An airplane is flying at an altitude of 10,000\,m with a turbojet engine at a velocity of 900\, km/h. The inlet and exit areas of the turbojet engine are 0.9\,m^2 and 1.3\,m^2. Find the thrust produced by the engine if the exhaust velocity and pressure are 500\,m/s and 32500\,N/m^2.
An airplane is flying at an altitude of 10,000\,m with a turbojet engine at a velocity of 900\, km/h. The inlet and exit areas of the turbojet engine are 0.9\,m^2 and 1.3\,m^2. Find the thrust produced by the engine if the exhaust velocity and pressure are 500\,m/s and 32500\,N/m^2.
Thrust produced by a turbojet engine is given as
T = \dot m\left( {{V_e} – {V_\infty }} \right) + \left( {{P_e} – {P_\infty }} \right){A_e}
At an altitude of 10 000\,m ,
{P_\infty } = 2.65 \times {10^4}\,N/{m^2}
{\rho _\infty } = 0.41351\,kg/{m^3}
{V_\infty } = \,900\,km/h = \,250\,m/s
\dot m = {\rho _\infty }{A_i}{V_\infty } = \,0.41351 \times 0.9 \times 250 = 93.04\,kg/s
Therefore , Thrust
T = 93.04\left( {500 – 250} \right) + \left( {32500 – 26500} \right)1.3 = 31060 \,N
