Astronomy & Space Sciences

Title :

Numerical modeling of vapour liquid interaction in cryogenic systems

Area of research :

Astronomy & Space Sciences

Focus area :

Cryogenic Engineering


Executive Summary :

In cryogenic systems, pressure measurement is carried out using pressure sensors which are designed to work at ambient temperature. To avoid the low temperature exposure of the sensing elements of these pressure sensors, lengthy canalisation tubes are used for warming up the cryogenic fluid. Because of this arrangement a large thermal gradient along the length of a vapour filled column which is closed at the warm end creates oscillations in pressure measurement. Those typical cryogenic oscillations include the thermal acoustic oscillations, the “Geyser” oscillations, gasification oscillations, and those oscillations under the periodic heat load from the wall of bare (Non-insulated) canalisation lines. The thermal acoustic oscillations occur when cryogenic liquid and vapour interacts each other. The warm gas in the column contracts due to the thermal interaction between the vapour liquid interactions. The gas expands at the other end due to the thermal interaction between the ambient through the canalisation walls. The inertia of the gas moving away from the warm section creates a low pressure in the warm section. This is aggravated by the high density and therefore high mass of the gas in the cold section which is being pushed away from the warm section. At low temperatures, the viscosity of the gas decreases; therefore there is a slug of high density gas, with low viscosity acting like a mass attached to a spring. In the two-phase fluid interactions subject to pressure variation in the cryogenic liquid flow, the compressibility of the vapour bubbles act as a spring with an asymmetric non-linear characteristic. The volume of the vapour bubbles increases or decreases differently if the pressure fluctuations are compressing or expanding. Aim of this work is to develop numerical model to simulate the pressure oscillations focus on the effect of diameter, wall thickness, length and material of the canalisation line on the formation of pressure oscillations and to develop the methodology to bias or eliminate the effects of pressure oscillation.


Shri R. Perumal Pillai, ISRO Propulsion Complex (IPRC), Mahendragir

Organizations involved