Ing Ind - Inf (Mag.)(ord. 270) - BV (477) ENERGY ENGINEERING - INGEGNERIA ENERGETICA

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097397 - DESIGN OF FLUID MACHINES FOR CLEAN POWER GENERATION

Ing Ind - Inf (Mag.)(ord. 270) - BV (479) MANAGEMENT ENGINEERING - INGEGNERIA GESTIONALE

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097397 - DESIGN OF FLUID MACHINES FOR CLEAN POWER GENERATION

Ing Ind - Inf (Mag.)(ord. 270) - BV (483) MECHANICAL ENGINEERING - INGEGNERIA MECCANICA

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097657 - DESIGN OF FLUID MACHINES FOR CLEAN POWER GENERATION B

Obiettivi dell'insegnamento

The course is addressed to master students of the last year in Energetic and Mechanical Engineering and is it is focused on design and operating principles of fluid machines in the frame of power production from renewable energy, namely wind and hydraulic turbines. The object of the course is to learn and apply the most important design methodologies typically used for the aerodynamic design and performance analysis of the turbines applied for the exploitation of renewable sources. Students, operating in working groups supported by tutors, will develop computer codes for the design and performance analysis of wind and hydraulic turbines

Risultati di apprendimento attesi

When passed the exam, the student will:

Know the fundamental operating principle of fluid machines in the frame of power generation from wind, hydro and other renewable energy sources

Be able to properly calculate the aerodynamic forces acting on an airfoil in the frame of rotating machinery in incompressible flow conditions.

Know the basics of 1D, 2D and 3D approaches for the aerodynamic design and the performance analysis of vertical and horizontal axis wind turbines.

Conceive and writea computational code based on the Blade Element Momentum approach for the design and the performance analysis of horizontal axis wind turbines, including some corrections for 3D effects, finite number of blades, etc.

Conceive and write a computational code based on the Double Multiple Stream Tube approach for the peculiar design and the performance analysis of vertical axis wind turbines.

Be able to develop a computational code for the design of an hydraulic turbine (only for 8 CFU)

Develop a code for the performance prediction of a fluid machine when operated at variable speed, starting from operating curves at a given rpm (only for 8 CFU)

Have the opportunity to develop abilities and skills associated to the experience of working in a design team and to present a design report by public oral presentation

Argomenti trattati

Introduction: Generalities on aerofoils for fluid machines. Aerodynamic profiles for low speed applications. Aerodynamic forces: the lift and drag coefficients. Effect of incidence. Stall. Effect of Reynolds number. Effect of roughness. Velocity triangles for rotating blades.Three dimensional effects. Operating curves.

Wind turbines: Generalities on wind as energy resource. Classification. Lift and drag driven wind turbines. Generalities on the aerodynamics of wind turbines. Betz's approach: 1D momentum theory. Power and thrust coefficients, limits of the Betz's approach. Effects of rotation. Blade number and optimum tip speed ratio. Shrouded rotors. Operating curves and power control: passive stall, fix and variable rotational speed, blade pitch control, active stall. Similarity and model tests: blockage effects in wind tunnels.

Horizontal axis wind turbines: Basic design of HAWT: The blade element theory and the optimal design of HAWT. The Blade Element Momentum method (BEM) for the performance analysis of HAWT. Optimal radial distribution of Glauert Correction for finite number of blades. Correction for high values of the induction factor. Effect of radial distrubution of the profile efficiency and Reynolds number. The optimal chord distribution. General computational scheme for HAWT optimal design and performance prediction. Principles of structural analysis.

Vertical axis wind turbines: The H-Darrieus and Troposkien geometry. The azimuthal distribution of blade load and torque. The Blade Element Momentum and the basic design of VAWT. The Blade Element Momentum method (BEM) for the design and the performance analysis of VAWT. Single and multiple stream tube methods. Double multiple stream tube (DMS). Improving DMS prediction capability: dynamic stall models, stream tubes expansion, etc. General computational scheme for VAWT. The problem of self-starting.

Wells turbine: operating principle and design criteria of Wells turbine for OWC application. Effect of guide vanes.

Hydraulic turbines (only for 8 CFU): Generalities on the hydraulic energy resource including mini-hydro. Review on turbine classification. The models theory for hydraulic machines and the non-dimensional analysis: relevant parameters. Review of classical hydraulic turbines. Single/double regulating machines, propeller-like and bulb turbines. Design procedures for single and double variable pitch axial turbines: kaplan, propeller-like and bulb turbine. Deriving the operating curves at variable rotational speed. The hill operating diagram of hydraulic turbines, in the frame of small hydro power

Prerequisiti

Students attending the course are expected to

Have solid bases in mathematics, incompressible fluid mechanics and fluid machines.

Know the basics of computer programming and to be able to write a simple computer code (based on Matlab, C++, Excel, etc.)

Modalità di valutazione

Course structure and final exam

The evaluation is based on the presentation and discussion of one of the design exercises developed by the working group (3-4 students) during the tutorials followed by an indicidual oral exam on the theoreical and design exercises contents.

Students will organize in working groups of three/four units for the aim of developing computer codes for the design and performance analysis of vertical axis wind turbines, horizontal axis wind turbines and (only for 8 CFU) hydraulic turbines. Different technical specification will be given to each group.

An important percentage of course hours will be devoted to tutoring sessions addressed to support the working groups in developing the specific design exercise. Students are warmly invited to participate to both tutoring sessions and theoretical lectures. At the end of the course each one of the working groups should produce: 1) a report containing the design procedure description and the outcome of each one of the given design exercises. 2) an oral presentation of one of design exercises, .

The exam is composed by two parts, that can be given in two different moments.

The first part should be given by the whole working group together. The group will give an oral presentation (slides) concerning the design exercise communicated by the professor at the beginning of the lectures; the presentation should last a maximum of 30 minutes. The report concerning ALL design exercises developped by the working group during the course should be delivered to the professor, prior the presentation. All group members should present a part of the project. The examination board will ask questions concerning the project (methods and outcomes) and all related theoretical course contents. At the end of the exam the examination board will assign an individual grade to each working group member. The report concerning all the design projects should have been delivered to the professor and will contribute to the final mark.

The second part of the exam can be given by each student independentlyand it will be based on all course contents (theoretical contents and design exercises). A separate grade will be given for the second part of the exam. The second part of the exam can be oral or written as it will be communicated by the professor prior the end of the course.

The final grade will be based on the marks obtained on the two parts.

Only the final mark can be rejected by the student: in this case the repetition of the exam will consist only on the second part, and will be again based on all course contents.

Bibliografia

Slides and teaching materials provided by the lecturers and tutors on Polimi "Beep"https://beep.metid.polimi.it/itMartin O.L. Hansen,, Aerodynamics of wind turbines Note:

For HAWT. Available on line

Ion Paraschivoiu,, Wind Turbine Design:With Emphasis on Darrieus Concept Note:

Only for VAWT. Only some chapters are concerned. Available @ library.