DESCRIPTION

Technical Description

HM 140 uses sand as an example to demonstrate important phenomena of bed-load transport in the area near the bottom. Open-channel flow without sediment transport is also possible. Discharge can be subcritical or supercritical.

The core element of the HM 140 experimental flume with closed water circuit is the inclining experimental section. The side walls of the experimental section are made of tempered glass, which allows excellent observation of the experiments. All components that come into contact with water are made of corrosion-resistant materials (stainless steel, glass reinforced plastic). The inlet element is designed so that the flow enters the experimental section with very little turbulence and no sediment can flow back. The tank after the water outlet contains a sediment trap for coarse sand.

The inclination of the experimental flume can be finely adjusted to produce slope and to create a uniform flow at a constant discharge depth.

In addition to bed-load transport in open channels, some models can also be used to observe fluvial obstacle marks, namely scour formation and siltation at structures. A rounded-nosed pier or a sluice gate can be inserted into the experimental section.

The discharge is measured via a measuring weir in the water outlet and a level gauge. The level gauge is also used for profile measurement in the sediment and to determine the discharge depth at each point of the experimental section. A contrast medium can be injected to visualise the flow conditions. 

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments

- bed-load transport in open channels 
  * subcritical and supercritical flow
  * formation of ripples, dunes and antidunes 
- how flow velocity affects bed-load transport 
- fluvial obstacle mark (siltation/scour formation)
  * bridge pier
  * sluice gate
- bed-load transport formulae 
  * Meyer-Peter and Müller formula
  * Einstein's formula
  * determining the transport rate
- visualisation of the flow
- open-channel flow without sediment transport
  * subcritical and supercritical flow
  * control structure: sluice gate
  * discharge measurement on the sharp-crested weir