Emission of ions and charged soot particles by aircraft engines

Abstract

Abstract. In this article, a model which examines the formation and evolution of chemiions in an aircraft engine is proposed. This model which includes chemiionisation, electron thermo-emission, electron attachment to soot particles and to neutral molecules, electron-ion and ion-ion recombination, ion-soot interaction, allows the determination of the ion concentration at the exit of the combustor and at the nozzle exit of the engine. It also allows the determination of the charge of the soot particles. For the engine considered, the upper limit for the ion emission index EI i is of the order of (2 − 5) × 10 16 ions/kg-fuel if ion-soot interactions are ignored and the introduction of ion-soot interactions lead about to a 50 % reduction. The results also show that most of the soot particles are either positively or negatively charged, the remaining neutral particles representing approximately 20% of the total particles. A comparison of the model results with the available ground-based experimental data obtained on the ATTAS research aircraft engines during the SULFUR experiments shows an excellent agreement.

Prediction and Measurement of Electron Density and Collision Frequency in a Weakly Ionised Pine Fire

“…The excited particles are then thermally ionised to produce electrons and ions on selective basis determined by temperature and ionization potential. Particles that appreciably thermally ionise in the flame are alkalis and graphitic carbon (C n ) owing to their low ionisation potential and work function of 4.34 and 4.35 eV respectively [5]. Thermal ionisation of flame species (P(g)) occurs by the following reaction equation:…”

“…Assuming that most of the potassium in the flame is that which is emitted as atoms from radical reduction of K-O-C complex then mass of potassium per unit volume per unit time (P mass ) as calculated from (3) (7) gives K I . The value of K I is then used with the value of N p to calculate electron density according to (5). In this case, electron density is calculated to be 1.32×10 16 m −3 .…”

An experimental study of ion-induced nucleation using a drift tube ion mobility spectrometer/mass spectrometer and a cluster-differential mobility analyzer/Faraday cup electrometer

“…Laboratory experiments focusing on pre-nucleation cluster ions containing sulphuric acid and water have also been reported (Froyd & Lovejoy, 2003a,b;Wilhelm, Eichkorn, Wiedner, Pirjola, & Arnold, 2004). In addition, ions are believed to participate in the formation of ultrafine particles in aircraft and diesel engine exhaust (Yu & Turco, 1997;Arnold, Kiendler, Wiedemer, Aberle, & Stilp, 2000;Yu, 2001Yu, , 2002Sorokin, Vancassel, & Mirabel, 2003).…”

Formation of charged soot aggregates by combustion and pyrolysis: charge distribution and photophoresis

“…It was shown (see, for example, Place & Weinberg, 1966;Ball & Howard, 1971;Wersborg, Howard, & Williams, 1973;Onischuk et al, 2003;Burtscher, Reist, & Schmidt-Ott, 1986;Roth & Hospital, 1994;Popovicheva, Persiantseva, Starik, & Loukhonitskaya, 2003;Sorokin, Vancassel, & Mirabel, 2003) that soot aggregates formed in combustion are charged as well as ame generated inorganic aggregates (see, for example, Katzer, Weber, & Kasper, 2001). The soot aggregate charge arises from bipolar ion di usion in the reaction zone (Calcote, 1981;Calcote & Gill, 1994;Burtscher et al, 1986;Rogak & Flagan 1992;Wen, Reischl, & Kasper, 1984a;Alonso, Hashimoto, Kousaka, Higuchi, & Nomura, 1998;Fuchs, 1964).…”