First slide

Fluid dynamics

Question

The speed of flow past the lower surface of a wing of an aeroplane is 50 ms^-1. What speed of flow over the upper surface will give a dynamic lift of 1000 Pa? Density of
air = 1.3 kg m^-3

Moderate

A

63.55 m/s
B

25.55 m/s
C

13.25 m/s
D

None

Solution

Applying Bernoulli's theorem to the lower and upper surface of a wing
$\begin{array}{l} P_{1} + \frac{1}{2} ρ v_{1}^{2} = P_{2} + \frac{1}{2} ρ v_{2}^{2} \\ ⇒ P_{1} - P_{2} = \frac{1}{2} ρ (v_{2}^{2} - v_{1}^{2}) \\ \Rightarrow 1000 = \frac{1}{2} \times 1.30 (v_{2}^{2} - 50^{2}) [∵ lift = P_{1} - P_{2}] \\ ⇒ v_{2}^{2} - 2500 = 2000 / 1.3 \\ ⇒ v_{2} = 63.55 m / s \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App