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Spyridon A Kinnas - One of the best experts on this subject based on the ideXlab platform.
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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, 2004Co-Authors: H B Lee, Spyridon A KinnasAbstract:Most marine propellers operate in nonaxisymmetric inflows, and thus$\$ntheir blades are often subject to an unsteady flow field. In recent$\$nyears, due to increasing demands for faster and larger displacement$\$nships, the presence of blade Sheet and tip vortex Cavitation has$\$nbecome very common. Developed tip vortex Cavitation, which often$\$nappears together with blade Sheet Cavitation, is known to be one$\$nof the main sources of propeller-induced pressure fluctuations on$\$nthe ship hull. The prediction of developed tip vortex cavity as well$\$nas blade Sheet cavity is thus quite important in the assessment of$\$nthe propeller performance and the corresponding pressure fluctuations$\$non the ship hull. A boundary element method is employed to model$\$nthe fully unsteady blade Sheet (partial or supercavitating) and developed$\$ntip vortex Cavitation on propeller blades. The extent and size of$\$nthe cavity is determined by satisfying both the dynamic and the kinematic$\$nboundary conditions on the cavity surface. The numerical behavior$\$nof the method is investigated for a two-dimensional tip vortex cavity,$\$na three-dimensional hydrofoil, and a marine propeller subjected to$\$nnonaxisymmetric inflow. Comparisons of numerical predictions with$\$nexperimental measurements are presented.
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analysis of supercavitating and surface piercing propeller flows via bem
Computational Mechanics, 2003Co-Authors: Yin Lu Young, Spyridon A KinnasAbstract:A low-order potential based 3-D boundary element method (BEM) is presented for the analysis of unsteady Sheet Cavitation on supercavitating and surface-piercing propellers. The method has been developed in the past for the prediction of unsteady Sheet Cavitation for conventional propellers. To allow for the treatment of supercavitating propellers, the method is extended to model the separated flow behind trailing edge with non-zero thickness. For surface-piercing propellers, the negative image method is used, which applies the linearized free surface boundary condition with the infinite Froude number assumption. The method is shown to converge quickly with grid size and time step size. The predicted cavity planforms and propeller loadings also compare well with experimental observations and measurements.
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a bem for the prediction of unsteady midchord face and or back propeller Cavitation
Journal of Fluids Engineering-transactions of The Asme, 2001Co-Authors: Yin Lu Young, Spyridon A KinnasAbstract:A boundary element method (BEM) is used for the numerical analysis of Sheet Cavitation on a propeller subjected to the non-axisymmetric wakes of marine vehicles. This method is extended in order to treat mixed partial and supercavity patterns on both the face and back of the blades with searched cavity detachment. The convergence of the method is studied
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Application of a numerical optimization technique to the design of cavitating propellers in nonuniform flow
Journal of Ship Research, 1997Co-Authors: Shigenori Mishima, Spyridon A KinnasAbstract:High-speed propulsor blades often experience moderate to substantial amounts of unsteady Cavitation, and up to now have been designed via design methods for noncavitating blades combined with methods for the analysis of cavitating flows in a trial-and-error manner. In this paper, a numerical nonlinear optimization algorithm is developed for the automated, systematic design of cavitating blades. The method is first applied to the design of propeller blades in uniform flow. The blade mean camber surface is defined via a cubic B-spline polygon net in order to facilitate the handling of the geometry, and to reduce the number of the design parameters. Noncavitating blade geometries designed by the present method are directly compared with those designed via an existing lifting-line/lifting-surface design approach. Finally, the optimization algorithm is applied to the design of cavitating blades in nonuniform flow. The objective of the design is to obtain maximum propeller efficiency for given conditions by allowing controlled amounts of Sheet Cavitation. Several constraints on the unsteady cavity characteristics, such as the area of cavity planform and the amplitudes of the cavity volume velocity harmonics, are incorporated in the optimization technique. The effect of the constraints on the efficiency of the propeller design is demonstrated with various test cases.
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A NONLINEAR BOUNDARY ELEMENT METHOD FOR THE ANALYSIS OF UNSTEADY PROPELLER Sheet Cavitation
1994Co-Authors: Spyridon A Kinnas, Neal E. FineAbstract:The unsteady flow around a cavitating marine propeller is treated in nonlinear theory by employing a low-order potential-based boundary element method and a time-marching scheme. The kinematic and dynamic boundary conditions, which are fully three- dimensional and time-dependent, are satisfied on the propeller surface beneath the cavity and on the portion of the blade wake surface which is overlapped by the cavity. The formulation and algorithm are developed to treat arbitrary cavity planforms in an efficient and robust manner. The results from the numerical method are shown to converge quickly with number of panels and number of time steps per propeller revolution. The produced cavity shapes are validated and shown to satisfy the imposed dynamic boundary condition within acceptable accuracy. Computed cavity planforms are compared to those from linear theory and linear theory with leading edge corrections.
Ge Muye - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of propeller induced hull pressure pulses using RANS and IDDES
2021Co-Authors: Ge Muye, Svennberg Urban, Bensow RickardAbstract:This paper investigates the numerical predictions of pressure pulses induced by a cavitating marine propeller operating in behind-hull condition in model scale. Simulations are performed using the commercial package Star-CCM+ using RANS and IDDES approaches. The predicted Sheet Cavitation agreed well compared to experimental recordings and the 1st- and 2ndorder blade passing frequency (BPF) pressure pulses also agreed well compared to measurements via pressure transducers mounted on the model scale ship hull. Tip vortex Cavitation (TVC)bursting was observed in the experiments and predicted as well in the numerical simulations. A traveling re-entrant jet from blade leading edge to blade tip was predicted underneath the Sheet cavity structure, and triggered the partly collapse of Sheet Cavitation and strong TVCdynamics. The hull pressure uctuations are found to be correlated with the rate of Cavitation volume growth/shrinkage and the TVC dynamics are found generating high levels of higherorder BPF pressure pulses, according to the deduced TVC volume time series. Significant Cavitation variations were recorded between blade passings and propeller revolutions in the experiments, while in the numerical predictions no noticeable Cavitation difference was predicted, and the predicted 3rd- to 5th-order BPF pressure pulse tonal values are generally higher than experimental measurements. The Cavitation variations in the experiments are suspected to be related with Sheet Cavitation inception rather than blade loading difference induced by wake dynamics
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Numerical investigation of tip vortex bursting and induced hull pressure pulses on a container vessel
2021Co-Authors: Ge Muye, Svennberg Urban, Bensow RickardAbstract:A rotating marine propeller generates pressure pulses on the hull above it. The dynamics of Cavitation, especially the tip vortex Cavitation (TVC) bursting and TVC destruction by Sheet cavity collapse have been found to induce high levels of pressure pulses on the ship hull body. The present study is focused on the numerical prediction of propeller induced pressure pulses on the hull with analysis on the interactions between ship wake, Sheet Cavitation and TVC. The predicted 1st – 2nd order Blade Passing Frequency (BPF) agree well with experimental measurements and higher order BPF pressure pulses are reasonably predicted as well. The study shows that the re-entrant jet, which can be related to the propeller inflow and convex shaped Sheet cavity closure line, plays an important role regarding Sheet Cavitation collapse as well as violent TVC dynamics, and induce significant levels of hull pressure pulses
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Investigation on RANS prediction of propeller induced pressure pulses and Sheet-tip Cavitation interactions in behind hull condition
'Elsevier BV', 2020Co-Authors: Ge Muye, Svennberg Urban, Bensow RickardAbstract:This paper investigates the numerical prediction of Cavitation and hull pressure pulses induced by a marine propeller operating in behind-hull conditions of a container vessel in model scale. Simulations are performed using commercial package Star-CCM+ and opensource package OpenFOAM using RANS approach and predictions are compared with experimental measurements. A mesh dependency study with respect to wake prediction is also presented. Operating conditions scaled to two different Reynolds numbers with the same propulsion characteristics and Cavitation number are considered to study scaling effect. Simulations using tip refined mesh are performed and compared with using base mesh to study the tip vortex generation, tip vortex Cavitation, its interaction with Sheet cavity and induced pressure pulses. The influence of time step length is also investigated. Star-CCM+ and OpenFOAM predict consistent results. The predicted Cavitation patterns agree well compared to experimental measurements as well as pressure pulse levels up to 3~4 times blade passing frequency (BPF) especially for the predictions with tip refined mesh. The Sheet Cavitation is the major contribution to 1st and 2nd order BPF pressure pulses and its closure has significant contributions to higher-order pressure pulses. Deduced pressure pulses by tip vortex Cavitation (TVC) are significant ranging from 3rd order to 10th order of BPFs. The TVC induced pressure pulses are related to its violent bursting behavior which is influenced by the closure of the Sheet cavity.\ua0\ua9 2020 Elsevier Lt
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Numerical Prediction of Propeller Induced Hull Pressure Pulses
2019Co-Authors: Ge MuyeAbstract:Ship propeller induced pressure pulses is one of the major sources of both onboard noise and vibration as well as underwater radiated noise. The need for accurate pressure pulse prediction is increasing due to rising concerns of environmental impacts and comfort and welfare of passengers and crews. More accurate pressure pulse prediction is needed to be able to reduce the margin between high efficiency propeller design and low pressure pulse propeller design.Experimental approaches are used for pressure pulse assessments in the final verification stage where models are produced, but they are limited in early design work. Potential flow based methods have been used for early estimation of pressure pulses, but due to the complexity of the pressure pulse generation mechanisms, including interaction between hull and propeller and various types of Cavitation, viscous numerical methods are being developing as a complement to potential flow method and a faster and cheaper alternative of experimental testing. This thesis deals with the numerical prediction of marine propeller induced pressure pulses adapted from typical experimental procedures, including both model scale and full scale marine propellers operating in open-water conditions and behind hull conditions with non-cavitating and cavitating flows. Simulations were conducted using open-source package OpenFOAM and commercial package Star-CCM+ with Reynolds-Averaged Navier-Stokes (RANS) method.Studied cases show that for propellers in behind conditions, the present RANS approach can provide good accuracy regarding 1 st and 2 nd order BPF (Blade Passing Frequency) hull pressure pulses early in design stage. Higher order BPF pressure pulses were also predicted reasonably well, and different mechanisms inducing higher order BPF pressure pulses, including small tip clearance, transient Cavitation appearance and Sheet Cavitation closure and its interaction with tip vortex Cavitation, are outlined in the thesis. For model scale propellers operating under nearly uniform inflows, Sheet Cavitation is often over-predicted and an improved Cavitation mass transfer model is proposed which take laminar separation as an additional inception criteria. Studies regarding mesh resolutions and scaling effects are also included in certain cases
Bensow Rickard - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of tip vortex bursting and induced hull pressure pulses on a container vessel
2021Co-Authors: Ge Muye, Svennberg Urban, Bensow RickardAbstract:A rotating marine propeller generates pressure pulses on the hull above it. The dynamics of Cavitation, especially the tip vortex Cavitation (TVC) bursting and TVC destruction by Sheet cavity collapse have been found to induce high levels of pressure pulses on the ship hull body. The present study is focused on the numerical prediction of propeller induced pressure pulses on the hull with analysis on the interactions between ship wake, Sheet Cavitation and TVC. The predicted 1st – 2nd order Blade Passing Frequency (BPF) agree well with experimental measurements and higher order BPF pressure pulses are reasonably predicted as well. The study shows that the re-entrant jet, which can be related to the propeller inflow and convex shaped Sheet cavity closure line, plays an important role regarding Sheet Cavitation collapse as well as violent TVC dynamics, and induce significant levels of hull pressure pulses
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Numerical investigation of propeller induced hull pressure pulses using RANS and IDDES
2021Co-Authors: Ge Muye, Svennberg Urban, Bensow RickardAbstract:This paper investigates the numerical predictions of pressure pulses induced by a cavitating marine propeller operating in behind-hull condition in model scale. Simulations are performed using the commercial package Star-CCM+ using RANS and IDDES approaches. The predicted Sheet Cavitation agreed well compared to experimental recordings and the 1st- and 2ndorder blade passing frequency (BPF) pressure pulses also agreed well compared to measurements via pressure transducers mounted on the model scale ship hull. Tip vortex Cavitation (TVC)bursting was observed in the experiments and predicted as well in the numerical simulations. A traveling re-entrant jet from blade leading edge to blade tip was predicted underneath the Sheet cavity structure, and triggered the partly collapse of Sheet Cavitation and strong TVCdynamics. The hull pressure uctuations are found to be correlated with the rate of Cavitation volume growth/shrinkage and the TVC dynamics are found generating high levels of higherorder BPF pressure pulses, according to the deduced TVC volume time series. Significant Cavitation variations were recorded between blade passings and propeller revolutions in the experiments, while in the numerical predictions no noticeable Cavitation difference was predicted, and the predicted 3rd- to 5th-order BPF pressure pulse tonal values are generally higher than experimental measurements. The Cavitation variations in the experiments are suspected to be related with Sheet Cavitation inception rather than blade loading difference induced by wake dynamics
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Investigation on RANS prediction of propeller induced pressure pulses and Sheet-tip Cavitation interactions in behind hull condition
'Elsevier BV', 2020Co-Authors: Ge Muye, Svennberg Urban, Bensow RickardAbstract:This paper investigates the numerical prediction of Cavitation and hull pressure pulses induced by a marine propeller operating in behind-hull conditions of a container vessel in model scale. Simulations are performed using commercial package Star-CCM+ and opensource package OpenFOAM using RANS approach and predictions are compared with experimental measurements. A mesh dependency study with respect to wake prediction is also presented. Operating conditions scaled to two different Reynolds numbers with the same propulsion characteristics and Cavitation number are considered to study scaling effect. Simulations using tip refined mesh are performed and compared with using base mesh to study the tip vortex generation, tip vortex Cavitation, its interaction with Sheet cavity and induced pressure pulses. The influence of time step length is also investigated. Star-CCM+ and OpenFOAM predict consistent results. The predicted Cavitation patterns agree well compared to experimental measurements as well as pressure pulse levels up to 3~4 times blade passing frequency (BPF) especially for the predictions with tip refined mesh. The Sheet Cavitation is the major contribution to 1st and 2nd order BPF pressure pulses and its closure has significant contributions to higher-order pressure pulses. Deduced pressure pulses by tip vortex Cavitation (TVC) are significant ranging from 3rd order to 10th order of BPFs. The TVC induced pressure pulses are related to its violent bursting behavior which is influenced by the closure of the Sheet cavity.\ua0\ua9 2020 Elsevier Lt
Jui-hsiang Kao - One of the best experts on this subject based on the ideXlab platform.
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Underwater acoustic field and pressure fluctuation on ship hull due to unsteady propeller Sheet Cavitation
Journal of Marine Science and Technology, 2011Co-Authors: Young Zehr Kehr, Jui-hsiang KaoAbstract:The main objective of this paper is to develop an efficient numerical method which can predict the underwater acoustic field and pressure fluctuation on a ship hull due to unsteady propeller Sheet Cavitation by linear acoustic theory. In addition, the noise scattered from the ship hull and reflected from the free surface are included. Concerning the computation of the acoustic field induced by unsteady Sheet Cavitation and forces of a marine propeller, a method is derived without making any approximation about the distance function between the noise source and field point. Thus, this method can be used to predict acoustic pressure at both far and near fields, and this is very important for the scattering problem because the ship hull is located very close to the propeller. For the computation of the scattering problem, a more efficient and robust method is derived in time domain, which can treat multi-frequency waves scattered from underwater obstacles. The acoustic fields of a container ship radiated by the propeller and scattered from the ship hull with free surface is investigated in this paper. The pressure fluctuations of low blade rate on the ship hull induced by the propeller are also computed by the present method and are found to be similar to the results obtained by a panel method satisfying the Laplace equation for the points near the propeller due to the small retarding time. However, for the points on the ship hull away from the propeller, the differences of the results between two methods will increase.
Ignacijo Bilus - One of the best experts on this subject based on the ideXlab platform.
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comparison of mass transfer models for the numerical prediction of Sheet Cavitation around a hydrofoil
International Journal of Multiphase Flow, 2011Co-Authors: Mitja Morgut, Enrico Nobile, Ignacijo BilusAbstract:Cavitating flows, which can occur in a variety of practical cases, can be modelled with a wide range of methods. One strategy consists of using the RANS (Reynolds Averaged Navier Stokes) equations and an additional transport equation for the liquid volume fraction, where mass transfer rate due to Cavitation is modelled by a mass transfer model. In this study, we compare three widespread mass transfer models available in literature for the prediction of Sheet Cavitation around a hydrofoil. These models share the common feature of employing empirical coefficients, to tune the models of condensation and evaporation processes, that can influence the accuracy and stability of the numerical predictions. In order to compare the different mass transfer models fairly and congruently, the empirical coefficients of the different models are first well tuned using an optimization strategy. The resulting well tuned mass transfer models are then compared considering the flow around the NACA66(MOD) and NACA009 hydrofoils. The numerical predictions based on the three different tuned mass transfer models are very close to each other and in agreement with the experimental data. Moreover, the optimization strategy seems to be stable and accurate, and could be extended to additional mass transfer models and further flow problems.
