Author Question: Under conditions of turbulent flow, what is the driving pressure? a. Proportional to the square ... (Read 41 times)

viki · **on:** Jul 16, 2018

Under conditions of turbulent flow, what is the driving pressure?

a. Proportional to the square of the flow
b. Inversely proportional to the flow
c. Linearly proportional to the flow
d. Inversely proportional to the density

Question 2

Which of the following conditions tend to cause laminar flow to become turbulent (producing a high Reynold's number)?

1. High linear gas velocity
2. High gas density
3. Low gas viscosity
4. Smaller tube diameter
a. 2, 3, and 4 only
b. 2 and 3 only
c. 1, 2, and 3 only
d. 1 and 4 only

vish98 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: A
This changeover from laminar to turbulent flow depends on several factors, including fluid den-sity (d), viscosity (h), linear velocity (v), and tube radius (r). In combination, these factors deter-mine Reynold's number (NR):
NR = v d 2r/h

Answer to Question 2

ANS: C
In a smooth-bore tube, laminar flow becomes turbulent when NR exceeds 2000 (the number is dimensionless). According to the previous formula, conditions favoring turbulent flow include increased fluid velocity, increased fluid density, increased tube radius, or decreased fluid viscos-ity. In the presence of irregular tube walls, turbulent flow can occur when NR is less than 2000.