利用空化现象进行水喷射泵转子叶片尖区流场结构的可视化

In this paper, we examine the occurrence of cavitation
in the tip region of a waterjet pump, and use the
observations to identify key features of the flow
structure. The rotor, stator and pump casing in our
recently upgraded facility are made of acrylic, whose
refractive index matches that of the working fluid, a
concentrated aqueous solution of sodium iodide. Such
matching makes the blades invisible, enab领 flow
structure visualization and optical measurements
without any obstructions. Our initial tests with fresh
water focus on cavitation in the vicinity of the tip
region close to design conditions. Near the leading
edge, cavitation inception near the tip corner of the
pressure side causes accumulation of bubbles along the
pressure side of the corner until mid blade. As roll-up
of the tip leakage vortex (TLV) starts in the mid blade
region, these bubbles travel across the tip-clearance to
the suction side, and become nuclei for cavitation
inception in the TLV. As the TLV migrates to the
vicinity of the pressure side of the neioring blade it
bursts, generating a cloud of bubbles that spreads over
most of the aft section of the passage. The leakage flow
in the tip gap along the aft side of the blade is strong
enough to cause sheet cavitation within the gap,
starting from the pressure side corner. The paper also
presents preliminary Particle Image Velocimetry (PIV)
data concentrating on the roll-up of TLV. Results are
consistent with observed cavitation phenomena. 德国LaVision PIV/PLIF粒子成像测速场仪 三维立体PIV