Fluid Flow In A Smooth Pipe

Abstract

In this experiment, three variable flow meters are used to alter the flowrate. Changes in pressure drop due to the change in flowrate are then observed from the three pressure gauges that can measure pressure at different range and recorded. The shift from laminar flow to turbulent flow is seen from the results recorded, but it is observed more clearly from the water-soluble dye experiment that was carried out by the demonstrator. Laminar flow turns to be turbulent when the Reynolds Number goes above a certain value, around 2000.

Aims

To look at how the pressure drop changes when the average velocity is altered in a circular pipe and to plot a graph of Friction Factor versus Reynolds Number. Another aim is to examine the shift from laminar flow to turbulent flow.

Schematic Diagram

Water Out

Inverted Water-air Manometer

Wet-wet Digital Differential Pressure (0-100kPa)

Capsuhelic Differential Pressure (0-250kPa)

1600 L/hr

250 L/hr

70 L/hr

1.5m

Water In

water-soluble dye

P

P

P

Figure 1: Schematic Diagram of Apparatus Used and Direction of Flow in a Smooth Pipe

Results

A graph of log - log plot of f versus Re is plotted, and a straight line of best fit through the data points for laminar flow is drawn:

Figure 2: Graph of log - log plot of f versus Re

Discussions

To calculate the slope of the best fit line from Figure 2, two points are selected: (600, 0.02) and (200, 0.07) slope=log(0.02)-log(0.07)log600-log(200)

slope=-1.14

Theoretically, in the laminar flow regime for pipe flow,

f=16Re

logf=log(16Re)

logf=log16-log(Re)

logf=-logRe+1.2

So, we expect the value of the slope to be -1. In Figure2, the slope found is -1.14, which is close to -1. Both values agree with each other. At the maximum flowrate, Q = 1600L/hr = 4.44 x 10-4 m3/s

The parameters:

d=0.0126 m ρ=999.44 kg/m3 μ=0.001222 kg/ms Sample calculation to...

(1)