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The experimental results of air evolution research by gravity fuel flow in a pipeline are presented. The pipe-line included an inclined section and a horizontal section connected by a bend. An orifice was installed at the entrance of the inclined pipeline section. The experimental investigations were carried out at pressures ranging from 20 to 80 kPa and temperatures varying between −20°C and +20°C. A significant fuel flow drop was observed by decreasing the pressure to a certain boundary value. This effect was caused by air evolution and the formation of two-phase air-fuel flow. It was shown that the boundary pressure value corresponding to the air evolution onset depended on temperature and fuel velocity values.

Fuel on-board dehydration during flight technologies has been modeled and experimentally studied on a laboratory testing setup in normal specific gas flow rates range of 0.0002-0.0010 sec-₁. Natural air evolution, ullage blowing and fuel sparging with dry inert gas have been studied. It has been shown that natural air evolution during aircraft climb provides a significant, substantial, but insufficient dehydration of fuel up to 20% relative. Ullage blowing during cruise leads to a constant, but a slow dehydration of fuel with sufficient column height concentration gradient. Dry inert gas sparging held after the end of the natural air evolution or simultaneously with natural air evolution provides rapid fuel dehydration to the maximum possible values. It potentially may eliminate water release and deposition in fuel to -50°C. It has been found that for proper dehydration, necessary and sufficient volume of dry inert gas to volume of fuel ratio is about 1.