HM15018E

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Equipment for Engineering Education

HM150.18 Osborne Reynolds

Demonstrator

G.U.N.T. Gerätebau GmbH

P.O. Box 1125

D-22881 Barsbüttel • Germany

Phone (040) 670854-0

Fax (040) 670854-41

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Test Instructions

Publication no.: 917.00018A15012 09/99

HM150.18 Osborne ReynoldsDemonstration Apparatus

A l l r i g h t s r e s e r v e d G . U . N . T .

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B a r s b ü t t e l , G e r m a n y ,

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Table of Contents

1 Unit description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Preparing and installing the unit . . . . . . . . . . . . . . . . . . . . . . . 2

3 Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.1 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6



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1 Unit description

The unit is intended for investigating and visua-

lising the Osborne Reynolds experiments.

The test setup allows laminar and turbulent flow to

be demonstrated. The flow is made visible with an

ink trace in a transparent pipe section.

The unit essentially comprises:

- Base plate [1] with the necessary connecti-ons for water supply [11] and waste water

discharge [10].

- Water reservoir [2] with a ball block to stem

the flow [9].

- Overflow section [3] to generate a constant

pressure level in the reservoir.

- Aluminium well [4] for ink with metering tap

[5] and brass inflow tip [6].

- Test pipe section [8] of Plexiglas with

flow-optimised inflow [7].

- Drain cock [12] to adjust the flow through the

test pipe section.

To visualise the flow we recommend blue ink,

which is carefully introduced into the flowing water

by way of the aluminium well and the inflow tip. The

water supply can be realised with the HM150 fluid

technics base module. The flow rate is measured

by means of a measuring vessel or using HM150.

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1 Unit description 1

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2 Preparing and installing the unit

The following steps are required to commission

and prepare the unit for experimenting:

- Place the unit on a bench or on the HM150. If

you are not using HM150, a permanent water

supply should be available close by.

- Remove the lid [13] of the reservoir and place

the glass balls [9] in the reservoir as shown inthe illustration.

ATTENTION! No glass balls must fall into

the pipe section; close it off with an appro-

priate block !

- Replace the reservoir lid, dampening the seal

ring (O-ring) [14] of the lid with water to do so.

- Connect up the water by a hose.

- Connect the waste water hoses to the drain

cock [12] and to the waste water connection

[10]. If you are using HM150, you can install the

unit so the waste water drains off directly into

the tank of the HM150.

The ink-contaminated water should not be al-

lowed to run into the tank of the HM150.

- Fill the aluminium well with ink. The ball cock

must be closed.

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2 Preparing and installing the unit 2

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3 Performing the experiment

- Close the drain cock [12].

- Switch on the water supply.

When using HM150, switch on the pump. Ca-

refully open the ball cock above the pump, or

the laboratory water tap as appropriate.

- Adjust the tap to produce a constant water level

in the reservoir.- After a time the test pipe section [8] is comple-

tely filled.

The experiment can begin.

Open the drain cock slightly to produce a low rate

of flow into the test pipe section. The coloured

waste water is best directed down the drain.

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Water level



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3.1 Experiments

The aim of this setup is to demonstrate laminar and

turbulent flow.

At a low flow rate laminar flow occurs.

To produce a low flow, open the drain cock slightly.

Blue ink is used to visualise the flow. A fine blue

thread of stream indicating the laminar flow can beproduced using the metering tap [9].

At a high flow rate turbulent flow occurs.

To produce a high flow, open the drain cock wider.

The thread of stream is broken up in turbulent flow.

The flow changes from laminar to turbulent when:Rekr ≈ 2300

Relam . ≤ 2300 means laminar flow

Retur . ≥ 2300 means turbulent flow

The Reynolds number is calculated from

Re = w ⋅ d ν

where

d= inside diameter of pipe section [m]

w= flow rate [m/s]

ν= viscosity of the medium [m2 /s,]

water: ν = 1 ⋅ 10 −6 [m

2 /s]

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Thread of stream



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The flow rate can be calculated from the volume

flow, which is determined with a measuring vesseland a stopwatch.

w = V .

A, A =

π ⋅ d 2

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diameter of pipe: d = 10mm = 0,01m

V .= Volume flow

A= Cross-sectional area of the pipe

The diagram below shows the three flow states:

- Laminar flow

- Transition laminar/turbulent flow

- Turbulent flow

Rekr ≈ 2300

critical

Retur . ≥ 2300

turbulent

Relam . ≤ 2300

laminar



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4 Technical data

Reservoir: 3.5 litres

Test pipe section:

Inside diameter: 10 mm

Length: 700 mm

Ink well: 270 ml

Main dimensions: 450 x 400 x 1400 mm

Weight: 32 kg



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HM15018E