bed topography not symmetrical with respect to the propeller longitudinal axis, with a deeper scour hole on one side and a higher deposition mound on the other side. Therefore, the scour hole induced by a propeller cannot be assimilated to that produced by a water jet and this behaviour can be noted only with a comprehensive and detailed analysis of a 3D model of the bed topography. Furthermore, it was shown that increasing n for the same h0 (or reducing h0 by keeping n constant) causes a longer, deeper and wider scour hole and a higher deposition mound, with a greater volume of sediments eroded from the bed and deposited nearby the scour hole. To be precise, this is the first study aiming at estimating the eroded and deposited sediment volumes by a propeller jet, thanks to the use of the high-resolution DEMs. The relationships between all the involved variables were analysed, providing equations, graphs and an abacus for the prediction of the effects induced by the propeller as a function of h0 and the Froude number.