A wind tunnel is designed to draw in air from the atmosphere and produce a velocity of 100m/s in the test section. THe fan is located downstream of the test section. What pressure is to be expected in the test section if the atmospheric temperature and pressure are -20C, 90kPa?
Bernoulli's Equation: P1 + 1/2pv2 + pgh1 = P2 + 1/2pv2 + pgh2
p = P/RT
The Attempt at a Solution
I cancelled out the heights as it doesn't state a height difference and says the fan is downstream, so assumed its a two dimensional problem. Leaving me with:
P1 + 1/2pv2 = P2 + 1/2pv2
Then I used p = P/RT to find the density of air, which came out to be 1.24kg/m3
Then Isolated P2 = P1 - 1/2pv2, using atmospheric pressure for P1, I solved for the pressure afterwards but it came out to be -560kPa.
Now i know taking the absolute value is acceptable with pressures but this number still seems wrong to me.