scholarly journals CONTRIBUTIONS TO THE MARINE PROPELLERS HYDRODYNAMIC DESIGN

2014 ◽  
Vol 13 (2) ◽  
pp. 41
Author(s):  
B. I. Favacho ◽  
J. R. P. Vaz ◽  
A. L. A. Mesquita
Keyword(s):  
Control Volume ◽  
Computational Cost ◽  
Momentum Balance ◽  
Marine Propellers ◽  
Energy And Momentum ◽  
Thrust And Torque ◽  
The Mathematical Model ◽  
Low Computational Cost ◽  
Bem Theory ◽  
Good Agreement

The navigation in Amazon region is very important due to the length of navigable rivers and the lack of alternative road network, as well as being a form of transportation costless for the flow of agricultural and manufacturing production. This kind of transportation present social, economic and technological importance for this region. Thus, this work objective to develop a mathematical approach for the marine propellers design, using a formulation for chord and pitch angle optimization, taken into account the equations of mass, energy and momentum balance for the theoretical calculation of thrust and torque relationships on an annular control volume, ie, the mathematical model is based in the Blade Element Momentum (BEM) theory. The proposed hydrodynamic model present low computational cost and it is easy to implement. The results are compared with classical Glauert's theory and the experimental data of the Wageningen B3-50 propeller, presenting good agreement.

scholarly journals Contribution to the marine propeller hydrodynamic design for small boats in the Amazon region

2016 ◽  
Vol 46 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Breno Inglis FAVACHO ◽  
Jerson Rogério Pinheiro VAZ ◽  
André Luiz Amarante MESQUITA ◽  
Fábio LOPES ◽  
Antonio Luciano Seabra MOREIRA ◽  
...  
Keyword(s):  
Control Volume ◽  
Classical Model ◽  
Computational Cost ◽  
Marine Propeller ◽  
Propeller Design ◽  
Thrust And Torque ◽  
The Mathematical Model ◽  
Hydrodynamic Relation ◽  
Hydrodynamic Optimization ◽  
Low Computational Cost

ABSTRACTIn the Amazon, river navigation is very important due to the length of navigable rivers and the lack of alternative road networks. Boats usually operate in unfavorable conditions, since there is no hydrodynamic relation among propellers, geometry, and the dimensions of the boat hull. Currently, there is no methodology for propeller hydrodynamic optimization with low computational cost and easy implementation in the region. The aim of this work was to develop a mathematical approach for marine propeller design applied to boats typically found on Amazon rivers. We developed an optimized formulation for the chord and pitch angle distributions, taking into account the classical model of Glauert. A theoretical analysis for the thrust and torque relationships on an annular control volume was performed. The mathematical model used was based on the Blade Element Momentum Theory (BEMT). We concluded that the new methodology proposed in this work demonstrates a good physical behavior when compared with the theory of Glauert and the experimental data of the Wageningen B3-50 propeller.

Validation of a CFD Condensation Model Based on Heat and Mass Transfer Analogy by TOSQAN Facility ISP47 Test

2006 ◽  
Author(s):  
Matteo Bucci ◽  
Walter Ambrosini ◽  
Nicola Forgione ◽  
Francesco Oriolo ◽  
Sandro Paci
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Nuclear Reactor ◽  
Momentum Balance ◽  
Average Temperature ◽  
Standard Problem ◽  
Computational Fluid Dynamics Analysis ◽  
Energy And Momentum ◽  
Transfer Mechanisms ◽  
Good Agreement

The content of this paper is focused on a computational fluid dynamics analysis of the test performed within the facility TOSQAN as a part of the International Standard Problem 47 (ISP 47). The aim of the study is to contribute to the understanding of the heat and mass transfer mechanisms and to check the possibility to use a commercial CFD code for simulating the mass transfer phenomena of interest in nuclear reactor containment design and safety analysis. In this aim, the FLUENT 6.2 code has been used. The effect of the condensation rate onto the vessel walls was simulated by appropriate source terms introduced by user-defined subroutines into the mass, energy and momentum balance equations. In the paper the time trends of the average temperature and pressure of the atmosphere inside the TOSQAN vessel have been compared with the available experimental data, obtaining a good agreement. Spatial profiles have been also analysed and compared with the experimental ones for the main physical variables in the first, second and fourth steady-state phases which the test consists of.

scholarly journals The revised FLORIDyn model: Implementation of heterogeneous flow and the Gaussian wake

2022 ◽  
Author(s):  
Marcus Becker ◽  
Bastian Ritter ◽  
Bart Doekemeijer ◽  
Daan van der Hoek ◽  
Ulrich Konigorski ◽  
...  
Keyword(s):  
Wind Farm ◽  
Computational Cost ◽  
Parametric Model ◽  
Computational Time ◽  
Flow Conditions ◽  
Heterogeneous Flow ◽  
The Mean ◽  
Wake Model ◽  
Low Computational Cost ◽  
Good Agreement

Abstract. In this paper a new version of the FLOw Redirection and Induction Dynamics (FLORIDyn) model is presented. The new model uses the three-dimensional parametric Gaussian FLORIS model and can provide dynamic wind farm simulations at low computational cost under heterogeneous and changing wind conditions. Both FLORIS and FLORIDyn are parametric models which can be used to simulate wind farms, evaluate controller performance and can serve as a control-oriented model. One central element in which they differ is in their representation of flow dynamics: FLORIS neglects these and provides a computationally very cheap approximation of the mean wind farm flow. FLORIDyn defines a framework which utilizes this low computational cost of FLORIS to simulate basic wake dynamics: this is achieved by creating so called Observation Points (OPs) at each time step at the rotor plane which inherit the turbine state. In this work, we develop the initial FLORIDyn framework further considering multiple aspects. The underlying FLORIS wake model is replaced by a Gaussian wake model. The distribution and characteristics of the OPs are adapted to account for the new parametric model, but also to take complex flow conditions into account. To achieve this, a mathematical approach is developed to combine the parametric model and the changing, heterogeneous world conditions and link them with each OP. We also present a computational lightweight wind field model to allow for a simulation environment in which heterogeneous flow conditions are possible. FLORIDyn is compared to SOWFA simulations in three- and nine-turbine cases under static and changing environmental conditions.The results show a good agreement with the timing of the impact of upstream state changes on downstream turbines. They also show a good agreement in terms of how wakes are displaced by wind direction changes and when the resulting velocity deficit is experienced by downstream turbines. A good fit of the mean generated power is ensured by the underlying FLORIS model. In the three turbine case, FLORIDyn simulates 4 s simulation time in 24.49 ms computational time. The resulting new FLORIDyn model proves to be a computationally attractive and capable tool for model based dynamic wind farm control.

scholarly journals Thermal analysis of blood flow of Newtonian, pseudo-plastic, and dilatant fluids through an inclined wavy channel due to metachronal wave of cilia

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110490
Author(s):  
Abdou Al-Zubaidi ◽  
Mubbashar Nazeer ◽  
Khadija Khalid ◽  
Sidra Yaseen ◽  
Salman Saleem ◽  
...  
Keyword(s):  
Biological Fluids ◽  
Nonlinear Partial Differential Equations ◽  
Medical Science ◽  
Computational Cost ◽  
Physical Parameters ◽  
Convective Boundary ◽  
Definition Of ◽  
Dilatant Fluid ◽  
The Mathematical Model ◽  
Low Computational Cost

This paper is organized to study the heat and mass transfer analyses by considering the motion of cilia for Newtonian, Pseudo-plastic, and Dilatant fluids through a horizontally inclined channel in the presence of metachronal waves and variable liquid properties. A non-Newtonian Rabinowitsch model is used to study the flow of peristalsis through ciliated walls. The slip and convective boundary conditions at the channel walls are taken into account. The mathematical model is developed in the form of complex nonlinear partial differential equations then transformed into simplified form by using the definition of low-Reynolds number with lubrication theory. The analytical solution is obtained by using the perturbation method due to its low computational cost and good accuracy. The graphical outcome is based on the behavior of certain physical parameters on velocity, temperature, and concentration profiles for all three types of fluid. A symbolic software named MATHEMATICA 12.0 is used to find the analytical expression and construct the graphical behavior of all profiles that are taken under discussion. The important results in this study depict that the velocity profile tends to increase in the central region of the channel for Newtonian and Pseudo-plastic fluids and decreases for Dilatant fluid while a reverse behavior is observed near the channel walls. A smaller wavelength causes the wavenumber to accelerate and it tends to decelerate for a larger wavelength. The current study will help to understand the use of the complex rheological behavior of biological fluids in engineering and medical science.

Accurate marine propellers flow field CFD through anisotropic mesh optimization

2019 ◽  
Vol 29 (9) ◽  
pp. 3148-3168
Author(s):  
Ahmed Abou El-Azm Aly ◽  
Wagdi G. Habashi
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Computational Cost ◽  
Open Water ◽  
Mesh Optimization ◽  
Complex Flow ◽  
Anisotropic Mesh ◽  
Content Type ◽  
Marine Propellers ◽  
Thrust And Torque

Purpose Computational fluid dynamics (CFD) simulation of the flow field around marine propellers is challenging because of geometric complexity and rotational effects. To capture the flow structure, grid quality and distribution around the blades is primordial. This paper aims to demonstrate that solution-based automatic mesh optimization is the most logical and practical way to achieve optimal CFD solutions. Design/methodology/approach In the current paper, open water propeller performance coefficients such as thrust and torque coefficients are numerically investigated. An anisotropic mesh adaptation technique is applied, believed for the first time, to marine propellers and to two computational domains. Findings The current study’s performance coefficients are compared with other previously published CFD results and improvements in terms of accuracy and computational cost are vividly demonstrated for different advance coefficients, as well as a much sharper capture of the complex flow features. Originality/value It will be clearly demonstrated that these two improvements can be achieved, surprisingly, at a much lower meshing and computational cost.

scholarly journals Hydrodynamic and Acoustic Performance Analysis of Marine Propellers by Combination of Panel Method and FW-H Equations

2019 ◽  
Vol 24 (3) ◽  
pp. 81 ◽  
Author(s):  
Abouzar Ebrahimi ◽  
Mohammad Saeed Seif ◽  
Ali Nouri-Borujerdi
Keyword(s):  
Maximum Error ◽  
Panel Method ◽  
Experimental Results ◽  
Good Reliability ◽  
Acoustic Performance ◽  
Marine Propellers ◽  
University Of Technology ◽  
Propeller Noise ◽  
Thrust And Torque ◽  
Good Agreement

The noise emitted by ships is one of the most important noises in the ocean, and the propeller noise is one of the major components of the ship noise. Measuring the propeller noise in a laboratory, despite the high accuracy and good reliability, has high costs and is very time-consuming. For this reason, the calculation of propeller noise using numerical methods has been considered in recent years. In this study, the noise of a propeller in non-cavitating conditions is calculated by the combination of the panel method (boundary element method) and solving the Ffowcs Williams-Hawkings (FW-H) equations. In this study, a panel method code is developed, and the results are validated by the experimental results of the model tests carried out in the cavitation tunnel of the Sharif University of Technology. Software for numerical calculation of propeller noise, based on FW-H equations, is also developed and the results are validated by experimental results. This study shows that the results of the panel method code have good agreement with experimental results, and that the maximum error of this code for the thrust and torque coefficients is 4% and 7%, respectively. The results of the FW-H noise code are also in good agreement with the experimental data.

Numerical Method to Provide Cavitation Index for Control Valves

2013 ◽  
Author(s):  
Stefano Malavasi ◽  
Marco M. A. Rossi ◽  
Gianandrea V. Messa ◽  
Giacomo Ferrarese
Keyword(s):  
Computational Cost ◽  
Technical Standards ◽  
Perforated Plates ◽  
Control Valves ◽  
Cavitation Inception ◽  
Mechanical Parts ◽  
Control Devices ◽  
Multi Phase ◽  
Low Computational Cost ◽  
Good Agreement

Cavitation is a harmful phenomenon for control valves. Starting from noise and vibration, cavitation can bring erosion and pitting of mechanical parts. Experimental costs for cavitation tests are high, not even considering the difficulties to test large-sized valves. For those reasons a CFD analysis could be an attractive solution to predict cavitation. However, a reliable numerical prediction of cavitation inception is hard to achieve and the computational cost of complex multi-phase models, necessary for a correct description of this phenomenon, is often very high. The purpose of this research is to overcome those difficulties by using a single-phase model to predict the onset of cavitation, in terms of the incipient cavitation index introduced in several technical standards. A method, based on the generalized pressure criterion reported in previous works, is applied to particularly complex control devices, namely the Cage Ball control valves, in which perforated plates are inserted to increase the energy dissipation with respect to a traditional Ball valve. Numerical results are compared with our own experimental data of acceleration induced by cavitation vibrations, showing good agreement. The final result is a simple and reliable method, with low computational cost, to evaluate the incipient cavitation index for control valves.

THD Analysis of Journal Bearings: A Finite Element Algorithm for Groove Mixing Conditions

2005 ◽  
Author(s):  
Fabrizio A. Stefani
Keyword(s):  
Finite Element ◽  
Solution Method ◽  
Energy Equation ◽  
Computational Cost ◽  
Three Dimensional ◽  
Mixing Conditions ◽  
Energy Conserving ◽  
Element Algorithm ◽  
Low Computational Cost ◽  
Good Agreement

A finite element method of solving the mass and energy-conserving lubrication problem, including the energy balance in the feed grooves, is proposed. As mass continuity in the whole film is considered, cavitation is taken into account properly. Both a two-dimensional (2D) and a quasi-three-dimensional (3D) solution of the energy equation in the lubricant film have been adopted. Some results are presented for a two-axial groove journal bearing. The quasi-3D solution method (cross-film conduction included in the model) showed good agreement with experimental results and incurred low computational cost.

A simple scheme for calculating the energy harvesting figures of merit of porous ceramics

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rogelio O. Caballero-Pérez ◽  
Julián Bravo-Castillero ◽  
Leslie D. Pérez-Fernández
Keyword(s):  
Energy Harvesting ◽  
Effective Properties ◽  
Computational Cost ◽  
Good Alternative ◽  
Porous Ceramics ◽  
Figures Of Merit ◽  
Effective Coefficients ◽  
Analytical Formulae ◽  
Low Computational Cost ◽  
Good Agreement

Abstract We propose a scheme based on recursively applying analytical formulae for effective properties to a class of porous ceramics for calculating their energy harvesting figures of merit. We approximate the structure of freeze-cast PZT parallel laminae joined by links (or bridges) by a model that can be broken down into two directions along which the structure resembles a laminate. The effective coefficients obtained in the first step of the recursion are then used as input on the second step which gives the final effective moduli. The comparison of those with calculations via Finite Element Method (FEM) on a non-recursive model shows good agreement. Finally, we calculate the piezoelectric and pyroelectric figures of merit and compare them with experimental results. The proposed scheme is a good alternative since it relies only on known simple analytical formulae and has a very low computational cost with respect to other methods that may be applied to such a geometry.

scholarly journals Computing Expectiles Using k-Nearest Neighbours Approach

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 645
Author(s):  
Muhammad Farooq ◽  
Sehrish Sarfraz ◽  
Christophe Chesneau ◽  
Mahmood Ul Hassan ◽  
Muhammad Ali Raza ◽  
...  
Keyword(s):  
Computational Cost ◽  
Real Life ◽  
Distance Measures ◽  
Computational Time ◽  
High Dimensional ◽  
Test Error ◽  
Nearest Neighbours ◽  
Comparable Performance ◽  
Asymmetric Least Squares ◽  
Low Computational Cost

Expectiles have gained considerable attention in recent years due to wide applications in many areas. In this study, the k-nearest neighbours approach, together with the asymmetric least squares loss function, called ex-kNN, is proposed for computing expectiles. Firstly, the effect of various distance measures on ex-kNN in terms of test error and computational time is evaluated. It is found that Canberra, Lorentzian, and Soergel distance measures lead to minimum test error, whereas Euclidean, Canberra, and Average of (L1,L∞) lead to a low computational cost. Secondly, the performance of ex-kNN is compared with existing packages er-boost and ex-svm for computing expectiles that are based on nine real life examples. Depending on the nature of data, the ex-kNN showed two to 10 times better performance than er-boost and comparable performance with ex-svm regarding test error. Computationally, the ex-kNN is found two to five times faster than ex-svm and much faster than er-boost, particularly, in the case of high dimensional data.

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