Engineering & Materials Sciences
http : // www.niscair.res.in
VOLUME 9
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NUMBER 6
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DECEMBER 2002
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CODEN : IEMSEW |
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ISSN :
0971-4588 |
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Foreword |
399 |
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Papers |
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Effect of
different annulus heights on performance of annular gas turbine model
combustor |
403 |
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Simulation
of small disturbance waves over alternate rigid and compliant panels |
409 |
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Dynamic
behaviour of indirect coupled heat exchanger systems |
414 |
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Distortion
of guide vane assembly in a bulb turbine due to cavitation and reverse water
flow |
419 |
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R Rudramoorthy, N Kuppuswamy,
D Rajenthirakumar & K V Manikandan |
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Experimental
investigation of tip clearance effects on flow field in an annular turbine
rotor cascade |
424 |
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Flow
distribution in spherical header of a liquid metal-cooled fast breeder
reactor |
432 |
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Design and
development of water hydraulic pressure compensated flow control valve |
440 |
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Saurabh Pandharikar,
Abhijit Khuperkar, N L Soni & R G Agrawal |
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A combined
numerical-experimental study of convection in an axisymmetric differentially
heated fluid layer |
448 |
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Convection
in differentially heated superposed air-water layers |
455 |
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An
experimental study of convective heat transfer from flat and ribbed surface |
464 |
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Effect of
inlet swirl and dump-gap on the wall pressure distribution of a model
can-combustor |
472 |
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Effects of
particle-size and size distribution on estimating erosion wear of cast iron
in sand-water slurries |
480 |
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Annual Index |
487 |
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp. 403-408
Effect of different annulus heights on performance of
annular gas turbine model combustor†
Gourav Garga,
Sanjeev Bharanib, S N Singha* & V Seshadria
Present study is a numerical investigation on an annular gas turbine combustor model with the simulation of dump diffuser and annuli. Uniform pressure distribution around the liner is desired for designed flow-split through the liner holes. An attempt has been made to achieve uniform velocity and pressure conditions in the annuli (around the liner) by changing the annuli height thereby changing the outer annulus area-to-inner annulus area ratio. It is found that for the area ratio of 2.56, uniform velocity and constant pressure condition is achieved around the bluff body representing the liner in the combustor model.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
409-413
Simulation of small disturbance waves
over alternate rigid and compliant panels†
P K Sena, S Hegdea & P W Carpenterb
In this paper, the simulation of two-dimensional small disturbance waves propagating over alternate rigid and compliant panels is discussed. Due to the abrupt change in the material properties of the wall at the junction of rigid-compliant panels, a sudden change is expected in the amplitude of the oncoming wave. An analytical-cum-numerical method is developed for the calculation of amplitude ratios at the two sides of rigid-compliant wall junctions.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
414-418
Dynamic behaviour of indirect coupled
heat exchanger systems†
N M Rao, B Maiti & P K Das
In this paper, the dynamic behaviour of the indirect coupled heat exchanger system has been reported. Three partial differential equations of energy balance for three fluids have been derived and solved simultaneously by adopting the finite element method. The responses of coupling fluid temperatures, hot and cold fluid temperatures have been studied for the step and sinusoidal changes in hot fluid inlet temperature. The maximum over-all effectiveness of the system has occurred at a unique value of the non-dimensional coupling fluid heat capacity rate. This unique value is identical to the value, which could be obtained from an analytically derived equation by the previous investigator. However, as expected, the situation changes when there is sinusoidal change in hot fluid inlet temperature.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp. 419-423
Distortion of guide vane assembly in a
bulb turbine due to cavitation
and reverse water flow†
R Rudramoorthy, N Kuppuswamy, D Rajenthirakumar & K V Manikandan
This paper focuses on the problems involved in a deep setting bulb turbine in a hydro- electric power plant and possible solutions to avoid cavitation. Analysis is carried out based on the measured data on the distortion in the guide vane assembly. To eliminate cavitation and distortion in these turbines, suggestions are evolved between the deep setting and reverse tailrace water flow into the turbine assembly.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
424-431
Experimental
investigation of tip clearance effects on flow field in an annular turbine
rotor cascade†
C Venkateswara Babu, N Sitaram* & M Govardhan
The present paper reports results of an experimental investigation on the effects of tip clearance in a high deflection annular turbine rotor cascade. The measurements are carried out at the inlet, in the blade passage and at the exit of the cascade using a five-hole probe and a seven-hole probe. The results indicate that the incoming flow to the rotor cascade is uniform and the incidence is about +2o. When the clearance is increased, the size and the magnitude of the tip clearance loss region increase. The flow near the hub experiences overturning, whereas near the casing the flow substantially underturns due to tip clearance. The underturning increases with tip clearance. Secondary and tip clearance losses steeply increase downstream of the blade trailing edge indicating losses due to the wake and clearance flow mixing with the main flow.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
432-439
Flow distribution in spherical
header of a liquid metal-cooled fast breeder reactor†
Liquid sodium from primary pump of a typical Liquid Metal-cooled Fast Breeder Reactor (LMFBR) reaches a spherical header through a vertical pipe and flows to the inlet plenum of the reactor through two discharge pipes, which connect the header to the plenum. The header is provided with a central cone and flow directing baffles for the purpose of having a smooth propagation of sodium flow and hence a reduced pressure drop. 3D hydraulic analyses of sodium flow in the header for various design configurations have been carried out to investigate the effectiveness of flow baffles and to assess the pressure drop in the header. It has been found that a configuration of 3D baffle combined with a central cone reduces the pressure drop in the header to the desirable level (1.7 mlc).
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
440-447
Design and development of water
hydraulic pressure compensated
flow control valve†
The Pressure Compensated Flow Control Valves (PCFCVs) are required for maintaining constant flow in a hydraulic circuit as there is fluctuation in supply or return pressure and other resistance on actuators. The water hydraulic PCFCV has been designed which can control the load flow as well as pump pressure. For achieving constant flow requirement, a hydrostate has been designed which maintains a constant differential pressure across a manually settable valve and hence maintain constant flow across the valve. The pump pressure control is achieved by controlling the sensing line pressure of hydrostate with the help of an air piston actuated pilot operated relief valve. The paper discusses conceptual design, mathematical modelling, parameter optimization and design of PCFCV.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp. 448-454
A
combined numerical-experimental study of convection in an axisymmetric
differentially heated fluid layer†
Buoyancy-driven
convection in a horizontal differentially heated fluid layer has been analysed
numerically and compared with the experimental results obtained for a circular
axisymmetric fluid layer, the side walls of the cavity being thermally
insulated and of constant radius. The employed Rayleigh numbers are 5861 and
12,124 and the working fluid air. The governing equations are continuity
equation, Navier-Stokes equation and the energy equation. Due to the
axisymmetric nature of the fluid cavity, the governing equations have been solved
in r-z coordinate system. A fine
uniform grid of 601x81 is employed. Experiments have been conducted in the
fluid layer of 0.64 m diameter and 23 mm vertical height with the same working
fluid as considered in numerical simulation. A Mach-Zehnder interferometer has
been used to visualize the long-time convection patterns in the fluid layer.
The goal of the study is to investigate the influence of Rayleigh number on the
steady (long time) thermal field, quantitative analysis of heat transfer rates
and comparison with the experimental results. A good agreement has been found
in qualitative as well as quantitative sense between theoretical and
experimental results.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
455-463
Convection
in differentially heated superposed air-water layers†
Sunil
Punjabi, Anamika Sethia & K Muralidhar
Convection
in a differentially heated two-layer system consisting of air and water has
been studied experimentally using laser-interferometry. The cavity used for
flow visualization is square in cross-section and rectangular in plan having
dimensions of 447×32.1×32.1 mm3. Experiments with the cavity
(half-filled with water, the rest being air) are reported here. The following
temperature differences have been imposed across the hot and the cold walls of
the superposed layers: (i) ΔT=10
K, (ii) ΔT=15 K , and (iii)
ΔT=18 K. The present study is
aimed at understanding the following issues: (a) the influence of Rayleigh
number on the steady thermal field, and (b) flow coupling mechanisms between
the layers. The present investigations show that the thermal field in the fluid
layers is primarily determined by the temperature difference and hence the
Rayleigh number. Further, the two-layers are thermally coupled at a lower
Rayleigh number, while the mechanical and thermal coupling both become
significant at higher Rayleigh numbers.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp.
464-471
An experimental study of convective heat transfer from flat and
ribbed surfaces†
Andallib Tariq, S K Swain & P K Panigrahi
Heat transfer and friction characteristics of flow in a rectangular channel with a solid rib mounted on the bottom surface of the channel have been investigated experimentally. The experiments have been carried out at Reynolds number (based on hydraulic diameter of the channel) range of 12,800 to 29,400. The skin friction coefficient, Nusselt number, velocity and temperature profile results are presented. The surface temperature images obtained with the help of liquid crystal thermography supplement the understanding of flow physics with qualitative explanation. The average Nusselt number for the ribbed flow case is higher in comparison to that for the flat surface. The increase in skin friction coefficient for the ribbed flow case is comparatively less than the Nusselt number increase, indicating the effectiveness of the ribbed surface in heat transfer enhancement applications. The liquid crystal thermography images show the flow in the downstream region of the rib to be two dimensional in nature. The recirculation and reattachment region for the ribbed flow case and their role in heat transfer effectiveness is clearly visible in the liquid crystal images.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp. 472-479
Effect of inlet swirl and dump-gap on
the wall pressure distribution of a model can-combustor†
Abdur Rahima, S V Veeravallib & S N Singhb
Wall static pressure distributions along the casing and liner wall have been measured using a Scanivalve digital manometer, for a model can-combustor under isothermal flow conditions for non-swirling and swirling flow at inlet with different positions of the liner (dump-gap). It is observed that swirl reduces the size of wall recirculation zone and permits earlier flow development whereas, dump-gap alters the reattachment length for weak swirling flows only. It is also observed that liner wall pressure (specially dome region) has a strong dependence on dump-gap for strong swirling flows due to formation of a central recirculation zone.
Indian Journal
of Engineering & Materials Sciences
Vol. 9, December 2002, pp. 480-486
Effects of particle size and size
distribution on estimating erosion wear
of cast iron in sand-water slurries†
Erosion wear of cast iron has been evaluated in a pot tester for narrow-sized and multi-sized particulate sand-water slurries. The effects of particle size and size distribution on erosion wear have been analyzed and the applicability of median diameter or weighted mean diameter as an effective particle size for multi-sized slurry for estimating erosion wear has been investigated. It is observed that the mean particle size of the narrow-sized particulate slurry can be taken as the effective particle size for evaluating the erosion wear. However, the observed trend of variation of erosion wear with particle size is not followed by median or weighted mean diameters of multi-sized slurries, showing large deviations.