EMBED Equation.3
Where, H-Total head (constant)
P- Pressure
g- Gravity
v- Velocity of flow
- Density of fluid
z- Elevation head.
The A-Noise Weighting scale has two main functions. The first one is that it measures the level of noise by integrating the levels of sound at all frequencies and then giving a single number. The second function is that it helps in giving the scale or the level of noise as perceived by the human ear (Schmid and Weisser, 2003).
The sketch of the propulsion is as shown below. As the speed of the shaft increases the output also increases exponentially.
Source Sample Ms excel sheet showing layout of propulsion.
Along the two streamlines the two controlling surfaces brings about wake. This is the friction between the water velocity and the ship, which is the velocity of water in relation to the ship. Wake consists of three major sections. First, the velocity due to water surrounding the hull secondly, the boundary layer between the dragged water by the hull and flow around it and thirdly, the waves due to the ships movement. The first two sections will lower the velocity or speed of water going into the propeller the additional section will either decrease or increase the velocity or speed but it depends on whether the water waves create or develop a trough or crest within the propeller.
The best choice of material for propeller is composites this is because composites consist of unique combinations of various materials selected in a way so as to achieve very unique mechanical properties. The combinations of have higher tensile strength ceramic fibers bided together by a resin polymer which allows material shape and volume hence providing the tough impact strength required in propellers.
The Bernoullis equation is as shown below Where, v velocity of fluid along the streamline, g downwards acceleration due to gravity, y elevation in the gravity field, p pressure within the streamline, - fluid density.
EMBED Equation.3
The calculation for question number six can be done using the equation as shown below
Where, VC is the velocity of the flow rate, hc actual height of the surface of water and the discharge point and g force of gravity
EMBED Equation.3
The nonlinear dynamic model of the marine diesel crankshaft system with a propeller and 6 cranks is established, in which the variable moment of inertia of the linkage and the piston, coupling effect between torsion and axial vibration, the actuating force applied on the piston, the actuating torque - response of the system to initial displacement and initial speed, variable moment of inertia, the pressure applied on the piston, the torque and the axial force applied on the propeller by fluid is needed. The variable moment of inertia and coupling effect between tensional and axial vibration are the fundamental reason for nonlinear vibration. Different actuating factors can not only result in different frequency components of the response, but make the same frequency component have different vibration amplitude. The dynamic behavior of the system is not influenced obviously by the actuating torque and force applied on the propeller. There is obvious difference in sensitivity of the dynamic response in the different direction to the same actuating factor.
The requirements of public address system include a suitable PAS system to the ships. There are some parameters that need to be measured. The parameters are the transfer functions and stationary noise spectrum. From these measurements one is able to know (1) the required dynamic range of receivers, (2) average attenuation at distribution boards and (3) phase coupling loss. Since the cables are shielded and the hull provides the good ground, the usage of the common-mode transmission in addition to the conventional differential-mode, which is referred to as a dual-mode transmission system, can also be used.
Sound pressure level is given by the equation below in terms of pressure level and sound pressure is the defined as the pressure of sound expressed in RMS value.
Figure SEQ Figure ARABIC 1 Typical torsional vibration stress response for intermediate shaft during normal operation of a conventional low-speed diesel engine propulsion plant. Stress limits for engines continuous and transient running are also included.
Source Sample Ms excel sheet
For barred speed range, the maximum vibration stress is 80 of the total rpm and from the graph this will give a speed range of 16-20 knots from the graph.
Acoustic emission is the energy released when a crack propagates, or its faces rub together. Since the crack growth on most engineering structures may be only a few microns or several millimeters. For plated steel structures planar location is most commonly used, calculating source origin from the time arrivals at three or more sensors and then signals being located from a growing fatigue crack in a plated steel structure.
Acoustic emissions are produced when the source location coincides with a possible discontinuity position such as a weld, or area of high stress. It can also result from particle impact, and objects rubbing together. Leaks also cause energy in this frequency range, though because they result in a continuous increasing signal rather than a transient, the presence of a leak in a pressurized system is obvious (Schmid and Weisser, 2003).
The idea of apparent slip leads to slip velocity and as a parameter of the boundary-value conditions, is sufficient for the description of the actually observable macroscopic flow patterns in non-Newtonian fluids. There is no substantiation for differentiating between true and or apparent slip. The choice you make on apparent slip determines the performance of the ship.
The strength, fracture toughness and the ductile to brittle transition temperatures are key properties of materials used in ship building. Analyzing a particular ship and the indented use the designer is in a position to know the degree of the above properties to be used.
Four allowing elements of forming carbide in steel include manganese, molybdenum, chromium and nickel
Response amplitude operator is a set of engineering statistics used to determine how a ship behaves in the sea. It can be determined from models of proposed ship designs tested in a model basin, from running specialized fluid dynamics computer programs or both (Bathe, 1996)
Figure SEQ Figure ARABIC 2 sketch of a typical operator
Source httpwww.ultramarine.comg_infomosescapabilrao.htm
A set of response operator values assist in making the necessary improvements on the performance and maintenance of the ship.
The diesel cycle involves
Induction Stroke
The induction stroke in a Diesel engine is used to draw in a new volume of charge air into the cylinder. The generated power in the engine is dependent on amount of fuel burnt and also by the amount of air present.
Compression Stroke
The compression stroke begins as the inlet valve closes and the piston is driven upwards in the cylinder bore by the momentum of the crankshaft and flywheel.
The function of this stroke in a engine is to increase the temperature in the charged air to until the fuel is injected into the cylinder.
Compression Ignition
Compression ignition takes place when the fuel from the high pressure fuel injector spontaneously ignites in the cylinder. In theoretical cycle, the fuel is injected at TDC, however as there is finite time for ignition in practical engines (ignition lag), fuel is then injected before the piston touches TDC to allow maximum power.
Power Stroke
The power stroke begins as the injected fuel spontaneously ignites with the air in the cylinder. As the quickly burning mixture tries to expand in the cylinder, it develops a great pressure which drives the piston in the cylinder bore. Linear motion is changed to a rotary motion by use of the crankshaft.
Exhaust Stroke
The exhaust stroke is as critical to the smooth and efficient operation of the engine as that of induction.
Turbo charge engines are usually used in marine ships because turbo charging ensures a high efficiency, use of smaller engines and low fuel consumption.
Model propellers, which usually operate at low Reynolds numbers, can display a considerably large region of laminar boundary layer and have a strong tendency to laminar separation. This is in contrast to the observations of full-scale propellers, which operate at high Reynolds numbers and, hence, at almost fully turbulent conditions. A high turbulence level is known to cause early transition of the boundary layer, which, in turn, can lead to the complete elimination of the laminar separation (Draminsky, 1961).
The minimization of green house gases in ships can be achieved by ensuring mandatory limit on the Energy Efficiency Design Index (EEDI) for new ship, voluntary reporting of the EEDI for new ships, mandatory or voluntary reporting of the Energy Efficiency Operational Indicator, mandatory or voluntary use of a Ship Efficiency Management Plan, mandatory limit on the EEOI value, combined with a penalty for non-compliance, maritime Emissions Trading Scheme (METS) and implementation of an International
Compensation Fund (ICF), to be financed by a levy on marine bunkers
ECDIS requirements include A port state control Officer (PSCO) should assess whether a ship is using electronic charts in accordance with SOLAS requirements, the STCW (Standards of Training, Certification and Watch-keeping) and ISM (International Safety Management) codes put the responsibility firmly on the ship owner to ensure that mariners on their vessels are competent to carry out the duties they are expected to perform. The ECS requirement include An ECS may be able to use either official ENCs, RNCs or other chart data produced privately and could have functionality similar to ECDIS, Because ECS is not intended to meet SOLAS requirements.
Asynchronous motor has a rotating secondary winding. The primary winding is connected to the actual source of power and the secondary winding carries the induced current. Torque is developed by the action of the secondary currents on air-gap flux. Synchronous motor various with asynchronous motor in operational characteristics and design.
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