ISSN Online: 2688-7231
ISBN Online: 978-1-56700-524-0
Proceedings of the 26thNational and 4th International ISHMT-ASTFE Heat and Mass Transfer Conference December 17-20, 2021, IIT Madras, Chennai-600036, Tamil Nadu, India
Design Verification of Modified Outlet of a Cryogenic Oxidiser Tank through CFD Simulations
Cryogenic stage uses liquid oxygen and liquid hydrogen as
oxidiser and fuel respectively for propulsion. Fuel and oxidiser are stored in cylindrical tanks with tori-spherical end domes. When the above fluids get depleted from the tanks, dip formation in the liquid surface and subsequent ullage gas entry into the outlet occurs. This could lead to malfunction of the liquid rocket engine. Hence estimation of critical height which is defined as elevation at which surface dip forms is very important in order to quantify unused propellant towards the end of the thrusting phase of an engine.
Design of outlet configuration plays a major role in reducing
the critical height there by reducing the unused propellant.
Critical height obtained for an original outlet configuration of a cryogenic oxidiser tank through numerical simulations using ANSYS CFD code due to sink phenomenon is higher resulted
in more left out not useful propulsion. Based on these studies,
modified outlet is arrived at and its design verification is
carried out through CFD simulations. This paper gives the
results of design verification carried out. Normalised critical
height reduces to 0.407 from 0.81. This resulted in oxidiser
left out to 32.6 kg compared to 102.5 kg for original outlet. In addition to above, it is also corroborated that critical height does not depend on Reynolds number which is useful for
finalising ground expulsion tests with de-mineralized water for
its design verification.