|SCIENTIFIC DISCIPLINARY SECTOR
The course provides the basic rules for the 1D and 2D design methods for axial and centrifugal machines. It provides the general guidelines for accurate numerical and experimental validations. Analytical and empirical correlations will be adopted to design all the components of a centrifugal and an axial machines. The detailed analysis of the internal aerodynamics of each component will allow the identification of the most influencing parameters affecting the machine operation and efficiency.
AIMS AND CONTENT
The course provides the basic rules for the 1D and 2D design methods for axial and centrifugal machines. It provides the general guidelines for accurate numerical and experimental validations. Analytical and empirical correlations will be adopted to design all the components of a centrifugal and an axial machine. The detailed analysis of the internal aerodynamics of each component will allow the identification of the most influencing parameters affecting the machine operation and efficiency.
AIMS AND LEARNING OUTCOMES
The student should be able to:
- identify the more appropriate machine architecture depending on the boundary conditions (mass flow and power);
- determine the velocity triangles from the characteristic dimensionless working parameters;
- obtain the lines defining the meridional channel of both axial and centrifugal machines;
- design the blade shape of axial and centrifugal machines, and other components like the scroll;
- analyze the machine efficiency and generate, by means of correlations, the characteristic curve of the machine.
A part of the design process will be developed by means of computer programs.
Frontal lessons will be mainly employed in the curse. The basic design rules will be provided. Design exercises complete the course. It is strongly suggested the participation of the student to the lessons.
Application of Continuity, Energy, Momentum and Euler equations to turbomachines. The preliminary design, based on similarity and statistics.
Axial machines: mean line design. Radial equilibrium equation. Different vortex laws (free vortex, forced vortex, exponential and fixed angle). Effects of enthalpy variation and entrophy radial gradient effects into the flow angle distribution. Correlations.
Centrifugal turbomachines: the blade loading and the blade shape; employ in the design problem. Slip factor effects and correlations (Stanitz, Stodola, Busemann, Wiesner). Japickse’s criterion for the loss evaluation inside centrifugal impeller. The jet and wake model. Logarithmic spiral trajectory. The design of the vaned and unvaned diffusers. Design of the volute.
- N. A. Cumpsty, Compressor Aerodynamics, Longman, 1989
- O. E. Balje, Turbomachines A guide to Design, Selection and Theory, J. Wiley and Sons, 1981
- D. Japickse, Centrifugal Compressor Design and Performance, Concepts ETI, Inc. 1996
TEACHERS AND EXAM BOARD
DANIELE SIMONI (President)
DAVIDE LENGANI (President Substitute)
L'orario di tutti gli insegnamenti è consultabile all'indirizzo EasyAcademy.
The examination is composed of two parts. The first consists in the discussion of a design exercise of an axial turbine stage, based on boundary conditions provided by the professor some days before the examination data. In the second part an oral discussion of theoretical topics related to the design of radial machines will be discussed. The examination data will be provided previous appointment.
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.
The oral examination will allow to verify the acquired knowledge of the student regarding the operation of the different kind of machines and their components, and how they can be optimized thanks to a better knowledge of the internal aerodynamics. The design exercise allows to verify the capability of the student in designing an axial turbine stage.
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