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Homework Help: Thermofluids Question wind tunnel u tube manometer

  1. Aug 20, 2007 #1
    1. The problem statement, all variables and given/known data
    Air at 20 degrees celsius and 100kpa is drawn into a wind tunnel. If the deflection h of a water manometer that is connected to a hole in the wall of the test section to measure the gauge pressure in the flow is 98mm. Calculate air speed in test section in m/s ignore fluid friction .
    Take R of air to be 287 j/kgK and density of water to be 1000 kg/m3 and g= 9.81

    part b) if the air speed is 45 m/s calculate the deflection h in the manometer.

    2. Relevant equations
    I have been having trouble with this for ages now and am really stuck have been looking at Pressure= density xg x height giving 961.38 Pa then using pv=nrt v=87.469 using this method unsure if im barking up the wrong tree?

    for part b) again using p=nRT/v = 1868.68 Pa then using P=densityxgxdelta h giving 190mm or 0.19m however this doesnt sound right to me as the 45 m/s air speed is causing a greater deflection that the previously worked out air speed so i am sure something is not quite right but what? I am converting 20 degrees to 293 K and using that any suggestion?

    If anyone needs a drawing i will attempt one in paint.

    Thanks very much in advance
  2. jcsd
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