Question

he drag characteristics of a torpedo are to be studied in a water tunnel using a 1 : 7 scale model. The tunnel operates with freshwater at 20 ˚C, whereas the prototype torpedo is to be used in seawater at 15.6 ˚C. To correctly simulate the behavior of the prototype moving with a velocity of 53 m/s, what velocity is required in the water tunnel?

Answer 1

Answer:20.03 m/s

Explanation:

Given

$L_r=1:7$

velocity of Prototype $v_p=53 m/s$

Taking Froude number same for both flow as it is a dimensionless number for different flow regimes in open Flow

$(\frac{v_m}{\sqrt{L_mg}})=(\frac{v_p}{\sqrt{L_pg}})$

$v_m=v_p\times \sqrt{\frac{L_m}{L_p}}$

$v_m=53\times \frac{1}{\sqrt{7}}$

$v_m=20.03 m/s$