Hydraulic analogy - Wikipedia, the free encyclopedia
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hydraulic analogy: Definition from Answers.com
hydraulic analogy ( h??drölik ??nal?j? ) ( fluid mechanics ) The analogy between the flow of a shallow liquid and the flow of a compressible gas;
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Talk:Hydraulic analogy - Wikipedia, the free encyclopedia
If you want a hydraulic analogy of voltage, then this will have to be equivalent ... Should this be renamed Hydraulic analogy to electric circuits? ...
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Quantitative flow visualization using the hydraulic analogy
The primary application of the hydraulic analogy is in the. study of supersonic gas ?ows. ... a hydraulic analogy water channel. Aeron Quart 2: 227-253. Pal AK; ...
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hydraulic analogy in the Froude number range of 0.04 to 0.22, ... It was seen that hydraulic analogy can give ... Hydraulic analogy has been identified as a ...
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Electronics beginner Tutorial, Part 1, Resistors, Volt and current
Ikalogic's repository of projects! You will find mostly electronics and ... I am proposing this simple analogy with a hydraulic system, which anybody can ...
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Fluid Power engineering - Hydraulic Analogy
The analogy often used is the electromotive force (E) is analagous to pressure ... Hydraulic valves are rated in terms of conductance or flow per unit of ...
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Analogy - Search Results - MSN Encarta
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An Experimental Analysis and Demonstration of the Non-Steady Flow in a ...
hydraulic analogy is an attractive tool to study. one and two-dimensional non-steady flows. ... Hydraulic analogy experiments. The driven region contained an ...
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Energy Citations Database (ECD) - - Document #6926316
Electrical analogy is used to study the influence of contact areas on the hydraulic flow through rock fractures.^The investigation has shown that in the case of ...
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The electronic Hydraulic analogy (derisively referred to as the Drain-pipe theory by Oliver Heaviside) is the most widely used analogy for "electron fluid" in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to understand in an intuitive way, it is common to teach electronics using analogies to everyday objects and processes. The analogy is made to a hydraulic system of water in pipes. The "electron fluid" in a metal conductor has many similarities to such a system, and the various electronic components have similar hydraulic equivalents. Electricity (as well as heat) was originally understood to be a kind of fluid. This hydraulic analogy is still of some use in teaching, not only for the fact that the names of the quantities are often struck by analogy. The water analogy is very useful in describing some aspects of electricity, but it breaks down for others.

Basic ideas There are two basic paradigms:

• Version with pressure induced by gravity. Large tanks of water that are held up high, and the potential energy of the water Head (hydraulic) is the pressure source. This is reminiscent of electrical diagrams with an up arrow pointing to +V, grounded pins that otherwise are not shown connecting to anything, and so on.
• Completely enclosed version with pumps providing pressure only; no gravity. This is reminiscent of a circuit diagram with a voltage source shown and the wires actually completing a circuit.

Component equivalents Wires All pipes are completely full of water, and none ever has an open end. If a pipe were to go somewhere without reconnecting to the circuit, it would have to have a cap on the end. This is because the wall of the pipe is like an insulator, and a wire just sticking out into insulating space/air is like a completely pipe-surrounded rod of water.Potential Equivalent to pressure.Voltage Also called potential difference. A difference in pressure between two pointscurrent (electricity) Equivalent to a hydraulic mass flow rate; that is, the quantity of flowing water over time.Ideal voltage source A pump with a pressure meter on both sides. It varies the speed of the pump to keep the difference in pressure constant.Ideal current source Also a pump, but with a current meter (little paddle wheel). The pump changes speed to maintain a constant speed of the little paddle wheel.Resistor A pipe with a small width. "So what makes this different from a regular-width pipe?". More water-preassure required to get the same amount of water through the pipe but it will flow faster (as less water gets through at the time). All pipes have some resistance, just like all wires have some resistance. Diode One-way valve or check valve. If it has a rubber flap it can be blown out permanently by too much P-n junction#Reverse-bias, which is similar to the real thing.Capacitor Big spherical tanks with a sheet of thick rubber separating the two halves. Inductor All flowing water has inertia, which has similar effects to inductance. A large, heavy, frictionless paddle wheel is like a dedicated inductor. As you try to increase a DC current, you encounter resistance as you speed up the paddle wheel, but after it is going, you can send a current at the same speed as the paddle wheel with no effort. If you try to put AC through it, the wheel will present a great resistance, as its inertia prevents you from moving it back and forth. Any real paddle wheel will have some friction associated with it, just as any real inductor has some resistance. The DC to DC converter uses inductance to change voltage in the way that a Hydraulic ram uses inertia to change pressure.Transistor A device similar to an EGR valve, where a diaphragm controlled by a low-current signal (either constant current — Bipolar junction transistor, or constant pressure — Field effect transistor) moves a plunger which allows a larger current to flow through another section of pipe, like a globe valve.CMOS A combination of two MOSFET transistors. As the input pressure changes, the pistons allow the output to connect to either zero or positive pressure.

Image:Diode analogie hydrodynamique bloquee.gif|The valve is closed, the current is blockedImage:Diode analogie hydrodynamique passante.gif|The valve is opened, the current passes

Principle equivalents EM wave speed (velocity of propagation) Speed of sound in water. When a light switch is flipped, the electric wave travels very quickly through the wires.Charge flow speed Particle speed of water. The moving charges themselves move rather slowly.Direct current Constant flow of water in a circuit of pipeLow frequency Alternating current Water oscillating back and forth in a pipehigh frequency AC and transmission lines Sound being transmitted through the water pipesInductive spark Used in induction coils, similar to water hammer, caused by the inertia of water

Equation examples Some examples of equivalent electrical and hydraulic equations:

{| class="wikitable"!type!hydraulic!electric!thermal|[volume V ] q |heat Q ]|pressure p ] \phi |temperature T ] \Phi_{V} |current (electricity) I |heat transfer rate \dot{Q} ] v |current density j ] \dot{Q} |-|linear model|Poiseuille's law \Phi_{V} = \frac{\pi r^{4-->{8 \eta} \frac{\Delta p^{\star-->{\ell}] j=-\sigma \nabla \phi|Fourier's law \dot{Q}=\kappa \nabla T|}

Limits to the analogy If taken too far, the water analogy can create misconceptions. For it to be useful, we must remain aware of the regions where electricity and water behave very differently.

Field (physics) Electrons can push or pull other distant electrons via their fields, while water molecules experience forces only from direct contact with other molecules. For this reason, waves in water travel at the speed of sound, but waves in a sea of charge will travel much faster as the forces from one electron are applied to many distant electrons and not to only the neighbors in direct contact. In a hydraulic transmission line, the energy flows as mechanical waves through the water, but in an electric transmission line the energy flows as fields in the space surrounding the wires, and does not flow inside the metal. Also, an accelerating electron will drag its neighbors along while attracting them, both because of magnetic forces.

Leaking pipes: If a hole is made in a hydraulic system, the water can leak out. But the movable charges present within electrical conductors are always attracted to unmoving opposite charges in the material. The "electric fluid" can be forcibly removed from metals, but enormous voltages arise if even a tiny amount is removed. For this reason, the surfaces of conductors act as if they always have a high energy-barrier preventing leaks. Also for this reason, continuing electric currents require closed loops rather than hydraulics' open source/sink resembling spigots and buckets. On the other hand non conductive surrounding gases such as air or SF6 behave as insulators and thus the water analogy would not have a hole in the pipe.

Fluid Velocity As with water hoses, the carrier drift velocity in conductors is directly proportional to current. However, charges' velocity within a conductor is typically less than centimeters per minute, and the "electrical friction" is extremely high. If charges ever flowed as fast as water can flow in pipes, the amperage would be immense, and the conductors would become incandescently hot and perhaps vaporize. To model the resistance and the charge-velocity of metals, perhaps a pipe packed with damp sand would be a better analogy than a clean, water-filled pipe.

Quantum Mechanics Conductors and insulators contain charges at more than one Energy level, while the water in one region of a pipe can only have a single value of pressure. For this reason there is no hydraulic explanation for such things as a battery (electricity)'s charge pumping ability, a diode's voltage drop, solar cell functions, Peltier effect, etc, however equivalent devices can be designed which exhibit similar responses, although some of the mechanisms would only serve to regulate the flow curves rather than to contribute to the component's primary function.

External links Good analogy

• Hyperphysics
• Hyperphysics 2 — Doesn't have the confusing reservoir.
• Reinventing constant current source by using a set of eight consecutive logically connected water analogies.

• With animations! — The paddle behaves like a resistor if the paddle itself is massless and has friction, and like an inductor if it is frictionless and has mass. Also has equivalent equations.
• Ohm's law
• Capacitor analogy
• Newsgroup thread with lots of good analogies and a few bad ones

Acceptable analogy

• Understanding Electricity — an analogy with water
• Water analogy to transistors Slightly better version would be something like an EGR valve
• Basic circuit theory
• Measuring electricity
• Plumbing analogy
• Animation

Hydraulic analogy - Wikipedia, the free encyclopedia
The electronic Hydraulic analogy (derisively referred to as the Drain-pipe theory by Oliver Heaviside) is the most widely used analogy for "electron fluid" in a metal conductor.

Hydraulic analogy | Flash simulation, Animation, Illustration, Picture ...
Summary. There is a close analogy between electric current and hydraulic current if you consider the electric voltage (potential difference) as a height (altitude difference), and ...

Hydraulic Adjusters - What does HYD stand for? Acronyms and ...
Acronym Definition; HyD: Highways Department (Hong Kong) HYD: How You Doin' HYD: Hyderabad ... Hydraulic analogy Hydraulic Association (UK) Hydraulic automata Hydraulic automata

Hydraulic accumulator - What does HYDAC stand for? Acronyms and ...
Acronym Definition; HYDAC: Hybrid Digital/Analog Computer: HYDAC: Hydraulic Accumulator? ... Hydraulic analogy Hydraulic Association (UK) Hydraulic automata: Hydraulic automata

hydraulic - Hutchinson encyclopedia article about hydraulic
Field of study concerned with utilizing the properties of water and other liquids ... Hydraulic analogy Hydraulic Association (UK) Hydraulic automata Hydraulic automata

hydraulic analogy: Definition and Much More from Answers.com
hydraulic analogy ( hī′drölik ə′naləjē ) ( fluid mechanics ) The analogy between the flow of a shallow liquid and the flow of a compressible gas;

hydraulic - definition of hydraulic by the Free Online Dictionary ...
adj. ... Hydraulic analogy Hydraulic Association (UK) Hydraulic automata Hydraulic automata

Hydraulic analogy of supersonic flow - lab notes
Von Karman Institute for Fluid Dynamics VDH Page 1/9 Hydraulic analogy of supersonic flow - lab notes By M. Carbonaro and V. Van der Haegen EUROAVIA symposium - November 2002 Von ...

INEX: Wikipedia, the free encyclopedia (Hydraulic analogy)
Table of Contents. 1 Basic ideas; 2 Component equivalents; 3 Principle equivalents; 4 Equation examples; 5 External links. 5.1. Good analogy; 5.2. Acceptable analogy

Performance Evaluation of a Reverse-flow Gas Turbine Combustor using ...
Performance Evaluation of a Reverse-flow Gas Turbine Combustor using Modified Hydraulic Analogy Dr M D Agrawal, Member Dr S Bharani, Member Experiments were performed on equivalent ...