# Department of Mechanical Engineering

Mechanics

Oct 24, 2013 (4 years and 8 months ago)

100 views

Department of Mechanical Engineering

SUBJECT: AMEE 202
-

FLUID MECHANICS I

DATE:
To be announced

TIME:
50 Minutes

INSTRUCTIONS TO CANDIDATES:

all

questions

from Section A and
two

question from Section B
.

All necessary work must be show
n. Wherever needed:

Student Name: ………………………….

Registration Number: …………….

___________________________________________________________________

SECTION A

QUESTION 1

[
20

Marks]

Fluid

with mean velocity 5 m/s flows over a sph
ere

to produce the flow pattern shown
on the left figure
.

The same fluid flows over a sphere half the size of the original
sphere and produces the same flow pattern

(r
ight figure).

a.

State whether the flow is laminar or turbulent and explain

b.

Determine the v
elocity of the fluid on the latter case.

QUESTION 2

[20 Marks]

Small
-
diameter, high
-
pressure liquid jets can be used to cut various materials as
shown in the Figure. If viscous effects are negligible, estimate the pressure needed
to produce a
-
diameter water jet with a speed of

Determine the
flowrate

and the Reynolds number.

SECTION B

QUESTION 3

[
3
0

Marks]

A static thrust stand as sketched in the figure is to be designed for testing a j
et
engine. The following conditions are known for a typical test:

i.

Intake air velocity =

ii.

E
xhaust gas velocity =

iii.

I
ntake cross
-
sectional area =

iv.

I
ntake static pressure =

v.

I
ntake static temperature =

vi.

E
xhaust static pressure =

Estimate the mass flow rate.

Note: the ideal gas equation of state is

QUESTION 4

[
30

M
arks]

The viscosity of liquids can be measured through the use of a
rotating cylinder
viscometer

of the type illustrated in the figure. In this device the outer cylinder is fixed
and the inner cylinder is rotated with an angular velocity,
. The torque

required
to develop

is measured and the viscosity is calculated from these two
measurements. If the liquid under testing is
oil with

determine the
to
rque developed if
the inner cylinder rotates with
. Neglect end effects and assume the
velocity distribution in the gap is linear.

a.

Find the velocity of the surface of the inner cylinder

b.

Find the Shear Stress on the inner cylinder
.

c.

Find the total force acting on the inner cylinder, and the Torque.

QUESTION
5

[
30

Marks]

A hot air balloon weighs
, including the weight of the balloon, the basket and
one person. If the density of the hot air inside
the balloon is
,
determine the required volume of the balloon to support the weight. If the balloon had
a spherical shape
, what would be the required diameter?