Your job is to design a hovercraft to transport a family of eelsacross the Engli
ID: 1717713 • Letter: Y
Question
Your job is to design a hovercraft to transport a family of eelsacross the English Channel. The hovercraft weights 50,000 newtons, it's a circle with a diameter D of 6 metres. The gap, h, is 3 cm Assume air at sea-level standard day conditions. Assume that the hovercraft "hovers" so the air at station is essentially stagnant. Estimate the gage pressure of air at station Estimate the airflow rate in m^3/sec Estimate the air mass flow rate in kg/sec Estimate the power delivered by the fan to the control volume (in W)Explanation / Answer
Due to some technical error I am unable to attach the pictures.
Solution:
a. Gauge pressure:
THe whole station load 50KN is balanced by air pressure.
Surface area of the station , neglecting the fan area
A = 2(pi)r^2 = 56.55m2
(Pgair +1) * A = F
50000 = (Pgair+1)*56.55
Pgair = 883.2 atms
b. Air flow rate.
Since the only way air can escape is per second through the gap of 3cm which is cylindrical in volume.
Vair = (pi)r^2h where h = 3cm
Vair = 0.848m3/sec
c. Mass Flow rate Mair = density of air * Vair
Mair = 1.225*0.848= 1.039kg/sec
d. power delivered by fan = air mass flow *g*distance diplaced
= 1.039 * 3*10
= 31.17W
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