Collection of questions of the oral exam

Pagina 1

ENERGY CONVERSION – QUESTIONS FOR THE ORAL EXAM WITH PROF VALENTI - Magnox: plant layout. How to control the mass of the CO2 (fan). Why is CO2 good? - General theorem of the 2nd law analysis and what is the waster work and what are the causes of ΔSirr - Project 5: goal, comment results of the 1st stage of the 3 stages machine, why is the total efficiency of the 3 stages machine higher than the efficiency of each stage (due a recuperative effect)? Sketch the blade profile for the first stage with the velocity triangle of the rotor. Velocity triangle for the first stage of 3-stage machine (velocity is not axial because can be recuperated by the next stage, we have tangential components)? Secondary losses and leakages with respect to the variable rotational speed? Eta TT with expansion process? How leakages should vary if the number of blades increase (they decrease since each blade has a lower deltaP to work)? Talk about the three stage configuration. Show graphically why we use eta tt for the intermediate stages and eta ts for the last one. Sketch the diffuser in the meridian plane. What is a diffuser? How to calculate eurlerian work, load coefficient and degree of reaction. Why do we have bad efficiency for high rpm? What are £D losses? - What is a De Laval nozzle? Sketch and show the diagram of the adaptive condition. When does post expansion happen in rockets? (Che figo Elon Musk!) - Sketch on the Mollier diagram the first stage of a turbine, showing the kinetic energy relative to absolute and relative velocities - Energy balance for the rotor - What’s wrong with high rotational speeds for the first stage of the turbine? - Why blades should be twisted? And sketch the blades profiles - Sketch BWR, in particular the steam turbine - How to control the condensate pump -…