Analysis of Power of Underwater Cylinder Excited by Propeller/Shaft System

2014 ◽  
Vol 488-489 ◽  
pp. 1211-1214
Author(s):  
Gang Ji ◽  
Q. Zhou ◽  
Chun Wen Huang
Keyword(s):  
Power Transmission ◽  
Propeller Shaft ◽  
Shaft System ◽  
Acoustic Reduction ◽  
Acting Load

To adopting means to reduce power radiated from the hull, power injected by the shaft system and that radiated by the hull are analyzed for an underwater cylinder excited by the propeller/shaft system. As the power is injected by combination of the solely acting loads on the junction and there concurrent, power transmitted by each solely acting load, radiated by the hull and the concurrent power are compared to understand the mechanism of power transmission and transformation. In the comparisons, quantities are decomposed according to circum orders to understand the radiation modes. The conclusion drawn in the paper will provide some guidance for acoustic reduction by shaft isolation design.

Non-Linear Coupled Dynamics of a Flexible Propeller-Shaft System Supported by Water Film Bearings

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Chang-Gang Lin ◽  
Ming-Song Zou ◽  
Can Sima ◽  
Li-Bo Qi ◽  
Yue Yu
Keyword(s):  
Nonlinear Vibration ◽  
Damping Ratio ◽  
Water Film ◽  
Vibration Characteristics ◽  
Superposition Method ◽  
Propeller Shaft ◽  
Chaotic Motions ◽  
Mode Superposition Method ◽  
Shaft System ◽  
Slice Method

Abstract A slice method to determine the boundary conditions between the stern bearing and shaft by dividing the journal in the stern bearing into several slice elements along the axial direction is proposed for the first time. A comprehensive finite element model considering the nonlinear force of the water film and the flexibility of the propeller blade is established for a propeller-shaft system. The long bearing approximation is adopted to calculate the pressure distribution around each journal element in the stern bearing. The mode superposition method is employed. The nonlinear equation of motion is solved iteratively using the Newmark method. A parametric study is implemented to analyze the nonlinear vibration characteristics of the system. It is shown that the real motion state of the journal in the stern bearing can be simulated more precisely by the slice method proposed. The responses of the system alternate among period-one, quasi-periodic, multi-periodic, and chaotic motions as the rotating speed increases. The damping ratio has a significant effect on the dynamic characteristics of the propeller-shaft system. The motion of the system is unstable when the damping ratio is very small. At this time, the modes of the flexible propeller blades can be excited readily. The slice method, which can also be extensively used in similar rotor-bearing systems in the engineering field, is very simple and efficient to analyze the nonlinear vibration characteristics of a flexible propeller-shaft system supported by water film bearings.

Eliminating Discharges in Oil/Sea Interfaces - a Return to Seawater Lubricated Propeller Shaft Systems for Commercial Ships

2015 ◽  
Author(s):  
Craig D. Carter
Keyword(s):  
New York ◽  
Oil Pollution ◽  
Operating Costs ◽  
General Description ◽  
Propeller Shaft ◽  
Environment Protection ◽  
Protection Agency ◽  
New Classification ◽  
Shaft System ◽  
Standard Designs

Oil discharges from a ship’s propeller shaft system are an issue for commercial ship owners. A 2010 study by a New York Consulting firm estimated the total worldwide amount of lubricants from operational discharges from ships would be about 130 to 244 million litres annually. To add perspective, oil pollution from the Exxon Valdez tanker spill in 1989 was 41.6 million litres. Most ships use mineral oil to lubricate the propeller shaft and the oil is contained in the propeller shaftline by the aft seal – which is the oil to sea interface. According to the new U.S. Environment Protection Agency Vessel General Permit (VGP), all vessels built on or after Dec. 19, 2013 and trading in US waters must use an environmentally acceptable lubricant (EAL) in all oil to sea interfaces before their next drydocking. This paper will review: the renaissance of seawater based systems, a general description of a seawater lubricated bearing system, current commercial ship users and results, lower operating costs with “free” seawater and no aft seal, conversions of existing ships and resistance of shipyards to change standard designs from oil to seawater. The paper will also review new Classification rules from LR, CCS and BV for seawater lubricated propeller shaft systems, allowing the shaft to remain in place if monitoring conditions are met - which removes a major obstacle that ship owners had with seawater-based propeller shaft bearing systems.

Parametric resonances for torsional vibration of excited rotating machineries with nonconstant velocity joints

2017 ◽  
Vol 24 (15) ◽  
pp. 3262-3277 ◽  
Author(s):  
Masoud SoltanRezaee ◽  
Mohammad-Reza Ghazavi ◽  
Asghar Najafi
Keyword(s):  
Torsional Vibration ◽  
High Speed ◽  
Power Transmission ◽  
Equations Of Motion ◽  
Monodromy Matrix ◽  
Parametric Instability ◽  
Constant Input ◽  
Inertia Moment ◽  
Disk Model ◽  
Shaft System

The shaft system is a rotating machinery with many applications due to its high speed. The angle between shafts may not be zero. So the shafts can be connected to each other through a nonconstant velocity U-joint, which transforms a constant input angular velocity into a periodically fluctuating velocity. Consequently, the mechanism is parametrically excited and may face resonance conditions. Herein, a power transmission system including three elastic shafts is considered. The polar inertia moment of each shaft is modeled as a dynamic system with two discrete disks at the shaft ends. The equations of motion consist of a set of Mathieu–Hill differential equations with periodic coefficients. The dynamic stability and torsional vibration of the shaft system are analyzed. The system geometry and inertia moment effect are the main issues in this contribution. Parametric instability charts are achieved via the monodromy matrix technique. The graphical numerical results are validated with the frequency analytical results. Finally, the stability regions are shown in the parameter spaces of velocity, misalignment angles and the inertia of disks. The results demonstrated that by changing the system inertia and geometry, stabilizing the whole system is possible. Moreover, to check the precision of the model, the results are compared with a basic single-disk model, which is prevalent in two-shaft systems.

Analysis of friction-induced vibration in a propeller–shaft system with consideration of bearing–shaft friction

2013 ◽  
Vol 228 (8) ◽  
pp. 1311-1328 ◽  
Author(s):  
Zhenguo Zhang ◽  
Feng Chen ◽  
Zhiyi Zhang ◽  
Hongxing Hua
Keyword(s):  
Stability Analysis ◽  
Dynamic Responses ◽  
Nonlinear Friction ◽  
Propeller Shaft ◽  
Shaft System ◽  
Modal Model ◽  
Lateral Coupling ◽  
Combined Action ◽  
The Stability ◽  
Friction Induced Vibration

This paper is concerned with friction-induced vibration of a continuous propeller–shaft system excited by nonlinear friction due to contact between a water-lubricated bearing and a shaft. The dynamic equation is derived using Hamilton’s principle in conjunction with the finite element method. The drooping characteristics of the nonlinear friction and the torsional–lateral coupling via the bearing–shaft interaction laws are considered. Both stability analysis and responses analysis are then investigated through various system parameters. Stability is analyzed by determining the eigenvalues of the Jacobian matrix of the linearized system at the equilibrium point. Dynamic responses of the system are calculated on the basis of a reduced order modal model using the numerical integration method in order to validate the stability analysis. Numerical simulation proved to be consistent with the linear stability analysis. Analytical and numerical investigations reveal that friction-induced vibration of the proposed system is due to the combined action of nonlinear friction and coupled dynamics of the system, rather than the velocity-dependent friction alone as is commonly assumed.

Fatigue Life Evaluation of Weld Surfacing LB 52 Grade

2017 ◽  
Vol 744 ◽  
pp. 259-263
Author(s):  
Siva Sitthipong ◽  
Prawit Towatana ◽  
Amnuay Sitticharoenchai ◽  
Chaiyoot Meengam
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Power Transmission ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Welding Process ◽  
Transmission Efficiency ◽  
Propeller Shaft ◽  
Metal Arc Welding ◽  
Short Service Life

The damage to the propeller shaft, a principal mechanical component in the power transmission system of Boats makes engines work harder than normal attributed to less transmission efficiency. Operating boats with the damaged propeller shaft increases the rate of fuel consumption per distance and cost of fishing which affects income of coastal fishermen. The result of a preliminary survey of Boats at Kaoseng Community revealed that the service life of the damaged propeller shafts caused by the fatigue failure would be repaired by shield metal arc welding process. The statistical analysis showed that the useful life depended on fatigue endurance limit of welding surface. When they were back to be used again. The objective of this research was to study the fatigue life of hardfacing surface by solid wire. The method of this research included (a) building up the hardfacing surface (b) forming specimen from hardfacing surface and (c) finding out the fatigue life by fatigue testing machine base on ASTM E739-91 standard. The results of this research indicated that hardfacing surface by solid wire could not receive fatigue stress exceed 500 MPa. The propeller shafts after being repaired will have very short service life, which is not feasible in engineering economy.

Vibration transmission suppression for propeller-shaft system by hub-embedded damping ring under broadband propeller force

2018 ◽  
Vol 91 (4) ◽  
pp. 2651-2666 ◽  
Author(s):  
Xiuchang Huang ◽  
Zhiwei Su ◽  
Zhenguo Zhang ◽  
Hongxing Hua
Keyword(s):  
Propeller Shaft ◽  
Vibration Transmission ◽  
Shaft System
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