Unsteady Numerical Simulation of Cavitating Turbulent Flow Around a Highly Skewed Model Marine Propeller

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Bin Ji ◽  
Xianwu Luo ◽  
Xin Wang ◽  
Xiaoxing Peng ◽  
Yulin Wu ◽  
...  
Keyword(s):  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Cavitating Flow ◽  
Tip Vortex ◽  
Wake Flow ◽  
Marine Propeller ◽  
Sheet Cavitation ◽  
Whole Process ◽  
Unsteady Numerical Simulation ◽  
Thrust And Torque

The cavitating flows around a highly skewed model marine propeller in both uniform flow and wake flow have been simulated by applying a mass transfer cavitation model based on Rayleigh–Plesset equation and k-ω shear stress transport (SST) turbulence model. From comparison of numerical results with the experiment, it is seen that the thrust and torque coefficients of the propeller are predicted satisfactory. It is also clarified from unsteady simulation of cavitating flow around the propeller in wake flow that the whole process of cavitating-flow evolution can be reasonably reproduced including sheet cavitation and tip vortex cavitation observed in the experiments. Furthermore, to study the effect of pressure fluctuation on the surrounding, pressure fluctuations induced by the cavitation as well as the propeller rotation are predicted at three reference positions above the propeller for comparison with the experimental data: The amplitudes of the dominant components corresponding to the first, second, and third blade passing frequencies were satisfactorily predicted. It is noted that the maximum difference of pressure fluctuation between the calculation and experiment reached 20%, which might be acceptable by usual engineering applications.

Numerical Simulation and Vorticity Analysis of Cavitating Flow Around a Marine Propeller Behind the Hull

2019 ◽  
Author(s):  
Yun Long ◽  
Chengzao Han ◽  
Bin Ji ◽  
Xinping Long ◽  
Zhirong Zhang
Keyword(s):  
Experimental Data ◽  
Pressure Fluctuations ◽  
Relative Vorticity ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Tip Vortex ◽  
Marine Propeller ◽  
Thrust Coefficient ◽  
Sheet Cavitation ◽  
Vorticity Transport

Abstract In this paper, the unsteady cavitating turbulent flow around a marine propeller behind the hull is simulated by the k-ω SST turbulence model coupled with the Zwart cavitation model. Three systematic refined structured meshes around the hull and propeller have been generated to study the predicted cavitation patterns and pressure fluctuations. Numerical results indicate that the predicted transient cavitating flow behind the hull wake, including sheet cavitation and tip vortex cavitation, shows quasi-periodic feature and agrees fairly well with the available experimental data. The deviations of pressure fluctuations between experimental data and numerical results are much small. With mesh refining, the cavitation region and the magnitudes of the calculated pressure fluctuations increase, while the differences between two adjacent sets of grids become smaller. In addition, the uncertainty of the thrust coefficient obtained by Factor of Safety method is significantly small. Further, the interaction between the cavitation and the vortex by the relative vorticity transport equation is illustrated. Results show that the magnitude of stretching term is obviously larger than the other three terms, and the dilatation term and the baroclinic term both have an important influence on the generation of vortices.

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

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.

CFD Validation for a Marine Propeller Using an Unstructured Mesh Based RANS Method

2003 ◽  
Author(s):  
Shin Hyung Rhee ◽  
Shitalkumar Joshi
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Tip Vortex ◽  
Computational Results ◽  
Marine Propeller ◽  
Experimental Conditions ◽  
Cfd Validation ◽  
Local Flow ◽  
Thrust And Torque

Results of computational fluid dynamics validation for flow around a marine propeller are presented. Computations were performed for various advance ratios following experimental conditions. The objectives of the study are to propose and verify a hybrid mesh generation strategy, and to validate computational results against experimental data with advanced computational fluid dynamics tools. Computational results for both global and local flow quantities are discussed and compared with experimental data. The predicted thrust and torque are in good agreement with the measured values. The pressure distribution and pathlines on and around the blade surface well reproduce the physics of highly skewed marine propeller flow with tip vortex. The circumferentially averaged velocity components compare well with the measured values, while the velocity and turbulence quantities in the highly concentrated tip vortex region are under-predicted. The overall results suggest that the present approach is practicable for actual propeller design procedures.

scholarly journals Detached eddy simulation of unsteady cavitation and pressure fluctuation around 3-D NACA66 hydrofoil

2015 ◽  
Vol 19 (4) ◽  
pp. 1231-1234 ◽  
Author(s):  
De-Sheng Zhang ◽  
Hai-Yu Wang ◽  
Lin-Lin Geng ◽  
Wei-Dong Shi
Keyword(s):  
Turbulence Model ◽  
Pressure Fluctuation ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Detached Eddy Simulation ◽  
Cavitation Model ◽  
Cloud Cavitation ◽  
Sheet Cavitation ◽  
Eddy Simulation ◽  
Unsteady Cavitating Flow

The unsteady cavitating flow and pressure fluctuation around the 3-D NACA66 hydrofoil were simulated and validated based on detached eddy simulation turbulence model and a homogeneous cavitation model. Numerical results show that detached eddy simulation can predict the evolution of cavity inception, sheet cavitation growth, cloud cavitation shedding, and breakup, as well as the pressure fluctuation on the surface of hydrofoil. The sheet cavitation growth, detachment, cloud cavitation shedding are responsible for the features of the pressure fluctuation.

A Numerical and Experimental Investigation of Wall-Pressure Fluctuations Induced by Sheet Cavitation Instabilities on Lifting Surface

2005 ◽  
Author(s):  
Jacques-Andre´ Astolfi ◽  
Jean-Baptiste Leroux ◽  
Olivier Coutier-Delgosha ◽  
Franc¸ois Deniset
Keyword(s):  
Flow Instability ◽  
Pressure Fluctuations ◽  
Homogeneous Medium ◽  
Cavitating Flow ◽  
Wall Pressure ◽  
Two Phase ◽  
Fluid Structure ◽  
Sheet Cavitation ◽  
Wall Pressure Fluctuations ◽  
Unsteady Loading

The paper is based on some previous works of the authors aimed to study the phenomenology of cavitation instabilities. In the present work, a particular attention is paid to the analysis of spatio-temporal wall-pressure fluctuations in the context of fluid structure coupling investigations. The work is based on a numerical and experimental study, whose objective was to analyze the wall-pressure fluctuations beneath an unsteady partial cavitating flow developing on an hydrofoil. Experiments were carried in a water tunnel, on a partially cavitating hydrofoil based on extended multi-point wall pressure measurements together with flow visualizations. 2D Navier-Stokes simulations solves the RANS equations combined with a physical model of cavitation The two-phase flow mixture is considered as a homogeneous medium for which the ratio of liquid and vapor is controlled by a barotropic state law. The numerical resolution is based on the SIMPLE algorithm, modified to take into account the high compressibility of the liquid/vapor mixture. The results show that various dynamics are caught by the model in agreement with the experiments. Two main unstable dynamics were observed leading to a strong variation of surface loading. The paper provides quantitative data about the severe unsteady loading that is experienced by the structure, which should very useful in a fully problem of Fluid Structure Interaction. The possibility of a structural response of the foil to the unsteady loading and how it could promote the cavitating flow instability is also discussed.

scholarly journals A Study on the Cavitation Model for the Cavitating Flow Analysis around the Marine Propeller

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Insu Lee ◽  
Sunho Park ◽  
Woochan Seok ◽  
Shin Hyung Rhee
Keyword(s):  
Fluid Dynamics ◽  
Flow Analysis ◽  
Cavitating Flow ◽  
Experimental Results ◽  
Test Case ◽  
Marine Propeller ◽  
Cavitation Model ◽  
Sheet Cavitation ◽  
Bubble Cavitation ◽  
Computational Fluid Dynamics Cfd

In this study, a cavitation model for propeller analysis was selected using computational fluid dynamics (CFD), and the model was applied to the cavitating flow around the Potsdam Propeller Test Case (PPTC) propeller. The cavitating flow around the NACA 66 hydrofoil was analyzed to select a cavitation model suitable for propeller analysis among various cavitation models. The present and the experimental results were compared to select a cavitation model that would be applied to propeller cavitation analysis. Although the CFD results using the selected cavitation model showed limitations in estimating some of the foam cavitation and bubble cavitation identified in the experimental results, it was identified that foam cavitation and sheet cavitation around the tip were well simulated.

Computational Analysis of Marine-Propeller Performance Using Transition-Sensitive Turbulence Modeling

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Xiao Wang ◽  
Keith Walters
Keyword(s):  
Experimental Data ◽  
Turbulence Model ◽  
High Load ◽  
Boundary Layer Transition ◽  
Tip Vortex ◽  
Marine Propeller ◽  
Cfd Simulations ◽  
Propeller Performance ◽  
Thrust And Torque ◽  
Load Conditions

Almost all computational fluid dynamics (CFD) simulations of flow around marine propellers use turbulence models that are only well suited for fully turbulent flows, which in some cases may lead to accuracy degradation in the prediction of propeller performance characteristics. The discrepancy between computed thrust and torque and corresponding experimental data increases with increasing propeller load. This is due in part to the fact that a large laminar flow region is found to exist and turbulence transition takes place on propeller blades of model scale and/or under high-load conditions. In these cases, it may be necessary to consider boundary-layer transition to obtain accurate results from CFD simulations. The objective of this work is to perform simulations of a marine propeller using a transition-sensitive turbulence model to better resolve the propeller flow characteristics. Fully turbulent flow simulations are also performed for comparison purposes at various propeller load conditions. Computational results are analyzed and compared with water-tunnel and open-water experimental data. It is found that the applied transition-sensitive turbulence model is better able to resolve blade-surface stresses, flow separations, and tip-vortex originations, and, consequently, improve the prediction accuracy in propeller performance, especially under high-load conditions. Furthermore, solutions obtained using the transition-sensitive turbulence model show tip-vortex flows of higher strength, whereas results by the standard k-ω SST turbulence model indicate excessive dissipation of the vortex core.

Pressure fluctuation characteristics in the sidewall gaps of a centrifugal dredging pump

2017 ◽  
Vol 34 (4) ◽  
pp. 1054-1069 ◽  
Author(s):  
Lei Cao ◽  
Yexiang Xiao ◽  
Zhengwei Wang ◽  
Yongyao Luo ◽  
Xiaoran Zhao
Keyword(s):  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Centrifugal Pumps ◽  
Axial Distribution ◽  
Content Type ◽  
Sst Model ◽  
Clearance Flow ◽  
Rotating Impeller ◽  
Frequency Components ◽  
Unsteady Numerical Simulation

Purpose The purpose of this paper is to study the pressure fluctuation characteristics in the sidewall gaps of a centrifugal dredging pump in detail and discover the excitation sources. Design/methodology/approach An unsteady numerical simulation with shear–stress transport–scale-adaptive simulation (SAS-SST) model was conducted for a centrifugal pump considering the sidewall gaps. The numerical codes were validated by a model test carried out in China Water Resources Beifang Investigation, Design and Research Co., Ltd. Fast Fourier transform was used to obtain the frequency components of the pressure fluctuation. Findings Pressure fluctuation characteristics inside the pump were analyzed for a condition near the design point. In the sidewall gaps, the circumferential, radial and axial distribution of the pressure fluctuation amplitude follow different laws. The non-axisymmetrical distribution of pressure fluctuation in the sidewall gaps shows that the unsteady flow in the volute casing which has a non-axisymmetrical geometry imposes an evident effect on the flow field in the sidewall gaps and the interaction between the main flow and the clearance flow cannot be neglected. There are several frequency components appearing as the dominant frequencies at different locations in the sidewall gaps, but the relatively stronger pressure fluctuations are all dominated by the rotating frequency. It indicates that the rotating impeller, which originally makes the shrouds rotate, is the primarily excitation source of the pressure fluctuations in the sidewall gaps. Originality/value The pressure fluctuation characteristics in the sidewall gaps of centrifugal pumps were first comprehensively analyzed. Unsteady flows in the sidewall gaps should be considered during the design and operation of centrifugal pumps.

scholarly journals Numerical Investigation on Pressure Fluctuations for Different Configurations of Vaned Diffuser Pumps

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Jianjun Feng ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Wake Flow ◽  
Trailing Edge ◽  
Vaned Diffuser ◽  
Blade Number ◽  
Radial Gap

Numerical simulations on impeller-diffuser interactions in radial diffuser pumps are conducted to investigate the unsteady flow, and more attention is paid to pressure fluctuations on the blade and vane surfaces. Calculations are performed at different operating points, different blade number configurations, and different radial gaps between the impeller and diffuser to examine their effects on the unsteady flow. Computational results show that a jet-wake flow structure is observed at the impeller outlet. The biggest pressure fluctuation on the blade is found to occur at the impeller trailing edge, on the pressure side near the impeller trailing edge, and at the diffuser vane leading edge, independent of the flow rate, radial gap, and blade number configuration. All of the flow rate, blade number configuration, and radial gap influence significantly the pressure fluctuation and associated unsteady effects in the diffuser pumps.

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