Air at 30 $$30 ^ { \circ } \mathrm { C }$$ C and 200 kPa is flowing in a 30-cm-diameter pipe and difference between the inside of the bend and the outside of the
Bend is approximately:
Passes through the bend shown. An estimate of the pressure
A) 110 Pa
B) 140 Pa
C) 180 Pa
D) 240 Pa

Question

Air at 30 $$30 ^ { \circ } \mathrm { C }$$ C and 200 kPa is flowing in a 30-cm-diameter pipe and difference between the inside of the bend and the outside of the
Bend is approximately:
Passes through the bend shown. An estimate of the pressure 
A) 110 Pa 
B) 140 Pa 
C) 180 Pa 
D) 240 Pa

Quizplus · Accepted Answer

$110 \mathrm {~Pa}$
$\text {The difference in pressure normal to curved streamlines is given by Eq. 3.4.15:}$
$$\Delta p = \rho \frac { V ^ { 2 } } { R } \Delta n = \frac { 200 } { 0.287 \times ( 273 + 30 ) } \times \frac { 8 ^ { 2 } } { 0.4 } \times 0.3 = \underline { 110 \mathrm {~Pa} }$$
$\text {We have dropped the minus sign since the equation gives the difference between the }$$\text {inside and the outside.}$

Air at 30 30∘C30 ^ { \circ } \mathrm { C }30∘C

Air at 30 $30 ^ { \circ } \mathrm { C }$