Development of a 2D+T theory for performance prediction of double-stepped planing hulls in calm water

2018 ◽  
Vol 233 (3) ◽  
pp. 886-904 ◽  
Author(s):  
Rasul Niazmand Bilandi ◽  
Abbas Dashtimanesh ◽  
Sasan Tavakoli
Keyword(s):  
Mathematical Model ◽  
Performance Prediction ◽  
Empirical Models ◽  
Two Dimensional ◽  
Reasonable Accuracy ◽  
Future Studies ◽  
Normal Forces ◽  
Calm Water ◽  
The Mean ◽  
The Mathematical Model

In this article, a mathematical model based on the 2D+T theory has been developed to predict the performance of two-stepped planing hulls in calm water. It has been attempted to develop a mathematical model without using regression formulas. It leads to development of a computational model with no common limitations related to empirical models which have an individual range of applicability. For this purpose, theoretical solution of water entry of a two-dimensional wedge section has been implemented to compute the pressure distribution over wedge section entering water, and then normal forces acting on the two-dimensional sections are computed. Bottom of the boat has been divided into three different planing surfaces including fore, middle and aft bodies. Computations are performed for each of these surfaces. By integrating the two-dimensional sectional normal forces over the entire wetted length of the vessel, the trim angle, wetted surface and resistance have been obtained. To evaluate the accuracy of the presented method, the obtained results are compared against experimental data and a previous empirical-based method developed by authors. The comparison suggests that the proposed method predicted dynamic trim angle, wetted surface and resistance of double stepped boats with reasonable accuracy. The mean errors in prediction of trim angle, wetted surface and resistance are, respectively, 13%, 16% and 8%. It should also be noted that although computation of running attitudes and resistance of double-stepped planing boats are targeted in this article, the mathematical model has been developed in such a way that it has the potential to model transverse and vertical motions of two-stepped planing hulls in future studies.

scholarly journals A Validation of Symmetric 2D + T Model Based on Single-Stepped Planing Hull Towing Tank Tests

2018 ◽  
Vol 6 (4) ◽  
pp. 136 ◽  
Author(s):  
Rasul Niazmand Bilandi ◽  
Simone Mancini ◽  
Luigi Vitiello ◽  
Salvatore Miranda ◽  
Maria De Carlini
Keyword(s):  
Mathematical Model ◽  
Design Stage ◽  
Reasonable Accuracy ◽  
Towing Tank ◽  
Future Studies ◽  
Early Design Stage ◽  
Normal Forces ◽  
Pitch Moment ◽  
Current Article ◽  
The Mathematical Model

In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by an analytical method and compared against towing tank tests. Using the 2D + T theory, the pressure distribution over the wedge section entering the water and the normal forces acting on the 2D sections have been computed. By integrating the 2D sectional normal forces over the entire wetted length of the vessel, the lift force acting on it has been obtained. Using lift forces as well as the consequence pitch moment, the equilibrium condition for the single-stepped planing hull is found and then resistance, dynamic trim, and the wetted surface are computed. The obtained hydrodynamic results have been compared against the experimental data and it has been observed that the presented mathematical model has reasonable accuracy, in particular, up to Froude number 2.0. Furthermore, this mathematical model can be a useful and fast tool for the stepped hull designers in the early design stage in order to compare the different hull configurations. It should also be noted that the mathematical model has been developed in such a way that it has the potential to model the sweep-back step and transverse the vertical motions of single-stepped planing hulls in future studies.

Development of a Mathematical Model for Performance Prediction of Planing Catamaran in Calm Water

2019 ◽  
Vol 161 (A2) ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Performance Prediction ◽  
Data Evaluation ◽  
Empirical Equations ◽  
Calm Water ◽  
Semi Empirical ◽  
The Mathematical Model ◽  
Comparison With Experimental Data

In this paper, an attempt has been made to predict the performance of a planing catamaran using a mathematical model. Catamarans subjected to a common hydrodynamic lift, have an extra lift between the two asymmetric half bodies. In order to develop a mathematical model for performance prediction of planing catamarans, existing formulas for hydrodynamic lift calculation must be modified. Existing empirical and semi-empirical equations in the literature have been implemented and compared against available experimental data. Evaluation of lift in comparison with experimental data has been documented. Parameters influencing the interaction between demi-hulls and separation effects have been analyzed. The mathematical model for planing catamarans has been developed based on Savitsky’s method and results have been compared against experimental data. Finally, the effects of variation in hull geometry such as deadrise angle and distance between two half bodies on equilibrium trim angle, resistance and wetted surface have been examined.

DEVELOPMENT OF A MATHEMATICAL MODEL FOR PERFORMANCE PREDICTION OF PLANING CATAMARAN IN CALM WATER

2021 ◽  
Vol 161 (A2) ◽  
Author(s):  
A Ghassemzadeh ◽  
A Dashtimanesh ◽  
M Habibiasl ◽  
P Sahoo
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Performance Prediction ◽  
Data Evaluation ◽  
Empirical Equations ◽  
Calm Water ◽  
Semi Empirical ◽  
The Mathematical Model ◽  
Comparison With Experimental Data

In this paper, an attempt has been made to predict the performance of a planing catamaran using a mathematical model. Catamarans subjected to a common hydrodynamic lift, have an extra lift between the two asymmetric half bodies. In order to develop a mathematical model for performance prediction of planing catamarans, existing formulas for hydrodynamic lift calculation must be modified. Existing empirical and semi-empirical equations in the literature have been implemented and compared against available experimental data. Evaluation of lift in comparison with experimental data has been documented. Parameters influencing the interaction between demi-hulls and separation effects have been analyzed. The mathematical model for planing catamarans has been developed based on Savitsky’s method and results have been compared against experimental data. Finally, the effects of variation in hull geometry such as deadrise angle and distance between two half bodies on equilibrium trim angle, resistance and wetted surface have been examined.

Effect of Freestream Radial Velocity Component on Hydrodynamic Analysis of Propellers

1983 ◽  
Vol 27 (02) ◽  
pp. 131-134
Author(s):  
Terry Brockett
Keyword(s):  
Mathematical Model ◽  
Radial Velocity ◽  
Performance Prediction ◽  
Velocity Component ◽  
Additional Term ◽  
Radial Component ◽  
Radial Velocity Component ◽  
Hydrodynamic Analysis ◽  
The Mathematical Model ◽  
Wake Fields

For wake fields with circumferential averages that include a small radial component, an additional termarises in the mathematical model used for design or performance prediction of propellers that has been previously overlooked. This term arises from the boundary condition that the blade is impenetrable and is a function of only geometry and the inflow radial velocity component. This simple additional term is shown to be important for the example considered, leading to a variable change in camber and a pitch reduction.

Numerical Simulation of Subsea Cluster Manifold Installation by the Sheave Method

2018 ◽  
Author(s):  
Yu Zhao ◽  
Yingying Wang ◽  
Liwei Li ◽  
Chao Yang ◽  
Yang Du ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
South China Sea ◽  
Deep Sea ◽  
High Reliability ◽  
Two Dimensional ◽  
Complex Environment ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
The Mathematical Model

The sheave installation method (SIM) is an effective and non-conventional method to solve the installation of subsea equipment in deep water (>1000m), which has been developed to deploy the 175t Roncador Manifold I into 1,885 meters water depth in 2002. With the weight increment of subsea cluster manifold, how to solve its installation with the high reliability in the deep sea is still a great challenge. In this paper, the installation of the 300t subsea cluster manifold using the SIM is studied in the two-dimensional coordinate system. The mathematical model is established and the lumped mass method is used to calculate the hydrodynamic forces of the wireropes. Taking into account the complex environment loads, the numerical simulation of the lowering process is carried out by OrcaFlex. The displacement and vibration of the subsea cluster manifold in the z-axis direction and the effective tension at the top of the wireropes can be gotten, which can provide guidance for the installation of the cluster manifold in the South China Sea.

Heat Convection from a Horizontal Cylinder Rotating in a Quiescent Fluid

1986 ◽  
Vol 10 (3) ◽  
pp. 141-152
Author(s):  
H.M. Badr ◽  
S.M. Ahmed
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Horizontal Cylinder ◽  
Heat Transfer Process ◽  
Two Dimensional ◽  
Two Dimensional Flow ◽  
Boussinesq Fluid ◽  
The Mathematical Model ◽  
Quiescent Fluid

The aim of this work is a theoretical investigation to the problem of heat transfer from an isothermal horizontal cylinder rotating in a quiescent fluid. The study is based on the solution of the conservation equations of mass, momentum and energy for two-dimensional flow of a Boussinesq fluid. The effects of the parameters which influence the heat transfer process namely the Reynolds number and Grashof number are considered while the Prandtl number is held constant. Streamline and isotherm patterns are obtained from the mathematical model and the results are compared with previous experimental data. A satisfactory agreement was found.

Warranty Costs Assessment for Automotive Applications

2012 ◽  
Vol 433-440 ◽  
pp. 6108-6115
Author(s):  
Zdenek Vintr ◽  
Michal Vintr
Keyword(s):  
Mathematical Model ◽  
Automotive Industry ◽  
Two Dimensional ◽  
Automotive Applications ◽  
Product Reliability ◽  
Warranty Period ◽  
Warranty Costs ◽  
The Mathematical Model ◽  
The Relationship

The article deals with current problems of warranty costs in automotive applications. The two-dimensional warranty widely used in automotive industry is presented. The relationship between warranty costs and product reliability is also presented. The article analyses problems with estimation of a number of failure occurrence over a warranty period and estimation of costs related to repair failures. The mathematical model enables to predict warranty costs for two-dimensional warranty is presented. The article also deals with problems of estimation of an instant of warranty period expiration and demonstrates its estimation on an example of a vehicle.

scholarly journals Characterization and Correction of the Geometric Errors using a Confocal Microscope for Extended Topography Measurement, Part II: Experimental Study and Uncertainty Evaluation

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1217 ◽  
Author(s):  
Wang ◽  
Gómez ◽  
Yu
Keyword(s):  
Mathematical Model ◽  
Measurement Data ◽  
Confocal Microscope ◽  
Geometric Errors ◽  
Data Partition ◽  
The Monte Carlo Method ◽  
Measurement Results ◽  
The Mean ◽  
The Mathematical Model ◽  
Certified Values

This paper presents the experimental implementations of the mathematical models and algorithms developed in Part I. Two experiments are carried out. The first experiment determines the correction coefficients of the mathematical model. The dot grid target is measured, and the measurement data are processed by our developed and validated algorithms introduced in Part I. The values of the coefficients are indicated and analyzed. Uncertainties are evaluated using the Monte Carlo method. The second experiment measures a different area of the dot grid target. The measurement results are corrected according to the coefficients determined in the first experiment. The mean residual between the measured points and their corresponding certified values reduced 29.6% after the correction. The sum of squared errors reduced 47.7%. The methods and the algorithms for raw data processing, such as data partition, fittings of dots’ centers, K-means clustering, etc., are the same for the two experiments. The experimental results demonstrate that our method for the correction of the errors produced by the movement of the lateral stage of a confocal microscope is meaningful and practicable.

scholarly journals ON APPLICATION OF A SIMPLIFIED TWO-DIMENSIONAL MODEL OF FORCED OSCILLATIONS TO THE POWER ANALYSIS OF FLAT STEELWORKS

2020 ◽  
pp. 109-119
Author(s):  
Холодняк Ю.С. ◽  
Подлєсний С.В. ◽  
Капорович С.В. ◽  
Коротенко Є.Д.
Keyword(s):  
Mathematical Model ◽  
Oscillatory System ◽  
Forced Oscillations ◽  
Simultaneous Action ◽  
Oscillatory Process ◽  
Power Calculation ◽  
Two Dimensional ◽  
Resonant Frequencies ◽  
Computational Tools ◽  
The Mathematical Model

Abstract. An analysis of existing methods of power calculation of steelworks under the influence of forced oscillations is performed. When considering the forced oscillations of flat steelworks, two-dimensional models are used, which are complex for wide practical use. Their implementation requires in-depth mathematical training and complex computational tools. The aim of this work is to develop a simplified two-dimensional mathematical model of forced oscillations of flat steelworks with following use of this model in power calculations. The mathematical model proposed in this paper describes oscillations of a weightless steelwork with a point mass of simultaneous action in vertical and horizontal harmonic disturbing forces acting on them. The model is based on the method of forces, establishes a link between the movements of the steelworks and the forces that act on them. Together with the model the dependences for calculating the resonant frequencies of the oscillatory system are obtained. The performed developments allow to determine the dynamic characteristics of the oscillatory process and to calculate a steelwork strength, stiffness and stability.

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