Regarding an experiment to find the mass flow rate of a fluid (air) using a venturi meter and a pitot tube: What could be the cause of a variance in results obtained using the 2 instruments mentioned? My mass flow rate for pitot tube is 10 times less than the mass flow rate found using the venturi. What limitations could have been the cause of this?
The venturi meter takes advantage of a constriction to change the speed of fluid flow, thus changing the dynamic pressure. In doing so, one can measure the relative difference in flow speed between the two sections.
The pitot meter also measures flow speed, but it forces the fluid to reach a stagnation point and abruptly change flow direction. This is the source of the difference in flow speed.