Abstract
The flow in a vaned diffuser radial pump is fully turbulent and strongly unsteady, caused by the rotor-stator interaction. In this paper, two-dimensional laser Doppler velocimetry (LDV) measurement results have been utilized to investigate the unsteady flow in a low specific speed radial diffuser pump with leaning impeller trailing edges. CFD simulations have been also conducted to provide more extensive results at different flow rates. The analysis has been mainly focused on the flow in the radial gap region between the impeller and diffuser where the unsteady interaction is the strongest. The velocity and turbulence fields are detailedly examined and quantitatively compared between CFD and LDV as well. In addition, the downstream effect from the impeller rotation has been compared between the leaning and normal trailing edges of the impeller.
Zusammenfassung
Auf Grund der Rotor-Stator Interaktion ist die Strömung in einem beschaufelten Diffusor einer Radialpumpe extrem zeitabhängig und turbulent. In dem vorliegenden Beitrag wird mittels zweidimensionaler Laser Doppler Velocimetry (LDV) die zeitabhängige Strömung in einer Kreiselpumpe kleiner spezifischer Drehzahl mit schrägen Laufradhinterkanten experimentell untersucht. Es werden zudem umfangreiche CFD Simulation durchgeführt, die Strömungsdaten bei verschiedenen Durchflussraten bereitstellen. Die Untersuchungen konzentrieren sich dabei auf den engen radialen Spalt zwischen Laufrad und Diffusor, wo die zeitabhängige Interaktion am größten ist. Die Strömungsgeschwindigkeit und die Turbulenz werden detailliert betrachtet und zwischen den LDV-Messungen und den CFD Simulationen wird ein quantitativer Vergleich durchgeführt. Zusätzlich werden die durch die Laufradrotation stromabwärts auftretenden Effekte zwischen einer geraden und der schrägen Laufradhinterkante verglichen.
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Abbreviations
- α :
-
Absolute flow angle
- θ :
-
Circumferential coordinate
- ϕ :
-
Impeller circumferential position
- Ca :
-
Absolute axial velocity
- Cr :
-
Absolute radial velocity
- Cu :
-
Absolute circumferential velocity
- K :
-
Turbulence kinetic energy
- Q :
-
Flow rate
- S ∗ :
-
Dimensionless distance
- S u :
-
Stator unsteady intensity
- T :
-
Period of the pump
- t :
-
Time
- U :
-
Circumferential velocity
- r,R:
-
Radius
- LE:
-
Leading edge
- PS:
-
Pressure side
- SS:
-
Suction side
- TE:
-
Trailing edge
- 1:
-
Impeller inlet
- 2:
-
Impeller outlet
- 3:
-
Diffuser inlet
- 4:
-
Diffuser outlet
- des:
-
Design
- i:
-
Impeller
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Feng, J., Benra, F.K. & Dohmen, H.J. Unsteady flow investigation in rotor-stator interface of a radial diffuser pump. Forsch Ingenieurwes 74, 233–242 (2010). https://doi.org/10.1007/s10010-010-0128-x
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DOI: https://doi.org/10.1007/s10010-010-0128-x