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Thiruvananthapuram, India

Singh S.P.,Institute of Management Sciences | Singh V.K.,Liquid Propulsion Systems Center
International Journal of Production Research | Year: 2010

Multi-objective facility layout problem (mFLP) generates a different layout by varying objectives weights. Since the selection of objective weights in mFLP is critical, stages of designing layout having multiple objectives, the objective weights therefore play an important role in the layout design of mFLP. In practice, it is selected randomly by the layout designer based on his/her past experience that restricts the layout designing process completely designer dependent and thus the layout varies from designer to designer. This paper aims to resolve the issues of selecting the objective weight for each objective. We propose four methods to determine objective weight which makes the design process of mFLP completely designer independent. Source

Shine S.R.,Indian Institute of Space Science and Technology | Sunil Kumar S.,Liquid Propulsion Systems Center | Suresh B.N.,Indian Space Research Organization
International Journal of Heat and Mass Transfer | Year: 2012

A one dimensional analytical model of liquid film cooling in rocket combustion chambers operating at subcritical conditions is developed. The approach followed involves the selection of a control volume for mass and energy balance. The coolant evaporation rate per area is obtained from this energy balance. The present model incorporates mass transfer via entrainment by adapting suitable correlations from literature pertaining to annular flow conditions. The model predicted favourably with the experimental data available in open literature and produced superior results compared to all existing models. Results are presented for a mixed gas-water system under different conditions. Results indicate that convection dominates the heat transfer at the gas-liquid interface. Effects of gas Reynolds number, coolant inlet temperature, combustion chamber pressure, mass flow ratio of the liquid coolant to the free stream and the free stream turbulence on the liquid film length are presented in detail. © 2012 Elsevier Ltd. All rights reserved. Source

Babu S.,Indian Institute of Technology Madras | Janaki Ram G.D.,Indian Institute of Technology Madras | Venkitakrishnan P.V.,Liquid Propulsion Systems Center | Reddy G.M.,Indian Defence Research And Development Laboratory | Rao K.P.,Indian Institute of Technology Madras
Journal of Materials Science and Technology | Year: 2012

Friction stir lap welds were produced in 3 mm thick Alclad sheets of Al alloy 2014-T4 using two different tools (with triangular and threaded taper cylindrical pins). The effects of tool geometry on weld microstructure, lap-shear performance and failure mode were investigated. The pin profile was found to significantly influence the hook geometry which in turn strongly influenced the joint strength and the failure mode. Welds produced in alloy 2014-T4 Alclad sheets by using triangular and threaded taper cylindrical tools exhibited an average lap-shear failure load of 16.5 and 19.5 kN, respectively, while the average failure load for standard riveted joints was only 3.4 kN. Welds produced in alloy 2014-T6 Alclad sheets and in alloy 2014-T4 bare sheets (i.e., no Alclad) were comparatively evaluated with those produced in alloy 2014-T4 Alclad sheets. While the welds made (with threaded taper cylindrical tool) in T6 and T4 conditions showed very similar lap-shear failure loads, the joint efficiency of the welds made in T6 condition (43%) was considerably lower (because of the higher base material strength) than those made in T4 condition (51%). The Alclad layers were found to present no special problems in friction stir lap welding. Welds made with triangular tool in alloy 2014-T4 Alclad and bare sheets showed very similar lap-shear failure loads. The present work provides some useful insights into the use of friction stir welding for joining Al alloys in lap configuration. © 2012 The Chinese Society for Metals. Source

Shine S.R.,Indian Institute of Space Science and Technology | Kumar S.S.,Liquid Propulsion Systems Center | Suresh B.N.,Indian Space Research Organisation
Energy Conversion and Management | Year: 2013

The flow field associated with cylindrical coolant jets inclined in tangential and azimuthal direction employed inside a circular pipe has been studied. Numerical results are compared with in-house experimental data for a row of circumferential film cooling holes with two distinct geometric configurations. Results provide insight into the film cooling performance and the heat transfer characteristics associated with this type of film-cooling jets. Secondary flow recirculation zones are found near the jet exit in the regimes close to the wall and the center. Its occurrence and length is found to be controlled by the geometric configuration of the coolant hole. This secondary flow structure and the jet impingement on the wall are found responsible for developing a maximum local Nusselt number downstream of coolant injection. Reverse heat transfer regimes are noted for conjugate walls with higher thermal conductivity. The spreading of the coolant around the circumference is mainly due to the asymmetric vorticity levels present at the jet exit plane. Higher tangential orientation of the coolant jet with the mainstream has resulted in lower injectant concentration near the test section wall and lower effectiveness throughout the test section. The results indicate that through the use of optimal coolant injector configurations, reduction in coolant requirement can be achieved. © 2013 Elsevier Ltd. All rights reserved. Source

Vinayaravi R.,Liquid Propulsion Systems Center | Kumaresan D.,College of Engineering, Trivandrum | Jayaraj K.,College of Engineering, Trivandrum | Asraff A.K.,College of Engineering, Trivandrum | Muthukumar R.,College of Engineering, Trivandrum
Journal of Sound and Vibration | Year: 2013

Impact damping is a method for improving damping of a dynamic system by means of energy dissipation due to repeated collisions of a free mass on the base structure. This paper deals with the theoretical and experimental investigations carried out to study and characterize damping with respect to the level of base excitation. The mathematical model consists of a two degree of freedom system (in which the main system is modelled as single degree of freedom system (sdof)) which undergoes momentum transfer between main mass and impact mass. The velocity response obtained from the mathematical model for the main mass and impact mass clearly indicates that the damping of the system depends on the number of effective impacts and not on the total number of impacts. Here the effect of impact damping is studied for low frequency and high amplitude excitation. Optimum parameters are determined for design of impact damper based on the mathematical model. Experiments are conducted on a cantilever beam for various excitation levels. The damping characteristics obtained from test data are compared with the predictions made from mathematical model. A good match is obtained between theoretical and experimental results. It is also observed that the energy gets re-distributed to higher modes due to the high shock that occurs during collision of the impact mass with main mass. © 2012 Elsevier Ltd. All rights reserved. Source

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