A circular hovercraft, of weight Mg, hovers a distance h above the ground, as shown in Figure P4.47. Far from the inlet the air is at atmospheric pressure and may be considered stationary. The air density remains constant throughout. The expansion downstream of the fan occurs without loss, and the exit streamlines are parallel to the ground. Find h in terms of the inlet velocity Vi , the diameter of the fan d, the diameter of the exit plane D, the density ρ and the weight Mg. Assume one-dimensional flow over the entry and exit areas.

A circular hovercraft, of weight Mg, hovers a distance h above the ground, as shown in Figure P4.47. Far from the inlet the air is at atmospheric pressure and may be considered stationary. The air density remains constant throughout. The expansion downstream of the fan occurs without loss, and the exit streamlines are parallel to the ground. Find h in terms of the inlet velocity Vi , the diameter of the fan d, the diameter of the exit plane D, the density ρ and the weight Mg. Assume one-dimensional flow over the entry and exit areas.