CFD Simulation of a Twin-Screw Ship Self-Propulsion Using DDES-Overset Method

2019 ◽  
Author(s):  
Jianhua Wang ◽  
Decheng Wan
Keyword(s):  
Cfd Simulation ◽  
Ship Hull ◽  
The Self ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Ship Model ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Twin Screw ◽  
Cfd Method

Abstract Rotating propellers and moving rudders are necessary for the simulation of free running ship with the purpose of resolving detailed flow interaction. In the present work, CFD method is used to numerically investigate self-propulsion behavior for a twin-screw fully appended ship. The simulation conditions are following the experiment performed at IIHR. The benchmark ship model ONR Tumblehome is used for all the numerical computations. Overset grids are used to fully discretize the ship hull, twin propellers and rudders. Self-propulsion simulation is carried out using a PI controller to achieve target ship speed of Fr = 0.20 in calm water and the ship model is free to trim and sinkage. All the numerical calculations are carried out by the in-house CFD solver naoe-FOAM-SJTU. Unlike most previous studies based on RANS method, the present self-propulsion simulations adopt the Delayed Detached-Eddy-Simulation (DDES) approach to resolve the complex flow around ship hull, propeller and rudder. The main parameters of the self-propulsion as well as flow visualizations are presented. The predicted results are compared with previous RANS data and the available experimental data. The comparison with the experiment is satisfactory and the flow field shows that the present DDES-overset method can give more flow details for the self-propulsion condition.

A DDES study of the flow past a prolate spheroid using a high-order U-MUSCL scheme

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040075
Author(s):  
Yu-Chen Yang ◽  
Zhen-Ming Wang ◽  
Ning Zhao
Keyword(s):  
Flow Separation ◽  
Vortex Structure ◽  
Prolate Spheroid ◽  
High Order ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Flow Past ◽  
Delayed Detached Eddy Simulation ◽  
Flow Phenomena

Flow past a prolate spheroid, which is a representative simplified configuration for vehicles such as maneuvering ships, submarines and missiles, comprises a series of complex flow phenomena including pressure-induced flow separation, which results in unsteady forces and movements that may be detrimental to vehicles’ performance. In this paper, a Delayed Detached Eddy Simulation (DDES) method combined with a new high-order U-MUSCL scheme is proposed to more precisely and accurately capture the flow separation and vortex structure. This method is applied to simulate the aerodynamic performance of the 6:1 prolate spheroid at an AOA of [Formula: see text] with the Reynolds number of [Formula: see text]. Axial pressure distribution of five individual chord wise sections and flow field structure of the aft body are analyzed. Numerical results agree well with the experimental data. It can be concluded that DDES combined with three-order U-MUSCL scheme demonstrates reliable performance since it captures the vortex structure of aft body distinctly and predicts the separation and reattachment points of the secondary vortex precisely.

Prediction of Aeroacoustic and Control over a Cavity by Delayed Detached Eddy Simulation

2014 ◽  
Vol 598 ◽  
pp. 505-509 ◽  
Author(s):  
Yu Liu ◽  
Ming Bo Tong
Keyword(s):  
Sound Pressure ◽  
Noise Suppression ◽  
Cfd Simulation ◽  
Leading Edge ◽  
Pressure Level ◽  
Detached Eddy Simulation ◽  
Suppression Effect ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
And Control

In the present study CFD simulation with delayed detached eddy simulation (DDES) are performed to investigate an open cavity at Mach 0.85. Two cavity configurations, clean cavity and cavity with a leading-edge saw tooth spoiler, are modeled. The results obtained from clean cavity prediction are compared with experimental sound pressure level (SPL) data from QinetiQ, UK. Furthermore, comparisons are made with the predicted SPL between the two configurations. The main focuses of this investigation are to obtain a further understanding of the cavity aeroacoustics and test the noise suppression effect by a saw tooth spoiler.

scholarly journals Aeroacoustic Investigation of Passive and Active Control on Cavity Flowfields Using Delayed Detached Eddy Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yu Liu ◽  
Yong Shi ◽  
Mingbo Tong ◽  
Fei Zhao ◽  
Binqi Chen
Keyword(s):  
Active Control ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Passive Control ◽  
Cfd Simulation ◽  
Pressure Level ◽  
Control Methods ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

In the present study, CFD simulation with delayed detached eddy simulation (DDES) is performed to investigate an open cavity at Mach 0.85. A clean cavity and cavity with passive and active control methods, including sawtooth spoiler, flat-top spoiler, crossflow rod, and steady leading edge blowing, are analyzed. The results obtained from all the control methods are compared with clean cavity, and all the flow control methods show positive effect on the overall sound pressure level reduction with the decrement up to 8 dB. The effect of active control on sound pressure level in the cavity is much better than that of passive control, with the magnitude of tone noise decreasing by 20-30 dB. The main focus of this investigation is to test the noise suppression effect by passive and active control methods.

Numerical Investigation of Flow Around a Multi-Element Airfoil with Hybrid RANS-LES Approaches Based on SST Model

2017 ◽  
Vol 34 (2) ◽  
pp. 123-134 ◽  
Author(s):  
L. Zhang ◽  
J. Li ◽  
Y. F. Mou ◽  
H. Zhang ◽  
W. B. Shi ◽  
...  
Keyword(s):  
Turbulence Modeling ◽  
Experimental Result ◽  
Numerical Dissipation ◽  
Small Scale ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Third Order ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

AbstractAccurate prediction of the flow around multi-element airfoil is a prerequisite for improving aerodynamic performance, but its complex flow features impose high demands on turbulence modeling. In this work, delayed detached-eddy-simulation (DDES) and zonal detached-eddy-simulation (ZDES) was applied to simulate the flow past a three-element airfoil. To investigate the effects of numerical dissipation of spatial schemes, the third-order MUSCL and the fifth-order interpolation based on modified Roe scheme were implemented. From the comparisons between the calculations and the available experimental result, third-order MUSCL-Roe can provide satisfactory mean velocity profiles, but the excessive dissipation suppresses the velocity fluctuations level and eliminates the small-scale structures; DDES cannot reproduce the separation near the trailing edge of the flap which lead to the discrepancy in mean pressure coefficients, while ZDES result has better tally with the experiment.

Numerical study of the flow over the modified simple frigate shape

2020 ◽  
pp. 095441002097775
Author(s):  
Tong Li ◽  
Yibin Wang ◽  
Ning Zhao
Keyword(s):  
Bluff Body ◽  
Recirculation Zone ◽  
Numerical Study ◽  
Reference Value ◽  
Flow Fields ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Simulation Results

The simple frigate shape (SFS) as defined by The Technical Co-operative Program (TTCP), is a simplified model of the frigate, which helps to investigate the basic flow fields of a frigate. In this paper, the flow fields of the different modified SFS models, consisting of a bluff body superstructure and the deck, were numerically studied. A parametric study was conducted by varying both the superstructure length L and width B to investigate the recirculation zone behind the hangar. The size and the position of the recirculation zones were compared between different models. The numerical simulation results show that the size and the location of the recirculation zone are significantly affected by the superstructure length and width. The results obtained by Reynolds-averaged Navier-Stokes method were also compared well with both the time averaged Improved Delayed Detached-Eddy Simulation results and the experimental data. In addition, by varying the model size and inflow velocity, various flow fields were numerically studied, which indicated that the changing of Reynolds number has tiny effect on the variation of the dimensionless size of the recirculation zone. The results in this study have certain reference value for the design of the frigate superstructure.

scholarly journals Numerical Investigation on the Influence of the Streamlined Structures of the High-Speed Train’s Nose on Aerodynamic Performances

2021 ◽  
Vol 11 (2) ◽  
pp. 784
Author(s):  
Zhenxu Sun ◽  
Shuanbao Yao ◽  
Lianyi Wei ◽  
Yongfang Yao ◽  
Guowei Yang
Keyword(s):  
Drag Reduction ◽  
Pressure Distribution ◽  
Flow Separation ◽  
High Speed ◽  
Leeward Side ◽  
Detached Eddy Simulation ◽  
Side Force ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Asymmetrical Design

The structural design of the streamlined shape is the basis for high-speed train aerodynamic design. With use of the delayed detached-eddy simulation (DDES) method, the influence of four different structural types of the streamlined shape on aerodynamic performance and flow mechanism was investigated. These four designs were chosen elaborately, including a double-arch ellipsoid shape, a single-arch ellipsoid shape, a spindle shape with a front cowcatcher and a double-arch wide-flat shape. Two different running scenes, trains running in the open air or in crosswind conditions, were considered. Results reveal that when dealing with drag reduction of the whole train running in the open air, it needs to take into account how air resistance is distributed on both noses and then deal with them both rather than adjust only the head or the tail. An asymmetrical design is feasible with the head being a single-arch ellipsoid and the tail being a spindle with a front cowcatcher to achieve the minimum drag reduction. The single-arch ellipsoid design on both noses could aid in moderating the transverse amplitude of the side force on the tail resulting from the asymmetrical vortex structures in the flow field behind the tail. When crosswind is considered, the pressure distribution on the train surface becomes more disturbed, resulting in the increase of the side force and lift. The current study reveals that the double-arch wide-flat streamlined design helps to alleviate the side force and lift on both noses. The magnitude of side force on the head is 10 times as large as that on the tail while the lift on the head is slightly above that on the tail. Change of positions where flow separation takes place on the streamlined part is the main cause that leads to the opposite behaviors of pressure distribution on the head and on the tail. Under the influence of the ambient wind, flow separation occurs about distinct positions on the train surface and intricate vortices are generated at the leeward side, which add to the aerodynamic loads on the train in crosswind conditions. These results could help gain insight on choosing a most suitable streamlined shape under specific running conditions and acquiring a universal optimum nose shape as well.

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