Deck 12: Turbomachinery

Question 1

Which of the following conditions is never a boundary condition in fluid mechanics?
(A) The velocity is zero at a boundary
(B) The normal component of velocity is zero in an inviscid flow at a boundary
(C) The tangential component of velocity is zero in an inviscid flow at a boundary
(D) The pressure is zero at a boundary

Answer 1

WHICH OF THE FOLLOWING CONDITIONS IS NEVER A BOUNDARY CONDITION IN FLUID MECHANICS?
(C) The tangential component of velocity is zero in an inviscid flow at a boundary
The tangential component of velocity must be tangential to the boundary at a solid
boundary, but usually, if not always, in an inviscid flow it is nonzero. A porous
boundary would provide a normal component of velocity to the fluid at the
boundary.
The pressure is zero (gage) at a boundary if the boundary is a free surface, the
atmosphere.
In a viscous flow, the fluid sticks to the boundary so it takes on the velocity of
the boundary, which is usually zero.

Question 2

$\text {If the \(x\)-component of velocity \(u\) depends only on \(y\) in a plane incompressible flow, the }$$y \text {-component of velocity } v \text { is: }$

A) f(y)
B) const
C) f(x)
D) 0

Answer 2

f(x)

Question 3

$\text {What four equations provide for the four unknowns \(u , v , w , p\) that are most often of interest in}$ $\text {fluid mechanics?}$

A) Continuity, momentum
B) Continuity, momentum, energy
C) Continuity, momentum, energy, equation of state
D) Continuity, momentum, energy, enthalpy relation

Answer 3

Continuity, momentum

Question 4

Three measurements are made of the x-component velocity in the diffuser of an incompressible plane flow to be 32 m/s, 28 m/s and 20 m/s. The measurement points are
Along the centerline of the symmetrical diffuser and are 4 cm apart. The y-component of the
Velocity 2 cm above the centerline is approximated to be:

A) 2 m/s
B) 3 m/s
C) 4 m/s
D) 5 m/s