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Karunanithi R.,Indian Institute of Science | Jacob S.,Indian Institute of Science | Nadig D.S.,Indian Institute of Science | Prasad M.V.N.,Liquid Propulsion System Center | And 4 more authors.
Physics Procedia | Year: 2015

The measurement of the cryogen level in a cryostage of space crafts is crucial. At the same time the weight of the sensor should be small as it affects the payload fraction of the space craft. An attempt to develop a HTS based level sensor of 400 mm for Liquid Oxygen (LOX) measurement was made. In the initial phase of testing, loss of superconductivity of HTS wire in LOX inside a cryostat was noticed. Thus, a new four wall cryostat was designed to have a stable LOX level to provide thermal stability to the HTS based LOX sensor. The calibration of the developed sensor was carried out against capacitance level sensor which was pre calibrated using diode array to verify its linearity and performance for different current excitation levels. The calibrations were carried out without heater wires. The automatic data logging was accomplished using a program developed in LabVIEW 11.0. © 2015 The Authors. Source


Sainadh A.,Vikram Sarabhai Space Center | Jeenu R.,Vikram Sarabhai Space Center | Jayaprakash J.,Vikram Sarabhai Space Center | Ramakrishnan S.,Liquid Propulsion System Center
62nd International Astronautical Congress 2011, IAC 2011 | Year: 2011

Rocket motors designed for high-altitude use is frequently tested under off-design conditions, for example at sea level. In such cases, it is expected that the flow in the rocket nozzle will separate for a considerable portion during test resulting in higher thrust than that computed assuming no flow separation. The thrust coefficient increment for this separated flow region has generally been predicted using empirical equations. In the present paper, the validity of the empirical equation developed by Kalt and Badalis verified for three solid motors of different size static tested at sea level conditions. The analysis showed that the empirical equations developed by Kalt and Badalcan give satisfactory results to compute the thrust with flow separation. Copyright ©2011 by the International Astronautical Federation. All rights reserved. Source


Rao G.S.,Vikram Sarabhai Space Center | Sharma V.M.J.,Vikram Sarabhai Space Center | Raman S.G.S.,Indian Institute of Technology Madras | Amruth M.,Liquid Propulsion System Center | And 3 more authors.
Materials Science and Engineering A | Year: 2016

Effects of temperature and strain rate on the tensile properties of Cu-Cr-Zr-Ti alloy in annealed condition were investigated by varying the initial strain rates from 10-4 s-1 to 10-1 s-1 at RT, 300 °C, 450 °C, 600 °C and 700 °C. The yield strength (YS) and ultimate tensile strength (UTS) of the alloy increased with an increase in strain rate at RT and 300 °C, whereas at 450 °C, the material exhibited the highest YS and UTS at the lowest strain rate of 10-4 s-1. At 600 °C, the YS and UTS of the alloy increased with an increase in strain rate and showed the highest YS compared to all the temperatures tested. The alloy showed serrated yielding at 300 °C and at an initial strain rate of 10-4 s-1 whereas at 450 °C, serrated yielding was observed at 10-3 s-1 and 10-4 s-1 strain rates. Microstructural observations showed the presence of creep cavities at 450 °C and strain rate of 10-4 s-1. The creep cavities were present at higher strain rates as the test temperature is increased. Fractography indicates that the fracture is predominantly dimple fracture at RT and 300 °C and intergranular cracks were observed at 600 °C and 700 °C. © 2016 Elsevier B.V. Source


Gupta R.K.,Vikram Sarabhai Space Center | Kumar V.A.,Vikram Sarabhai Space Center | Gururaja U.V.,Mishra Dhatu Nigam Ltd | Subramani K.,Liquid Propulsion System Center | And 4 more authors.
Metal Science and Heat Treatment | Year: 2015

Rings from titanium alloy Ti6Al4V used for making pressure vessels for launch vehicles are studied after annealing and after solution treatment and aging. The mechanical characteristics of the rings after quenching and aging do not always have the specified values, especially in thicker sections. The studied rings are of two sizes and have a final wall thickness of 30.5 and 17.5 mm. The effect of the temperatures of solution treatment and aging, of the quenching rate, and of the section thickness on the mechanical properties is studied, and the process is updated to provide the required properties. © 2015, Springer Science+Business Media New York. Source


Manikanda Kumaran R.,Indian Institute of Technology Madras | Sundararajan T.,Indian Institute of Technology Madras | Raja Manohar D.,Liquid Propulsion System Center | Dason D.,Liquid Propulsion System Center
AIAA Journal | Year: 2012

The performance of a two-stage ejector during high-altitude testing of large-area-ratio satellite thrusters is numerically investigated. Since the flow rateof the exhaust from the satellite thrusterisvery low, self-ejector action of the exhaust is quite weak; therefore, a two-stage external ejector is required to create the desired low vacuum in the test chamber. The present work attempts to investigate the effects of various operational and geometric parameters on the performance of the two-stage ejector. Predicted results show that the downstream ejector (E2) operation is more critical for maintaining the required vacuum. However, for optimal performance, it is possible to tune the parameters such that both ejectors deliver the same suction effect. Maximum performanceofeach ejector is obtained when the primary jet expanding from the nozzle smoothly seals the mixer throat against backflow. Employing a low molecular weight fluid and high stagnation temperature helps in reducing the quantity of fluid required for test facility evacuation. Useful correlations have been derived to quantify the suction performance of the two-stage ejector, and the predicted results compare well with in-house experimental data. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. Source

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