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In a nozzle or other constriction, the discharge coefficient (also known as coefficient of discharge or efflux coefficient) is the ratio of the actual discharge to the ideal discharge, [1] i.e., the ratio of the mass flow rate at the discharge end of the nozzle to that of an ideal nozzle which expands an identical working fluid from the same initial conditions to the same exit pressures.
By means of a high-voltage discharge (5–15 kV, 10–100 kHz) a pulsed electric arc is generated. A process gas, usually oil-free compressed air flowing past this discharge section, is excited and converted to the plasma state. This plasma passes through a jet head to the surface of the material to be treated.
Surface micro-machining involves as many layers as are needed with a different mask (producing a different pattern) on each layer. Modern integrated circuit fabrication uses this technique and can use as many as 100 layers. Micro-machining is a younger technology and usually uses no more than 5 or 6 layers.
Electrical discharge machining (EDM), also known as spark machining, spark eroding, die sinking, wire burning or wire erosion, is a metal fabrication process whereby a desired shape is obtained by using electrical discharges (sparks). [1]
Note: the Strickler coefficient is the reciprocal of Manning coefficient: Ks =1/ n, having dimension of L 1/3 /T and units of m 1/3 /s; it varies from 20 m 1/3 /s (rough stone and rough surface) to 80 m 1/3 /s (smooth concrete and cast iron). The discharge formula, Q = A V, can be used to rewrite Gauckler–Manning's equation by substitution for V.
For low viscosity liquids (such as water) flowing out of a round hole in a tank, the discharge coefficient is in the order of 0.65. [4] By discharging through a round tube or hose, the coefficient of discharge can be increased to over 0.9. For rectangular openings, the discharge coefficient can be up to 0.67, depending on the height-width ratio.
Right: The reduction in flux passing through a surface can be visualized by reduction in F or dS equivalently (resolved into components, θ is angle to normal n). F•dS is the component of flux passing through the surface, multiplied by the area of the surface (see dot product). For this reason flux represents physically a flow per unit area.
An electric arc (or arc discharge) is an electrical breakdown of a gas that produces a prolonged electrical discharge. The current through a normally nonconductive medium such as air produces a plasma, which may produce visible light. An arc discharge is initiated either by thermionic emission or by field emission. [1]