Technique for flowrate calculation of cryogenic two-phase flows in Venturi flowmeters without separation

A technique for calculating the flowrate of cryogenic two-phase flows in separationless flowmeters based on a venturi is proposed. The technique takes into account the equation of state of the two-phase medium, that is changes in density, mass vapour quality and temperature of cryogens two-phase flows against pressure in the venturi. It is shown that without an accounting of the flow parameters evolution, an additional flowrate error appears and therefore it is impossible to correctly determine the sensitivity and measurement range of the flowmeter. The most optimal measurement range of the pressure drop is chosen as well as a method of the flowrate measuring by the temperature difference across the venturi is proposed. The problem of determining the flowrate of two-phase cryogenic flows is topical for accelerator, aerospace and gas-transport engineering.

Ultrasound Measurement Technique for Validation of Cryogenic Flows

An ultrasound sensor system based on the transmission-mode approach is developed to enable the monitoring and sensing of cryogenic liquids and gases—especially gaseous bubbles and gas-liquid interfaces in liquid nitrogen (LN2). Common sensors do not meet requirements of cryogenic and microgravity-environments. Therefore, a special encapsulation design for the optimization of the electrical connection and the mechanical coupling of the ultrasound sensors is needed. The ultrasound system is qualified in LN2 and is able to measure bubbles (size and location) and fill levels with a high spatial resolution in a submillimetre range and a sampling rate of more than 500 Hz.

Flows of liquid4He due to oscillating grids

We investigate cryogenic flows of liquid4He between two grids oscillating in phase, at temperatures ranging from approximately 1.3 to 2.5 K, resulting in suitably defined Reynolds numbers up to$10^{5}$. We specifically study the flow-induced motions of small particles suspended in the fluid by using the particle tracking velocimetry technique. We focus on turbulent flows of superfluid4He that occur below approximately 2.2 K and are known to display, in certain conditions, features different from those observed in flows of classical viscous fluids, such as water. We find that, at large enough length scales, larger than the mean distance between quantized vortices, representing the quantum length scale of the flow, the shapes of the velocity and velocity increment statistical distributions are very similar to those obtained in turbulent flows of viscous fluids. The experimental outcome strongly supports the view that, in the range of investigated parameters, particles probing flows of superfluid4He behave as if they were tracking classical flows.