Numerical prediction of steady and unsteady tip vortex cavitation on hydrofoils

ABSTRACT The article presents the numerical method for prediction of tip vortex cavitation generated on hydrofoils. This method has been developed in the course of numerical and experimental research described in earlier publications. The objective of the research was to design the optimum discrete grid structure for this specific computational task and to select the best turbulence model for such an application The article includes a short description of the method and a computational example demonstrating its performance. In this example the results of numerical prediction of the cavitating tip vortex obtained from two commercial CFD codes are compared with experimental photographs taken in the cavitation tunnel in the corresponding flow conditions. Altogether nine different flow conditions are tested and analyzed, but only selected results are included. The accuracy of the numerical predictions is discussed and the reasons for minor existing discrepancies are identified. The unsteady tip vortex calculations are also presented, showing the fluctuations of the transverse velocity components predicted for three cross-sections of the cavitating vortex kernel.

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Application of a Boundary Element Method in the Prediction of Unsteady Blade Sheet and Developed Tip Vortex Cavitation on Marine Propellers

Journal of Ship Research ◽

10.5957/jsr.2004.48.1.15 ◽

2004 ◽

Vol 48 (01) ◽

pp. 15-30

Author(s):

Hanseong Lee ◽

Spyros A. Kinnas

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Pressure Fluctuations ◽

Ship Hull ◽

Tip Vortex ◽

Tip Vortex Cavitation ◽

Marine Propellers ◽

Sheet Cavitation ◽

Numerical Predictions ◽

Element Method

Most marine propellers operate in nonaxisymmetric inflows, and thus their blades are often subject to an unsteady flow field. In recent years, due to increasing demands for faster and larger displacement ships, the presence of blade sheet and tip vortex cavitation has become very common. Developed tip vortex cavitation, which often appears together with blade sheet cavitation, is known to be one of the main sources of propeller-induced pressure fluctuations on the ship hull. The prediction of developed tip vortex cavity as well as blade sheet cavity is thus quite important in the assessment of the propeller performance and the corresponding pressure fluctuations on the ship hull. A boundary element method is employed to model the fully unsteady blade sheet (partial or supercavitating) and developed tip vortex cavitation on propeller blades. The extent and size of the cavity is determined by satisfying both the dynamic and the kinematic boundary conditions on the cavity surface. The numerical behavior of the method is investigated for a two-dimensional tip vortex cavity, a three-dimensional hydrofoil, and a marine propeller subjected to nonaxisymmetric inflow. Comparisons of numerical predictions with experimental measurements are presented.

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An experimental and numerical study of the vortices generated by hydrofoils

Polish Maritime Research ◽

10.2478/v10012-008-0027-3 ◽

2009 ◽

Vol 16 (3) ◽

pp. 11-17 ◽

Cited By ~ 4

Author(s):

J. Szantyr ◽

R. Biernacki ◽

P. Flaszyński ◽

P. Dymarski ◽

M. Kraskowski

Keyword(s):

Velocity Field ◽

Cross Sections ◽

Numerical Study ◽

Turbulence Models ◽

Marine Propeller ◽

Flow Conditions ◽

Tip Vortices ◽

Cavitation Tunnel ◽

Computer Codes ◽

Propeller Blades

An experimental and numerical study of the vortices generated by hydrofoils The article presents the results of the research project concerning the process of formation of the tip vortices shed from hydrofoils of different geometry in different flow conditions. Three hydrofoils resembling the contemporary marine propeller blades have been selected for the study. The experimental part of the project consisted of the LDA measurements of the velocity field in three cross-sections of the vortex generated by the hydrofoils in the cavitation tunnel. The numerical part of the project consisted of calculations of the corresponding velocity field by means of three computer codes and several selected turbulence models. The comparative analysis of the experimental and numerical results, leading to the assessment of the accuracy of the numerical methods, is included.

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An Experimental and Numerical Study of Tip Vortex Cavitation

Polish Maritime Research ◽

10.2478/v10012-011-0021-z ◽

2011 ◽

Vol 18 (4) ◽

pp. 14-22 ◽

Cited By ~ 8

Author(s):

J. Szantyr ◽

P. Flaszyński ◽

K. Tesch ◽

W. Suchecki ◽

S. Alabrudziński

Keyword(s):

Cross Sections ◽

Laboratory Experiments ◽

Numerical Study ◽

Numerical Calculations ◽

Tip Vortex ◽

Experimental Conditions ◽

Tip Vortex Cavitation ◽

Marine Propellers ◽

Hydraulic Machines ◽

Noise Vibration

An Experimental and Numerical Study of Tip Vortex Cavitation The article presents the results of the research project concerning tip vortex cavitation. This form of cavitation is very important in operation of many types of rotary hydraulic machines, including pumps, turbines and marine propellers. Tip vortex cavitation generates noise, vibration and erosion. It should be eliminated or significantly limited during the design of these types of machines. The objective of the project was to develop an accurate and reliable method for numerical prediction of tip vortex cavitation, which could serve this purpose. The project consisted of the laboratory experiments and numerical calculations. In the laboratory experiments tip vortex cavitation was generated behind a hydrofoil in the cavitation tunnel and the velocity field around the cavitating kernel was measured using the Particle Image Velocimetry method. Measurements were conducted in three cross-sections of the cavitating tip vortex for a number of angles of attack of the hydrofoil and for several values of the cavitation index. In the course of numerical calculations two commercial CFD codes were used: Fluent and CFX. Several available approaches to numerical modeling of tip vortex cavitation were applied and tested, attempting to reproduce the experimental conditions. The results of calculations were compared with the collected experimental data. The most promising computational approach was identified.

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Numerical prediction of tip vortex cavitation behavior and noise considering nuclei size and distribution

Applied Acoustics ◽

10.1016/j.apacoust.2008.08.003 ◽

2009 ◽

Vol 70 (5) ◽

pp. 674-680 ◽

Cited By ~ 24

Author(s):

Kwangkun Park ◽

Hanshin Seol ◽

Wooyoung Choi ◽

Soogab Lee

Keyword(s):

Numerical Prediction ◽

Tip Vortex ◽

Tip Vortex Cavitation ◽

Cavitation Behavior

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Investigation of the Role of Polymer on the Delay of Tip Vortex Cavitation

Journal of Fluids Engineering ◽

10.1115/1.1792260 ◽

2004 ◽

Vol 126 (5) ◽

pp. 724-729 ◽

Cited By ~ 6

Author(s):

R. Latorre ◽

A. Muller ◽

J. Y. Billard ◽

A. Houlier

Keyword(s):

Pure Water ◽

Tip Vortex ◽

Core Radius ◽

Polymer Injection ◽

Tip Vortex Cavitation ◽

Cavitation Inception ◽

Main Effect ◽

Cavitation Tunnel ◽

Small Bubbles

Cavitation tunnel measurements have shown tip vortex cavitation inception is delayed when polymers are injected from the hydrofoil tip. Experiments with polymers have also shown that the polymers cause the cavitation to become more violent. To better understand the role of polymer in the delay of tip vortex cavitation, a theoretical analysis of tip vortex cavitation inception in pure water and in polymer solution is presented. The analysis shows that while polymer injection causes instability in small bubbles, its main effect is an increase in tip vortex core radius, resulting in the delay of tip vortex cavitation inception.

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Application of Vortex Flow Model in Propeller-Stator System Design and Analysis

Polish Maritime Research ◽

10.2478/pomr-2018-0004 ◽

2018 ◽

Vol 25 (1) ◽

pp. 24-32

Author(s):

Przemysław Król ◽

Tomasz Bugalski

Keyword(s):

System Design ◽

Vortex Flow ◽

Flow Model ◽

Tip Vortex ◽

Design Algorithm ◽

Tip Vortex Cavitation ◽

Vortex Model ◽

Wide Range ◽

Cavitation Tunnel ◽

The Subject

Abstract The paper covers basics of the vortex model used for propeller-stator systems. The outline of the design algorithm is given and the results of its application are shown. The designed propeller-stator system was the subject of model tests run at the CTO model basin and cavitation tunnel. Stator’s influence on the delivered power required by the propeller and its revolution rate has been examined by conducting self-propulsion tests with and without stator. The tests performed in the cavitation tunnel revealed only weak tip vortex cavitation on the propeller. No cavitation was observed on the stator at the design point. A wide range of the performed tests allowed the authors to identify details of the developed theory which will require further improvement.

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