Thermo-structural analysis of cryogenic tanks with common bulkhead configuration

Abstract

In launch vehicles, cryogenic propulsion stages store liquid oxygen (LOX) at 76 K and liquid hydrogen (LH2) at 20 K, generally in two separate insulated tanks connected through tubular truss components. Consequently, load transfer from the LH2 tank to the LOX tank is very much localized, resulting in a nonoptimal design. This article presents an alternative single tankage design using a common bulkhead (CBH) to enhance the payload capability, which enables maintaining LH2 temperature within a specified temperature when exposed to a temperature gradient. A sandwich insulator using aramid honeycomb embedded with polyimide foam keeps the LH2 temperature within 20 ± 1 K is proposed, based on transient heat transfer analysis for 1000 s. The foam-filled honeycomb core is treated as equivalent foam in the analysis as the thermal conductivity of the core and the foam is quite close. The efficacy of the insulator is established by an experiment to measure the back wall temperature when liquid nitrogen is loaded on the top skin of the panel, and the insulator maintains a temperature gradient of 123 K for 1000 s. A good agreement is obtained between the transient finite element analysis results with experimental data. An externally insulated LOX tank configuration with an optimum length of the skirt–cylinder where the temperature reaches 80 K is arrived at based on slosh, buckling, and thermal analyses. No thermal gradient is found across the thickness of the skirt, while the thermal gradient is observed along the length of the skirt as anticipated. An integrated thermo-structural analysis of the cryo-system is carried out considering temperature-dependent material properties. A positive margin for the skirt is obtained. A payload gain of 366 kg is estimated based on the present study for the new design option with a CBH and skirt as compared to the traditional tubular truss arrangements.

Overview of safety challenges associated with integration of hydrogen-based propulsion systems for climate neutral aviation

“…In order to store hydrogen in a liquid state, cryogenic temperature of 20 K or less are necessary [13]. The temperature is limiting for the material selection as the material properties must possess the capability to perform effectively under these conditions [14]. It is crucial to acknowledge that the mechanical properties of materials may undergo significant alterations given cryogenic conditions [15], as indicated in Figures 1 and 2.…”

Study on geosynchronous satellite launch vehicle propellants and combustion mechanism of each stage

“…This stage has been the most challenging in GSLV and it works on liquefied LH2 and LOX gases [51]. Combustion of this stage is similar to that of other stages, initially, LH2 and LOX are separately ignited which results in the production of hot gases which get collected to a common chamber, called "bulkhead", where hot gases react and provide desired thrust [52]. At the cryogenic upper stage, the position of liquefied fuel is not easy to determine due to the low gravity effect and flow pattern changes due to reduced gravity [51][53].…”

New approach to injection of pressurizing gas into fuel tanks of power units

“…Their main drawback is that they do not take into account the constraining eff ect of the tank design on the penetration of a non-isothermal jet and the infl uence of the fl ight factor of longitudinal overload, which signifi cantly increases the buoyancy force on the jet of the pressurized working medium. In the study [5] carried out on liquid oxygen and hydrogen, the eff ect of external heat fl ows on the behavior of gas pressure in tanks, evaporation of cryogenic liquids at diff erent pressures was studied. How and in what manner this pressure was generated, how long these important points were not considered.…”