Boggling result of venturi experiment

[charitym]

Hi! I'm boggled by the results of my experiment...maybe you can help me... I made an improvised venturi meter which I used to determine for the velocity of water flowing in a pipe. Then just to confirm my velocity value I allowed the water to just gush out of the venturi meter (disconnected on the outflowing part) then I measured the height and maximum distance of its trajectory (by the way the pipe & venturi meter set-up were horizontal) and solve for the water velocity using equations of projectile motion. The velocity computation I got using the second method was much less than the one I got using the venturi meter. I wanted to account for the head loss when I stumbled into the Darcy-Weisbach equation... can I use it to solve for the head loss in the conical portions of the venturi meter? If yes, can you help me how? If no...any idea what alternative method I can use? Thanks in advance!

 

[FredGarvin]

First thing I would do is to repeat your test but instead of calculating the distance/trajectory stuff, simply allow the flow to be collected in a bucket or graduate cylinder to measure the volume. That is going to be much easier and more reliable than the previous method you chose. By your descriptions, I am doubtful about your method using projectile motion equations.