Indian Journal of Engineering & Materials Sciences

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Indian Journal of

Engineering & Materials Sciences


VOLUME 9

NUMBER 4

AUGUST 2002


CONTENTS


Engineering

Numerical simulation of supersonic turbulent jets impinging on an axisymmetric
deflector


227



R C Mehta




Leak
-
before
-
break analysis of shell
-
nozzle junction of steam generator

237



Vijay G Ukadgaonker, Yogesh D Khairnar, Pratichi Vaidya & P Chellapandi




Lean
-
knock limits for dual
-
fuel combustion of natural
gas in diesel engine

250



O M I Nwafor




On improving the spectral purity of the regenerated clock signal in a data clock
recovery circuit


255



M Ghosh, A Hati & B C Sarkar




Determination of b
us security governed by sensitivity indicator in a reactive power
constraint longitudinal power supply (LPS) system


260



C K Chanda, Sunita Dey, A Chakrabarti & A K Mukhopadhyay




Amplification and attenuation of acoustic wav
es in silicon inversion layer of MOSFET
structure


265



Kasala Suresha & P S Naik




Materials Science


Evaluation of intralaminar fracture toughness of angle ply laminate

269



R Ramesh Kumar, S Jos
e & G Venkateswara Rao




Studies on the upgrading of Indian ilmenites to synthetic rutile

275



D V Baubande, P R Menon & J M Juneja




Influence of certain metal ions on thermoluminescence of A
2
O
-
CaF
2
-
B
2
O
3

glasses

282



G Venkateswara Rao, G Srinivasa Rao, P Yadagiri Reddy & N Veeraiah




Organic/inorganic hybrid fibre reinforced thermoplastic composites and their
rheological properties


289



S A R Hashmi, T Kitano, S

R Vashishtha & Navin Chand




Effect of temperature on slip and deformation twinning in Cd single
-
crystal

295



A E Akinci, N Ucar, G Cankaya & B Duzgun




Sliding wear behaviour of woven glass fibre reinforced polyster co
mposites

299



Navin Chand & Somit Neogi




Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 227
-
236


Numerical simulation of supersonic turbulent jets impinging on

an axisymmet
ric deflector

R C Mehta


The objective of this work is to model under
-

and over
-
expanded turbulent compressible supersonic
jets impinging on an axisymmetric jet deflector. The closure of the system of equations is achieved using
a two
-
equation turbulence m
odel with, an optional compressibility correction. A finite
-
volume
discretization is carried out in spatial coordinates to compute inviscid and viscous flux vectors. A
multistage Runge
-
Kutta time stepping scheme is used to obtain a steady state solution. T
he numerical
algorithm is developed by taking into consideration structured grid arrangement. The numerical results are
obtained for nozzle exit Mach number of 2.2 and 3.1, exit to ambient pressure ratio of 0.8 and 1.2, and at
different distance from nozzl
e exit to the apex of the deflector. The numerical scheme is shown to be
computationally fast, easy to program and efficient. The centre line pressure variation inside the jets
differs in the presence of the jet deflector. The numerical results are compare
d with the available
experimental data and are found to be in reasonably good agreement.


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 237
-
249


Leak
-
before
-
break analysis of shell
-
nozzle junction of st
eam generator

Vijay G Ukadgaonker
a
, Yogesh D Khairnar
a
, Pratichi Vaidya
a

& P Chellapandi
b


Investigations on leak
-
before
-
break analysis of shell
-
nozzle junction of steam generator (SG) are
presented here. Steam generators are integral parts of the nuclear
power plants. So, to prevent the
catastrophic failure of such components nowadays, leak
-
before
-
break (LBB) concept is used. There are
three levels of checking LBB behavior, namely leve1 1,

level 2 and level 3. Level 1 is inherent in the design philosophy o
f ASME Sec. III, which is normally
followed in the pipe design. This paper describes level 2 and level 3 LBB analysis for SG shell
-
nozzle
junction.

In level 2, crack propagation analysis of surface crack at the most critical locations of SG shell
-
nozzle ju
nction was carried out, showing thereby, that crack growth is insignificant during the complete
one power plant life cycle. Crack propagation analysis was conducted as defined in RCC
-
MR code. The
methodology based on Paris law, which needs evaluation of ef
fective



(


eff
) taking into account
effect of plasticity and crack closure coefficient, was used.

In level 3, through
-
wall leak size cracks (LSC) were postulated at the most critical locations and
crack instability analysis was carried out under maximum

credible loading conditions (e.g. earthquake).
For crack instability analysis, various steps namely determination of leakage area and leak size crack
(LSC) using leak
-
rate model, elastic
-
plastic fracture mechanics analysis (
J
-
integral/tearing modulus
appr
oach) and limit load analysis (twice elastic slope method) were carried out. For the evaluation of
critical load, elastic
-
plastic fracture mechanics analysis and for the evaluation of limit load, limit load
analysis were carried out. Since no geometrical s
implifications were possible for SG shell
-
nozzle junction,
complete three
-
dimensional non
-
linear finite element analysis was performed. And, it has been proved
that, because of postulated cracks, SG shell nozzle junction would not fail in ductile tearing a
nd plastic
collapse under maximum credible load that may act during a safe shutdown earthquake (SSE).


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 250
-
254


Lean
-
knock limits for dual
-
fuel combustion o
f natural gas in diesel
engine



O M I Nwafor


The use of natural gas as energy source for internal combustion (IC) engines has an attractive
intuitive appeal due to its environmentally friendly nature. Whilst successful commercialisation of this
energy sour
ce, it requires that it offers cost advantages over competing fuels. It has been considered as
potential source of fuel energy for compression ignition (CI) engines due to its high octane value (RON
131) necessitating for the use of high compression ratios
. In this paper, the operating range (lean
-
knock
limits) for dual
-
fuel combustion of natural gas in an unmodified diesel engine has been investigated. The
factors influencing the knock and lean limits have been identified. The delay period has been noted t
o
feature in defining knock limit and high concentrations of hydrocarbon (HC) in the exhaust. The cylinder
pressure diagram indicated longer ignition delay and reduced maximum peak cylinder pressure when
operating beyond these limits, with an increased pre
ssure fluctuation.


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 255
-
259


On improving the spectral purity of the regenerated clock signal in a
data clock
e
covery circuit

M Ghosh, A Hati & B C Sarkar


The present paper reports a novel phase locked loop (PLL) based clock recovery circuit, which makes
use of a sample and hold circuit to improve the spectral characteristics of the regenerated clock signal.
Experimental results are incorporated to verify th
e predicted operation of the system.


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 260
-
264


Determination of bus security governed by sensitivity indicator in a
reactive power constraint longitudinal p
ower supply (LPS) system

C K Chanda
a
, Sunita Dey
b
, A Chakrabarti
a*

& A K Mukhopadhyay
c


Degree of weakness of a bus in a longitudinal power supply (LPS) system, governed by the reactive
power sensitivity of the concerned bus being investigated, simulations

have been performed in order to
exhibit the variation of real and reactive power sensitivity with respect to bus voltages for variations in
load levels of that bus. The effects of Static Var Compensator (SVC) application in capacitive as well as
in induct
ive modes of operation on the bus power sensitivities, the variation in corresponding margins of
bus power sensitivities, as well as on bus voltage magnitudes are reported here.


Indian Journal of Engineering & Materials Sciences

Vol
. 9, August 2002, pp. 265
-
268


Amplification and attenuation of acoustic waves in silicon inversion
layer of MOSFET structure

Kasala Suresha* & P S Naik




Calculations of electron
-
acoustic phonon interaction and phonon absorption of Si(001) inversion
layer

have been studied at low temperature for the MOSFET structure by using displaced Fermi
-
Dirac
distribution function. The strong dependence of normalized dc field on emission and absorption of
phonons has been analyzed. If the electron drift velocity is hig
her (smaller) than sound velocity, phonon
emission (absorption) takes place. The numerically calculated phonon absorption shows a good agreement
with the existing experimental data. The dependence of layer thickness on scattering rate has been
discussed.



Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 269
-
274


Evaluation of intralaminar fracture toughness of angle ply laminate

R Ramesh Kumar
a
, S Jose
b

& G Venkateswara Rao
a
*


Intralaminar fracture toughn
ess values of [0

]
30
, [45

]
30

and [90

]
30

carbon/epoxy
laminates are theoretically evaluated based on the well
-
known MCCI method
corresponding to the fracture loads obtained by testing C(T) specimens. Comparison of
fracture toughness of angle ply laminate,

which is associated with both mode I and mode
II, show a very good agreement with the theoretical prediction. A

new empirical
relationship is developed to obtain
the intralaminar fracture toughness of an angle ply
laminate

from the corresponding value of
the 0


laminate. The new formula is used to
compare fracture toughness of angle ply laminates available in literature for glass epoxy
Scotch ply 1002 laminate and a reasonably good agreement is observed between the test
data and the predictions. As a perce
ntage of total fracture toughness value, toughness due
to mode II is maximum of 15.5% when fibre orientation is 45

.



Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 275
-
281


Studies on the upgrading of
Indian ilmenites to synthetic rutile

D V Baubande, P R Menon & J M Juneja


A process based on solid state reduction of iron oxide content of ilmenite with carbon in presence of
alkali carbonate catalysts followed by removal of iron content of reduced ilmen
ite by rusting in NH
4
Cl
solution has been investigated for upgrading the Indian ilmenites (Quilon and Orissa grades) to synthetic
rutile. The process variables such as the temperature of reduction, presence of catalytic agents during
reduction and rusting
conditions etc. were examined to obtain an upgraded product containing


92%
TiO
2
. Whereas Quilon ilmenite could be reduced with carbon at 950

C for 2 h in presence of 5% Na
2
CO
3
,
the reduction of Orissa ilmenite required a pre
-
oxidation treatment in air at

850

C followed by reduction
with carbon at 1025

C for 4 h in presence of 5% K
2
CO
3

catalyst. The upgraded rutile product containing
92
-
93% TiO
2

was obtained when reduced ilmenite was rusted in 1% NH
4
Cl solution at a
p
H of 4.5 and a
temperature of 65

C.


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 282
-
288




Influence of certain metal ions on thermoluminescence of A
2
O
-
CaF
2
-
B
2
O
3

glasses

G Venkateswara Rao
a
, G Srinivasa Rao
a
, P Yadagiri Reddy
b

& N Veeraiah
a

Thermoluminescence study on X
-
ray irradiated A
2
O
-

CaF
2
-

B
2
O
3

(where A=Li, Na and K) glasses
has been carried out in the temperature range 303
-
600 K. All these glasses exhibit a single TL glow peak
between 480
-
500 K; the study is further extended after t
hese glasses are doped with different conventional
activating or killing ions (viz., Sn
2+
, Ag
+
, Ce
3+
, Bi
3+

and Cu
2+
) in small concentration (0.2%). All these
ions are observed to inhibit the TL light output in these glasses. The trap depth parameters with
the
observed TL glow curves have been evaluated using Chen’s formulae. The probable mechanism
responsible for quenching of thermoluminescence emission by dopant ions in these glasses has been
suggested.



Indian Journal of Engineeri
ng & Materials Sciences

Vol. 9, August 2002, pp. 289
-
294


Organic/inorganic hybrid fibre reinforced thermoplastic composites and
their rheological properties

S A R Hashmi
a*
,

T Kitano
b
, S R Vashishtha
a

& Navin Chand
a



Kevlar and glass fibres have been use
d to reinforce linear low density polyethylene (LLDPE) and the
composite sheets of 0.8 mm thickness have been obtained by using a compression molding technique.
Dynamic viscoelastic properties of non
-
hybrid and hybrid composites of various compositions are

evaluated at 200°C. Dynamic viscosity (η΄), storage modulus (

) and loss modulus (
G
΄΄) have been
determined at different angular frequencies (ω). Dynamic viscosity η΄ increases with reinforcements.


and
G
΄΄ increase with angular frequency (

) and reinf
orcement. Replacement of glass fibre by Kevlar at
constant loading of fibres in LLDPE, increases the value of
G
΄,
G
΄΄ and η΄.


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 295
-
298


Effect of temperat
ure on slip and deformation twinning in Cd single
-
crystals

A E Ekinci
a
, N Uçar
b*
, G Çankaya
c

& B Düzgün
a


The temperature effect on slip and deformation twinning has been investigated in Cd single
-
crystals
in tension in the temperature range from room temp
erature to 500 K. The observations of traces on the
surfaces of the crystals show that there are twinning and slip at room temperature. Above 430 K slip takes
place on the limited slip plane. On the other hand, as the temperature increases deformation twin
ning
occurs on some new twinning plane after considerable slip, although deformation twinning is a common
low temperature mode of plastic deformation. It is shown that the multiplicity of twinning systems aids
deformation by twin rather than by slip in Cd
single
-
crystals at high temperatures.


Indian Journal of Engineering & Materials Sciences

Vol. 9, August 2002, pp. 299
-
306




Sliding wear behaviour of woven glass fibre reinforced polyester
composites

Navin Chand & Somit Neogi


The
dry sliding wear behaviour of woven glass fibre reinforced polyester composites has been studied
by using pin
-
on
-
disc machine. The friction and wear experiments have been conducted on three different
orientation of glass fibre with respect to sliding direc
tion. The coefficient of friction and wear of the
composites at various applied load and sliding speeds have been determined. The lowest coefficient of
friction and wear values observed for the fibres oriented in 0°
-
90° direction and highest are for normal
-
longitudinal (N
-
L) orientation. The applied load further increase the friction and wear of the composites
for all orientations. The friction and wear behaviour have been dominated by a number of mechanisms.
The wear of the fibres has been dominated by the

fibre fracture. The fibres have been fractured because of
bending of fibre due to dragging by the steel disc in the sliding direction. The microscopic observations of
the worn surfaces revealed and supported the involved mechanism.