THE AIM OF THE COURSE IS TO PROVIDE STUDENTS WITH PRELIMINARY DESIGN PROCEDURES AND CRITERIA FOR TURBOMACHINES. (FROM GAS, STEAM, AND HYDRAULIC TURBINES TO PUMPS, FANS, BLOWERS AND COMPRESSORS).
MOVING FROM PERFORMANCE TARGETS AND SPECIFIC DESIGN BOUNDARY CONDITIONS, THE STUDENT WILL LEARN SOME SIMPLIFIED DESIGN METHODOLOGIES TAKING MATERIAL, MECHANICAL AND THERMAL STRESSES, TRANSONIC FLOW LIMITS AND CAVITATION INTO ACCOUNT. THE OPTIMIZATION OF THE DEGREE OF FREEDOM WILL BE IMPLEMENTED IN THE DESIGN PROCEDURES.
THE STUDENT WILL BE ABLE TO ANALYSE MACHINE PERFORMANCE ONCE THE MAIN GEOMETRIC QUANTITIES ARE GIVEN.
MOVING FROM PERFORMANCE TARGETS AND SPECIFIC DESIGN BOUNDARY CONDITIONS, THE STUDENT WILL LEARN SOME SIMPLIFIED DESIGN METHODOLOGIES TAKING MATERIAL, MECHANICAL AND THERMAL STRESSES, TRANSONIC FLOW LIMITS AND CAVITATION INTO ACCOUNT. THE OPTIMIZATION OF THE DEGREE OF FREEDOM WILL BE IMPLEMENTED IN THE DESIGN PROCEDURES.
THE STUDENT WILL BE ABLE TO ANALYSE MACHINE PERFORMANCE ONCE THE MAIN GEOMETRIC QUANTITIES ARE GIVEN.
teacher profile teaching materials
- Criteria and limits;
- Dimensional analysis and performance laws;
- Relevant applications to design and analysis of turbomachines;
Hydraulic machines
1) Centrifugal and axial pumps
- Basic principles and performance
- Influence of cavitation on pump selection and design;
- Preliminary design of the main components (radial and axial impellers, unvaned and vaned diffusers, volutes)
- Main parameters which affect pump performance;
- Operation and control: basic principles.
2) Hydraulic turbines
- Basic principles and performance
- Preliminary design of Pelton turbines;
- Preliminary design of reaction turbines (Francis and Kaplan);
- Draft tube and cavitation in reaction turbines;
- Performance characteristics;
- Operation: basic principles.
Compressible flow turbomachines
3) Fluid-dynamics in ducted flows
- Review of applied thermodynamics and gas-dynamics;
- Steady one-dimensional and two-dimensional flows, vorticity, Crocco’s theorem, shock waves. Shock and expansion waves on complex aerofoils.
- Two-dimensional cascades;
- Boundary layers on complex aerofoils, effect of pressure gradients on stall in cascades, thermal boundary layers.
- Shock wave/ boundary layer interaction;
- Three-dimensional effects: secondary flows.
4) Axial compressors
- Basic principles, application of dimensional analysis, performance characteristics;
- Preliminary design: elementary theory, factors affecting stage pressure ratio, blockage in the compressor annulus, degree of reaction, design process;
- Mean-line analysis: efficiency optimization.
- Three-dimensional flow: free-vortex law, constant degree of reaction law, constant rotor absolute inlet angle law;
- Stage efficiency: three-dimensional optimization.
- Correlations for the evaluation of losses and deviation.
5) Steam Turbine
- Basic principles and performance characteristics.
- Analysis of: impulse stage, velocity-compounded impulse stage, reaction stage. Comparison and discussion.
- Total-to-total and total-to-static blade efficiency, windage losses, partial admission losses, humidity losses.
- Preliminary design: principles for selecting the path of multistage turbines, rough estimation of the process of steam flow in the path, estimation of stage diameter, number of stages and distribution of enthalpy drops. Calculation of the steam path.
6) Axial gas turbines
- Basic principles, application of dimensional analysis, performance characteristics;
- Preliminary design: elementary theory, vortex theory (free-vortex design, constant nozzle angle design);
- Stage performance limitations;
- Cooling methods: basic principles.
Students will apply design methodologies and procedures on several case studies.
• D.G. Wilson, T. Korakianitis, "The design of high-efficiency Turbomachinery and Gas Turbines", Ed. Prentice Hall;
• H. Cohen, G.F.C. Rogers, H.I.H. Saravanamuttoo, "Gas Turbine Theory", Ed. Longman;
• C. Caputo, "Le turbomacchine", Casa Editrice Ambrosiana;
• C. Osnaghi, “Teoria delle Turbomacchine”, Ed. Esculapio
• Materiale a cura del Docente messo a disposizione su piattaforma Moodle
Mutuazione: 20801825 TURBOMACCHINE in Ingegneria meccanica LM-33 N0 GIOVANNELLI AMBRA
Programme
The similitude theory applied to turbomachines- Criteria and limits;
- Dimensional analysis and performance laws;
- Relevant applications to design and analysis of turbomachines;
Hydraulic machines
1) Centrifugal and axial pumps
- Basic principles and performance
- Influence of cavitation on pump selection and design;
- Preliminary design of the main components (radial and axial impellers, unvaned and vaned diffusers, volutes)
- Main parameters which affect pump performance;
- Operation and control: basic principles.
2) Hydraulic turbines
- Basic principles and performance
- Preliminary design of Pelton turbines;
- Preliminary design of reaction turbines (Francis and Kaplan);
- Draft tube and cavitation in reaction turbines;
- Performance characteristics;
- Operation: basic principles.
Compressible flow turbomachines
3) Fluid-dynamics in ducted flows
- Review of applied thermodynamics and gas-dynamics;
- Steady one-dimensional and two-dimensional flows, vorticity, Crocco’s theorem, shock waves. Shock and expansion waves on complex aerofoils.
- Two-dimensional cascades;
- Boundary layers on complex aerofoils, effect of pressure gradients on stall in cascades, thermal boundary layers.
- Shock wave/ boundary layer interaction;
- Three-dimensional effects: secondary flows.
4) Axial compressors
- Basic principles, application of dimensional analysis, performance characteristics;
- Preliminary design: elementary theory, factors affecting stage pressure ratio, blockage in the compressor annulus, degree of reaction, design process;
- Mean-line analysis: efficiency optimization.
- Three-dimensional flow: free-vortex law, constant degree of reaction law, constant rotor absolute inlet angle law;
- Stage efficiency: three-dimensional optimization.
- Correlations for the evaluation of losses and deviation.
5) Steam Turbine
- Basic principles and performance characteristics.
- Analysis of: impulse stage, velocity-compounded impulse stage, reaction stage. Comparison and discussion.
- Total-to-total and total-to-static blade efficiency, windage losses, partial admission losses, humidity losses.
- Preliminary design: principles for selecting the path of multistage turbines, rough estimation of the process of steam flow in the path, estimation of stage diameter, number of stages and distribution of enthalpy drops. Calculation of the steam path.
6) Axial gas turbines
- Basic principles, application of dimensional analysis, performance characteristics;
- Preliminary design: elementary theory, vortex theory (free-vortex design, constant nozzle angle design);
- Stage performance limitations;
- Cooling methods: basic principles.
Students will apply design methodologies and procedures on several case studies.
Core Documentation
• S.L. Dixon, "Fluid Mechanics and Thermodynamics of Turbomachinery", Ed. Butterworth Heinemann;• D.G. Wilson, T. Korakianitis, "The design of high-efficiency Turbomachinery and Gas Turbines", Ed. Prentice Hall;
• H. Cohen, G.F.C. Rogers, H.I.H. Saravanamuttoo, "Gas Turbine Theory", Ed. Longman;
• C. Caputo, "Le turbomacchine", Casa Editrice Ambrosiana;
• C. Osnaghi, “Teoria delle Turbomacchine”, Ed. Esculapio
• Materiale a cura del Docente messo a disposizione su piattaforma Moodle
Type of delivery of the course
The course consists of lectures and exercises. The reports related to exercises must be presented at the examination. During the pandemic emergency, virtual classes on Microsoft Teams will be arranged. Books, presentations and other relevant documents will be uploaded on Moodle.Attendance
Attendance is optional. Documents related to the course program are uploaded on Moodle.Type of evaluation
The examination is organized with an oral test and some practical exercises related to the main topics.