Figure 3.25: Flow through an Orifice Body A fully developed flow prevails at the upstream of the orifice. The presence of the orifice makes the flow accelerate through it thus increasing the velocity.
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It may appear that the flow fills the orifice completely and expands downstream of it. But this is not true. As the flow expands downstream it cannot fill the entire diameter of the pipe at once. It requires a distance before it does. A recirculating flow develops immediate downstream of the nozzle. As a consequence the smallest diameter of flow is not equal to the orifice diameter, but smaller than it. The position of the smallest diameter occurs downstream of the orifice.
We can deduce the flow rate through the pipe by measuring the pressure difference upstream of the nozzle and at the orifice. We make a few assumptions about the flow as follows -. The flow is steady. The flow is incompressible. There is no friction or losses.
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Orifice K-Values Flow Example DP Example Friction Factor Example NRe Example Shortcut Home Avg Avg Avg bar bar. Chapter 1: Fluid Flow by Stephen Hall. Isothermal Gas Calculation Friction factor Pipe roughness Standard volumetric rate Weymouth MM ft3/day.
The velocities at sections (1) and (2) are uniform, i.e, they do not vary in a radial direction. The pipe is horizontal, i.e., z is the same at (1) and (2), i.e., z 1 = z 2. This assumption can be relaxed easily. It is possible to have a fluid flowing through an inclined pipe.
Then the gz term does not cancel out from LHS and RHS of the Bernoulli Equation. The equations we consider are (a) Continuity and (b) Bernoulli equations. A) Continuity Equation.
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