Numerical Calculation of Radiated Noise of a Submersible

论文摘要

The studies related to cylindrical shell is the research on reduction of the noise radiated by the submarines to avoid the detection of the submarine by the enemy and to lower structural vibration to maintain a good environment for onboard members and instruments. It has become necessary for the submarines to reduce their radiated noise to such an extent to avoid detection due to the advancements in anti-submarine warfare. This aspect has gained a lot of attention of researchers and they have achieved much production in this regard. This dissertation mainly focuses on the analysis of sound radiation from the pressure hull of submersiblesThe purpose of the thesis is to study a numerical method to calculate the structural noise of a submersible. It is systematically studied on single cylindrical shell by studying the effects of various design factors, comparison between single and double cylindrical shell, double cylindrical shell with the effect of various design factors, use of damping material and the comparison with the double cylindrical shell without viscoelastic materials and at the end comparison of the numerical method calculated results with the experimental results and to study the effectiveness and accuracy in calculating the noise and vibration characteristics.At the beginning, some old analysis methods and research achievement in the history of vibration and acoustics study are presented. The investigative evolvement on sound radiation of the cylindrical shells, research background and use of different approaches by different researchers are mentioned. Then the theoretical background and involved elementary theory used in the thesis is emphatically expatiated.The effect of number of ring stiffeners, thickness of ring stiffeners and the effect of direction of force on the noise and vibration characteristics is studied for the single cylinder shell. Then the double cylinder is modeled and a comparison is done between the noise and vibration characteristics of single and double cylinders. Then the effect of various design factors like type of connections, thickness of outer cylinder, positioning of propulsion machinery, radius of outer cylinder and the thickness of inner shell on the noise and vibration characteristics are studied. Then a comparison is done between double cylinder without viscoelastic material and double cylinder with viscoelastic material. Finally the available experimental results are used for comparison with the results of this numerical method to analyze the accuracy of the method.

论文目录

• ABSTRACT
• RESEARCH PAPERS
• ACKNOWLEDGEMENT
• CHAPTER 1 INTRODUCTION
• 1.1 MOTIVATION
• 1.2 LITERATURE REVIEW
• 1.3 OVERVIEW OF CONTRIBUTIONS
• CHAPTER 2 THEORETICAL BACKGROUND
• 2.1 INTRODUCTION
• 2.2 ACOUSTIC FLUID FUNDAMENTALS
• 2.3 ABSORPTION OF ACOUSTICAL PRESSURE WAVE
• 2.4 ACOUSTICS FLUID-STRUCTURE COUPLING
• 2.5 ACOUSTICS OUTPUT QUANTITIES
• 2.6 BOUNDARY ELEMENT MODEL THEORY
• 2.6.1 RADIATION EFFICIENCY
• 2.6.2 INPUT POWER
• 2.6.3 ACTIVE OUTPUT POWER
• 2.6.4 MEAN QUADRATIC VELOCITY
• 2.7 CONCLUSION
• CHAPTER 3 EFFECT OF VARIOUS DESIGN FACTORS ON NOISE AND VIBRATIONOF SINGLE CYLINDER
• 3.1 INTRODUCTION
• 3.2 NUMERICAL SIMULATION
• 3.3 MODELING OF THE FLUID
• 3.4 EFFECT OF NUMBER OF STIFFENERS
• 3.4.1 ANALYSIS OF VIBRATION CHARCTERISTICS
• 3.4.2 ANALYSIS OF NOISE CHARCTERISTICS
• 3.4.3 ANALYSIS OF DIRECTIVITY OF SOUND PRESSURE LEVEL
• 3.5 EFFECT OF THICKNESS OF STIFFENERS
• 3.5.1 ANALYSIS OF VIBRATION CHARACTERISTICS
• 3.5.2 ANALYSIS OF NOISE CHARCTERISTICS
• 3.5.3 ANALYSIS OF DIRECTIVITY OF SOUND PRESSURE LEVEL
• 3.6 EFFECT OF DIRECTION OF FORCE
• 3.6.1 ANALYSIS OF VIBRATION CHARCTERISTICS
• 3.6.2 ANALYSIS OF NOISE CHARCTERISTICS
• 3.7 CONCLUSION
• CHAPTER 4 EFFECT OF VARIOUS DESIGN FACTORS ON NOISE AND VIBRATIONOF DOUBLE CYLINDER
• 4.1 INTRODUCTION
• 4.2 MODELLING OF DOUBLE CYLINDER
• 4.3 COMPARSION OF ACOUSTIC CHRACTERISTICS OF SINGLE AND DOUBLE CYLINDER
• 4.3.1 ANALYSIS OF VIBRATION CHARACTERISTICS
• 4.3.2 ANALYSIS OF NOISE CHARCTERISTICS
• 4.3.3 DIRECTIVITY ANALYSIS OF SOUND PRESSURE LEVEL
• 4.4 EFFECT OF CONNECTIONS
• 4.4.1 ANALYSIS OF VIBRATION CHARCTERISTICS
• 4.4.2 ANALYSIS OF NOISE CHARCTERISTICS
• 4.4.3 DIRECTIVITY ANALYSIS OF SOUND PRESSURE LEVEL
• 4.5 EFFECT OF THICKNESS OF OUTER CYLINDER
• 4.5.1 ANALYSIS OF VIBRATION CHARACTERISTICS
• 4.5.2 ANALYSIS OF NOISE CHARCTERISTICS
• 4.5.3 DIRECTIVITY ANALYSIS OF SOUND PRESSURE LEVEL
• 4.6 EFFECT OF POSITIONING OF PROPULSION MACHINERY
• 4.7 EFFECT OF THE RADIUS OF THE OUTER CYLINDER
• 4.7.1 ANALYSIS OF VIBRATION CHARCTERISTICS
• 4.7.2 ANALYSIS OF NOISE CHARACTERISTCS
• 4.7.3 DIRECTIVITY ANALYSIS OF SOUND PRESSURE LEVEL
• 4.8 EFFECT OF THICKNESS OF INNER SHELL
• 4.8.1 ANALYSIS OF VIBRATION CHARACTERISTICS
• 4.8.2 ANALYSIS OF NOISE CHARCTERISTICS
• 4.8.3 DIRECTIVITY ANALYSIS OF SOUND PRESSURE LEVEL
• 4.10 CONCLUSION
• CHAPTER 5 NUMERICAL AND EXPERIMENTAL RESULTS COMPARISON
• 5.1 USE OF DAMPING MATERIAL
• 5.1.1 INTRODUCTION
• 5.1.2 MODELING OF DAMPING MATERIAL
• 5.1.3 ANALYSIS OF THE EFFECTS OF DAMPING MATERIAL
• 5.2 COMPARISON OF FEM/BEM AND EXPERIMENTAL RESULTS
• 5.2.1 EXPERIMENTAL FACILTIES AND EQUIPMENTS
• 5.2.2 ANALYSIS OF THE RESULTS
• 5.3 CONCLUSIONS
• CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS
• 6.1 CONCLUSION
• 6.2 RECOMMENDATIONS FOR FUTURE WORK
• REFERENCES