Positive displacement pumps and motors find application in countless scenarios: from fluid power transmission to lubrication, from fluid transfer through a processing line, for instance in food or chemical industries, up to application in small medical devices, and much more. More specifically, despite the increasing prevalence of electric machinery, positive displacement pumps and motors, owing to their high power density, continue to be the sole viable solution for power transmission in many applications. Moreover, in a period marked by intense emphasis on decarbonization and hybridization, hydraulic technology is experiencing a resurgence in optimizing components, as well as in integrating them with electric machinery. Additionally, hydraulic machines are discovering new applications, such as in wave energy converters, brake control and blade rotation regulation systems for wind turbines, or mirror positioners for photovoltaic systems.¿ In this context, the course introduces and examines various types of piston, vane and gear machines used in mobile and industrial applications in terms of kinematic behaviour, efficiencies, steady-state characteristics and peculiar features. Subsequently, the course focuses on the modelling of pumps and motors using the more recent 0D and CFD commercial tools.¿ Students learn to evaluate performance, determine the appropriate machine type for each specific application and create simulation models.¿ The course includes numerous real component examples to demonstrate the practical implementation of theoretical principles.¿ Overall, aim of the course is to acquaint students with methods for analysis and critical evaluation of positive displacement machines.¿

Awareness of basic concepts covered in Physics and Fluid Mechanics.

Main topics are the following:¿ - Fundamentals of working fluids: liquid properties, dissolved and undissolved gas fraction, gaseous and vapour cavitation, basic flow equations (1.5 hours). ¿ - Evaluation of the geometric quantities (displacement, kinematic flow ripple, kinematic speed, chamber volume variation, portplate flow areas) (1.5 hours).¿ - Types of displacement controls: pressure compensator, load sensing, torque limiter, electro-hydraulic servo-controls (1.5 hours).¿ - Specific features: hydrostatic and hydrodynamic slippers, gap compensation and balancing systems, integrated mechanical holding brake (2 hours).¿ - Real machine behaviour: working cycle, sources of volumetric loss (leakages, incomplete filling, compressibility flow rate) and hydraulic-mechanical loss (pressure and speed dependent friction, internal pressure drops), efficiencies, steady-state characteristics (2.5 hours).¿ - Basics of lumped parameter simulation: modelling of hydraulic resistances and capacities, modelling of specific leakage passageways in piston, vane and gear machines, construction of the equivalent circuit of hydraulic machines (1.5 hours).¿ - Lumped parameter modelling with Simcenter Amesim: examples of construction of pump and motor models (3 hours).¿ - CFD model with SimericsMP+ of a gerotor pump: import of the CAD surfaces and definition of the control volumes, creation of the Mismatched Grid Interface (MGI), mesh generation, setting of boundary conditions and of fluid properties, analysis of the results (3 hours). ¿ - Laboratory session on dismantling and critical analysis of real components. Axial (swash plate and bent axis) and radial piston (with fixed and rotating cylinder block) machines, vane machines (balanced and unbalanced rotor), spur gear, internal gear, gerotor, orbit machines (2 hours).¿ - Laboratory session on measuring the steady-state characteristics of a pump or a motor (1.5 hours).¿

In presenza

Presentazione orale

P.D.2-2 - Ottobre