A ramjet engine operates as follows: 1-2: air is decelerated isentropically in a diffuser 2-3: fuel...

   

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A ramjet engine operates as follows: 1-2: air is decelerated isentropically in a diffuser 2-3: fuel addition and combustion are approximated as an isobaric addition of heat to the system. No mass addition due to the fuel. 3-4: air is accelerated isentropically in a nozzle FUEL BURNERS AIR INTAKE COMBUSTION CHAMBER PROPELLING NOZZLE The ambient temperature is -53C and the ambient pressure is 0.6 bar. Relative to the airframe, air approaches the engine at a supersonic speed, C = 3.5KRT1 where k = 1.4 is the ratio of heat capacities. After the diffuser, air has decelerated to c = 84 m.s1. The same velocity is observed at the outlet of the combustion chamber. The heat addition is 800 kJ.kg 1. The pressure of the exhaust gas equals the ambient pressure. Calculate the temperatures at each point, the pressure inside the combustion chamber, the exit velocity C4, and hence the Mach number of exit gas from M4 C4 = KRT4 Maximum marks will be awarded as follows: a) A succinct problem statement (1 mark) b) A plant diagram (3 marks) c) A T-S diagram (3 marks) d) A list of assumptions made to solve the question (2 marks) e) A list of physical laws used to solve the question (2 marks) f) Calculations (17 marks) 1. Calculate T2, T3 and T4. (9 marks) 2. Calculate the pressure in the combustion chamber. (3 marks) 3. Calculate the exit velocity. (3 marks) 4. Calculate the exit Mach number. (2 marks) A ramjet engine operates as follows: 1-2: air is decelerated isentropically in a diffuser 2-3: fuel addition and combustion are approximated as an isobaric addition of heat to the system. No mass addition due to the fuel. 3-4: air is accelerated isentropically in a nozzle FUEL BURNERS AIR INTAKE COMBUSTION CHAMBER PROPELLING NOZZLE The ambient temperature is -53C and the ambient pressure is 0.6 bar. Relative to the airframe, air approaches the engine at a supersonic speed, C = 3.5KRT1 where k = 1.4 is the ratio of heat capacities. After the diffuser, air has decelerated to c = 84 m.s1. The same velocity is observed at the outlet of the combustion chamber. The heat addition is 800 kJ.kg 1. The pressure of the exhaust gas equals the ambient pressure. Calculate the temperatures at each point, the pressure inside the combustion chamber, the exit velocity C4, and hence the Mach number of exit gas from M4 C4 = KRT4 Maximum marks will be awarded as follows: a) A succinct problem statement (1 mark) b) A plant diagram (3 marks) c) A T-S diagram (3 marks) d) A list of assumptions made to solve the question (2 marks) e) A list of physical laws used to solve the question (2 marks) f) Calculations (17 marks) 1. Calculate T2, T3 and T4. (9 marks) 2. Calculate the pressure in the combustion chamber. (3 marks) 3. Calculate the exit velocity. (3 marks) 4. Calculate the exit Mach number. (2 marks)