Problems: Space Propulsion

Problems:

1.A rocket moves with a velocity of 10,000 km/hr with an effective exhaust velocity of 1400 m/sec, the propellant flow rate is 5 kg/sec and the propellant mixture has a heating value of 6500 kJ/kg. Find

1.    Propulsion efficiency

2.    Engine output power

3.    Thermal efficiency

Overall efficiency

Tutorial problems:

1. Calculate the orbital and escape velocities of a rocket at mean sea level and an altitude of 300km from the following data:

Radius of earth at mean sea level =6341.6Km Acceleration due to gravity at mean sea level =9.809 m/s²

2. A missile has a maximum flight speed to jet speed ratio of 0.2105 and specific impulse equal to 203.88 seconds .Determine for a burn out time of 8 seconds

a) Effective jet velocity

b) Mass ratio and propellant mass functions c) Maximum flight speed, and

d) Altitude gain during powered and coasting flights

A ramjet engine operates at M=1.5 at an altitude of 6500m.The diameter of the inlet diffuser at entry is 50cm and the stagnation temperature at the nozzle entry is 1600K.The

calorific value of the fuel used is 40MJ/Kg .The properties of the combustion gases are same as those of air (y =1.4, R=287J/Kg K ). The velocity of air at the diffuser exit is negligible. Calculate

(a)the efficiency of the ideal cycle,

(b) flight speed

(c)  air flow rate

(d) diffuser pressure ratio

(e) fuel –ratio (f)nozzle pressure ratio

(g) nozzle jet Mach number

(h) propulsive efficiency

(i) and thrust.

Assume the following values:0D =0.90,0B =0.98, 0 j= 0.96. Stagnation pressure loss in the combustion chamber =0.002Po2.