Tveitnes, Trym (2001) Application of added mass theory in planing. PhD thesis. http://theses.gla.ac.uk/2890/ Copyright and moral rights for this thesis are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Glasgow Theses Service http://theses.gla.ac.uk/ [email protected] Application of Added Mass Theory in Planing by Trym Tveitnes BEng, University of Glasgow Thesis Submitted for the Degree of Doctor of Philosophy Department of Naval Architecture and Ocean Engineering Department of Mechanical Engineering University of Glasgow July 2001 ._1: 31 ® Trym Tveitnes, 2001 ,,. To my Parents, Sidsel and Johannes DECLARATION Except where reference is made to the work of others, this thesis is believed to be original. ACKNOWLEDGEMENTS This thesis is the result of the work carried out by the author for the degree of Doctor of Philosophy at the University of Glasgow. Thanks are due to those who directly or indirectly contributed to the completion of this thesis. First of all, sincerely thanks to my two supervisors: Dr. A. C. Fairlie-Clarke, for guidance, discussions and consistent supervision throughout these studies. Dr. K. S. Varyani for his advice, for fighting my case for required equipment and for his ever prompt responseto any enquiries. Thanks to the heads of the two departments, under which this work has been carried out, for providing the necessary financial support: Professor N. Barltrop, Naval Architecture and Ocean Engineering and Professor J. Hancock, Mechanical Engineering. A very special thanks to my favourite ladies in Glasgow, Thelma Will and Maureen McGrady, secretary staff at NAOE. I can not express enough gratitude for what you have meant to me during my stay with the department. Also, thanks to David James Percival at NAOE and Yassamine Mather at ME for providing computer support. Thanks are due to George Falconer, Brian Robb, George Silvie, Alexander Torry at the Mechanical Engineering Workshop for their excellent manufacture of components for the test rig and, equally important, for the nice conversations we had. I would like to thank Chief Technician David Sinclair and his staff at the Hydrodynamics Laboratory, not only for their involvement in the experimental work, but also for the joyful and friendly atmosphere at the "tank". Thanks to Bernie Reiley for assistancewith manufacture of the test rig, Bill Wright for his skilful model making, Frank Sweeney for guidance with the electronics and Donald Nicholson and Grant Dunning for their assistance with conducting the experiments. Thanks to my friend Frode Sxtren who helped manufacture models for the experiments. A special thanks to the janitor at JamesWatt Building, Michael, for always having a humorous comment to spare, and for brightening up many grey days. Thanks also to the nice cleaner at James Watt Building, Florence, for the early morning conversationsand her smiles. To my research colleges during my years in Glasgow, Ioannis Tsarouchas and Robert Olsen, I wish to expressgratitude for getting to know you, for your honest friendship and the many good moments we have shared. All the best for the future. Finally, most indebted am I to my parents, Sidsel and Johannes Tveitnes. Thanks for your continuos support and encouragement, for your trust, and most of all for your love. I owe you everything.... LIST OF CONTENT DECLARATION 1 ACKNOWLEDGEMENTS 2 LIST OF CONTENT 4 SUMMARY 10 NOTATION 11 CHAPTER 1, INTRODUCTION 17 I. I. Planing Concept 18 1.2. Planing Lift Prediction 20 1.3. Research Motivation 21 1.4. Aims and Objectives 23 1.5. Layout of Thesis 23 CHAPTER 2, RESEARCH APROACH 25 CHAPTER 3, PLANING THEORY AND LITERATURE REVIEW 29 3.1. Planing and Impact Theory 30 3.2. Experimental Investigations of Planing And Impact 55 CHAPTER 4, CFD SIMULATION OF TWO-DIMENSIONAL WATER ENTRY 57 4.1. Finite Volume Method 58 4.1.1. GoverningEquations 58 4.1.2. Solutionof The Differential Equations 61 4.1.3. Free-SurfaceModel 63 4.2. Simulation Issues 63 4.2.1. Grid Generation 64 4.2.2. Pre-Processing 68 4.2.3. Solving 71 4.2.4. Post-Processing 72 4.3. Simulation Program 72 4.4. Results 72 4.4.1. Force Data 72 4.4.2. PressureData 76 4.4.3. Free-SurfaceElevation 80 4.4.4. Gravity Effect Analysis 101 CHAPTER 5, EXPERIMENTAL WORK 107 5.1. Design Requirements 112 5.1.1. Vertical Loads and Accuracy 112 5.1.2. Side Loads 113 5.1.3. Model Carrier 113 5.1.4. Sensorsand Data Acquisition 114 5.2. Description of Test Equipment 115 5.2.1. Drive System 115 5.2.2. Guide and Support Structure 119 5.2.3. Test Sections 124 5.2.4. Model Carrier 125 5.2.5. Sensorsand Data Acquisition 126 5.3. Design Evaluation 128 5.3.1. Drive System 128 5.3.2. GuideSystem and Support Structure 130 5.3.3. Model Carrier 131 5.3.4. Sensorsand Data Acquisition 131 5.4. Manufacture and Assembly 133 5.4.1. Parts 133 5.4.2. Rig Assembly 134 5.5. Operation of Test Rig 142 5.5.1. Commissioning and Drive Optimisation 143 5.5.2. Motion Tasks 144 5.5.3. Limit Switches 144 5.5.4. Data Acquisition 146 5.5.5. Video Recording 147 5.6. Test Program 147 5.6.1. Constant Velocity Water Entry 147 5.6.2. Constant Velocity Water Exit 149 5.6.3. Accelerated/DeceleratedWater Entry 150 5.6.4. Oscillation Tests 150 5.7. Test Rig Performance 152 5.8. Test Results 153 5.8.1. Vertical Position of Test Section 153 5.8.2. Viscous Force 154 5.8.3. Force Data 157 5.8.4. Water Surface Shape 178 CHAPTER 6, COMPARISON AND DISCUSSION OF RESULTS 186 6.1. Comparison Between CFD and Experiment 187 6.1.1. Forces 187 6.1.2. Wetting Factor 193 6.1.3. FreeSurface Elevation 195 6.2. Comparison with the Work of Others 197 6.2.1. SlammingForce Coefficient 197 6.2.2. Maximum Pressures 198 6.2.3. WettingFactor 199 6.3. Validation of Buoyancy Ratio Function using CFD Data 200 6.4. Most Reliable Source of Data for Development of Theory 202 CHAPTER 7, ADDED MASS THEORY FOR WATER ENTRY AND EXIT 204 7.1. Water Entry Theory 205 7.1.1. Hypothesis for Separationof Water Entry Forces 206 7.1.2. Analysis of Constant Velocity Water Entry Data 208 7.1.3. Comparison of Water Entry Theory with Experimental Results 214 7.1.4. Comparison of Water Entry Theory with Results from ConstantVelocity Simulations by Others 219 7.2. Water Exit Theory 220 7.2.1. Analysis of Constant Velocity Water Exit Data 221 7.3. Verification of Theory by Analysis of Remaining Test Data 225 7.3.1. Max Added Mass - Analysis of Wet Chines Oscillation Test Data 226 7.3.2. Dry Chines Added Mass - Analysis of Accelerated Water Entry Data 230 7.3.3. Evidenceof Flow MomentumForce 234 7.4. Comparison of Added Mass Coefficients 235 7.4.1. Dry Chines 236 7.4.2. Wet Chines 237 7.5. Prediction of Dry Chines Oscillation Forces - Comparison with Dry Chines Oscillation Experiment 238 CHAPTER 8, APPLICATION OF WATER ENTRY THEORY IN PLANING 245 8.1. Hydrodynamic Lift on Slender Planing Surfaces 246 8.2. Hydrostatic Lift on Planing Surfaces 250 8.2.1. Flat Plates 250 8.2.2. Prismatic Surfaces 252 8.3. Comparison of PresentSlender Theory with Planing Data 253 8.3.1. Flat Plates 253 8.3.2. Wet Chines Prismatic Surfaces 255 8.3.3. Dry Chines Prismatic Surfaces 257 8.4. Hydrodynamic Lift on Non-Slender Planing Surfaces 259 8.4.1. Flat PlateTheory 261 8.4.2. Two-Dimensional Planing Plate 262 8.4.3. Prismatic Theory, Wet Chines 266 8.4.4. Prismatic Theory, Dry Chines 270 8.5. Validation of The Applied Hydrostatic Lift Component 271 8.6. Comparison of Non-Slender Body Equations with Experiments 274 CHAPTER 9, CONCLUSIONS AND RECOMMENDATIONS 278 9.1. Conclusions 279 9.2. Recommendations for Future Work 282 9.3. Closure 283 APPENDIX A- EARLIER WATER ENTRY EXPERIMENTS 285 APPENDIX B- TEST RIG MANUFACTURE DRAWINGS 293 APPENDIX C- TEST RIG EQUIPMENT SHEETS 313 C. I. DDE 1000 Load Cell -Datasheet 314 C.2. Load Cell 1- Calibration Sheet 315 C.3. Load Cell 2- Calibration Sheet 316 C.4. Load Cell 3- Calibration Sheet 317 C.5. Load Cell 4- Calibration Sheet 318 C.6. Ball Screw - Drawing 319 C.7. Timing Belt Drive - Calculation 320 C.8. Servomotor - Datasheet 321 C.9. Digital Servo Amplifier - Datasheet 322 LIST OF FIGURES 323 LIST OF TABLES 335 REFERENCES 336 SUMMARY Prediction of the hydrodynamic forces on planing craft by strip method requires the force acting on two-dimensional sections in vertical motion on the free surface to be known. The motion of a transverse section of a prismatic hull in steady planing correspondsto a constant velocity water entry of a wedge shaped section. The force acting on the wedge section before the chines get wetted is found from a consideration of the rate of change of the section added mass. The current added mass impact theory does not give a satisfying definition of the change in added mass after chines wetting, and hence predictions of non-constant velocity water entry can not be made accurately.