scholarly journals OPTIMISATION OF HULL FORM OF OCEAN-GOING TRAWLER

Brodogradnja ◽  
2021 ◽  
Vol 72 (4) ◽  
pp. 33-46
Author(s):  
Cheng Zhao ◽  
◽  
Wei Wang ◽  
Panpan Jia ◽  
Yonghe Xie ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Free Form ◽  
Deformation Method ◽  
Nsga Ii ◽  
Hull Form ◽  
Free Form Deformation ◽  
Before And After ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow ◽  
Aided Design

This paper proposes a method for optimising the hull form of ocean-going trawlers to decrease resistance and consequently reduce the energy consumption. The entire optimisation process was managed by the integration of computer-aided design and computational fluid dynamics (CFD) in the CAESES software. Resistance was simulated using the CFD solver and STAR-CCM+. The ocean-going trawler was investigated under two main navigation conditions: trawling and design. Under the trawling condition, the main hull of the trawler was modified using the Lackenby method and optimised by NSGA-II algorithm and Sobol + Tsearch algorithm. Under the design condition, the bulbous bow was changed using the free-form deformation method, and the trawler was optimised by NSGA-Ⅱ. The best hull form is obtained by comparing the ship resistance under various design schemes. Towing experiments were conducted to measure the navigation resistance of trawlers before and after optimisation, thus verifying the reliability of the optimisation results. The results show that the proposed optimisation method can effectively reduce the resistance of trawlers under the two navigation conditions.

An Integrated Ship Re-Design/Modification Strategy

2019 ◽  
Vol 161 (A1) ◽  
Keyword(s):  
Computer Aided Design ◽  
Modular Design ◽  
Ship Hull ◽  
Cfd Model ◽  
Hull Form ◽  
Design Modification ◽  
Technical Parameters ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow ◽  
Aided Design

Herein, we present an integrated ship re-design/modification strategy that integrates the ‘Computer-Aided Design (CAD)’ and ‘Computational Fluid Dynamics (CFD)’ to modify the ship hull form for better performance in resistance. We assume a modular design and the ship hull form modification focuses on the forward module (e.g. bulbous bow) and aft module (e.g. stern bulb) only. The ship hull form CAD model is implemented with NAPA*TM and CFD model is implemented with Shipflow**TM. The basic ship hull form parameters are not changed and the modifications in some of the technical parameters because of re-designed bulbous bow and stern bulb are kept at very minimum. The bulbous bow is re-designed by extending an earlier method (Sharma and Sha (2005b)) and stern bulb parameters for re-design are computed from the experience gained from literature survey. The re-designed hull form is modeled in CAD and is integrated and analyzed with Shipflow**TM. The CAD and CFD integrated model is validated and verified with the ITTC approved recommendations and guidelines. The proposed numerical methodology is implemented on the ship hull form modification of a benchmark ship, i.e. KRISO container ship (KCS). The presented results show that the modified ship hull form of KCS - with only bow and stern modifications - using the present strategy, results into resistance and propulsive improvement.

AN INTEGRATED SHIP RE-DESIGN/MODIFICATION STRATEGY

2021 ◽  
Vol 161 (A1) ◽  
Author(s):  
A K P Patel ◽  
R Sharma
Keyword(s):  
Computer Aided Design ◽  
Modular Design ◽  
Ship Hull ◽  
Cfd Model ◽  
Hull Form ◽  
Design Modification ◽  
Technical Parameters ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow ◽  
Aided Design

Herein, we present an integrated ship re-design/modification strategy that integrates the ‘Computer-Aided Design (CAD)’ and ‘Computational Fluid Dynamics (CFD)’ to modify the ship hull form for better performance in resistance. We assume a modular design and the ship hull form modification focuses on the forward module (e.g. bulbous bow) and aft module (e.g. stern bulb) only. The ship hull form CAD model is implemented with NAPA*TM and CFD model is implemented with Shipflow**TM. The basic ship hull form parameters are not changed and the modifications in some of the technical parameters because of re-designed bulbous bow and stern bulb are kept at very minimum. The bulbous bow is re-designed by extending an earlier method (Sharma and Sha (2005b)) and stern bulb parameters for re-design are computed from the experience gained from literature survey. The re-designed hull form is modeled in CAD and is integrated and analyzed with Shipflow**TM. The CAD and CFD integrated model is validated and verified with the ITTC approved recommendations and guidelines. The proposed numerical methodology is implemented on the ship hull form modification of a benchmark ship, i.e. KRISO container ship (KCS). The presented results show that the modified ship hull form of KCS - with only bow and stern modifications - using the present strategy, results into resistance and propulsive improvement.

scholarly journals ADDITIVE MANUFACTURING - APPLICATION OPPORTUNITIES FOR THE AVIATION INDUSTRY

2015 ◽  
Vol 6 (2) ◽  
pp. 63-86
Author(s):  
Dipesh Dhital ◽  
Yvonne Ziegler
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Computer Aided Design ◽  
Free Form ◽  
Aviation Industry ◽  
Layer By Layer ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Subtractive Manufacturing ◽  
Aided Design

Additive Manufacturing also known as 3D Printing is a process whereby a real object of virtually any shape can be created layer by layer from a Computer Aided Design (CAD) model. As opposed to the conventional Subtractive Manufacturing that uses cutting, drilling, milling, welding etc., 3D printing is a free-form fabrication process and does not require any of these processes. The 3D printed parts are lighter, require short lead times, less material and reduce environmental footprint of the manufacturing process; and is thus beneficial to the aerospace industry that pursues improvement in aircraft efficiency, fuel saving and reduction in air pollution. Additionally, 3D printing technology allows for creating geometries that would be impossible to make using moulds and the Subtractive Manufacturing of drilling/milling. 3D printing technology also has the potential to re-localize manufacturing as it allows for the production of products at the particular location, as and when required; and eliminates the need for shipping and warehousing of final products.

Computational Fluid Dynamics Applied to River Boat Hull Optimization

2021 ◽  
Vol 55 (5) ◽  
pp. 94-108
Author(s):  
Harlysson W. S. Maia ◽  
Said Mounsif ◽  
Jassiel V. Hernández-Fontes ◽  
Rodolfo Silva
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computer Aided Design ◽  
Resistance Coefficient ◽  
Wave Profile ◽  
Total Resistance ◽  
Nsga Ii ◽  
Pressure Distributions ◽  
Aided Design ◽  
Geometric Variation

Abstract This paper extends the work of Maia and Said (“Analysis for Resistance Reduction of an Amazon School Boat through Hull Shape Modification Utilizing a CFD Tool,” 2019), proposing the optimization of a school boat hull using genetic algorithms and computational fluid dynamics (CDF) simulations. The study examines a school boat used for the transportation of children to schools in riverine communities of the Brazilian Amazon. The optimization was focused on reducing the hydrodynamic hull resistance by modifying the hull lines, using the NSGA-II (non-dominated sorting genetic algorithm II) algorithm in the CAD (computer aided design) CAESES environment. The objective of the study was to reduce the resistance coefficients: C wp (wave profile) and C wp trans (transverse wave profile), thus reducing the total resistance coefficient (C t) and the generated wave amplitude. Pressure distributions and flow lines were then evaluated to obtain an optimal modified hull with reduced wave emission (lower wave resistance) and, consequently, lower forward resistance. The proposed methodology resulted in a maximum reduction of 5% in the total resistance coefficient C t and in the identification of a trend of geometric variation of the hull for investigation in further studies.

Algorithmen-basierte Freiformflächenstrukturierung/Generation of NC programs for the micromilling structuring of free-form surfaces – Algorithm-based free-form surface structuring

2021 ◽  
Vol 111 (11-12) ◽  
pp. 797-802
Author(s):  
Leonhard Alexander Meijer ◽  
Torben Merhofe ◽  
Timo Platt ◽  
Dirk Biermann
Keyword(s):  
Computer Aided Design ◽  
Computational Effort ◽  
Free Form ◽  
Process Chain ◽  
Surface Structuring ◽  
Computer Aided ◽  
Cad Cam ◽  
Free Form Surface ◽  
Aided Design ◽  
Free Form Surfaces

In diesem Beitrag wird ein neuer Ansatz zum Erstellen von Maschinenprogrammen zur mikrofrästechnischen Oberflächenstrukturierung vorgestellt und die Anwendung der Prozesskette für ein komplexes, industrielles Verzahnungswerkzeug beschrieben. Durch die Reduzierung des Berechnungsaufwandes in der CAD/CAM (Computer-aided Design & Manufacturing)-Umgebung können die Limitierungen konventioneller Softwarelösungen umgangen und Bearbeitungsprogramme für komplexe Strukturierungsaufgaben effizient erstellt werden.   A new method for generating machine programs for micromilling surface structuring is presented, and the application of the process chain to a complex, industrial gearing die is described. By reducing the computational effort in the CAD/CAM (Computer-aided Design & Manufacturing) environment, the problems of conventional software solutions can be avoided and complex machining programs can be created.

Novel Active Inflow Control Technology for Optimized Flow and Reduced Intervention

2021 ◽  
pp. 1-12
Author(s):  
Ashutosh Dikshit ◽  
Vivek Agnihotri ◽  
Mike Plooy ◽  
Amrendra Kumar ◽  
Seymur Gurbanov ◽  
...  
Keyword(s):  
Flow Control ◽  
Computer Aided Design ◽  
Process Development ◽  
Horizontal Wells ◽  
Field Trials ◽  
Control Device ◽  
Computational Fluid Dynamics Cfd ◽  
Inflow Control Device ◽  
Aided Design ◽  
Subsequent Intervention

Summary Integrating a flow control sliding sleeve into a sand screen can provide multiple advantages to the user in controlling the production inflow, but it comes with an increased completion cost as well as an increase in the number of interventions required when it is time to operate those valves. Especially in long horizontal wells, this can become time-consuming and inefficient. A few technologies exist to address this issue, but they either are too complex or require specialized rigging equipment at the wellsite, which is not desirable. As described herein, a unique, fit-for-application modular sliding sleeve sand screen assembly with dissolvable plugs was developed that eliminates the need for washpipe during run-in-hole (RIH) and allows flow control from several screens by means of a single sliding sleeve door (SSD), thereby also optimizing the subsequent intervention operations by reducing the number of SSDs in the well. The design and field installation of these modular screens is presented in this paper. The new modular sand screen consisted of an upper joint, modular middle joint, modular middle joint with an inflow control device (ICD) integrated into an SSD (with optional dissolvable plugs), a lower joint, and novel field-installable flow couplings between them. The design allows for any number of non-ICD/SSD screen joints to be connected to any number of ICD/SSD joints in any order. A computer-aided design was followed to achieve all the operational and mechanical requirements. Computational fluid dynamics (CFD) was used to optimize the flow performance characteristics. Prototypes were manufactured and tested before conducting successful field trials. The design process, development, and field installation results are presented herein.

scholarly journals Free Form Deformation Method Applied to Modeling and Design of Hypersonic Glide Vehicles

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 61400-61413 ◽  
Author(s):  
Bin Zhang ◽  
Zhiwei Feng ◽  
Boting Xu ◽  
Tao Yang
Keyword(s):  
Free Form ◽  
Deformation Method ◽  
Free Form Deformation

Interval Method for Interrogation of Implicit Solid Models

2000 ◽  
Author(s):  
Jack Chang ◽  
Mark Ganter ◽  
Duane Storti
Keyword(s):  
Computer Aided Design ◽  
Boundary Representation ◽  
Free Form ◽  
Solid Models ◽  
Cad Cam ◽  
Implicit Modeling ◽  
Manufacturing Applications ◽  
Determine Surface Area ◽  
Implicit Solid ◽  
Aided Design

Abstract Computer-aided design/manufacturing (CAD/CAM) systems intended to support automated design and manufacturing applications such as shape generation and solid free-form fabrication (SFF) must provide not only methods for creating and editing models of objects to be manufactured, but also methods for interrogating the models. Interrogation refers to any process that derives information from the model. Typical interrogation tasks include determine surface area, volume or inertial properties, computing surface points and normals for rendering, and computing slice descriptions for SFF. While currently available commercial modeling systems generally employ a boundary representation (B-rep) implementation of solid modeling, research efforts have considered implicit modeling schemes as a potential source of improved robustness. Implicit implementations are available for a broad range of modeling operations, but interrogation operations have been widely considered too costly for many applications. This paper describes a method based on interval analysis for interrogating implicit solid models that aims at achieving both robustness and efficiency.

A Dual Environment for 3D Modeling With User-Defined Free Form Features

2007 ◽  
Author(s):  
Thomas R. Langerak ◽  
Joris S. M. Vergeest
Keyword(s):  
Computer Aided Design ◽  
Shape Representation ◽  
Target Surface ◽  
Free Form ◽  
Dynamic Feature ◽  
Cad Models ◽  
Form Features ◽  
Definition Of ◽  
High Level ◽  
Aided Design

Modeling with free form features has become the standard in Computer-Aided Design (CAD). With the increasing complexity of free form CAD models, features offer a high-level approach to modeling shapes. However, in most commercial modeling packages, only a static set of free form features is available. Researchers have tried to solve this problem by coming up with methods for user-driven free form feature definition, but failed to connect their methods to a means to instantiate these user-driven free form features on a target surface. Reversely, researchers have proposed tools for modeling with free form features, but these methods are time-intensive in that they are as of yet unsuitable for pre-defined features. This paper presents a new method for user-driven feature definition, as well as a method to instantiate these user-defined features on a target surface. We propose the concept of a dual environment, in which the definition of a feature is maintained simultaneously with its instance on a target surface, allowing the user to modify the definition of an already instantiated feature. This dual environment enables dynamic feature modeling, in which the user is able to change the definition of instantiated features on-the-fly. Furthermore, the proposed instantiation method is independent from the type of shape representation of the target surface and thereby increases the applicability of the method. The paper includes an extensive application example and discusses the results and shortcomings of the proposed methods.

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