TAM 335 Partial Report 6

In this experiment, we are calibrating a Venturi flowmeter by relating pressure difference to flow rate and figuring out how accurate it is. We also compare it to a paddlewheel flowmeter and see how reliable both are. The goal is to determine the discharge coefficient and check how well theory matches real data

The Venturi meter works by measuring a pressure drop caused by a change in pipe area. Flow rate depends on the manometer height difference:

Flow rate increases as pressure difference increases and the theoretical relation is nonlinear

So our whole job is basically checking if your data actually follows this.

Open the discharge valve slowly and let flow stabilize

Make sure to record:

1.Manometer height difference (Δh)

2.Paddlewheel voltage

3.Flow rate using weight–time method

Repeat for multiple flow rates adjusting the rates from high values to lower

After plotting the calibration curve from our gathered data, we see a nonlinear curve and that as change in height increases, the flow rate increases as well.

In our logarithmic scale of the graph, we see that the data points fall along a straight line, indicating the existence of the power-law relation.

We calculated the maximum velocity using the Q = AV formula using the maximum flow rate from the graph and the diameter of the throat of the Venturi plate, we found that it is 2.39 m/s.

Through our graph, we can see that Cd varies slightly from the Reynold's number. Some corrections that can be made are reducing friction or any other energy losses. Although the theory is valid, in real systems there will always be some energy loss causing it to no be completely ideal

The Paddlewheel is more accurate at higher flow rates. In general, the Venturi flowmeter is the most reliable.