Influence of Pressure and Porosity on Early-Stage Jet-Fuel Fouling for Aviation Fuel Injector Screens

As advanced jet engines push into supersonic and hypersonic regimes, their fuel systems are exposed to supercritical temperatures and pressures. Under these conditions, fuel temperature increases, initiating chemical breakdown and phase instability, triggering cracking reactions and nucleation, ultimately leading to the formation of carbonaceous deposits, also known as coke. Fuel injectors are particularly susceptible to coke deposits; therefore, last-chance screens are incorporated to filter particulate matter and maintain injector operability. However, screens themselves may progressively clog under thermal exposure and different relative engine pressures. To address this, an experimental investigation was conducted to quantify how system pressure and screen porosity influence the onset and progression of fouling in woven injector screens under a controlled engine-relevant environment. Two woven screens with distinct porosities (Screen A: high porosity; Screen B: lower porosity) were evaluated at system pressures of 200 psig and 400 psig to isolate geometric effects from pressure dependence. Differential-pressure measurements were used to determine the onset of fuel fouling (clogging induction time) at 0 psid and screen replacement (time-to-overhaul) at 1 psid. Results show that, within the tested range, system pressure has minimal effect on early-stage fouling and screen replacement. In contrast, screen porosity strongly governs the rate and variability of obstruction. A comparison between the highly porous screen (Screen A) and the lower-porosity screen (Screen B) revealed pronounced differences in fouling progression and associated uncertainty, indicating that geometric characteristics of woven-mesh and permeability can dominate over pressure effects. These findings highlight the importance of screen design in mitigating fouling and show that porosity-driven flow redistribution, rather than system pressure, governs the evolution of coking behavior in advanced propulsion systems.