A practical two-transducer ultrasonic flow meter

Abstract: Nowadays ultrasonic transducers are extensively used. Many industrial systems
carry out their measurement process by taking the advantage of ultrasound
waves. Sound of frequencies above audible range is called ultrasound,
ultrasonic waves are classified under category of mechanical waves. Likewise
all other mechanical waves, ultrasound needs material environment called
medium to propagate through by moving the particles.

Since the end of seventies, ultrasonic flow meters have been widely designed
and applied in different industrial plans mainly related to fluid mechanics,
chemistry, oil industry, etc. However, the initial motive of this thesis was
to design a reliable mass flow meter applicable in controling the precise
amount of energy transferred through gas pipe lines.

The mass flow meter presented in this thesis is based on a two-transducer
ultrasonic measurement set up where both transducers emit ultrasonic beam
simultaneously. In this thesis we describe how by checking the
amplitudes and timings of the received echoes many valuable physical
properties of the flowing liquid can be revealed. In other words, we are
able to calculate the speed of sound in the liquid, the flow velocity as
well as the liquid's acoustic impedance and its density by only
investigating the amplitudes and timings of the received ultrasonic echoes.
Moreover, we show that frequency behaviour of the system and the liquid can
be illuminated thoroughly.

As a master thesis, this project partially stands on previous works in this
field and mainly on the works done by Dr. Jan van Deventer and Dr. Jonny
Johansson and various scientific publications. In coming discussions not only
do we systematically take advantage of previous thoughts, designs and results
in order to explore further achievements, but also we present many new solu-
tions. This thesis aims towards introducing new electronic solutions
and signal processing techniques to reduce the uncertainty of the
estimations and to speed up the computation.