CE 2250 Chapter : CE 2250 Lab 6
CE 2250-Section 1-Wednesday
Fluid Mechanics Lab
Christopher Siverd
Lab 6
Venturi and Orfice Meters
Group #3
Submitted by:
Trevor Gaubert
Mattie FairChild
Chelsea Hulin
Lance Pitre
Date Tested: Date Submitted:
March 9th , 2016 March 16th , 2016
Department of Civil and Environmental Engineering
Louisiana State University
Spring 2016
Introduction
Across the world piping systems are used to transport fluids from one place to another.
In order to plan and design a piping system like this, engineers need to be able to determine the
losses that will occur in the network. There are different devices/meters that can be used to
determine the losses, for this lab in particular a venturi meter and an orifice meter were used.
These found losses can be used in junction with the known geometries of the piping and meters
to calculate the discharge within the piping system.
As stated before a venturi and an orifice meter were used for this lab. Their use was to
observe the relationship between flow and pressure drop through these meters. A venturi meter is
a fitting on a pipe that causes a gradual contraction of the flow through a narrow section which is
then followed by a gradual expansion where the pipe gets bigger. The setup of the meter causes
an increase in the velocity in the narrow section because the flowrate goes through a smaller
area, and velocity equals flowrate divided by area. This increase in velocity then causes a
decrease in pressure between the entrance of the meter and the middle narrow section. An orifice
positioned in a pipe causes a larger loss than those in the same pipe without the orifice which is
another way of causing a pressure drop. That being said, the purpose of this lab is to find the
characteristics of the venturi and orifice meters and find the relationship between the flow and
pressure drops across both meters.
Methodology
Theoretical background
The Venturi meter is based on the work of the 18th century Italian physicist Giovanni B.
Venturi. Venturi meters contain a short cylindrical portion where a pressure transducer
measures the static pressure of the incoming fluid. Following the entrance, a convergence
portion leads to the throat of the tube. This portion is responsible for the gradual increase
in flow velocity and consequential decrease in static pressure. The static pressure at the
throat is also measured via a pressure transducer. As compared with the diameter of the
entrance, that of the throat is typically between one-half and one-fourth in size. Once the
fluid passes the throat, its pressure and velocity are restored to its original values, via a
diverging cone placed at the meter’s exit. There are many different types of venturi
meters available in the market and all are identified by their pipe and throat diameters.
Venturi meters can be used to measure flow rate via the initial application of Bernoulli’s
principle between points 1 and 2 of Figure 1.
Equation 1
Figure 1: Venturi Meter
The continuity equation is then applied at points 1 and 2:
Equation 2
Substituting yields
Equation 3
The ideal discharge is obtained
Equation 4
