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 bus 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 waves 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 Jose & 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 A2O-CaF2-B2O3 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 composites

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 axisymmetric 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 model 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. The 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 nozzle 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 compared 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 steam generator

Vijay G Ukadgaonkera, Yogesh D Khairnara, Pratichi Vaidyaa & P Chellapandib

 

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 of 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 junction 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 effective DK (DKeff) 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 approach) 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 simplifications 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 and 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 of 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 source, 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 to 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 pressure 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 ecovery 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 the 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 power supply (LPS) system

C K Chandaa, Sunita Deyb, A Chakrabartia* & A K Mukhopadhyayc

 

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 inductive 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 higher (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 Kumara , S Joseb & G Venkateswara Raoa*

 

Intralaminar fracture toughness 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 percentage 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 ilmenite by rusting in NH4Cl 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 ³ 92% TiO2. Whereas Quilon ilmenite could be reduced with carbon at 950°C for 2 h in presence of 5% Na2CO3, 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% K2CO3 catalyst. The upgraded rutile product containing 92-93% TiO2 was obtained when reduced ilmenite was rusted in 1% NH4Cl solution at a pH 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 A2O-CaF2-B2O3 glasses

G Venkateswara Raoa, G Srinivasa Raoa, P Yadagiri Reddyb & N Veeraiaha

Thermoluminescence study on X-ray irradiated A2O - CaF2 - B2O3 (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 these glasses are doped with different conventional activating or killing ions (viz., Sn2+, Ag+, Ce3+, Bi3+ and Cu2+) 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 Engineering & Materials Sciences

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

 

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

S A R Hashmia*, T Kitanob, S R Vashishthaa & Navin Chanda

 

Kevlar and glass fibres have been used 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 (w) and reinforcement. 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 temperature on slip and deformation twinning in Cd single-crystals

A E Ekincia, N Uçarb*, G Çankayac & B Düzgüna

 

The temperature effect on slip and deformation twinning has been investigated in Cd single-crystals in tension in the temperature range from room temperature 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 twinning 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 direction. 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.