Ask Question
22 March, 00:52

You are testing a new jet engine in a test cell at sea level conditions. You measure the mass flow through the engine and find it is 125 kg/sec of air plus 2.5 kg/sec of fuel. The velocity ahead of the engine may be assumed to be zero (it is a static test). The velocity of the exhaust is 340 meters/second. The load cell in the test stand (which measures engine thrust) reads 60,000 Newtons. Is the load cell reading correctly within 2%? If not, what should the load cell read?

+5
Answers (2)
  1. 22 March, 01:09
    0
    43248 newtons.

    Explanation:

    Force = mass x accelerations and units of force are newtons which are given in the question.

    here mass = 125 of air and 2.2 of fuel, total = 125+2.2=127.5kg/s and the velocity of the exhaust is 340m/s.

    force = 340m/s * 127.5kg/s = 43248 newtons technically this is wrong (observe units) but i will expalin how i have taken acceleration as a velocity here and mass/unit time as simply mass.

    see force is mass times acceleration or deceleration, here our velocity is not changing therefore it is constant 340m/s but if it were to change and become 0 in one second then there would be - 340m/s^2 (note the units) of deceleration and there would be force associated with it and that force is what i have calculated here. similarly there would be mass in flow rate of mass per second, which is also in that one second of time.

    let's calculate error.

    error = (actual-calculated) / actual. = (43248-60000) / 43248 = - 38.734% less is ofcourse greater than 2%.

    So the load cell is not reading correct to within 2% and it should read 43248newtons.
  2. 22 March, 03:56
    0
    The answer is 43350 newton

    Explanation:

    As per the question,

    Mass=125.

    Air = 2.5

    Velocity=340.

    So the formula is,

    F=ma.

    Total=125+2.5=127.5

    Applies the formula now,

    F=ma

    force = 340*127.5 = 43350

    Calculate error now,

    Error = ((actual-calculated) / actual))

    (43350-60000) / 43350 = - 38.40%

    Hence greater than 2%.
Know the Answer?
Not Sure About the Answer?
Find an answer to your question ✅ “You are testing a new jet engine in a test cell at sea level conditions. You measure the mass flow through the engine and find it is 125 ...” in 📘 Engineering if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions.
Search for Other Answers