3 General principles
FLUXUS G809
3.1 Measurement principle
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UMFLUXUS_G809V2-2EN, 2020-06-25
Fig. 3.1:
Sound path of the signal in the flow direction
c – sound speed
1 – transducer (emitter)
2 – transducer (receiver)
3 – pipe wall
Fig. 3.2:
Sound path of the signal against the flow direction
c – sound speed
1 – transducer (emitter)
2 – transducer (receiver)
3 – pipe wall
Fig. 3.3:
Transit time difference Δt
1 – signal in the flow direction
2 – signal against the flow direction
c
β
β
α
γ
c
γ
3
2
1
c
α
c
α
reduction of the
sound path
flow direction of
the fluid
sound path with flow
sound path
without flow
c
β
flow direction of
the fluid
sound path with flow
sound path with
-
out flow
β
α
γ
c
γ
increase of the
sound path
3
1
2
c
α
c
α
1
2
Δt
