VKI: Research Expertise Group on Liquid & Solid Propulsion (mobility)

General expertise of the research group

Design and optimisation of critical compontents for a LH2 propulsion system, such as LH2 fuel tanks, valves, heat exchangers, …

Experimental testing and numerical simulation of the fluid dynamics behaviour for two-phase flows, with application for liquid hydrogen (LH2). Extensive expertise is available from research on the propellant management system for space launchers. This expertise which has been developed for space applications, is now being transferred to terrestrial mobility applications in ships, aircraft, heavy duty trucks…

Specific hydrogen- related expertise & research topics

• In general: numerical simulations of fluid dynamics behaviour of liquid hydrogen (LH2) and performing experimental tests to validate the modelling
• Fluid Dynamics Phenomena of Liquid Hydrogen in a propellant management system (in pumps, piping, valves…):
  • cavitation
  • boil-offs and heat transfer
  • fluid hammering
• Sloshing of cryogenic fuels in a fuel tank (on board of a ship, a plane, a truck or in a space launcher…)

Available equipment/tools

• Numerical simulation platforms for CFD (Computational Fluid Dynamics), e.g. EcosimPro, OpenFOAM®
• Experimental test facilities:
  • PREDICT and BECASSINE Facility: for testing for densified cryogenic (e-)fuels.
  • Particle Image Velocimetry

Participating in FL/B/EU funded projects with H2 related research:

• Numerical simulation platforms for CFD (Computational Fluid Dynamics), e.g. EcosimPro, OpenFOAM®
• Experimental test facilities:
  • Cryoline Facility: a large multipurpose facility, which allows the characterization of cryogenic valves and the study of cryogenic water hammer and chill-down phenomena. The CryoLine facility can be placed horizontally, vertically and at intermediate angles to study the effect of gravity direction on cryogenic two-phase flows. Characterization of The facility allows measurement of temperature, pressure, flow rate and visualization of the flow (single phase or two-phase) during transient and at steady state.
  • The “CryME” (Cryogenic Microgravity Experiments) facility is a fully customized cryostat, for the characterization of cryogenic sloshing, boiling and thermal stratifi cation on earth and in microgravity conditions at temperature down to 70 K. The presence of large windows allows the use of non-intrusive optical techniques such as particle image velocimetry or high-speed visualization.
  • CHIEF Facility and upgraded CHIEF Facility: for testing cryo-valves
  • PREDICT and BECASSINE Facility: for testing for densified cryogenic (e-)fuels.
  • Sloshing table
  • Particle Image Velocimetry

International and industrial collaborations

• Airbus
• Ariane Group (FR, DE)
• CiRA (UK)
• DLR (DE)
• Numeca (BE)
• Open Engineering (BE)
• Pipistrel Vertical Solutions (SLO)
• Polytecnico di Torino (IT)
• Safran Aero Boosters (BE, FR)
• Waseda University Tokyo (JPN)

Participating in FL/B/EU funded projects with H2 related research:

• [SPACE] CRYOSLOSH and its continuation SLOSH II deal with the problem of sloshing in cryogenic propellants, stored in a reservoir. The main scope is to improve the state-of-the-art knowledge of the numerical simulation of liquid hydrogen, by refining actual models and performing coordinated
  experiments for their validation. SLOSH II focuses on introducing non-isothermal conditions on the hydrodynamic problem and provides model(s) for the contact-angle boundary condition. Funding: ESA – GSTP; partners: Numeca).
• [SPACE] The SPARGE I & II projects concern the isothermal characterization of sloshing in microgravity conditions, when surface tension forces are dominant. Parabolic flights represent a good tool to achieve microgravity conditions which are compatible with the ones obtained in real conditions (satellite or space vehicle propeller tanks). Funding: ESA – Continuously Open Research Announcement.
• [SPACE] CRYOBUBBLE is related to the experimental study and modelling of the transient chill down phenomena occurring when a cryogenic liquid is introduced into a system at ambient conditions. Such situation is happening at the initial start of a cryogenic system prior to operation. Heat exchanges between the cryogenic fluid and the system lead to vaporization and boiling phenomena as well as a cool down of the whole system. In this project, the cool-down created by a LN2 flow into a pipe at ambient temperature is studied both experimentally and numerically.
• [SPACE] CRYOVANNE II focuses on the multiphysics study of the behavior of a cavitating valve in cryogenic conditions. The development of new valves for space applications is going more and more towards electromechanically operated valves to reduce the mass demands. It requires improving the prediction of the expected thermo-mechanical loads on the valves, in particular during its transient operations. Due to the complexity of the multi-phase phenomena and the lack of literature describing benchmark experiments, the physical models implemented in the numerical codes cannot be validated properly. Therefore, the scope of this project was to investigate the physics involved during transient phenomena, such as flashing and water hammer, due to the fast closure or opening of valves designed for cryogenic fluids. Funding: ESA – GSPT. Partners: Safran Aero Boosters, Open Engineering, ET Energy Technology.
• [MARITIME / SHIPPING] CHyPS (Clean Hydrogen Propulsion for Ships) focuses on development of high fidelity 3D simulation models, needed for the engineering of clean propulsion for ships, with fuels such as H2, e-methane or methanol. The projects aims at developing models for the storage of cryogenic fuels in a tank, looking at phenomena such as sloshing and boil-off, and models for the combustion of these fuels in an Internal Combustion Engine (ICE) for ships. Flemish regional funding via VLAIO and the Blue Cluster.
• [AVIATION] HYPSTER (HYdrogen Propulsion System: Thermique Et Régulation): aims at designing, manufacturing and demonstrating 2 key components in the fuel delivery system for future hydrogen powered aircraft, namely the cryogenic valves and the heat exchanger. The project team, lead by Safran Aero Booster, will provide these components to Airbus, for integration in the ZEROe A380 flying testbed. In this project team, VKI is in charge of the design of the heat exchanger and of the testing in subcritical and supercritical regimes. The heat exchanger is used to bring the cryogenic LH2 to the right gaseous conditions. VKI also does the 1D modeling of the fuel delivery system. Walloon regional funding via the Skywin cluster.
• [AVIATION] fLHYing tank: this project, lead by Pipistrel Vertical Solutions from Slovenia, aims at developing a liquid hydrogen (LH2) load bearing fuel tank, which can fit in the tail cone of smaller aircraft. It will be demonstrated in flight with a Pipistrel NUUVA large cargo UAV. VKI will develop the digital twin for the thermo-fluid dynamics of the LH2 tank, will design the instrumentation for the performance characterisation and will perform the  experimental validation. Funding by the European Clean Aviation R&D programme.

Main relevant publications

1. Two-Phase Flows Investigations in Liquid Propulsion Systems: “TRL Booster” research at the von Karman Institute, by Jean-Baptiste Gouriet, Cryogenic Heat & Mass Transfer symposium, TU Twente (Enschede), november 2019