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Find the Mass Flow Rate Through the Nozzle

  1. Feb 18, 2013 #1
    1. The problem statement, all variables and given/known data
    Helium gas flows through a well-insulated nozzle at steady state. The temperature and the velocity at the inlet are 550°R and 150 ft/s, respectively. At the exit, the temperature is 400°R and the pressure is 40 lbf/in2. The area of the exit is 0.0085 ft2. Using the ideal gas model with k = 1.67, and neglecting potential energy effects, determine the mass flow rate in lb/s through the nozzle

    2. Relevant equations

    3. The attempt at a solution

    My initial response is to use:

    m' = ρvA

    but I'm not sure if this is how they want me to find the answer. My professor mentioned:

    Cp - Cc = R

    Is this referring to specific heats?

    My notes also say Cp is constant. What is this referring to? Likewise, what is the significance of the k=1.67?
  2. jcsd
  3. Feb 18, 2013 #2


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    k is the ratio of specific heats of the gas:

    k = Cp/Cv
  4. Feb 18, 2013 #3
    What is the significance of giving me the ratio of the specific heats of the helium?
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