Lab 6 Partial Report

In lab 6, we work to calibrate flowmeters by conducting testing in order to find their respective Reynold's number. This number works as a coefficient and allows us to use these flowmeters accurately over a wide range of values.

Here is the main testing apparatus, with closer views of both the venturi tube and orifice plate measuring devices. The differential pressure transducer will be hooked up to a lab computer and will automatically take and plot data collected from these measuring devices.

The transducer must first be set to zero on the box next to the computer. Since there is no flow in the pipe at the moment, the value must be zero.

Now, you will open the flow valve to five different speeds, each time measuring both the value of the transducer and the height difference on the manometer attached to the wall.

The LabVIEW program will conduct an analysis, giving both the slope and y-intercept of the data using linear regression. This information will be used later to collect data.

Now data is needed from the flow meters. For the hydraulic flow meter and the paddlewheel flow meter, the gain adjust on the digital readout must be set to 6.25 turns for P1 and P4, and 3.00 turns for P3. Then use the zero adjust to zero out the paddlewheel output.

Now that both of these flowmeters are ready to output data, slowly open the discharge value and simultaneously measure both on the compute. Start exactly when there are non-zero values.

Simultaneously, with the help of your lab group, take data from the paddle wheel, orifice plate flowmeter and weight-time system. Each of these points should be taken at increments of 10% of the maximum flow. This goes by increments .9^2, .8^2, .7^2 . . . all the way to the last non-zero measurement.

Using the data collected previously, the labVIEW software will automatically calculate the Reynolds value associated with the flow rate.

Here is a linear comparison between the flow rate and manometer readings using the venturi meter

Here is a logarithmic comparison between the flow rate and manometer readings using the venturi meter

Here is the plot of theoretical Reynold's values associated with this testing setup, as well as the experimental.

Here are the paddlewheel values plotted against the flow rate using the weight-time method. Paddlewheel cutoffs at .022 m^3/sec and .00404 m^3/sec.

The experimental discharge coefficients do not stay constant, and instead, seem to increase with the Reynolds number. The experimentally measured values are not close to the ideal value of unity derived theoretically. This could be due to the fact that the fluid is being treated as 'dry', or at least the friction and tension between particles is not being accounted for.

The paddlewheel flowmeter seems to be relatively reliable, however, it seems to lose some accuracy at the higher values.