Development of a Waveguide-Type Flowmeter Using a Microwave Method for Slush Hydrogen(<Special Issue>Experimental Mechanics in Heat and Fluid Flow)

Slush hydrogen is a two-phase solid-liquid cryogenic fluid consisting of solid hydrogen particles in liquid hydrogen, and various applications are anticipated such as fuel for reusable space shuttles. At a solid mass ratio (solid fraction) of within 50%, piped transport can be conducted in the same manner as for normal fluids. A new method is proposed for measuring the slush hydrogen mass flow rate using a microwave method. Noting the slight fluctuation in the distribution of solid hydrogen particles in slush hydrogen, i.e., slush hydrogen density, waveguide-type densimeters are placed at two locations along the piped flow to measure the density and to detect the density fluctuations. The flow velocity is also calculated from the densimeter distance and the delay time when the cross correlation function of the two density signals is at a maximum. This waveguide-type flowmeter has no moving mechanical parts in the flow stream. This paper reports the development of a new slush hydrogen waveguidetype flowmeter, together with the fabrication of required test apparatus and the confirmation of flowmeter accuracy.