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The onboard inert gas generation system with turbocharger (OBIGGSTC) was proposed for better inerting performance of an aircraft fuel tank. The operating principle and method of the system were introduced, and the mathematical model of the major component was deduced. Then, the characteristic of the system was simulated based on the software AMESim. Compared with the traditional onboard inert gas generation system (OBIGGS), the proposed system has the potential advantages of reducing the weight and volume of the air separation system by decreasing the number of hollow fiber membrane modules (HFMMs) from a maximum number of eight to one at 0.3 MPa of the bleed air from the engine. When both inerting systems have a single HFMM configuration, the OBIGGSTC can substantially reduce the inerting time by 66.6% compared with the OBIGGS at 0.3 MPa of the bleed air. Due to the turbine applied, the mass flow rate of the bleed air of the inerting system with turbine is greater than the traditional system. The compensatory loss of the proposed system is less than the OBIGGS by a maximum of 57.39% when the bleed air pressure varies from 0.3 to 0.8 MPa with a range in flight time from 4 h to 10 h. By analyzing the two inerting system, the OBIGGSTC has better performance than the OBIGGS.

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Fuel vapor concentration is a key parameter for assessing the flammability of aircraft fuel tanks. However, the current research on RP-3 (Rocket Propellant-3) fuel vapor concentration is inadequate. This study categorizes fuel components by the number of carbon atoms and utilizes Raoult’s law to estimate the gas–liquid equilibrium relationship of each constituent element under equilibrium conditions. The equilibrium-state model is experimentally validated, and the differences in the constituents and fuel vapor concentrations of RP-3 and Jet-A (Jet Fuel-A) fuels are analyzed. In addition, an empirical correlation between the overall hydrocarbon concentration of RP-3 fuel vapor and the temperature and pressure in the equilibrium state is established, providing a theoretical basis for determining RP-3 fuel vapor concentration in related investigations. Furthermore, a transient prediction model of fuel vapor concentration is developed using the lumped parameter approach that considers the heat exchange among the fuel, gas, wall, and environment. The model’s accuracy is confirmed by comparing it to existing literature. Then, the temperature and fuel vapor concentration variation patterns in the fuel tank are calculated and evaluated under two typical flight scenarios. The results show a significant difference between the calculated fuel vapor concentration values obtained through equilibrium-state and transient models. Therefore, in the design of fuel vapor catalytic inerting systems, it is crucial to consider both the equilibrium and transient fuel vapor concentration values rather than relying solely on the former. Throughout the flight envelope, gas phase and fuel phase temperatures in RP-3, Jet-A, and C10H22 fuel tanks exhibit minimal differences. However, significant variations in fuel vapor concentration exist depending on the flight state and envelope. Hence, regarding RP-3 as equivalent to C10H22 is inappropriate. Additionally, fuel vapor concentration is a more suitable metric than fuel temperature for assessing fuel tank flammability.

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