Venturi, Orifice and Nozzle

[Merttt]

Hello everyone. When I try to do mass flow systematic uncertainty estimation for venturi nozzle and orifice, I am getting the biggest error from venturi nozzle. What is the reason for it? ( Why coefficient of velocity of venturi nozzle is too big compared to orifice and nozzle.)

 

[jim hardy]

Why coefficient of velocity of venturi nozzle is too big compared to orifice and nozzle.

i am unfamiliar with "coefficient of velocity".
Did you mean perhaps "discharge coefficient " c_d ?
see http://www.engineeringtoolbox.com/orifice-nozzle-venturi-d_590.html
c_d IS larger for a venturi than for an orifice.

What do you mean by error ?
A question well stated is half answered.
Without knowing your test setup, the results you expected and those you got,
how could anyone do anything but serve you up a word salad??

ASME publishes a most excellent reference , titled simply "Fluid Meters"