Teacher

prof. Carlo NONINO

Credits

12 CFU

Language

Italian

Objectives

Teaching mechanical engineering students some additional topics that cannot be dealt with in the courses of Applied Thermodynamics and Heat Transfer; flow of compressible fluids (gasdynamics) and sizing of heat exchangers are the main topics of the course.

Acquired skills

- Analysis of compressible isoentropic flows and flows with friction and heat transfer.
- Analysis of simple shock phenomena.
- Selection of heat exchangers.
- Sizing of shell-and-tube heat exchangers.
- Fundamentals of the finite volume method.
- Fundamentals of the finite element method.
- Ability to use a computer code for the numerical solution of thermal-fluid dynamic problems.

Lectures and exercises (topics and specific content)

Introduction to gasdynamics: fundamental equations for one-dimensional flows; sound speed and Mach number; total enthalpy and total pressure; adiabatic flow; critical speed and critical Mach number (5 hours).
Normal and oblique shock waves: Prandtl-Meyer equation; relationship between parameters upstream and downstream a shock wave; oblique compression waves and isoentropic expansion waves (10 hours).
Isoentropic flow in ducts: Hugoniot equation, nozzles and diffusers; critical state. Converging nozzle; converging-diverging nozzle (8 hours).
Fanno and Rayleigh flows: Fanno line; evolution of Fanno flow; maximum length. Rayleigh line; evolution of Rayleigh flow; maximum heat transferred (10 hours).
Types of heat exchangers: double-pipe heat exchangers; air-cooled heat exchangers, fin-tube heat exchangers; gasketed plate heat exchangers; condensers and reboilers; heat pipes; recuperators and regenerators; cooling towers; shell-and-tube heat exchangers (5 hours).
Analysis of shell-and-tube heat exchangers: basic mechanical features; multiple passes; effective temperature difference; correction factor; effectiveness; NTU (8 hours).
Sizing of shell-and-tube heat exchangers: Kern method; Bell-Delaware method; number of tubes; economic velocity; number of passes; number of baffles; size of the heat exchanger (14 hours).
Thermal-fluid dynamics review: mass conservation equation; energy conservation equation; momentum conservation equations; general transport equation (9 hours).
Finite difference method (basics): domain discretization; approximation of derivatives; truncation error (5 hours).
Finite volume method: computational grids; spatial discretization; volume and surface integrals; interpolation techniques; two-level time integration algorithms; stability (12 hours).
Methods for the solution of systems of linear equations: direct methods; iIterative methods (4 hours).
Solution of Navier-Stokes equations: coupled methods; segregated methods; position of variables on the grid (6 hours).
Finite element method: shape and weighting functions; Green's formulae; Galerkin method; assembly; time integration; isoparametric transformation; numerical integration (10 hours).
Exercises (10 hours).
Labs (14 hours).

References

- Teacher's notes 
- S.L. Dixon - Fluid Mechanics, Thermodynamics of Turbomachinery - Pergamon Press, Oxford (UK)

Type of exam

Written and oral