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HYDRAULIC ENGINEERING OPEN-CHANNEL FLOW
AN OVERVIEW OF GUNT EXPERIMENTAL FLUMES
GUNT experimental flumes and their accessories open
up a wide range of experiments and demonstrations
on the topics of open-channel flow, running waters,
hydraulic engineering and coastal protection. They form
the expandable foundation for custom investigations and
research work. Experimental flumes from GUNT have
been successfully put to use around the world for many
years.
For each of the experimental flumes, there is a variety of
models for discharge control, such as weirs, sills, stilling
basins, as well as wave generators, beach elements and
bridge piers. Technical solutions for sediment feed and
removal are also available.
In addition, we can also provide specially adapted instrumentation such as water level gauges, pitotstatic tubes,
tube manometers and velocity meters.
HM 162 (12,5m)
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HM 161
HM 161
HM 162
HM 161
Tried and trusted
products:
GUNT provides three experimental flumes with
different cross-sections, depending on the purpose of
use and the local conditions: HM 160 (86 x 300 mm),
HM 162 (309x450mm) and HM 161 (600x800mm). Two
of the experimental flumes have different lengths of
experimental section to choose from: HM 160 with 2,5m or
5m and HM 162 with experimental sections of 5m, 7,5m,
10m or 12,5m. As a result, the length of the experimental
section can be adjusted to the individual requirements of
the laboratory. HM 161 is the largest GUNT experimental
flume and has an experimental section that is 16m long.
HM 160 (5m)
The HM 160 flume is perfectly suited as an introduction
to the topic of Open-Channel Flow and the demonstration of many of the basic principles. The experimental
flume even fits in lecture theatres, as it is relatively small
and compact. HM 160 with an experimental section of
2,5m requires an area of approximately 6x4m, including
sufficient space to observe the experiments. This allows
the instructor to provide practical demonstrations of
phenomena during lectures.
...from small to large
...for demonstration
and research
The HM 162 experimental flume can be supplied in four
different lengths. The short experimental flume, with an
experimental section of 5m, is particularly well suited for
demonstrations and can easily be set up even in smaller
laboratories.
As the length of the experimental section increases and
the inlet and outlet conditions improve the phenomena
become closer to those observed in reality. For example,
with an experimental section of 12,5m we can clearly see
to what extent a damming body affects the upstream flow.
The largest GUNT experimental flume HM 161 with a
cross-section of 600x800mm and a 16m long experimental section offers a large number of possibilities for your
own research projects. The phenomena to be observed
move beyond mere demonstration and become closer to
reality. The HM 161 flume provides an initial impression of
the natural force of water.
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HYDRAULIC ENGINEERING OPEN-CHANNEL FLOW
TECHNICAL DETAILS FOR GUNT EXPERIMENTAL FLU MES THE CLOSED WATER CIRCUIT
THE WATER CIRCUIT
THE INLET ELEMENT
In all experimental flumes, the inlet element is designed
for optimum flow so that the flow is less turbulent as it
enters the experimental section.
1
2
3
4
5
6
F
All experimental flumes can be operated independently
of the laboratory water supply and have a closed water
circuit with water tanks, pump and flow meter. To protect
The water enters from below through a flow straightener. A
damping plate calms the water further. The damping plate
floats on the water and is mounted on a guide.
In the plan view we can see that the inlet element has a
nozzle-like contour.
water tank,
outlet element,
pump,
experimental section,
control butterfly valve,
inlet element,
flow meter
against overfilling of the experimental section, level
switches turn off the pump when the maximum level in the
inlet or outlet element is exceeded.
1 damping plate, 2 flow straightener,
3 guide
THE PUMP
Plan view of the inlet element with streamlines
THE OUTLET ELEMENT
1
2
3
4
The centrifugal pump is separated from the experimental
section in both experimental flumes HM 162 and HM 161
and is mounted on its own foundation. It is connected to
the piping to the inlet element via a hose. This ensures
that there is no transmission of vibrations between the
experimental section and the pump. In the small experimental flume HM 160 the vibrations that occur are negligible, so the pump is integrated in one of the experimental
flumes supports.
The outlet element of all experimental flumes contains a
plate weir. A maximum of two elements can be removed
from this weir, so that two damming heights are available
to choose from. If both elements are removed, it corre-
water tank,
pump,
hose,
flow meter
Pump (HM 162) with shut-off
valve in the intake side (left)
and control butterfly valve
with manual actuation in the
delivery side for adjusting
the flow rate (above the
pump). The pumps delivery
line also contains the hose
and the electromagnetic flow
meter.
sponds to free discharge without a weir. Moreover, the
weir is mounted to rotate around a fixed point and can
thus be lowered. As such, any desired top water level can
be set (see illustrations).
Principle of the plate weir with two damming heights:
both elements used,
only lower element used,
max. height of damming if upper element has
been removed,
max. height of damming when 2 elements are used;
1 plate weir, 2 removable element
Plate weir with full damming height in different
positions to adjust the top water level in the outlet of the
experimental section.
METHODS FOR ADJUSTING THE VOLUMETRIC FLOW IN THE INLET
TO THE EXPERIMENTAL SECTION
All experimental flumes allow adjusting the volumetric
flow. The pump is fitted with a control butterfly valve or
a gate valve equipped that is operated either manually
(HM 160, HM 162) or electrically (HM 161) until the desired
flow rate is achieved. The flow rate in HM 160 is measured
by a rotameter, while HM 161 and HM 162 are both
equipped with an electromagnetic flow meter.
Plate weir with medium damming height in different
positions to adjust the top water level in the outlet of the
experimental section.
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HYDRAULIC ENGINEERING OPEN-CHANNEL FLOW
TECHNICAL DETAILS FOR GUNT EXPERIMENTAL FLU MES STRUCTURAL FEATURES
RIGIDITY AGAINST DEFORMATION
The experimental section of HM 162 is available in several
lengths. The components used are essentially the same
(modular design). In order to realise different lengths
with the modular design, while maintaining inclination
adjustment, the experimental flume is supported by an
auxiliary carrier with two supports. In the version with
long experimental section, the inevitable deformations
are absorbed by the supports. The individual adjustability
of the elements enables precise alignment of the experimental section.
The elements of the self-supporting experimental section
in HM 161 are mounted on 4 supports, so that there is only
ever a minimal deformation.
In HM 160 the stresses that occur in comparison to
HM 162 are small, so that doubling the length of the experimental section does not pose a problem for the rigidity of
the self-supporting experimental flume with two supports.
Side view of the experimental section:
ideal flume bottom,
deformation of the bottom by bending
For all experimental flumes we can state that, with careful
design, the maximum deviation from the ideal geometric
shape for flatness and torsion is 0,1%. In the illustrations
the deformations are shown greatly enlarged, e.g. 0,1%
of the length L. In the general tolerances for straight-
Plan view of the experimental section:
ideal contour of the side walls,
deformed side walls
ness and flatness according to ISO 2768, this satisfies
the tolerance classes medium to fine. In this case the
maximum deviation refers to the length of the experimental section.
INCLINATION ADJUSTMENT
All experimental flumes can be inclined, which means that
the slope is adjustable. The slope range is -1/200...1/40.
The current slope can be read directly on a scale
(HM 160, HM 162) or a digital display (HM 161).
HM 160
HM 162
HM 160
HM 162
HM 161
Inclination adjustment in HM 160 is manual and electrical
in HM 161.
In HM 162 the inclination can be adjusted either manually
or electrically. With an experimental section above 7,5m
we recommend electrical inclination adjustment.
Manual inclination adjustment in HM 162:
left: scale, right: entire mechanism
HM 161
carrier (rigidity against bending),
frame (rigidity against water pressure),
fixed support,
height-adjustable support (flume inclination adjustment),
inlet and outlet element
experimental section,
1 welded frame,
2 bottom element of an
element of the experimental section,
3 diagonal rib,
F water pressure force
Manual inclination
adjustment in HM 160
Electrical inclination adjustment in HM 161
MATERIALS USED
The rigidity of the elements of the
experimental section against water
pressure is ensured by the welded
frame. The frames support the glass
side walls.
Bottom element of an element of the
HM 162 experimental section,
reinforced with diagonal ribs to increase
stiffness against bending and torsion.
In all experimental flumes, the bottom of the experimental section is made of stainless steel. Tempered glass
is used for the side walls of the experimental section. It
is scratch resistant, does not age and does not deform.
The water tank, inlet and outlet elements are made of
corrosion-resistant GRP (glass reinforced plastic) or steel.
The piping is PVC. The models used in the experimental flumes consist of aluminium, stainless steel, PVC or
Plexiglas.
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HYDRAULIC ENGINEERING OPEN-CHANNEL FLOW
GUNT EXPERIMENTAL FLUMES: INSTRUMENTATION
Instrument carriers for HM 162 and HM 161
Measuring methods in your laboratory
The experimental flumes HM 161 and HM 162 extend
above the side wall guide rails. An instrument carrier can
be placed on the rails and moved. The different instruments are mounted on the instrument carrier, for example
a level gauge or a pitotstatic tube. Using the carrier, the
instruments can be moved to nearly every point of the
flow. The carrier can be locked during the measurements
with fixing devices. The position of the carrier along the
experimental section is read on a scale (see photo). On
the carrier itself is another scale, used to determine the
position transverse to the direction of flow.
Of course, you can also use your own laboratory
measuring methods to determine the flow velocity, such
as PIV (Particle Image Velocimetry) or LDA (Laser
In the small experimental flume HM 160 no instrument
carrier is necessary. The instruments are placed directly
on the top of the experimental section and clamped in
place.
Pitotstatic tube HM 162.50
with instrument carrier
Doppler Anemometry) and ultrasound to determine the
discharge depth.
Example of a pressure measurement along the experimental section
Scale along the experimental
section
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A broad-crested weir (HM 162.31) and a sluice gate
(HM 162.29) have been inserted in the 5m long experimental section of HM 162. The elements of the experimental section of HM 162 each contain 10 pressure measuring
points, which are uniformly distributed over the length
of the 2,5m element. The pressure at these measuring
points is called the pressure head and corresponds to the
discharge depth. The pressure heads are displayed on
the manometer panel HM 162.53. When the experimental
section is inclined, i.e. open-channel flow with a slope, it
is more accurate to measure the discharge depth via the
pressure head than via a level gauge.
The manometer panel HM 162.53 contains 10 tubes
Depending on the length of the experimental section, we
can either represent selected points on a panel or use
multiple panels to show all pressures.
Flow velocity
GUNT offers two methods of measuring the flow rate in all experimental flumes: the
traditional pitotstatic tube or a digital velocity meter. The pitotstatic tube HM 16x.50
measures the static pressure and the total pressure at any point of the flow. A digital
pressure gauge displays the difference between the two pressures. The pressure
difference corresponds to the dynamic pressure, from which the flow velocity can
be calculated.
The core element of the velocity meter HM 16x.64 is an impeller that is rotated by
the flow. The speed of the impeller is proportional to the
flow velocity. The flow velocity is read directly from the
digital display.
Discharge depth
To measure the discharge depth, the level gauge
HM 16x.52 or HM 16x.91 with digital display is used. The
tip of the probe is moved to the surface of the water from
above.
Level gauge HM 162.52 with
instrument carrier
Pressure measurement
All experimental flumes are equipped with pressure Velocity meter
measuring points in the flume bottom. The pressure HM 16x.64
measuring points are evenly distributed over the length of
the experimental section. To read these pressures, the pressure measuring points
are connected to the optional manometer panel HM 16x.53 via hoses. This allows
directly reading a profile of discharge depth over the entire length of the experimental section on the manometer panel.
HM 162 with sluice gate 1, broad-crested weir 2 and manometer panel 3.
The manometer panels are enlarged so they can be clearly seen.
The elements of the experimental section in the experimental flume HM 160 contain 10 pressure measuring
points over a length of 2,5m. The manometer panel
HM 160.53 contains 10 tubes.
In the experimental flume HM 161, forty-eight pressure
measuring points are evenly distributed over the experimental section with 16 m length. The manometer panel
HM 161.53 contains 20 tubes.
Tube manometers HM 162.53
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HYDRAULIC ENGINEERING OPEN-CHANNEL FLOW
GUNT EXPERIMENTAL FLUMES: LABORATORY DESIGN
The following table lists the space requirements of all
GUNT experimental flumes including the water tank.
A lifting device is recommended when placing larger
models in the experimental sections of HM 162 and especially HM 161.
GUNT will gladly undertake the precise laboratory planning
for you to set up the experimental flumes.
An example of laboratory planning
This section provides some tips for planning a laboratory
in which an experimental flume is going to be set up:
the laboratory should be on the ground floor
the floor must have sufficient load capacity
the floor and the skirting area of the walls should be
water-resistant
The drawing below shows the planning for a laboratory
that contains the experimental flume HM 162 (10m long
experimental section), a few other GUNT units on fluid
mechanics and workstations for the students.
In this case the models for HM 162 are stored on tables.
A small cabinet in the corner contains tools and can be
used to store instruction manuals.
the transportation routes to and within the laboratory
must be spacious
the water supply and drains must be big enough for
larger amounts of water
the two larger experimental flumes HM 162 and HM 161
require three-phase alternating current.
experimental section
sediment transport (sediment trap G, feeder H with steps)
additional space required for installation
(excl. G)
1,0m
1,5m
(min. 1m)
1,0m
1,0m
2,0m
2,0m
1,0m
1,5m
(min. 1m)
4,0m
2,0m
3,6m
6,1m
0,6m
5,0m 9,2m
7,5m 11,7 m
10,0 m 13,6 m
12,5 m 16,0 m
HM 161 16,0 m 20,0 m
HM 160
HM 162
2,5m
5,0m
1,5m
(min. 1m)
Height
Height
(excl. H)
(incl. H)
1,35m
1,80 m
2,3m
2,90 m
with sediment
transport:
min. 3,9m
Required
room height
Dimensions of the laboratory, LxWxH: 20,00x7,60x4,00m
2,0m
2,0m
1,0m
1,0m
1,0m
1,1m
in C
incl.
0,9m
1,85m
2,50 m
3,30 m
with sediment
transport:
min. 4,5m
water drain
water supply
power supply 230V, 50Hz, 1 phase
power supply 400V, 50Hz, 3 phases
HM 162 with 10m experimental section,
13,00 x1,00m
table for storing models for HM 162,
160x80cm
table, 120x80cm
base module HM 150, 120x76cm,
with different modules
cabinet
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HYDRAULIC ENGINEERING OPEN-CHANNEL FLOW
OPEN-CHANNEL FLOW IN THE LAB
HM 162.29 Sluice Gate
HM 162.38 Rake
HM 162.40 Radial Gate
HM 162.31 Broad-Crested Weir
HM 162.36 Siphon Weir
HM 162.32 Ogee-Crested Weir with 2 Weir Outlets
HM 162.33 Crump Weir
HM 162.34 Ogee-Crested Weir with Pressure Measurement
HM 162.35 Elements for Energy Dissipation
HM 162.30 Set of Plate Weirs
HM 162.63 Trapezoidal Flume
HM 162.51 Venturi Flume
HM 162 with an
experimental
section of 7,5m
HM 162.44 Sill
HM 162.46 Set of Piers
HM 162.55 Parshall Flume
HM 162.45 Culvert
HM 162.77 Flume Bottom with Pebble Stones
HM 162.71 Closed Sediment Circuit
Control structures
Changes in cross-section
(losses, flow formulae)
Discharge measurement
HM 162.61 Vibrating Piles
HM 162.80 Set of Beaches
A wide range of typical models allows the user to design a broad and
individual programme of experiments with GUNT experimental flumes. The
programme of experiments shown in this catalogue for HM 162 applies, in
principle, for all GUNT experimental flumes.
HM 162.72 Sediment Trap
Other experiments: including
waves, sediment transport
HM 162.41 Wave Generator
The appropriate instrumentation
for measuring the discharge depth
and the flow velocity is also
available as additional accessories.
The models of the other GUNT experimental flumes are similar.
HM 162.73 Sediment Feeder
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