What happens when the water flows approaching a weir?

Let the upstream level of the liquid be z0 above the level of the weir crest. As the liquid approaches the weir, the liquid level gradually drops and the flow velocity increases. Downstream from the weir, a jet is formed.

Why V notch is preferable over rectangular weir as a flow measuring device?

It is used to meter flow of water in the channel, by measuring the head of water over the v notch crest. The v notch weir is especially good for measuring a low flow rate, because the flow area decreases rapidly as the head over the v notch gets small.

What is the principle behind weir flow measurement?

Weirs to Measure Flow It works by raising the water level upstream of the weir, and then forcing the water to spill over. The more water is flowing over the weir, the deeper the water will be upstream of the weir. So measuring flow rate (CFS) can be done by simply measuring the depth of the water upstream.

What is flow over weirs?

The depth of water above the base of a weir is related to the flow rate through it; therefore, the weir can be used as a flow measuring device. The relationships of flow over weirs can be obtained by applying the energy equation from a point well upstream of the weir to a point just above the weir crest.

What are the results of flow over weirs?

This approach requires a number of assumptions, and it yields the following results: for a triangular weir (Figure 9.2a): for a rectangular weir (Figure 9.2b): Cd: discharge coefficient to account for the effects of simplifying assumptions in the theory, which has to be determined by experiment [9].

How is the coefficient of discharge determined for weirs?

A coefficient of discharge needs to be determined experimentally for each weir to account for errors in estimating the flow rate that is due to these assumptions. 2. Practical Application

How are Weir notches used to measure flow?

A vernier hook and point gauge, mounted on an instrument carrier, to allow measurement of the depth of flow above the base of the notch. The weir notches that are mounted in a carrier at the outlet end of the flow channel [9]. 7. Theory

Where to place glass spheres in a weir?

1. Place the flow stilling basket of glass spheres into the left end of the weir channel and attach the hose from the bench regulating valve to the inlet connection into the stilling basket. 2.