scholarly journals Numerical Prediction of Propeller-Hull Interaction Characteristics Using RANS Method

2019 ◽  
Vol 26 (2) ◽  
pp. 163-172
Author(s):  
Tu Tran Ngoc ◽  
Do Duc Luu ◽  
Thi Hai Ha Nguyen ◽  
Thi Thu Quynh Nguyen ◽  
Minh Vu Nguyen
Keyword(s):  
Open Water ◽  
Body Motion ◽  
Test Cases ◽  
Interaction Coefficients ◽  
Sliding Mesh ◽  
Water Characteristics ◽  
Computational Evaluation ◽  
Sinkage And Trim ◽  
Unsteady Rans ◽  
Multi Phase

Abstract The paper presents the results of computational evaluation of the hull-propeller interaction coefficients, also referred to propulsive coefficients, based on the unsteady RANS flow model. To obtain the propulsive coefficients, the ship resistance, the open-water characteristics of the propeller, and the flow past the hull with working propeller were computed. For numerical evaluation of propeller open-water characteristics, the rotating reference frame approach was used, while for self-propulsion simulation, the rigid body motion method was applied. The rotating propeller was modelled with the sliding mesh technique. The dynamic sinkage and trim of the vessel were considered. The free surface effects were included by employing the volume of fluid method (VOF) for multi-phase flows. The self-propulsion point was obtained by performing two runs at constant speed with different revolutions. The well-known Japan Bulk Carrier (JBC) test cases were used to verify and validate the accuracy of the case studies. The solver used in the study was the commercial package Star-CCM+ from SIEMENS.

scholarly journals Prediction of Propeller Open Water Characteristics for High Speed Boat by CFD Method

2019 ◽  
Vol 9 (1) ◽  
pp. 3701-3706
Keyword(s):  
High Speed ◽  
Open Water ◽  
Design Stage ◽  
Water Characteristics ◽  
Computational Evaluation ◽  
Mesh Density ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Commercial Solver ◽  
Computational Resources

Nowadays with the development of computational resources, calculating the open water characteristics of the propeller using Computational Fluid Dynamics (CFD) has been used widely at the initial design stage because of relatively accurate result, time and cost saving, in comparison with experimental approach. This paper presents the results of computational evaluation of propeller open water characteristics for high speed boat, based on steady RANSE flow model with rotating reference frame approach. The effects of mesh density, mesh generation are analyzed in order to improve obtained numerical results. The well-known Gawn propeller series, that is often used for high speed vessel is used to verify and validate the accuracy of case studies. In this study, the authors use the commercial solver Star CCM+ by SIEMENS

Low-Pressure Compressor Near-Stall Predictions Using Unsteady CFD Methods

2021 ◽  
Author(s):  
David Vanpouille ◽  
Dimitrios Papadogiannis ◽  
Stéphane Hiernaux
Keyword(s):  
Low Pressure ◽  
Navier Stokes ◽  
Phase Lag ◽  
Sliding Mesh ◽  
Tip Leakage ◽  
Eddy Simulation ◽  
Surge Margin ◽  
Large Eddy ◽  
Unsteady Rans ◽  
Pressure Compressor

Abstract Surge margin is critical for the safety of aeronautical compressors, hence predicting it early in the design process using CFD is mandatory. However, close to surge, steady-state Reynolds Averaged Navier-Stokes (RANS) simulations are proven inadequate. Unsteady techniques such as Unsteady RANS (URANS) and Large Eddy Simulation (LES) can provide more reliable predictions. Nevertheless, the accuracy of such methods are dependent on the method used to handle the rotor/stator interfaces. The most precise method, the sliding mesh, requires simulating the full annulus or a periodic sector, which can be very costly. Other techniques to reduce the domain exist, such as the phase-lagged approach or geometric blade scaling, but introduce restrictive assumptions on the flow at near-stall conditions. The objective of this paper is to investigate the near-stall flow of a low-pressure compressor using unsteady methods of varying fidelity: URANS with the phase lag assumption, URANS on a periodic sector and a high-fidelity LES on a smaller periodic sector achieved using geometric blade scaling. Results are compared to experimental measurements. An overall good agreement is found. Results show that the tip leakage vortex is not the origin of the stall on the studied configuration and a hub corner separation is initiated. LES further validates the (U)RANS flow predictions and brings additional insight on unsteady flow separations.

Numerical Investigation of Unsteady Film Cooling on the Turbine Shroud With the Blade Passing

2018 ◽  
Author(s):  
Chao Gao ◽  
Cun-liang Liu ◽  
Hai-yong Liu ◽  
Qi-ling Guo ◽  
Rui-dong Wang ◽  
...  
Keyword(s):  
Film Cooling ◽  
Experimental Studies ◽  
Relative Rotation ◽  
Film Blowing ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Sliding Mesh ◽  
Blowing Ratio ◽  
Blade Rotation ◽  
Unsteady Rans

Numerical simulations have been performed on the turbine shroud unsteady film cooling under the blade passing. There are many published experimental studies for turbine shroud heat transfer and a few computational fluid dynamics data. In this paper, unsteady RANS method has been performed to study the effect of the blade rotation speeds and the film blowing ratios on the behavior of film cooling effectiveness. And the sliding mesh in Fluent was used to achieve relative rotation between blade and shroud. These results are reported for blowing ratios of 1.0, 1.5, 2.0, blade rotation speeds of 1600 rpm, 1800rpm, 2089rpm, 2400rpm. The results show that the time instantaneous film cooling effectiveness on the shroud have a notable different distribution with the steady blade case. And at the rotation results, the film cooling effectiveness is even coverage with the blowing ratio increasing. The time-averaged film cooling effectiveness on the shroud increases by increasing the blowing ratio on all blade rotational velocities. And in this study, the blade at different rotation speeds, the distribution of time-averaged film cooling effectiveness has a significantly reduce on the shroud because of the relative movement of blade and shroud.

A 2.5D numerical study on open water hydrodynamic performance of a Voith-Schneider propeller

2019 ◽  
Vol 20 (6) ◽  
pp. 617
Author(s):  
Mohammad Bakhtiari ◽  
Hassan Ghassemi
Keyword(s):  
Numerical Method ◽  
Thrust Force ◽  
Numerical Study ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Maximum Efficiency ◽  
Water Efficiency ◽  
Blade Thickness ◽  
Unsteady Rans ◽  
Marine Vessels

Marine cycloidal propeller (MCP) is a special type of marine propulsors that provides high maneuverability for marine vessels. In a MCP, the propeller axis of rotation is perpendicular to the direction of thrust force. It consists of a number of lifting blade. Each blade rotates about the propeller axis and simultaneously pitches about its own axis. The magnitude and direction of thrust force can be adjusted by controlling the propeller pitch. Voith-Schneider propeller (VSP) is a low-pitch MCP with pure cycloidal blade motion allowing fast, accurate, and stepless control of thrust magnitude and direction. Generally, low-pitch cycloidal propellers are used in applications with low speed maneuvering requirements, such as tugboats, minesweepers, etc. In this study, a 2.5D numerical method based on unsteady RANS equations with SST k-ω turbulent model was implemented to predict the open water hydrodynamic performance of a VSP for different propeller pitches and blade thicknesses. The numerical method was validated against the experimental data before applying to VSP. The results showed that maximum open water efficiency of a VSP is enhanced by increasing the propeller pitch. Furthermore, the effect of blade thickness on open water efficiency is different at various advance coefficients, so that the maximum efficiency produced by the VSP decreases with increasing blade thickness at different propeller pitches.

scholarly journals State Uncertainty Normality Detection

2019 ◽  
Vol 67 (3) ◽  
pp. 1044-1062
Author(s):  
Sven K. Flegel ◽  
James C. Bennett
Keyword(s):  
State Estimation ◽  
Orbit Determination ◽  
Estimation Error ◽  
The State ◽  
Body Motion ◽  
Optical Observations ◽  
Test Cases ◽  
Unscented Transform ◽  
State Uncertainty ◽  
Random Particle

AbstractTwo fundamentally different approaches of determining normality of the probability density function of the state estimation error are compared by application to a range of test cases. The first method is the Henze-Zirkler test, which operates on a random particle sample. The variability of its result is quantified. Using this method, departure from normality has been found to occur in three stages which are detailed. The second test compares the offset in whitened space of the predicted state to the predicted covariance mean obtained from the unscented transform. This test is much more efficient than the random particle based approach and can be applied using any perturbations model. The comparison is performed on the state estimation error in Cartesian space and using two-body motion without process noise. The more efficient, unscented transform based approach shows excellent agreement with the Henze-Zirkler test for constructed test cases. Application to orbit determination results from passive optical observations assessed with a Batch-Least-Squares orbit determination however reveals some discrepancies which have yet to be understood and underline the importance of rigorous testing.

A Simulation of the Liquid Shock and Cavitation Based on a Multi-Equation Model

2016 ◽  
Vol 13 (04) ◽  
pp. 1641010
Author(s):  
Yang-Yao Niu
Keyword(s):  
Equation Of State ◽  
Blunt Body ◽  
Equation Model ◽  
Test Cases ◽  
Riemann Solver ◽  
Temperature Dependent ◽  
Two Phase ◽  
One Dimensional ◽  
Condensation Shock ◽  
Multi Phase

In this paper, an unsteady preconditioning formulation for multi-phase flows with arbitrary equation of state based on the approximated Riemann solver is developed for multi-phase flows at all speed. This paper considers a homogeneous two-phase multi-equation mixture model with the assumption of kinematics and thermodynamics equilibriums. The thermodynamics behaviors of liquid phase, vapor phase and their phase transitional process are described by a temperature-dependent hybrid equation of state. Benchmark test cases, including one-dimensional (1D) condensation shock in the cavitated nozzle and two-dimensional (2D) cavitated blunt body problem, demonstrate accurate capturing of interfaces, shock waves and cavitation zones.

Experimental and Numerical Investigation of DARPA Suboff Submarine Propelled with INSEAN E1619 Propeller for Self-Propulsion

2019 ◽  
Vol 63 (4) ◽  
pp. 235-250
Author(s):  
Yasemin Arıkan Özden ◽  
Münir Cansın Özden ◽  
Ersin Demir ◽  
Sertaç Kurdoğlu
Keyword(s):  
Open Water ◽  
Test Method ◽  
The Self ◽  
Propulsive Efficiency ◽  
Ship Model ◽  
Rotation Rates ◽  
Water Characteristics ◽  
Numerical Studies ◽  
Computational Fluid Dynamics Cfd ◽  
Thrust And Torque

The Defense Advanced Research Projects Agency (DARPA) Suboff Submarine propelled by the Italian Ship Model Basin (INSEAN) E1619 propeller is extensively used in submarine validation studies. Although there are several numerical studies where the DARPA Suboff submarine is used in combination with E1619 propeller there are no experimental data available in open literature for the self-propulsion condition. In this article, the self-propulsion characteristics of the DARPA Suboff submarine model with INSEAN E1619 propeller obtained with experimental and numerical methods are presented and discussed by means of Taylor wake fraction, thrust deduction, hull efficiency, relative rotative efficiency, and propulsive efficiency. To experimentally investigate the submarine form, a self-propulsion experimental setup is designed and manufactured. Resistance and self-propulsion experiments are conducted in Istanbul Technical University Ata Nutku Ship Model Testing Laboratory. Resistance tests are carried out for three different speeds, and the results show good agreement with the published experimental results. Propulsion tests are conducted by using the load-varying self-propulsion test method for constant speed and seven different propeller rotation rates. Rotational speed, thrust, and torque forces at self-propulsion point are investigated. For the numerical computations a commercial Computational Fluid Dynamics (CFD) code is used. Propeller open water characteristics and nondimensional velocities behind the propeller are calculated. Self-propulsion point of the submarine and propeller assembly is also solved numerically and the results are compared with the results obtained from the experiments, and it is seen that especially the propeller rate of revolution and thrust force are predicted with very good approximation.

The effect of the aerofoil thickness on the performance of the MAV scale cycloidal rotor

2015 ◽  
Vol 119 (1213) ◽  
pp. 343-364 ◽  
Author(s):  
Y. Hu ◽  
H.L. Zhang ◽  
C. Tan
Keyword(s):  
Flow Pattern ◽  
Cfd Simulation ◽  
Leading Edge ◽  
Dynamic Stall ◽  
Test Cases ◽  
Sliding Mesh ◽  
Large Fluctuations ◽  
Edge Vortex ◽  
Rotor Cage ◽  
Different Thickness

AbstractThe numerical simulations for cycloidal propellers based on five aerofoils with different thickness are presented in this paper. The CFD simulation is based on sliding mesh and URANS. The results of CFD simulation indicates that all test cases share similar flow pattern. There are leading edge vortex and trailing-edge vortex due to blade dynamic stall. Interaction between the vortices shed from upstream blade and the downstream blade can be observed. There is variation of blade relative inflow velocity due to downwash in the cycloidal rotor cage. These factors result in large fluctuations of the aerodynamics forces on the blade. The comparison of the forces and flow pattern indicates that the thickness and leading edge radius of the aerofoil can significantly influent the flow pattern and hence the performance of the cycloidal propeller.

scholarly journals Investigation on Resistance, Squat and Ship-Generated Waves of Inland Convoy Passing Bridge Piers in a Confined Waterway

2021 ◽  
Vol 9 (10) ◽  
pp. 1125
Author(s):  
Peng Du ◽  
Abdellatif Ouahsine ◽  
Philippe Sergent ◽  
Yannick Hoarau ◽  
Haibao Hu
Keyword(s):  
Stokes Equations ◽  
Lateral Position ◽  
Wave Pattern ◽  
Body Motion ◽  
Bridge Piers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Sliding Mesh ◽  
Experimental Approaches ◽  
Mesh Technique

The average and unsteady hydrodynamics of an inland convoy passing bridge piers in a confined waterway were investigated using both numerical and experimental approaches. The numerical simulations are realized by solving the RANS (Reynolds-averaged Navier–Stokes) equations accounting for the solid body motion using the sliding mesh technique, while the experiments were carried out in the towing tank. The advancing resistance, trim, sinkage and ship-generated waves were analyzed as functions of the water depth, distance between bridge piers, draught and velocity. The existence of the piers is found to only influence the transient hydrodynamics of the convoy, but not the averaged properties. The ship-generated waves, especially the wave profiles at a specific lateral position, were characterized. Two wave crests exist at the pier position because of the additional reflections, creating a very complex wave pattern in the confined waterway.

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