Aeronautical Engineering Aerospace Technology
1. Investigate the history, development of aerospace propulsion systems. Examples may be chosen from air-breathing propulsions such as piston engine, gas turbine engines (turbojet, turbofan, turboprop, turboshaft engines), ramjet, scramjet, etc.; or non-air breathing systems such as rocket, electromagnetic and electrical propulsions etc. [Marks: 10] 2. Determine the thrust for the following rocket motor that is mounted on a test stand. Inside its thrust chamber, liquid oxygen (LOX) and liquid hydrogen are steadily injected at 8 kg/s and 1 kg/s respectively and ignited. The combustion products are expelled from the rocket through a nozzle with a diameter of 21.2 cm. The static pressure of the exhaust gases existing the nozzle is 128 kPa. Assume that the ambient air pressure is 101.3 kPa, and the density of the combustion gases is 0.177 kg/m3 . [Marks: 10] 3. Explain what is meant stoichiometric condition, and discuss the applications of this condition in aerospace and aeronautical industries. Find stoichiometric Air/Fuel ratio for the combustion of liquid ethyl alcohol (C2H6O). [Marks: 10] 4. For a turbojet engine shown in the following figure, the total temperatures at the following stations are given that ð‘‡ð‘¡1 = 288.2 K, ð‘‡ð‘¡3 = 1300 K, 3 ð‘‡ð‘¡4 = 940 K. The mass flow rates are ð‘šÌ‡ ð‘Žð‘–ð‘Ÿ = 75 kg/s, ð‘šÌ‡ð‘“ð‘¢ð‘’ð‘™ = 1.27kg/s, and the specific heat for cold air is ð¶ð‘,ð‘ð‘œð‘™ð‘‘ = 1005 J/kg.K, and for hot gas is ð¶ð‘,â„Žð‘œð‘¡ = 1100 J/kg.K. Assume that the turbine only provided the power required by the compressor, determine: (ð‘Ž) the total temperature of the air at the outlet of the compressor ð‘‡ð‘¡2; (ð‘) combustor efficiency ðœ‚ð‘ð‘, if the lower heating value (LHV) of the fuel is 45 MJ/kg. [Marks: 10] 5. A rocket motor is expected to design for the use of the 2nd stage of a space launcher. It is required to work at altitude of 19.3 km, at which the atmosphere pressure ð‘ƒ0 = 6200 Pa. If the propellants are given, and chamber pressure Pc =6.20 MPa, and the exhausted gaseous products of combustion have a ratio of specific heats ï§ = 1.32. Assume this is an ideal rocket with a steady and isentropic flow through the chamber. Determine the nozzle expansion ratio ðœ€ so that the nozzle is performed for optimal (full) expansion. [Marks: 10] 6. Discuss the thrust profiles, with the aid of thrust-time diagram, for the following different grain cross-section geometries used in solid rockets: Tubular; Rod and Tube; Double Anchor; Start; Multi-fin; Dual Composition. [Marks: 10] 7. Consider an axisymmetric ramjet intake with a conical nose plug having a half-nose angle ðœƒ = 10°. The ramjet operates at sea level while flying at ð‘€0 = 2.2. Using the two-dimensional shock relations, determine the total pressure ð‘ƒð‘¡2, static pressure ð‘ƒ2, total temperature ð‘‡2ð‘¡ , and static temperature ð‘‡2. Note, the standard sea-level conditions are used where ð‘ƒ0 = 101.3 kPa, ð‘‡0 = 288.2 K, and ð›¾ = 1.4. The oblique shock relations and normal shock tables shall be used in the calculation as well, which have been given as handouts. [Marks: 10] 8. With the aid of a diagram, explain how a turbo-ramjet operates, and give examples of the turbo-ramjet engines that are used in aerospace and aeronautical industries. [Marks: 10] 4 9. An artificial satellite is orbiting at an altitude of 200 km above the Earth's surface. Assume that the radius of the Earth is 6378.140 km, and the parameter GM of the Earth is equal to 3.986005 × 1014 m 3 /s2 . (a) Determine the velocity of the satellite orbiting the Earth. (b) Determine the period of revolution of the satellite. (c) show that the velocity of an artificial satellite, ð‘‰, is r R GM V ï€« ï€½ [Marks: 10] 10.Explain what is meant by compressor surge in gas turbine engines. Discuss the causes of the compressor surge, as well as the effects of it
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