Effect of injection parameters on combustion characteristics of an aviation kerosene piston engine with blended alcohol-to-jet synthetic paraffin kerosene (ATJ-SPK)

The application of ATJ-SPK is critical for carbon emission reduction in the aviation industry. However, its relatively high viscosity may deteriorate the engine’s power performance, while appropriate injection parameters can enhance combustion efficiency and mitigate emissions. The effects of injection parameters on the combustion performance of an in-cylinder direct-injection aviation piston engine are systematically investigated in this study, based on the determination of the optimal blending ratio of ATJ-SPK. The results indicate that as the nozzle inclination angle increases, the maximum in-cylinder average pressure exhibits a trend of first increasing and then decreasing. The peak value occurs at a nozzle inclination angle of 46°, where it is 10.3 % higher than that at 44°. Similarly, the maximum in-cylinder average pressure follows the same trend with the spray cone angle, reaching its peak value at 105°—51.2 % greater than that at 70°. The maximum in-cylinder average pressure also demonstrates a trend of increasing initially and then decreasing with the advancement of injection timing. It peaks at 288° CA BTDC, where the value is 32.7 % higher than that at 280° CA BTDC. The coupling of the three optimal injection parameters promotes the efficient combustion of the engine. Finally, the impact of injection parameters on engine power performance was quantitatively analyzed using the sensitivity coefficient. The parameters are prioritized in descending order of influence magnitude as follows: injection timing > nozzle inclination angle > spray cone angle.