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Stagnation Enthalpy
In thermodynamics and fluid mechanics, the stagnation enthalpy of a fluid is the static enthalpy of the fluid at a stagnation point. The stagnation enthalpy is also called total enthalpy. At a point where the flow does not stagnate, it corresponds to the static enthalpy of the fluid at that point assuming it was brought to rest from velocity V isentropically.Van Wylen, G.J. and Sonntag, R.E. (1976) ''Fundamentals of Classical Thermodynamics'', section 14.1 (SI Version 2e), John Wiley & Sons, Inc., New York That means all the kinetic energy was converted to internal energy without losses and is added to the local static enthalpy. When the potential energy of the fluid is negligible, the mass-specific stagnation enthalpy represents the total energy of a flowing fluid stream per unit mass. Stagnation enthalpy, or total enthalpy, is the sum of the static enthalpy (associated with the temperature and static pressure at that point) plus the enthalpy associated with the dynamic pressure, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermodynamics
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering and mechanical engineering, but also in other complex fields such as meteorology. Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Pressure
In fluid dynamics, dynamic pressure (denoted by or and sometimes called velocity pressure) is the quantity defined by:Clancy, L.J., ''Aerodynamics'', Section 3.5 :q = \frac\rho\, u^2 where (in SI units): * is the dynamic pressure in pascals (i.e., kg/ m⋅ s2), * is the fluid mass density (e.g. in kg/m3), and * is the flow speed in m/s. It can be thought of as the fluid's kinetic energy per unit volume. For incompressible flow, the dynamic pressure of a fluid is the difference between its total pressure and static pressure. From Bernoulli's law, dynamic pressure is given by : p_0 - p_\text = \frac\rho\, u^2 where and are the total and static pressures, respectively. Physical meaning Dynamic pressure is the kinetic energy per unit volume of a fluid. Dynamic pressure is one of the terms of Bernoulli's equation, which can be derived from the conservation of energy for a fluid in motion. It can also appear as a term in the incompressible Navier-Stokes equation whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rothalpy
Rothalpy (or trothalpy) I, a short name of rotational stagnation enthalpy, is a Fluid mechanics, fluid mechanical property of importance in the study of flow within rotating systems. Concept Consider we have an inertial frame of reference XYZ and a Rotating reference frame, rotating frame of reference xyz which both are sharing common origin O. Assume that frame xyz is rotating around a fixed axis with angular velocity \mathbf . Now assuming fluid velocity to be \mathbf and fluid velocity relative to rotating frame of reference to be \mathbf =\mathbf -\mathbf : Rothalpy of a fluid point P can be defined as I=h_-\frac where \mathbf =\mathbf \times\mathbf and \mathbf =\vec and h_ is the stagnation enthalpy of fluid point P relative to the rotating frame of reference xyz, which is given by h_=h+\frac and is known as relative stagnation enthalpy. Rothalpy can also be defined in terms of absolute stagnation enthalpy: I=h_0-uV_\theta where V_\theta is tangential component of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stagnation Temperature
In thermodynamics and fluid mechanics, stagnation temperature is the temperature at a stagnation point in a fluid flow. At a stagnation point the speed of the fluid is zero and all of the kinetic energy has been converted to internal energy and is added to the local static enthalpy. In both compressible and incompressible fluid flow, the stagnation temperature is equal to the ''total temperature'' at all points on the streamline leading to the stagnation point. See gas dynamics. Derivation Adiabatic Stagnation temperature can be derived from the First Law of Thermodynamics. Applying the Steady Flow Energy Equation and ignoring the work, heat and gravitational potential energy terms, we have: :h_0 = h + \frac\, where: :h_0 =\, mass-specific stagnation (or total) enthalpy at a stagnation point :h =\, mass-specific static enthalpy at the point of interest along the stagnation streamline :V =\, velocity at the point of interest along the stagnation streamline Substituting for ent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stagnation Pressure
In fluid dynamics, stagnation pressure is the static pressure at a stagnation point in a fluid flow.Clancy, L.J., ''Aerodynamics'', Section 3.5 At a stagnation point the fluid velocity is zero. In an incompressible flow, stagnation pressure is equal to the sum of the free-stream static pressure and the free-stream dynamic pressure. Stagnation pressure is sometimes referred to as pitot pressure because the two pressures are numerically equal. Magnitude The magnitude of stagnation pressure can be derived from Bernoulli equation for incompressible flow and no height changes. For any two points 1 and 2: :P_1 + \tfrac \rho v_1^2 = P_2 + \tfrac \rho v_2^2 The two points of interest are 1) in the freestream flow at relative speed v where the pressure is called the "static" pressure, (for example well away from an airplane moving at speed v); and 2) at a "stagnation" point where the fluid is at rest with respect to the measuring apparatus (for example at the end of a pitot tube in an ai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Energy
The internal energy of a thermodynamic system is the total energy contained within it. It is the energy necessary to create or prepare the system in its given internal state, and includes the contributions of potential energy and internal kinetic energy. It keeps account of the gains and losses of energy of the system that are due to changes in its internal state. It does not include the kinetic energy of motion of the system as a whole, or any external energies from surrounding force fields. The internal energy of an isolated system is constant, which is expressed as the law of conservation of energy, a foundation of the first law of thermodynamics. The internal energy is an extensive property. The internal energy cannot be measured directly and knowledge of all its components is rarely interesting, such as the static rest mass energy of its constituent matter. Thermodynamics is chiefly concerned only with ''changes'' in the internal energy, not with its absolute value. Instea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stagnation Properties ''
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Stagnation may refer to one of the following *Economic stagnation, slow or no economic growth. *Era of Stagnation, a period of economic stagnation in Soviet Union *Lost Decade (Japan), a period of economic stagnation in Japan *Stagnation in fluid dynamics, see "Stagnation point" *Water stagnation *Air stagnation *"Stagnation", song from Genesis' album ''Trespass Trespass is an area of tort law broadly divided into three groups: trespass to the person, trespass to chattels, and trespass to land. Trespass to the person historically involved six separate trespasses: threats, assault, battery, wounding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intensive And Extensive Properties
Physical properties of materials and systems can often be categorized as being either intensive or extensive, according to how the property changes when the size (or extent) of the system changes. According to IUPAC, an intensive quantity is one whose magnitude is independent of the size of the system, whereas an extensive quantity is one whose magnitude is additive for subsystems. The terms ''intensive and extensive quantities'' were introduced into physics by German writer Georg Helm in 1898, and by American physicist and chemist Richard C. Tolman in 1917. An intensive property does not depend on the system size or the amount of material in the system. It is not necessarily homogeneously distributed in space; it can vary from place to place in a body of matter and radiation. Examples of intensive properties include temperature, ''T''; refractive index, ''n''; density, ''ρ''; and hardness, ''η''. By contrast, extensive properties such as the mass, volume and entropy of syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static Pressure
In fluid mechanics the term static pressure has several uses: * In the design and operation of aircraft, ''static pressure'' is the air pressure in the aircraft's static pressure system. * In fluid dynamics, many authors use the term ''static pressure'' in preference to just ''pressure'' to avoid ambiguity. Often however, the word ‘static’ may be dropped and in that usage pressure is the same as static pressure at a nominated point in a fluid. * The term ''static pressure'' is also used by some authors in fluid statics. Static pressure in design and operation of aircraft An aircraft's static pressure system is the key input to its altimeter and, along with the pitot pressure system, also drives the airspeed indicator. The static pressure system is open to the aircraft's exterior through a small opening called the static port, which allows sensing the ambient atmospheric pressure at the altitude at which the aircraft is flying. In flight, the air pressure varies slightly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Mechanics
Fluid mechanics is the branch of physics concerned with the mechanics of fluids ( liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical and biomedical engineering, geophysics, oceanography, meteorology, astrophysics, and biology. It can be divided into fluid statics, the study of fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion. It is a branch of continuum mechanics, a subject which models matter without using the information that it is made out of atoms; that is, it models matter from a ''macroscopic'' viewpoint rather than from ''microscopic''. Fluid mechanics, especially fluid dynamics, is an active field of research, typically mathematically complex. Many problems are partly or wholly unsolved and are best addressed by numerical methods, typically using computers. A modern discipline, called computational fluid dynamics (CFD), is dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called ''centigrade''), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible to extract energy as heat from a body at that temperature. Temperature is important in all fields of natur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potential Energy
In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. Common types of potential energy include the gravitational potential energy of an object, the elastic potential energy of an extended spring, and the electric potential energy of an electric charge in an electric field. The unit for energy in the International System of Units (SI) is the joule, which has the symbol J. The term ''potential energy'' was introduced by the 19th-century Scottish engineer and physicist William Rankine, although it has links to Greek philosopher Aristotle's concept of potentiality. Potential energy is associated with forces that act on a body in a way that the total work done by these forces on the body depends only on the initial and final positions of the body in space. These forces, that are called ''conservative forces'', can be represented at every point in space by vec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
