WK 3 TUTE
description
Transcript of WK 3 TUTE
M. Gumulya Transport Phenomena CHEN 3001
TransportPhenomenaCHEN3001Week 3 tutorial
TOPIC: Boundary layer, drag & lift
1. For a thin plate 15.2 cm wide and 0.914 m long, estimate the boundary layer thickness at the end of the plate and friction force in air moving at a velocity of 12.2 m/s, assuming: a. turbulent flow b. laminar flow
The flow is parallel to the width of the plate.
2. A hollow sphere of mass 0.05 g with diameter of 5 mm is released in a column of liquid and attains a terminal velocity of 0.5 cm/s. The density of the liquid is 0.9 g/cm3 and the wall effects on the moving sphere maybe neglected. Compute the drag force, friction factor (drag coefficient) and the viscosity ofthe liquid.
3. A commercial airplane has a total mass of 70,000 kg and a wing platform of 150 m2. The
plane has a cruising speed of 558 km/h and a cruising altitude of 12,000 m, where the air density of 0.312 kg/m3. The plane has double‐slotted flaps for use during take‐off and landing, but it cruises with all flaps retracted. Assuming the list and drag characteristics of the wings can be approximated using the graphs in Figure 2 (National Advisory committee for Aeronautics), determine:
a. The minimum safe speed for take‐off and landing with and without extending the flaps
b. Power that needs to be supplied to provide enough thrust to overcome wing drag
Figure: Lift and drag coefficients of the wing of an airplane