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Orifice plate showing vena contracta. An orifice plate is a thin plate with a hole in it, which is usually placed in a pipe. When a fluid (whether liquid or gaseous) passes through the orifice, its pressure builds up slightly upstream of the orifice [1] but as the fluid is forced to converge to pass through the hole, the velocity increases and the fluid pressure decreases.
A restrictive flow orifice (RFO) is a type of orifice plate.They are used to limit the potential danger, damage, or wastage of an uncontrolled flow from, for example, a compressed gas cylinder [1] [2] They are generally not limiting the flow during normal operation but if a fault or failure occurs causing uncontrolled flow the orifice will present a restriction, limiting the flow.
If the fluid is a liquid, a different type of limiting condition (also known as choked flow) occurs when the venturi effect acting on the liquid flow through the restriction causes a decrease of the liquid pressure beyond the restriction to below that of the liquid's vapor pressure at the prevailing liquid temperature.
A flow limiter or flow restrictor is a device to restrict the flow of a fluid, in general a gas or a liquid. [1] Some designs use single stage or multi-stage orifice plates to handle high and low flow rates. Flow limiters are often used in manufacturing plants as well as households. Safety is usually the main purpose of using a flow limiter.
The liquid limit test is defined by ASTM standard test method D 4318. [4] The test method also allows running the test at one moisture content where 20 to 30 blows are required to close the groove; then a correction factor is applied to obtain the liquid limit from the moisture content. [5]
Both gas and liquid flow can be measured in physical quantities of kind volumetric flow rate or mass flow rates, with respective SI units such as cubic meters per second or kilograms per second, respectively. These measurements are related by the material's density. The density of a liquid is almost independent of conditions.
The boundary layer thickness, , is the distance normal to the wall to a point where the flow velocity has essentially reached the 'asymptotic' velocity, .Prior to the development of the Moment Method, the lack of an obvious method of defining the boundary layer thickness led much of the flow community in the later half of the 1900s to adopt the location , denoted as and given by
where is the area of the moving plate and the stagnant plate, is the spatial coordinate normal to the plates. In this experimental setup, value for the force F {\displaystyle F} is first selected. Then a maximum velocity u m a x {\displaystyle u_{max}} is measured, and finally both values are entered in the equation to calculate viscosity.