Abstract:
The operational performance criteria of fluidic oscillators are described in relation to
the requirements of a domestic water meter. The problems associated with developing
a novel water meter using fluidic oscillatory technology are discussed and the
performance enhancements required to develop a fluidic oscillator capable of meeting
the BS5728 (1979) domestic water meter specifications are presented.
A sensingc onfigurationi s describedw hich providesa dequates ensitivityo ver the range
required for a water meter with a nominal flowrate of one cubic meter per hour. The
nozzled imensionsa re investigatedto reducet he pressured rop acrosst he fluidic water
meter whilst still maintainingt he requiredt urndown rangea nd adequates ensitivity at
low flowrates.
The development of a novel fluidic oscillator flow conditioning device is described
which radically improves the linearity of the fluidic oscillator and helps to reduce
susceptibilityt o upstreamd isturbancesT. he device allows debris to passt hrough the
meter without causing blockage and has an acceptable low pressure drop.
Modificationst o the fluidic oscillatort ransducegr eometrya rei nvestigatedw hich reduce
the minimum point of oscillation, thus increasing the turndown range of the water
meter. Also geometry modifications are developed which improve the strength of the
jet oscillation at low flowratesa nd therebys ignificantly increaseth e strengtho f signal.
The effects of geometry modification on meter linearity and meterfactor response are
investigated and a transducer design with enhanced range performance and improved
linearity is described. Transducer designs are presented which are capable of meeting
the BS5728 (1979) specification for both Class C and Class D QNLO domestic water
meters.
