An Experimental Study of the
Flow Field Inside the Diffuser
Passage of a Laboratory
Centrifugal Pump
type de publication |
article dans une revue internationale avec comité de lecture |
date de publication |
2015 |
auteur(s) |
Si Qiaorui; Dupont Patrick; Bayeul-Laine Annie-Claude; Dazin Antoine; Roussette Olivier; Yuan Shouqui |
journal (abréviation) |
Journal of Fluids Engineering (J Fluid Eng) |
volume (numéro) |
137 (6) |
numéro de papier |
061105 |
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Sous presse |
résumé |
Measurements are processed on a centrifugal pump model, which works with air and performs
with the vane-island type diffuser of a real hydraulic pump, under five flow rates to
investigate the internal flow characteristics and their influence on overall pump performance.
The mean flow characteristics inside the diffuser are determined by using a miniature
three-hole probe connected to an online data acquisition system. The flow structure
at the inlet section of the diffuser is analyzed in detail, with a focus on the local pressure
loss inside the vaneless gap and incidence angle distributions along the hub-to-shroud
direction of the diffuser. Some existing calculations, including leakage effects, are used
to evaluate the pressure recovery downstream of the impeller. Furthermore, particle
image velocimetry (PIV) measurement results are obtained to help analyze the flow characteristics
inside the vane-island diffuser. Each PIV measuring plane is related to one
particular diffuser blade-to-blade channel and is analyzed by using the time-averaged
method according to seven different relative positions of the impeller. Measurement
results show that main loss is produced inside the vaneless part of the diffuser at low flow
rates, which might have been caused by the strong rotor–stator interaction. When the
impeller flow rate is greater than the diffuser design flow rate, a large fluctuating
separated region occurs after the throat of the diffuser on the pressure side. Mean loss
originates from the unsteady pressure downstream of the diffuser throat. For better characterization
of the separations observed in previous experimental studies, complementary
unsteady static pressure measurement campaigns have been conducted on the diffuser
blade wall. The unsteadiness revealed by these measurements, as well as theirs effects on
the diffuser performance, was then studied. |
mots clés |
vane-island diffuser, mean flow characteristics, three-hole probe, PIV, flow separation |
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