Investigation on the particle loss and applicability of aviation nvPM measurement methodology for wide particle size ranges

The precise measurement of non-volatile Particulate Matter(nvPM)is outlined in aviation engine emissions regulations by the International Civil Aviation Organization(ICAO).However,assessing particle losses in the sampling and transfer unit presents challenges,raising concerns about the system's reliability.Moreover,nvPM emissions from small and medium aircraft engines,with thrust not exceeding 26.7 kN,vary widely in size,adding complexity to the measurement process.To provide a comprehensive analysis of particle losses in the sampling and transfer subsystems,this study established a test bench equipped with a nanoparticle generator.The generator simulates nvPM emissions from medium and small aircraft engines and can consistently produce nvPMs with a wide range of concentrations(103–107/cm^(3))and size distributions(20–160 nm).Thermophoretic loss verification experiments were conducted within the sampling pipeline under significant temperature differences,investigating the effects of particle size,temperature gradient,and airflow rate on thermophoretic particle losses.The experimental results demonstrated good agreement with the predictions of the model proposed by United Technologies Research Centre(UTRC).After correcting for temperature,the experimental data showed a maximum disparity of 2%under typical engine exhaust conditions,validating the predictability of the thermophoretic loss model for various engine types.Furthermore,verification experiments for particle diffusion and bending losses were performed.Comparative analysis with the UTRC model revealed nvPM inertial deposition under laminar flow conditions with low Reynolds numbers(Re).As the Re increased,the measured data more closely aligned with the simulations.Bending losses due to secondary flow patterns ranged from 1%to 10%,depending on particle size and flow rate.This finding supports the applicability of aviation nvPM measurement methods across a wide particle size range.This research provides theoretical support for future nvPM measurements on various aircraft engines,laying the groundwork for improved accuracy and reliability in emissions monitoring.

民用涡扇和涡喷发动机非挥发性颗粒物排放符合性方法研究

通过建立国际民航组织航空环境保护委员会第10次会议非挥发性颗粒物(nvPM)排放符合性验证思路,分别针对民用涡扇和涡喷发动机nvPM排放测量试验的采样和测量系统搭建、仪器和系统校准、试验用燃油、试验程序、颗粒物损失修正、试验数据分析和符合性判据开展研究,形成了相应的符合性方法和审查关注要点。研究成果可为国内工业方表明nvPM排放符合性提供符合性方法,为国内适航审定人员开展nvPM排放审查提供指导。