scholarly journals Computational hydrodynamic analysis of a highly skewed marine propeller

2019 ◽  
Vol 16 (1) ◽  
pp. 21-32
Author(s):  
Houari Hussein ◽  
Kadda Boumediene ◽  
Samir Belhenniche ◽  
Omar Imine ◽  
Mohamed Bouzit
Keyword(s):  
Open Water ◽  
Navier Stokes ◽  
Marine Propeller ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Ship Wake ◽  
Sliding Mesh ◽  
Wide Range ◽  
Volume Method ◽  
Thrust And Torque

 The objective of the current paper is to study the flow around Seiun Maru Highly Skewed (HSP) marine propeller by assessment of blade forces and moments under non-cavitating case. The calculations are performed in open water (steady case) and non-uniform ship wake (Unsteady case). The governing equations based on Reynolds Averaged Navier-Stokes Equation (RANSE) are solved using Finite Volume Method. Ansys Fluent 14.0 is used to implement the simulation. For the steady case, Moving Reference Frame (MRF) is selected while sliding mesh technique is adopted for the unsteady case. Calculated open water performances in terms of thrust and torque coefficients fit very well with experimental data for a wide range of advance ratio. In the unsteady calculations, axial velocities, deduced from the nominal wake, are introduced in the Ansys fluent code. To locate suitably the non-uniform wake in the propeller front plane, three positions of inlet wake have been taken into account to determine their effects on the accuracy of the results. Obtained results show that computed performances are improved compared to panel method when the inlet is close to the propeller.  

Numerical Simulation of the Resistance and Self-Propulsion Model Tests1

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Adrian Lungu
Keyword(s):  
Complex Structure ◽  
Turbulence Models ◽  
Open Water ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Local Flow ◽  
Complex Investigation ◽  
Flow Features ◽  
Thrust And Torque

Abstract The paper proposes a series of numerical investigations performed to test and demonstrate the capabilities of a Reynolds-averaged Navier–Stokes equation (RANSE) solver in the area of complex ship flow simulations. The focus is on a complete numerical model for hull, propeller, and rudder that can account for the mutual interaction between these components. The paper presents the results of a complex investigation of the flow computations around the hull model of the 3600 TEU MOERI containership (KCS hereafter). The resistance for the hull equipped with a rudder, the propeller open-water (POW hereafter) computations, as well as the self-propulsion simulation are presented. Comparisons with the experimental data provided at the Tokyo 2015 Workshop on Computational Fluid Dynamics (CFD) in Ship Hydrodynamics are given to validate the numerical approach in terms of the total and wave resistance coefficients, sinkage and trim, thrust and torque coefficients, propeller efficiency, and local flow features. Verification and validation based on the grid convergence tests are performed for each computational case. Discussions on the efficiency of the turbulence models used in the computations as well as on the main flow features are provided aimed at clarifying the complex structure of the flow around the ship stern.

Optimization of RANS Solver Simulation Setup for Propeller Open Water Performance Prediction

2015 ◽  
Author(s):  
Mohammed Islam ◽  
Fatima Jahra ◽  
Michael Doucet
Keyword(s):  
Domain Size ◽  
Open Water ◽  
Fractional Factorial ◽  
Navier Stokes ◽  
Calm Water ◽  
Simulation Results ◽  
Open Water Performance ◽  
Thrust And Torque ◽  
Simulation Time ◽  
Fixed Pitch

Mesh and domain optimization strategies for a RANS solver to accurately estimate the open water propulsive characteristics of fixed pitch propellers are proposed based on examining the effect of different mesh and computation domain parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations to be carried out in a limited memory environment, and in a timely manner; without compromising the accuracy of results. A Reynolds-Averaged Navier Stokes solver is used to predict the propulsive performance of a fixed pitch propeller. The predicted thrust and torque for the propeller were compared to the corresponding measurements. A total of six meshing parameters were selected that could affect the computational results of propeller open water performance. A two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent parameters: namely simulation time, propeller thrust and propeller torque. A total of 32 simulations were carried out only to find out that the selected six meshing parameters were significant in defining the response parameters. Optimum values of each of the input parameters were obtained for the DOE technique and additional simulations were run with those parameters. The simulation results were validated using open water experimental results of the same propeller. It was found that with the optimized meshing arrangement, the propeller opens simulation time was reduced by at least a factor of 6 as compared to the generally popular meshing arrangement. Also, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using STAR-CCM+, a commercial CFD package; however the findings can be applied to any RANS solver.

Numerical Study on Control of Sunroof Buffeting

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
K. Vijaykumar ◽  
S. Poonkodi ◽  
A.T. Sriram
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Dominant Frequency ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Flow Modification ◽  
Numerical Result ◽  
Modification Technique ◽  
Commercial Solver

Sunroof has become one of the essential features of a luxury car, and it provides natural air circulation and good illumination into the car. But the primary problem associated with it is the buffeting noise which causes discomfort to the passengers. Though adequate studies were carried out on sunroof buffeting, efficient control techniques are needed to be developed from fundamental mechanism. To reduce the buffeting noise, flow modifications at the entrance of the sunroof is considered in this study. The internal portion of the car with sunroof is simplified into a shear driven open cavity, and two-dimensional numerical simulations are carried out using commercial solver, ANSYS Fluent. Reynolds averaged Navier-Stokes equation is used with the realizable k-? turbulence model. The unsteady numerical result obtained in this study is validated with the available experimental results for the dominant frequency. The prediction is good agreement with experiment. Flow modification technique is proposed to control the sunroof buffeting by implementing geometric modifications. A hump has been placed near the leading edge of the cavity which resulted in significant reduction of pressure oscillations. Parametric studies have been performed by varying the height of hump and the distance of hump from the leading edge. There is no prominent difference when the height of the hump is varied. As the distance of the hump from the leading edge is reduced, the sound pressure level decreases.

Conjugate Free Convection Heat Transfer and Thermodynamic Analysis of Infrared Suppression Device with Cylindrical Funnels

2022 ◽  
Author(s):  
Vikrant Chandrakar ◽  
Arnab Mukherjee ◽  
Jnana Ranjan Senapati ◽  
Ashok Kumar Barik
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Convection Heat Transfer ◽  
Navier Stokes ◽  
Bejan Number ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Geometric Ratio ◽  
Flow Rate Increase ◽  
Free Convection Heat

Abstract A convection system can be designed as an energy-efficient one by making a considerable reduction in exergy losses. In this context, entropy generation analysis is performed on the infrared suppression system numerically. In addition, results due to heat transfer are also shown. The numerical solution of the Navier-stokes equation, energy equation, and turbulence equation is executed using ANSYS Fluent 15.0. To perform the numerical analysis, different parameters such as the number of funnels, Rayleigh number (Ra), inner surface temperature, and geometric ratio are varied in the practical range. Results are shown in terms of heat transfer, entropy generation, irreversibility (due to heat transfer and fluid friction), and Bejan number with some relevant parameters. Streamlines and temperature contours are also provided for better visualization of temperature and flow field around the device. Results show that heat transfer and mass flow rate increase with the increase in Ra. Entropy generation and the irreversibility rise with an increase in the number of funnels and geometric ratio. Also, the Bejan number decreases with an increase in Ra and the number of funnels. A cooling time is also obtained using the lumped capacitance method.

Method for Non-Dimensional Tip Leakage Flow Characterization in Radial Turbines

2018 ◽  
Author(s):  
José Ramón Serrano ◽  
Roberto Navarro ◽  
Luis Miguel García-Cuevas ◽  
Lukas Benjamin Inhestern
Keyword(s):  
Suction Side ◽  
Tip Clearance ◽  
Navier Stokes ◽  
The Novel ◽  
Tip Leakage Flow ◽  
Navier Stokes Equation ◽  
Tip Clearance Flow ◽  
Tip Leakage ◽  
Wide Range ◽  
Clearance Flow

Tip leakage loss characterization and modeling plays an important role in small size radial turbine research. The momentum of the flow passing through the tip gap is highly related with the tip leakage losses. The ratio of fluid momentum driven by the pressure gradient between suction side and pressure side and the fluid momentum caused by the shroud friction has been widely used to analyze and to compare different sized tip clearances. However, the commonly used number for building this momentum ratio lacks some variables, as the blade tip geometry data and the viscosity of the used fluid. To allow the comparison between different sized turbocharger turbine tip gaps, work has been put into finding a consistent characterization of radial tip clearance flow. Therefore, a non-dimensional number has been derived from the Navier Stokes Equation. This number can be calculated like the original ratio over the chord length. Using the results of wide range CFD data, the novel tip leakage number has been compared with the traditional and widely used ratio. Furthermore, the novel tip leakage number can be separated into three different non-dimensional factors. First, a factor dependent on the radial dimensions of the tip gap has been found. Second, a factor defined by the viscosity, the blade loading, and the tip width has been identified. Finally, a factor that defines the coupling between both flow phenomena. These factors can further be used to filter the tip gap flow, obtained by CFD, with the influence of friction driven and pressure driven momentum flow.

Numerical Analysis of Streamlines in Kaplan Turbine with Different Distributor Fins Design

2020 ◽  
Vol 35 ◽  
pp. 46-54
Author(s):  
Daniele Twardowski ◽  
Diego Alves de Miranda
Keyword(s):  
Stokes Equations ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Flow Profile ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Kaplan Turbine ◽  
Current Lines ◽  
High Level ◽  
Volume Method

With each passing day companies are looking more and more in the initial phase of the project, to understand the phenomena arising, so that in the execution of the project there are no failures, much less when the project is in operation. For this, the numerical simulation has been shown an increasingly efficient tool to assist the engineers and designers of machines and equipment. The Kaplan turbine design requires a high level of engineering expertise combined with a high level of knowledge in fluid mechanics, as poor design of a diffuser fin can lead to disordered turbulent flow which, when mixed with a high pressure drop, can cavitate into turbine blades. The aim of this study is to evaluate different types of diffuser fin profiles in the inlet at Kaplan turbines. For this, numerical computer simulation was used with the aid of the Ansys Fluent software, in which simulations of water flow in a steady state occurred. The software works with the finite volume method for the discretization of the Navier-Stokes equations. The simulations have proved to be efficient in capturing current lines and pointing out the best flow profile in a project, avoiding more complex turbine blade problems.

Flow Across a Butterfly Valve in a Dam Penstock

2017 ◽  
Author(s):  
Dominic Lattouf ◽  
B. P. Huynh
Keyword(s):  
Navier Stokes ◽  
Butterfly Valve ◽  
Maximum Torque ◽  
Ansys Fluent ◽  
Water Head ◽  
Models Comparison ◽  
Flow Through ◽  
Volume Method ◽  
Grid Independence ◽  
Valve Angle

Butterfly valves are typically used as emergency closure devices in dam penstocks; these valves must be capable of closing if a penstock bursts. This paper summarizes a 3D CFD (Computational Fluid Dynamics) study that was conducted on the water flow across a sizable butterfly valve (1.6m in diameter) in a dam penstock with 57m of water head. The main aim is to determine the maximum torque required to close the valve. Thus semi steady flow conditions across the valve at various degrees of closure were investigated and the corresponding torque calculated. A maximum torque of about 87 700 N-m has been obtained, occurring at valve angle 40° (with valve totally closed at 0°, and fully open at 90°). Visual results were analyzed at each valve angle to understand the nature of the flow through the butterfly valve using various 2D contours and streamline images. The CFD software ANSYS Fluent has been used employing a Finite Volume Method. The RANS (Reynolds-Averaged Navier-Stokes) approach with Realizable K-epsilon turbulence model was employed. A grid independence study with up to 10 million cells has also been carried out, resulting in the adoption of 7.5 million cells in all models. Comparison with other available data was also completed, adding to the reliability of the computational results. Distribution of pressure, flow velocity, and turbulence parameters are also presented.

Propeller Cavitation Breakdown Analysis

2005 ◽  
Vol 127 (5) ◽  
pp. 995-1002 ◽  
Author(s):  
Jules W. Lindau ◽  
David A. Boger ◽  
Richard B. Medvitz ◽  
Robert F. Kunz
Keyword(s):  
Multiphase Flow ◽  
Computational Model ◽  
Navier Stokes ◽  
Water Tunnel ◽  
Computational Results ◽  
Cavity Size ◽  
Size And Shape ◽  
Wide Range ◽  
Reynolds Averaged Navier Stokes ◽  
Thrust And Torque

A Reynolds-averaged Navier-Stokes computational model of homogeneous multiphase flow is presented. Cavitation driven thrust and torque breakdown over a wide range of advance ratios is modeled for an open propeller. Computational results are presented as a form of validation against water tunnel measured thrust and torque breakdown for the propeller. Successful validation of the computational model is achieved. Additional observations are made with regards to cavity size and shape as well as cavitation breakdown behavior.

Simulation on the Process of Cavity Wall Expansion of Cone at Constant Speed Water-Entry

2013 ◽  
Vol 419 ◽  
pp. 97-102
Author(s):  
Wei Cao ◽  
Chun Tao He ◽  
Cong Wang
Keyword(s):  
Computational Simulation ◽  
Water Entry ◽  
Constant Speed ◽  
Cavity Wall ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Half Angle ◽  
Expansion Dynamic ◽  
Different Depths ◽  
Volume Method

Computational simulation investigation which is based on the Navier-Stokes equation, finite-volume method, dynamic mesh method, and volume of fluid method, was carried out principally on the constant speed vertical water entry of the cone with 75 degree and a half angle. Based on this, the cavity generation and the process of cavity wall expansion of the cone with 75 degree and a half angle were analyzed. Through analyzing the expansion dynamic for the cavity wall in different depths, the velocity and acceleration with time in the process of cavity wall expansion were obtained, and the disturbances and splash feature laws of the free surface near the entrance of the cavity after cones water-entry were analyzed too.

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