Genova's pump

Authors: Ubaldi

Type: Numerical

Status:

Contents

Description

Flow Parameters

Reference Publications

Results

Description

The chosen test case is one among ERCOFTAC's test case ("test case U3":Centrifugal Pump with a Vaned Diffuser. It is a simplified model of centrifugated turbo machinery with a vaned diffuser. The experimental device was built by Professor Ubaldi's team of the University of Genova. This test case was described exhaustively in the report dealing with rotation. We invite you to refer to [1] for details about the geometry and vocabulary specific to the pumps. In this note, we only represent the geometry showed on Figure 1 and the pump's operating conditions in table 1.

Figure 1 - Geometric details

In table 1 Q is defined as volumic flow, Pt as the total pressure, U as the training velocity and l as the rope lenght. Indices 1,2,3 and 4 correspond to inlet and outlet of the wheel and inlet and outlet of the diffuser, respectively. The fluid temperature at the inlet stay around 298K during all th experiment, so its density can be assumed constant and equals to %$1.2kg.m^{-3}$%.
The device is equipped with pressure transducers with fast response mounted on the casing wall and a hot wire probe (3 components) in the air gap. The latter gives complete access to the velocity field on a cylindrical section located 4 mm from the wheel's training edge and 8 mm from the diffuser vanning edge (at r=0.214m). Unstationary data are reconstituted assuming temporal periodicity of physical quantities. For more details, see [1].

Table 1 - geometric data and pump characteristics

Flow Parameters

Table 2 - Data settings for simulation

At the inlet, absolute velocity is given along the rotation axis, and the formula modified to calculate the flooding velocity is the following :
%BEGINLATEX{label="bal_mom"}% \begin{equation} V_{d}=\frac {\phi\pi\omega R_{2}^{3}}{S_{e}} =\frac {\phi\omega R_{2}^{3}}{R_{max}^{2}-R_{min}^{2}} \end{equation} %ENDLATEX%
%$R_{min}$% and %$R_{max}$% are inner and outter radius of the inlet section, respectively. The inlet turbulence is calculated with the classical formulas for round section pipes with smooth walls.
The Reynolds number is about 10000 and R=0.041m is the radius at the center of the inlet pipe.
Turbulence initialisation is done through a reference length and a reference velocity according to classical formulas.

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Reference Publications

[1] Combès, J.F., "Test Case U3: Centrifugal Pump with a Vaned Diffuser", ERCOFTAC Seminar and Workshop on Turbomachinery Flow Prediction VII, Aussois, jan 4-7 , 1999.

[2] Ubaldi, M., Zunino, P., Barigozzi, G. and Cattanei, A., "An Experimental Investigation of Stator Induced Unsteadiness on Centrifugal Impeller Outflow", Journal of Turbomachinery, vol.118, 41-54, 1996.

[3] Ubaldi, M., Zunino, P., Barigozzi, G. and Cattanei, A., "LDV Investigation of the Rotor-Stator Aerodynamic Interaction in a Centrifugal Turbomachine", 8th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, 1996.

Results

Simulation results available for this case:

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