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Research Papers: Multiphase Flows

Numerical Simulation of Cavitation Around a Hydrofoil and Evaluation of a RNG $κ-ε$ Model

[+] Author and Article Information
Lingjiu Zhou

College of Water Conservancy and Civil Engineering, China Agricultural University, Beijing, China 100083zlj09@263.net

Zhengwei Wang

Department of Thermal Engineering, Tsinghua University, Beijing, China 100084wzw@mail.tsinghua.edu.cn

J. Fluids Eng 130(1), 011302 (Dec 19, 2007) (7 pages) doi:10.1115/1.2816009 History: Received January 17, 2007; Revised June 30, 2007; Published December 19, 2007

Abstract

Cavitating flow around a hydrofoil was simulated using a transport equation-based model with consideration of the influence of noncondensable gases. The cavity length and the pressure distributions on the suction side can be well predicted for stable cavities using the standard renormalization-group (RNG) $κ-ε$ turbulence model with proper noncondensable gas mass fraction. The unstable cavity shedding at lower cavitation numbers was not well predicted by the standard RNG $κ-ε$ turbulence model. A modified RNG $κ-ε$ turbulence model was evaluated by comparing the calculated spatial-temporal pressure distributions on the suction wall with experimental data. The results showed that the predicted cavity growth and shedding cycle and its frequency agree well with the experimental data. However, the pressure increase caused by interaction of the reentrant flow and the cavity interface is overestimated, which caused the time-averaged pressure on the front part of the hydrofoil to be overestimated. The time-averaged pressure on the rear of the hydrofoil was low because the small cavity shedding on the rear part of the cavity was not predicted.

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Figures

Figure 1

Calculation domain and seven block structured grid with 27,961 nodes

Figure 2

Distributions of y* of the wall-adjacent cell’s centroid for noncavitating and cavitating flow

Figure 6

Calculated void fraction contours and velocity vectors for σ=1.25 using the standard RNG κ-ε model, fncg=8×10−8 (to get a clear view, every four vector is displayed)

Figure 7

Calculated pressure variations at P4 for σ=1.25 using the standard RNG κ-ε model, fncg=8×10−8

Figure 8

Predicted pressure fluctuations during cavity growth and destabilization for σ=1.25 using the modified RNG κ-ε model, fncg=8×10−8

Figure 9

Calculated void fraction contours and velocity vectors for σ=1.25 using the modified RNG κ-ε model, fncg=8×10−8 (to get a clear view, every four vector is displayed)

Figure 10

Comparison of the pressure distribution on the suction surface for σ=1.25. The calculated data were obtained using the modified RNG κ-ε model, fncg=8×10−8.

Figure 11

Influence of parameter n on the predicted pressures at P4 and P7. fncg=8×10−8 was used for both n=3 and n=10.

Figure 3

Comparison of calculated result and experimental data for a noncavitating flow

Figure 4

Calculated cavity shape for σ=1.41 using various fncg with the standard RNG κ-ε model

Figure 5

Predicted pressure distribution on the suction side for various noncondensable gas mass fractions

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