|SCIENTIFIC DISCIPLINARY SECTOR||ING-IND/08|
|MODULES||This unit is a module of:|
The course provides basic information about pumps and compressors with regard to choice, installation, the operation of the machine.
The course aims at providing the basic information about the functioning of compressors, fans, and pumps. The effects of the kind of fluid, and of structural and economic issues on the machine architecture are also considered. On such a basis, choice and installation criteria are derived, and information are provided about the machine operation, also considering the system in which the machine is installed. Preliminarily, physical properties of technical fluids are recalled, together with thermodynamic and fluid dynamic equations relevant to fluid machinery.
By means of active attendance of classes and individual study, the student will gain:
An operative knowledge of: the physical properties of the commonly processed fluids, the followed thermodynamic transformations, the balance equations employed for studying the flow, the similarity theory and the statistical approach, and the effect of the main aerodynamic and structural constraints on the blade design.
A basic knowledge of the effect of the density variation on ducts and fluid machinery operation.
With reference to turbomachine (fans, multistage compressors, and pumps), a basic knowledge of: the machine architecture, the features of the various parts, the variation of fundamental fluid dynamic and thermodynamic quantities along the machine, and the characteristic curve.
A basic knowledge of the effect of aerodynamic and structural constraints on a turbomachine design.
A basic knowledge of anomalous operation of pumps and compressors.
With reference to positive displacement pumps and compressors, a basic knowledge of the functioning and of the causes of deviation from the ideal behavior.
Basic knowledge of Fluid Dynamics, Thermodynamics, and Fluid Machinery.
Theoretical and applied classes.
1. Basic concepts of fluid machinery Fluid Dynamics and Thermodynamics
1.1. The typical engineering problems (direct, design, and choice ones). The main properties of the technical fluids. The state equation and the main thermodynamic relations. The basic equations for the study of open and closed systems and turbomachines and positive displacement ones (continuity, momentum, energy, Euler); definitions of the important quantities for the study of fluid machinery (head, efficiency, specific work).
1.2. The similarity theory: choice of the reference dimensional parameters, main non-dimensional parameters for turbomachines (pumps, fans, compressors). Relation between the similarity theory and the statistical approach; choice of the kind of machine for given performance: the Cordier plot.
2. Typical applications of the balance equations
Effect of Mach number and density variation on: the work input, the shape of a nozzle, and the heat transfer in a duct; adiabatic, polytropic and isothermal efficiency; thrust of moving fluids on duct walls, boundary layer separation and airfoil lift and drag. Overall efficiency and energy cascade for a fan.
3. Turbomachines (compressors, blowers, fans, and pumps, of axial and radial type)
3.1. Typical architecture and functioning principle, blade shape, analogy with an isolated airfoil, relation between blade angle and characteristic curve, flow deviation at the blade outlet and slip effect in centrifugal rotors, typical applications. Mechanical strain on blades, rotors, stators, shaft and shroud. Effect of centrifugal force and aerodynamic thrust on the blade. Limitations of the operation: stall and surge in compressors; pumps cavitation, suction height and ways of avoiding them.
3.2. Similarity and characteristics curves of turbomachines and of typical fluid dynamic loadings (hydraulic circuits and choked nozzles). Determination of the operating point: matching of the characteristic curves for compressible and incompressible flow.
4. Positive displacement machines
4.1. Reciprocating and rotary screw/vane compressors and pumps: functioning principle, effect of the valves kind, characteristic curves, and typical applications.
Course notes by the lecturer.
L. A. Catalano, M. Napolitano, Elementi di Macchine operatrici a fluido, Pitagora Editrice.
R.I. Lewis, Turbomachinery performance analysis, John Wiley and Sons.
ANDREA CATTANEI (President)
LUCA ANTONIO TAGLIAFICO
VINCENZO BIANCO (President Substitute)
All class schedules are posted on the EasyAcademy portal.
Oral exam at the end of the course, normally every Tuesday. Please contact the lecturer at Andrea.Cattanei@unige.it at least one week in advance.
Students with SLD, disability or other regularly certified special educational needs are advised to contact the instructor at the beginning of the course to agree on teaching and examination methods that, in compliance with the course objectives, take into account the individual learning requirements.
General discussion of the treated topics based on two questions. The exam aims at ascertain comprehension of physical meaning and engineering interest.
Basic knowledge of Fluid mechanics, Thermodynamics and Fluid machinery.