


Politecnico di Torino  
Academic Year 2017/18  
03OJZND Thermal machines II and structural mechanics 

Master of sciencelevel of the Bologna process in Energy And Nuclear Engineering  Torino 





Subject fundamentals
The course is composed of two modules, one relative to Hydraulic and Thermal Machines, the other to the design of the Structural Mechanics.
The Hydraulic and Thermal Machines module aims at supplying the complements of the main fluidflow machines, with specific reference to principles of operation, evaluation of performance and offdesign operations of both the single fluidflow machine and the energy system in which it is inserted. As regards the Structural Mechanics module, it will analysed the problems of static, fatigue and thermomechanical fatigue failure of components and will be presented the methodology of analytical study and technical standard rule on pressure vessels. 
Expected learning outcomes
Through the systematic application of the principles of thermofluiddynamics to energy conversion systems and their components, the Hydraulic and Thermal Machines module provides the students with the ability not only to choose engines and engineeringplant solutions in relation to their applications, but also to approach and solve specific design problems by integrating the concepts acquired in the module with advanced notions on specific topics.
The Structural Mechanics module is designed to provide the student with the knowledge to understand the component failure mode under constant or cyclic loads and to perform the main calculations related to the project/ verification of pressure vessels with respect the technical standard specifications. 
Prerequisites / Assumed knowledge
Preliminary knowledge acquired in the courses of Hydraulic and Thermal Machines Fundamentals, Thermodynamics and Thermokinetics, Applied Mechanics, Fluid Mechanics, Fundamentals of Structural Mechanics (in particular tension, bending, torsion loading condition and the theory of the stress and strain states).

Contents
PART OF "FLUIDFLOW MACHINES II"
Power plants with steam turbine. Turbine steam massflow rate vs. inlet and condensing pressure. Steam mass flowrate control by throttling and choking. Cogenerative power plant control with steam turbine. Gas turbine power plant: actual cycle, work and efficiency. Single and double shaft gas turbine control. Combined heat and power plant control through steam injection and afterburner. Hydraulic turbine fundamentals: ideal and actual cycles, break mean effective pressure and power Construction features and performance of Pelton, Francis and Kaplan turbines. Reciprocating internal combustion engine fundamentals. Four stroke engine valve train and volumetric efficiency. Air/fuel ratio influence on Otto engine performance. Supercharging and Turbocharging: comparison of engine performance. Fuel feeding systems for spark ignition engines and emission control system. Lean burn engines. Engine performances: full load and partload characteristics. Combustion in Diesel engine. Fuel feed systems for compression ignition engines. PART OF "STRUCTURAL MECHANICS" 3D state of stress and strain  stress vector and stress tensor. Principal stresses and principal directions. Invariants of the stress state. Hydrostatic and deviatoric tensors. Mohr circles. Stress typical cases. Kinematics of deformation. Deformation tensor. Principal strains. Relationship between stress and strain: Hooke's law. Static strength  Tensile testing of brittle and ductile materials. Static failure hypothesis for brittle and ductile materials. Static safety factor. Effect of temperature on mechanical properties. Creep. Notch factor and stress concentration factor. Notch effect in the static failure. Fatigue strength  Phenomenology and characteristic parameters. Wöhler curve. Fatigue limit. Estimation of the SN diagram of the material. Influence of the mean stress: Haigh diagram of the material. Effect of load type, size, surface finishing and presence of notch effect. Fatigue strength of the component. Haigh diagram and SN curve of the component. Safety factor in fatigue. Stress with cycles of variable amplitude. Multiaxial fatigue. Cyclic and thermomechanical behaviour  Low cycle fatigue, isothermal and thermomechanical tests. Characterization parameters of the low cycle fatigue behaviour and corresponding constitutive models. Parameters characterizing the thermomechanical fatigue behaviour and corresponding constitutive models Damage models: classification, uniaxial models, multiaxial models. Prediction of residual life. Vessels subject to pressure  Problem setting, differential equation of equilibrium and solution. Determination of the stress states produced by internal/external pressure and thermal gradient. Construction solutions for high pressure condition. The case of thin tubes. Axisymmetric plates. Axisymmetric shells. Edge effects. Guidelines for construction and use of pressure equipment: European Pressure Equipment Directive (PED) , EN 13445 standard, ASME Code Section VIII Division 1  Pressure Vessels. 
Delivery modes
The classroom training consists in solving exercises and practical problems by applying the concepts covered in the lessons. The aim of the training is to give the students the order of magnitude of the main parameters and to improve their degree of understanding.
An experimental activity carried out on a reciprocating internal combustion engine is also planned. 
Texts, readings, handouts and other learning resources
PART OF "FLUIDFLOW MACHINES II"
The lectures subjects, text of exercises as well as datasheets and materials for laboratory practice are available on Corse website. Reference textbooks for improving the study A. Capetti: Motori Termici. Ed. UTET, 1967. A.E. Catania: Complementi di macchine. Ed. Levrotto & Bella, 1979. G. Lozza: Turbine a gas e cicli combinati. Ed Esculapio, 1997. G. Cornetti: Macchine Idrauliche. Ed. Il Capitello, 2006. G. Cornetti – F. Millo: Macchine Termiche. Ed. Il Capitello, 2007. G. Ferrari: Motori a combustione interna. Ed Il Capitello, 2007 A. Dadone: Macchine idrauliche. Ed. CLUTTorino, 1987 PART OF "STRUCTURAL MECHANICS" The didactic material about lecture subjects and exercises is available on the Corse website. Reference textbooks for improving the study: F.A. Raffa, Elementi di meccanica strutturale, CLUT, 2008. L. Goglio, Resistenza dei materiali e dei collegamenti, Levrotto & Bella, 2006. M. Rossetto, Introduzione alla fatica dei materiali e dei componenti, Levrotto & Bella, 2000. 
Assessment and grading criteria
The exam consists of a written test both on practical problems and theory.
The test duration is 3 hours (1,5 hours for each part). The exam is composed of two practical problems and four openended questions related to the theory (one practical problem and two questions for each part of the course). During the exam a sheet with formulas is allowed for the practical problem part only (closed book). The final mark is an average of the marks achieved for the two course parts with a minimum mark for each part of 18/30. 
