Experimental Study on Electrostatic Accumulation Mechanism in Liquid Hydrogen Pipe Flow

To investigate electrostatic accumulation induced by cryogenic liquid hydrogen (LH₂) flow in pipelines, a test system was constructed with LH₂ as the primary working medium. Using vacuum insulation, insulated connections, electrostatic shielding, and other measures, as well as the application of the leakage charge method, safe and accurate measurement of extremely low-level charge quantities generated by LH₂ flow under cryogenic conditions was achieved. The charge accumulation characteristics under multiple flow conditions with Reynolds numbers (Re) below 2×10⁵ were analyzed. The experimental results indicated that notable flow charging phenomena occurred during LH₂ flow with extremely low electrical conductivity in pipelines. Furthermore, charge accumulation demonstrated a linear growth during the test period. Within the range of pipe lengths and Reynolds numbers covered by the experiment, the average charge density decreased with an increase in the flow velocity; however, the rate of decrease gradually diminished. The average charge density of flow decreased with increasing pipe diameter. The developed electrostatic accumulation test system for low-temperature LH₂ pipe flow provided an important platform support for conducting LH₂ electrostatic tests. This study validated the feasibility of the electrostatic measurement method for LH₂, providing design guidance for exploring the electrostatic laws of LH₂ and the boundary of safe flow velocity.