Semi-Cryo Inter tank Structure Design with a Common Bulk Head using non metallic Honeycomb Core

Paper number

IAC-07-D2.I.02

Author

Prof. Vedachalam Nagarajan, Indian Space Research Organisation (ISRO), India

Coauthor

Dr. R. Ramesh Kumar, Indian Space Research Organisation (ISRO), VSSC, India

Year

2007

Abstract

Future space transportation for Manned and unmanned mission envisage use of large liquid rocket booster and high thrust semi-cryogenic propulsion systems. Semi cryogenic propulsion systems are widely used because of its versatile advantages such as high density impulse ratio, specific impulse and less storage volume, non-toxic in nature, environment friendly. The propulsion stage stores liquid oxygen at 80 K and propellant such as Kerosene at 300K in two separate tanks generally connected through either an inter tank structure or tubular truss elements. In this common bulk head design to diffuse the thermal gradient and weight saving, a non metallic honeycomb (NOMEX) core, filled with cork as insulator with metallic back up structure  and skirt are introduced.

Experimental investigation of a scaled model of non metallic honeycomb core filled with cork with metallic back up structure filled with liquid nitrogen is conducted over 1000 seconds and temperature at the outer surface of honeycomb core was measured and compared with the results based a heat transfer analysis. A good agreement is established between the two approaches. The specific heat and thermal conductivity of the NOMEX core is found to be 17275 J/ kg K and 0.0485 W/m K.   

An optimum length of the skirt where the temperature reaches the ambient temperature of 300K is arrived at by a transient analysis for a period of 1000 seconds. It is observed from the thermal analysis that through the thickness of the skirt there is no thermal gradient and hence no bending is expected. An integrated thermo structural analysis was carried out considering temperature dependent material property for modulus and coefficient of thermal expansion and associated strength values. Further buckling analysis of the skirt was also carried out to ensure very high margin. A Payload gain of 250 to 500 kg is estimated based on the present study for the new design option with common bulk head and skirt in the place of the conventional inter tank structure or tubular truss arrangements.

Abstract document

IAC-07-D2.I.02.pdf

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