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EGR 4347 Analysis and Design of Propulsion Systems

EGR 4347 Analysis and Design of Propulsion Systems. Review. EGR 4347 - Review. Explain the difference between units and dimensions. Dimensions – physical quantity that can be characterized EX. length, mass Units – arbitrary magnitudes assigned to the dimensions EX. meter, feet.

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EGR 4347 Analysis and Design of Propulsion Systems

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  1. EGR 4347 Analysis and Design of Propulsion Systems Review

  2. EGR 4347 - Review • Explain the difference between units and dimensions. • Dimensions – physical quantity that can be characterized EX. length, mass • Units – arbitrary magnitudes assigned to the dimensions EX. meter, feet EGR 4347

  3. EGR 4347 - Review • Explain extensive and intensive properties. • Extensive depends on system • Intensive is independent of system EGR 4347

  4. EGR 4347 - Review • Give at least four forms of energy which make up the term total energy, E. • Thermal 2. Mechanical • 3. Potential 4. Electric • Chemical 6. Nuclear • Kinetic 8. Magnetic EGR 4347

  5. EGR 4347 - Review • Give the unit of mass in the SI, Old English and English Engineering system. • SI - kg • Old English - lbm • English Engineering - slug EGR 4347

  6. EGR 4347 - Review • What is gc and how is it used? • Conversion constant - used with mass • What is a simple compressible substance? • The only important reversible work mode is volume change or pdv work. EGR 4347

  7. EGR 4347 - Review • What is the state postulate? • The state of a simple compressible system is completely specified by two independent, intensive properties. EGR 4347

  8. EGR 4347 - Review • What is a perfect or ideal gas (physical meaning)? • No dissociation • Intermolecular forces negligible • Occurs at low pressures and high temperatures (compared to critical point) • What is the ideal gas law? • P =  R T EGR 4347

  9. EGR 4347 - Review • Explain R in the ideal gas law. • Specific Gas Constant-depends on molecular weight • Give the equation for and define the Conservation of Mass. • dm/dt = 0 EGR 4347

  10. EGR 4347 - Review • Give the equation for and define Continuity. EGR 4347

  11. EGR 4347 - Review • Give the equation for and define 1st Law for a Control Volume. EGR 4347

  12. EGR 4347 - Review • Give the equation for and define the 2nd law for a Control Volume. EGR 4347

  13. EGR 4347 - Review • Define adiabatic. • No heat interaction. • Define reversible. • A process that can be reversed without leaving any trace on the surroundings. • Define isentropic. • ds=0 EGR 4347

  14. EGR 4347 - Review • Is an adiabatic, reversible process isentropic? • Yes • Is an isentropic process always adiabatic and reversible? • No • Is an isentropic, adiabatic process reversible? • Yes EGR 4347

  15. EGR 4347 - Review • Is an isentropic, reversible process always adiabatic? • No • What is a calorically perfect gas? • cp/cv = constant =  • For a calorically perfect gas what is du? • du=cvdT EGR 4347

  16. EGR 4347 - Review • For a calorically perfect gas what is dh? • dh=cpdT • What is Gibbs Equation? • Tds=dh-vdp=du+pdv • What is specific enthalpy? • h=u+pdv EGR 4347

  17. EGR 4347 - Review • Define total properties. • Fluid brought to rest isentropically (or adiabatically) • Write the equation for total enthalpy and total temperature. • ht=h+V2/(2gc) Tt=T+V2/(2gccp) EGR 4347

  18. EGR 4347 - Review • Explain the concept of isentropic efficiency as it applies to a turbine. EGR 4347

  19. EGR 4347 - Review • Draw the T-s diagram showing Turbine Isentropic Efficiency. EGR 4347

  20. EGR 4347 - Review • Derive cp = cv+ R from h = u + pv using the ideal gas law • h = u+pv = u+RT • dh = du + RdT +TdR dR=0 • dh/dT = du/dT + R • cp = cv + R EGR 4347

  21. EGR 4347 - Review • What is Mach number? • V/a where a is the speed of sound • Using Gibbs equation Tds = du + pdv find • s = cv ln(T2/T1) + R ln(v2/v1). EGR 4347

  22. EGR 4347 - Review • Find the following in terms of  using cp=cv+R • 1) R/cv • R/ cv = (cp/ cv) - 1 =  - 1 • 2)R/ cp • R/ cp = 1 - (cv / cp) = 1 - (1/  ) = ( - 1)/  EGR 4347

  23. EGR 4347 - Review • 3) (cv - R) / cp • (cv - R)/ cp = (cv / cp) - (R / cp) = 1/ - ( -1) /  = (2- )/ • 4) (cv - R) / cv • (cv - R)/ cv = 1 - ( - 1) = 2 -  EGR 4347

  24. EGR 4347 - Review • Use s = cp ln(T2/T1) - R ln(p2/p1) to find the isentropic relationship for pressure and temperature • cp ln(T2/T1) = R ln(p2/p1) • ln(T2/T1) = (R/cp ) ln(p2/p1) R/cp=(-1)/ • raise “e” to this power • (T2/T1) = (p2/p1) (-1)/ EGR 4347

  25. EGR 4347 - Review • Use Tt=T+V2/(2gccp) to find Tt/T in terms of  and Mach number • V = M a where a is SQRT(gc RT) • Tt=T+M2 RTgc/(2gccp) • (Tt/T) = 1 - M2 ( R)/(2cp) R/cp=(-1)/ • (Tt/T) = 1 - M2 (-1)/2 EGR 4347

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