Research on transport loss characteristics and quantitative correction of aero-engine nvPM emitted from sustainable aviation fuel

The combustion of sustainable aviation fuel (SAF) produces non-volatile particulate matter (nvPM) with a size distribution significantly shifted toward the ultrafine range, which exacerbates transport losses within measurement sampling systems. Existing airworthiness correction frameworks, established primarily for conventional aviation fuels (CAF), fail to adequately account for these size-sensitive losses, leading to an underestimation of SAF emission concentrations. Utilizing a scaled turbofan engine platform, this study comparatively analyzed the thermal emission characteristics of HEFA-SAF and RP-3 fuels and quantified the effects of heat transfer and fluid dynamics on particle transport. Experimental results indicate that thermophoretic loss is governed by the convective heat transfer and radial temperature gradient between the exhaust gas and the sampling wall, while diffusion and bending losses are highly size-dependent, resulting in an inverted U-shaped distribution of the system's total penetration efficiency with respect to particle size. Because the geometric mean diameter (GMD) of HEFA-SAF particles is consistently below 30 nm, they fall deeply into the high diffusion loss zone; consequently, even within sampling systems complying with airworthiness standards, the maximum penetration efficiency remains below 70%. Based on these physical laws, this study proposed and validated a particle size distribution (PSD) transport loss correction model incorporating the ultrafine particle characteristics of SAF. This model can accurately reconstruct the true emission levels at the engine exit plane, providing critical theoretical and data support for establishing a high-precision airworthiness certification system for SAF aviation emissions.