Departamento de Arquitectura y Construcción Navales Escuela Técnica Superior de Ingenieros Navales Universidad Politécnica de Madrid PhD Thesis DESIGN OF A GENERALIZED TOOL FOR THE PERFORMANCE ASSESSMENT UNDER SAIL BASED ON ANALYTICAL, NUMERICAL AND EMPIRICAL RESULTS. A GLOBAL SAILING YACHT META-MODEL By Manuel Ruiz de Elvira M. Sc. in Naval Architecture Supervisors: Prof. Luis Pérez-Rojas Ph.D. in Naval Architecture Prof. Ricardo Zamora Ph.D. in Naval Architecture 2015 This page intentionally left blank ii ABSTRACT The assessment of the performance of sailing yachts, and ships in general, has been an objective for naval architects and sailors since the beginning of the history of navigation. The knowledge has grown from identifying the key factors that influence performance (length, stability, displacement and sail area), to a much more complete understanding of the complex forces and couplings involved in the equilibrium. Along with this knowledge, the advent of computers has made it possible to perform the associated tasks in a systematic way. This includes the detailed calculation of forces, but also the use of those forces, along with the description of a sailing yacht, to predict its behavior, and ultimately, its performance. The aim of this investigation is to provide a global and open definition of a set of models and rules to describe and analyze the behavior of a sailing yacht. This is done without applying any restriction to the type of yacht or calculation, but rather in a generalized way, capable of solving any possible situation, whether it is in a steady state or in the time domain. First, the basic definition of the factors that condition the behavior of a sailing yacht is given. Then, a methodology is provided to assist with the use of data from different origins for the calculation of forces, always aiming towards the solution of the problem. This last part is implemented as a computational tool, PASim, intended to assess the performance of different types of sailing yachts in a wide range of conditions. Several examples then present different uses of PASim, as a way to illustrate some of the aspects discussed throughout the definition of the problem and its solution. Finally, a global structure is presented to provide a general virtual representation of the real yacht, in which not only the behavior, but also its handling is close to the experience of the sailors in the real world. This global structure is proposed as the core (a software engine) of a physical yacht simulator, for which a basic specification is provided. iii RESUMEN La evaluación de las prestaciones de las embarcaciones a vela ha constituido un objetivo para ingenieros navales y marinos desde los principios de la historia de la navegación. El conocimiento acerca de estas prestaciones, ha crecido desde la identificación de los factores clave relacionados con ellas (eslora, estabilidad, desplazamiento y superficie vélica), a una comprensión más completa de las complejas fuerzas y acoplamientos involucrados en el equilibrio. Junto con este conocimiento, la aparición de los ordenadores ha hecho posible llevar a cabo estas tareas de una forma sistemática. Esto incluye el cálculo detallado de fuerzas, pero también, el uso de estas fuerzas junto con la descripción de una embarcación a vela para la predicción de su comportamiento y, finalmente, sus prestaciones. Esta investigación tiene como objetivo proporcionar una definición global y abierta de un conjunto de modelos y reglas para describir y analizar este comportamiento. Esto se lleva a cabo sin aplicar restricciones en cuanto al tipo de barco o cálculo, sino de una forma generalizada, de modo que sea posible resolver cualquier situación, tanto estacionaria como en el dominio del tiempo. Para ello se comienza con una definición básica de los factores que condicionan el comportamiento de una embarcación a vela. A continuación se proporciona una metodología para gestionar el uso de datos de diferentes orígenes para el cálculo de fuerzas, siempre con el la solución del problema como objetivo. Esta última parte se plasma en un programa de ordenador, PASim, cuyo propósito es evaluar las prestaciones de diferentes tipos de embarcaciones a vela en un amplio rango de condiciones. Varios ejemplos presentan diferentes usos de PASim con el objetivo de ilustrar algunos de los aspectos discutidos a lo largo de la definición del problema y su solución. Finalmente, se presenta una estructura global de cara a proporcionar una representación virtual de la embarcación real, en la cual, no solo el comportamiento sino también su manejo, son cercanos a la experiencia de los navegantes en el mundo real. Esta estructura global se propone como el núcleo (un motor de software) de un simulador físico para el que se proporciona una especificación básica. iv ACKNOWLEDGMENTS I would like to thank the following persons and institutions for their assistance with this investigation and the hard work of putting it in writing: x To professors Luis Pérez Rojas and Ricardo Zamora, my supervisors and longtime friends who helped me believe I could actually finish this and guided me through the whole process. x To Oracle Team USA for permitting me to use data generated during the last America’s Cup campaigns for this research, as well as for the role it played in increasing my personal knowledge through my work there. x To the Offshore Racing Congress and the members of its International Technical Committee, colleagues and friends that for many years fed my interest in performance prediction with their generously shared knowledge. x To Andrew Mason that put together some optimization projects for America’s Cup campaigns, especially the one for the 32nd America’s Cup campaign, that became his PhD thesis and in which this author had the opportunity to collaborate in the deterministic performance prediction side through a challenging, new and rewarding process. I have to thank him as well for pushing me to start writing the first lines of this work. x To Bruce Rosen and South Bay Simulations for allowing the use of calculations performed with their code SPLASH, as well as additionally kindly providing me with a license with the purpose of generating new data for its use in this research. x To Prof. Klaus Schittkowski from the University of Bayreuth (Germany) for kindly allowing me to use his optimization code NLPQLP for this research. x To Adriana Oliva from the CEHINAV who started to proofread my work when it was at its roughest version and helped to make it more understandable. x To Ignacio Castañeda from the CEHINAV who read repeated times from the first to the last word of this work with a bulletproof enthusiasm, proposing corrections, offering insightful suggestions and, in many occasions, helping me understand myself. x To Caroline Muselet from the Institute of Ocean Technology in St. John’s (Canada) for showing to one of the strongest believers in the concept of the “big picture” the importance of the attention to detail with her expertise in tank testing. I also need to thank her for her merciless and meticulous work proofreading these pages, challenging every word or explanation she believed that could be improved with the tenacity of an editor. x Finally I need to thank my father who has always encouraged and supported my curiosity and whose kind version of “are we there yet?” gently pushed me to finish writing the last of these lines. v This page intentionally left blank vi INDEX CONTENTS NOMENCLATURE XIII NAVAL ARCHITECTURE XIII THEORY OF SAILING XIII FORCES AND MOMENTS XIV ACRONYMS XV BRIEF COMMENTS ON SEMANTICS XVII 1| OVERVIEW 1 PROBLEM DEFINITION 1 BACKGROUND AND CONTEXT. STATE OF THE ART 2 SCOPE 3 CONTRIBUTIONS 4 OUTLINE OF THIS THESIS 5 A NOTE ON THIS THESIS APPROACH TO THE PROBLEM 7 2| DESCRIPTION OF THE PROBLEM 9 GEOMETRY OF SAILING AND APPARENT WIND 9 SYSTEMS OF REFERENCE. SETS OF AXES 13 THE ORIGIN OF FORCES. BASIC EQUILIBRIUM 18 KERWIN’S PROPOSAL 19 THE IMS VPP 21 SIX DEGREES OF FREEDOM 22 2.6.1 MOTIONS 23 2.6.2 FORCES 24 2.6.3 MOMENTS 28 2.6.4 MOMENTS AND FORCES CREATED BY NON-STATIONARY MOTIONS 30 3| THE ORIGIN OF FORCES 31 HOW ARE FORCES GENERATED 31 3.1.1 STATIC FORCES 32 3.1.2 AERODYNAMIC FORCES DUE TO STATIONARY-STATE MOVEMENT 34 3.1.3 HYDRODYNAMIC FORCES DUE TO STATIONARY MOVEMENT 38 3.1.4 FORCES DUE TO NON-STATIONARY MOTIONS 42 PARAMETRIZATION AND ANALYTICAL MODELS 44 3.2.1 MODELS AND META-MODELS 45 3.2.2 ENVIRONMENTAL PARAMETERS 47 3.2.3 GEOMETRICAL CHARACTERIZATION AND PARAMETRIZATION 47 3.2.4 BASIC ANALYTICAL MODELS 51 3.2.5 SOME EXAMPLES OF MORE COMPLEX ANALYTICAL MODELS 52 STRATEGY IDENTIFYING SOURCES OF FORCES 56 vii INDEX 4| EVALUATING FORCES WITH EMPIRICAL AND NUMERICAL TOOLS 59 A BRIEF DISCUSSION ON DESIGN OF EXPERIMENTS AND MANAGEMENT OF NUMERICAL AND EXPERIMENTAL DATA 60 TYPES OF EXPERIMENTAL TESTS 61 TOWING TANK TESTS 62 4.3.1 TESTING TECHNIQUES 62 4.3.2 REPEATABILITY AND ACCURACY 64 4.3.3 THE MODELS 65 4.3.4 THE MODEL SETUP, DYNAMOMETER AND DATA ACQUISITION SYSTEMS 67 4.3.5 THE WATER CONDITION AND WAITING TIMES. TEST SEQUENCE 70 4.3.6 DIFFERENT MODELS AND TEST SESSIONS 74 4.3.7 DATA EXPANSION TO FULL SCALE 75 4.3.8 A NOTE ON TESTS WITH FULLY-CAPTIVE MODELS 76 4.3.9 SEAKEEPING AND MANEUVERABILITY TESTS 77 WIND TUNNEL TESTS 78 4.4.1 WIND TUNNEL TESTS FOR APPENDAGES EVALUATION 79 4.4.2 WIND TUNNEL TESTS FOR AERODYNAMIC FORCES 80 GENERATION OF NUMERICAL DATA 83 4.5.1 TYPES OF CODES 83 4.5.2 SOME PRECAUTIONS ON THE USE OF DIFFERENT CODES 85 4.5.3 USES OF THE DIFFERENT CODES 88 5| VPP INPUT