Flow straighteners consist of arrays of narrow ducts placed in a flow to remove swirl and other transverse (secondary) velocities. One element can be idealised as a square box with

thin sides as shown below. Calculate the pressure drop across a box with L-22 cm anda= 2.7 cm, if air with free-stream velocity of U= 13.4 m/s flows though the straightener. Use laminar flat-plate theory and takeu = 1.85 x 10- Pas and p=1.177kg/m3