A CFD Based Investigation for Evaluation of Steady and Unsteady Hydrodynamic Performance of 3D Tailfin as an Isolated Surface and When Attached as an Appendage with UUV Body

论文摘要

The development of Autonomous unmanned underwater vehicles （UUVs） has progressed quite significantly in the past decade due in large part to the increasing interest in unmanned underwater surveillance and monitoring which has led the researchers to turn there attention on the evaluation of hydrodynamic performance of fin and control surfaces associated with such underwater vehicles. The study of fin and control surfaces of underwater vehicle whether stationary or moving in a fluid is an interesting and challenging research subject in the field of underwater locomotion and propulsion for underwater vehicle. Typically the effect of Fin oscillation on fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions. An understanding of the complexities of such flows is of interest to engineers interested in developing vehicles capable of emulating the high dynamic performance of propulsion and maneuvering. A useful tool for gaining an understanding of the performance of a UUV is a dynamic simulation of the equations of motion of the vehicle. To perform these simulations the hydrodynamic coefficients of the vehicle must first be provided, these coefficients are specific to the vehicle and provide the description of the hydrodynamic forces and moments acting on the vehicle in its underwater environment. A part of the contribution to these hydrodynamic coefficients is provided by the lifting surfaces such as propeller, stern plane, bow plane etc which are attached as an appendage to the UUV body. As matter of fact out of five longitudinal and three lateral hydrodynamic coefficients [30] few largely depends upon the tailfin geometry as well as the forces and moments acting on the tailfin. In the present study, a computational fluid dynamic （CFD） RANSE simulation of a 3D Tailfin body has been developed to investigate the hydrodynamic performance （Lift, Drag and Moment Coefficient） as an isolated surface and when attached as an appendage to the UUV body in steady and unsteady flow conditions. The present work is accomplished in three different parts:1. In the first part Hydrodynamic performance of an isolated 3D Tailfin body in interaction with the viscous flow is evaluated separately with structured and unstructured grid in steady state flow conditions at various values of attack angles, results are supported using the experimental data.2. The second part addresses the evaluation of unsteady state hydrodynamic performance of an isolated 3D Tailfin at two different Oscillation frequencies T= 4.5 seconds and T= 5.928 Seconds, results are supported using the experimental data.3. The third part briefly covers the steady and unsteady state analyses of 3D Tailfin used as an appendage with the UUV body of 10 meters, here the results are compared with the experimental data of isolated 3D Tailfin along with the traditional theoretical Lifting-line theory or Lanchester-Prandtl wing theory in order to support the work.In this simulation, an implicit pressure-based finite volume method is used for time dependent and independent accurate computation of incompressible flow using first and second order accurate convective flux discretisation schemes. A parametric analysis of the factors that affect the hydrodynamic performance of the 3D Tailfin body is presented, along with the comparison of results with the experimental data and supporting theoretical material.

论文目录

• Abstract
• Acknowledgement
• Table of Contents
• CHAPTER 1 REVIEWED LITERATURE
• 1.1 Introduction
• 1.2 Compressible vs. incompressible flow
• 1.3 Viscous vs. inviscid flow
• 1.4 Steady vs. unsteady flow
• 1.5 Laminar Flow
• 1.6 Turbulence Flow
• 1.6.1 Explanation
• 1.7 Hydrodynamic Forces
• 1.7.1 Drag Force
• 1.7.2 Drag Coefficient
• 1.7.3 Lift Force
• 1.7.4 Lift Coefficient
• CHAPTER 2 INTRODUCTION TO CFD
• 2.1 The Need For CFD
• 2.2 Definition
• 2.3 Description
• 2.4 Technicalities
• 2.5 Methodology
• 2.6 Discretization Methods
• 2.6.1 Finite Volume Method
• 2.6.2 Finite Element Method
• 2.6.3 Finite Difference Method
• 2.6.4 Boundary Element Method
• 2.6.5 High Resolution Methods
• 2.7 Turbulence Models
• 2.7.1 Direct Numerical Simulation
• 2.7.2 Reynolds Averaged Navier-Stokes
• 2.7.3 Large Eddy Simulation
• 2.7.4 Detached Eddy Simulation
• CHAPTER 3 3D TAILFIN DESIGNING& EXPERIMENTAL DETAILS
• 3.1 Foil
• 3.2 Physics of Foil
• 3.3 Basic Design Considerations
• 3.4 Tail Fin Model Designing and Construction
• 3.5 Experimental Model Details
• CHAPTER 4 ISOLATED 3D TAILFIN-STEADY STATE HYDRODYNAMICPERFORMANCE
• 4.1 Introduction
• 4.2 Un-Structured Grid Model
• 4.2.1 Model Designing
• 4.2.2 Model Meshing
• 4.2.3 Mesh Quality
• 4.2.4 Problem Setup For Steady-State Simulation
• 4.2.5 Post Processing And Results
• 4.3 Structured Grid Model
• 4.3.1 Advantages Of Structured Grid Over Un-Structured Topology
• 4.3.2 Model Designing
• 4.3.3 Model Meshing
• 4.3.4 Turbulent model and Boundary Conditions
• 4.3.5 Post Processing and Results
• 4.4 Comparison between Structured and Unstructured Grid Results
• CHAPTER 5 ISOLATED 3D TAILFIN UN-STEADY STATE HYDRODYNAMICPERFORMANCE
• 5.1 Model Designing and Meshing
• 5.2 Turbulent model and Boundary Conditions
• 5.3 Mesh Structure and Moving Mesh
• 5.4 User Defined Function
• 5.5 Problem Set Up For Unsteady State Analyses
• 5.6 Post Processing and Results
• CHAPTER 6 STEADY & UN-STEADY HYDRODYNAMIC PERFORMANCE UUV-3D TAILFIN
• 6.1 UUV-TAILFIN Model Designing Aspects
• 6.2 Steady State Analyses UUV-Tailfin model
• 6.2.1 Mesh model and Boundary Conditions
• 6.2.2 Results and Discussions
• 6.3 Unsteady State Analyses UUV-Tailfin model
• 6.3.1 Mesh Structure and Moving Mesh
• 6.3.2 User Defined Function
• 6.3.3 Results and Discussions
• CHAPTER 7 CONCLUSION AND RECOMMENDATIONS
• 7.1 Conclusion
• 7.2 Recommendations
• References