# Find the thrust produced by turbojet engine.

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 $$32500\,N/m^2$$.

Asked on 12th February 2021 in

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

$T = 93.04\left( {500 – 250} \right) + \left( {32500 – 26500} \right)1.3 = 31060 \,N$