Effect of water injection on the cavitation control:experiments on a NACA66 (MOD) hydrofoil
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RESEARCH PAPER
Effect of water injection on the cavitation control:experiments on a NACA66 (MOD) hydrofoil W. Wang1,2 · T. Tang1 · Q. D. Zhang1 · X. F. Wang1,2 · Z. Y. An1 · T. H. Tong1 · Z. J. Li1 Received: 6 May 2020 / Revised: 4 July 2020 / Accepted: 28 July 2020 © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The objective of this work is to investigate experimentally controlling cavitating flow over NACA66 (MOD) hydrofoils by means of an active water injection along its suction surface. The continuous water vertically jets out of the chamber inside the hydrofoil through evenly distributed surface holes. Experiments were carried out in cavitation water tunnel, using high-speed visualization technology and the particle image velocimetry (PIV) system to study the sheet/cloud cavity behaviors. We studied the effects of this active control on cavity evolution with four kinds of jet flow at two different jet positions. We analyzed the effect of water injection on the mechanism of the cavitating flow control. The results were all compared with that for the original hydrofoil without jet and show that the active jet can effectively suppress the sheet/cloud cavitation characterized by shrinking the attached cavity size and breaking the large-scaled cloud shedding vortex cavity into small-scaled ones. The optimum effectiveness of cavitation suppression is affected by the jet flow rates and jet positions. The water injection at flow rate coefficient 0.0245 with the jet position of 0.45C reduces the maximum sheet cavity length by 79.4% and the cavity shedding is diminished completely, which gives the most superior effect of sheet cavitation suppression. The jet blocks the re-entrant jet moving upstream and weakens the power of re-entrant jet and thus restrains the cavitation development effectively and stabilizes the flow field.
Keywords Cavitation active control · Sheet/cloud cavitation · Water injection · Re-entrant jet
Abbreviations α NACA66 (MOD) hydrofoil spanwise length (m) C NACA66 (MOD) hydrofoil chord length (m) Injected mass flow coefficient (−) CQ Buoyancy (N) Fb Lift force of the shedding cavity (N) Fcav h Height of the test foil midsection (m) Cavity length (m) L cav The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2020.
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W. Wang [email protected]
1
School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China
2
Key Laboratory of Ocean Energy Utilization and Energy, Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China
m inj m0
P0 PV p Q Re Sc Scav Tcycle U0 Uinj u
Mass flow rate of jet flow (kg/s) Equivalent mass flowrate of liquid of the main flow that would pass through the frontal (midsection) area S0 of the hydrofoil in case of its absence (kg/s) Statics pressure (Pa) Saturated vapor pressure (Pa) Instantaneous pressure of particles in PIV experiment Volume flow rate (m3 /h)
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