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Department of Civil
and Environmental
Engineering
Spring 2017
Air Return in Brook
Intake Shafts
Supervisor:
Prof. Leif Lia
Co-supervisor:
Morten Skoglund
Stefan Perzyna
Background
During construction of hydropower plants in
an alpine landscape, long transport tunnels
with many small brook intakes are often built.
Bad design can lead to air entrainment into the
system by water flowing through the shaft. If not
handled properly, the air will accumulate into
larger air pockets which may result in head loss
or harmful blowouts.
Objective
Specialization project on air entrainment and
blowouts in brook intakes written in the autumn
of 2016 resulted in the conclusion that there is
a need for a research on air pocket behaviour
in steep shafts in terms of hydraulic conditions
needed for the air to return. In order to study
two-phase flow in detail, a physical model has
to be built. The aim of this master thesis is to
design and build a physical model needed for
the research, and further to set up a testing
program for air return in shafts. The results
of the experiment are to be compared with
previous experiments and field observations.
The conclusion and report will be written based
on the research process and findings of the
experiments.
MASTER THESIS
Air blowout at
Holmaliåna
Model used in previous studies at NTNU in 2009