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Ship Motion Test
In marine engineering, a ship motion test is hydrodynamic test performed with ship models for the purpose of designing a new (full sized) ship, or refining the design of a ship to improve its performance at sea. Tests are carried out in a ship model basin or "towing tank". There are various types of test: the model may be towed along a straight line or circular path, and may be subjected to oscillations. Forces acting on the vessel are measured using a dynamometer. The tests may be evaluating the overall design, or focusing on the characteristics of a propeller. Straight line test The velocity-dependent derivatives Yv and Nv of the ship at any draft and trim can be determined from the model test carried in the towing tank. The model is towed with a constant velocity corresponding to a given ship Froude number at various angles of attack, β. A dynamometer at the origin O, measures the force Y and the moment N experienced by the model at each value of β. The dimensional ship value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emma Maersk 2
Emma may refer to: * Emma (given name) Film * ''Emma'' (1932 film), a comedy-drama film by Clarence Brown * ''Emma'' (1996 theatrical film), a film starring Gwyneth Paltrow * ''Emma'' (1996 TV film), a British television film starring Kate Beckinsale * ''Emma'' (2020 film), a British drama film starring Anya Taylor-Joy Literature * ''Emma'' (novel), an 1815 novel by Jane Austen * ''Emma Brown'', a fragment of a novel by Charlotte Brontë, completed by Clare Boylan in 2003 * ''Emma'', a 1955 novel by F. W. Kenyon * ''Emma: A Modern Retelling'', a 2015 novel by Alexander McCall Smith * ''Emma'' (manga), a 2002 manga by Kaoru Mori and the adapted Japanese animated series * ''EMMA'' (magazine), a German feminist journal, published by Alice Schwarzer Music Artists * E.M.M.A., a 2001–2005 Swedish girl group * Emma (Welsh singer) (born 1974) * Emma Bunton (born 1976), English singer * Emma Marrone or Emma (born 1984), Italian singer Songs * "Emma" (Hot Chocolate song), 197 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Engineering
Marine engineering is the engineering of boats, ships, submarines, and any other marine vessel. Here it is also taken to include the engineering of other ocean systems and structures – referred to in certain academic and professional circles as “ocean engineering.” Marine engineering applies a number of engineering sciences, including mechanical engineering, electrical engineering, electronic engineering, and computer science, to the development, design, operation and maintenance of watercraft propulsion and ocean systems. It includes but is not limited to power and propulsion plants, machinery, piping, automation and control systems for marine vehicles of any kind, as well as coastal and offshore structures. History Archimedes is traditionally regarded as the first marine engineer, having developed a number of marine engineering systems in antiquity. Modern marine engineering dates back to the beginning of the Industrial Revolution (early 1700s). In 1712, Thomas New ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrodynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Model
Ship models or model ships are scale models of ships. They can range in size from 1/6000 scale wargaming miniatures to large vessels capable of holding people. Ship modeling is a craft as old as shipbuilding itself, stretching back to ancient times when water transport was first developed. History Ancient Mediterranean Ancient ship and boat models have been discovered throughout the Mediterranean, especially from ancient Greece, Egypt, and Phoenicia. These models provide archaeologists with valuable information regarding seafaring technology and the sociological and economic importance of seafaring. In spite of how helpful ancient boat and ship models are to archaeologists, they are not always easily or correctly interpreted due to artists’ mistakes, ambiguity in the model design, and wear and tear over the centuries. Ships "were among the most technologically complex mechanisms of the ancient world." Ships made far-flung travel and trade more comfortable and eco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Model Basin
A ship model basin is a basin or tank used to carry out hydrodynamic tests with ship models, for the purpose of designing a new (full sized) ship, or refining the design of a ship to improve the ship's performance at sea. It can also refer to the organization (often a company) that owns and operates such a facility. A ship model basin company is an engineering firm that acts as a contractor to the relevant shipyards, and provides hydrodynamic model tests and numerical calculations to support the design and development of ships and offshore structures. History The eminent English engineer, William Froude published a series of influential papers on ship designs for maximising stability in the 1860s. The Institution of Naval Architects eventually commissioned him to identify the most efficient hull shape. He validated his theoretical models with extensive empirical testing, using scale models for the different hull dimensions. He established a formula (now known as the Froude n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamometer
A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed ( RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the dynamometer itself as kW or bhp. In addition to being used to determine the torque or power characteristics of a machine under test, dynamometers are employed in a number of other roles. In standard emissions testing cycles such as those defined by the United States Environmental Protection Agency, dynamometers are used to provide simulated road loading of either the engine (using an engine dynamometer) or full powertrain (using a chassis dynamometer). Beyond simple power and torque measurements, dynamometers can be used as part of a testbed for a variety of engine development activities, such as the calibration of engine management controllers, detailed investigations into combustion behavior, and tribology. In the medical termino ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propeller
A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working fluid such as water or air. Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are specially shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft (ship), propeller shaft with an approximately horizontal axis. History Early developments The principle employed in using a screw propeller is derived from sculling. In sculling, a single blade is moved through an arc, from side to side taking care to keep presenting the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Draft (hull)
The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water. The more heavily a vessel is loaded, the deeper it sinks into the water, and the greater its draft. After construction, the shipyard creates a table showing how much water the vessel displaces based on its draft and the density of the water (salt or fresh). The draft can also be used to determine the weight of cargo on board by calculating the total displacement of water, accounting for the content of the ship's bunkers, and using Archimedes' principle. The closely related term "trim" is defined as the difference between the forward and aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Froude Number
In continuum mechanics, the Froude number (, after William Froude, ) is a dimensionless number defined as the ratio of the flow inertia to the external field (the latter in many applications simply due to gravity). The Froude number is based on the speed–length ratio which he defined as: \mathrm = \frac where is the local flow velocity, is the local external field, and is a characteristic length. The Froude number has some analogy with the Mach number. In theoretical fluid dynamics the Froude number is not frequently considered since usually the equations are considered in the high Froude limit of negligible external field, leading to homogeneous equations that preserve the mathematical aspects. For example, homogeneous Euler equations are conservation equations. However, in naval architecture the Froude number is a significant figure used to determine the resistance of a partially submerged object moving through water. Origins In open channel flows, introduced first t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Of Attack
In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the body's reference line and the oncoming flow. This article focuses on the most common application, the angle of attack of a wing or airfoil moving through air. In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is simply defined. Often, the chord line of the root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuselage as the reference line (and also as the longitudinal axis). Some aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Velocity
In physics, angular velocity or rotational velocity ( or ), also known as angular frequency vector,(UP1) is a pseudovector representation of how fast the angular position or orientation of an object changes with time (i.e. how quickly an object rotates or revolves relative to a point or axis). The magnitude of the pseudovector represents the ''angular speed'', the rate at which the object rotates or revolves, and its direction is normal to the instantaneous plane of rotation or angular displacement. The orientation of angular velocity is conventionally specified by the right-hand rule.(EM1) There are two types of angular velocity. * Orbital angular velocity refers to how fast a point object revolves about a fixed origin, i.e. the time rate of change of its angular position relative to the origin. * Spin angular velocity refers to how fast a rigid body rotates with respect to its center of rotation and is independent of the choice of origin, in contrast to orbital angular v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Principal Axes
An aircraft in flight is free to rotate in three dimensions: '' yaw'', nose left or right about an axis running up and down; ''pitch'', nose up or down about an axis running from wing to wing; and ''roll'', rotation about an axis running from nose to tail. The axes are alternatively designated as ''vertical'', ''lateral'' (or ''transverse''), and ''longitudinal'' respectively. These axes move with the vehicle and rotate relative to the Earth along with the craft. These definitions were analogously applied to spacecraft when the first manned spacecraft were designed in the late 1950s. These rotations are produced by torques (or moments) about the principal axes. On an aircraft, these are intentionally produced by means of moving control surfaces, which vary the distribution of the net aerodynamic force about the vehicle's center of gravity. Elevators (moving flaps on the horizontal tail) produce pitch, a rudder on the vertical tail produces yaw, and ailerons (flaps on the win ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
