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Exhaust Velocity Calculation

  1. Mar 3, 2009 #1
    Please check my calculations for the exhaust velocity of a rocket that uses Nitrogen Tetroxide (N2H4) & Aerozine 50 as its propelants. This is the formula that I'm using to find out the exhaust velocity:

    V_e = \sqrt{{\frac{T*R}{M}}*{\frac{2*k}{k-1}}*[1-(P_e/P)^(^k^-^1^)^/^k] }

    Ve = Exhaust velocity at nozzle exit, m/s
    T = absolute temperature of inlet gas, K
    R = Universal gas law constant = 8314.5 J/(kmol·K)
    M = the gas molecular mass, kg/kmol (also known as the molecular weight)
    k = cp / cv = isentropic expansion factor
    cp = specific heat of the gas at constant pressure
    cv = specific heat of the gas at constant volume
    Pe = absolute pressure of exhaust gas at nozzle exit, Pa
    P = absolute pressure of inlet gas, Pa

    T = 3110 Kelvin
    R = 8314.5
    M = 20.24
    k = 1.2314
    Pe = Pa = 1 atm
    P = 25 atm

    V_e = \sqrt{1,277,573.864 * 10.643 * 0.454}[/tex]

    V_e = \sqrt{6,173,137.26}

    Ve = 2,484.5799 meters per second

    Are this calculations correct or did I make a mistake? I got the equation and most of the data from these two sites: http://en.wikipedia.org/wiki/Rocket_engine_nozzles, http://www.braeunig.us/space/problem.htm#1.10, and http://www.braeunig.us/space/comb-NA.htm.
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
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