![Mass distribution and concentrations of negative chemiions in the exhaust of a jet engine: Sulfuric acid concentrations and observation of particle growth [An article from: Atmospheric Environment]](https://www.ebooknetworking.net/books/B00/0RR/bigB000RR4IM2.jpg)
Mass distribution and concentrations of negative chemiions in the exhaust of a jet engine: Sulfuric acid concentrations and observation of particle growth [An article from: Atmospheric Environment]
Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Measurements of negative-ion composition and density have been made in the exhaust of a J85-GE-5H turbojet, at ground level, as part of the NASA-EXCAVATE campaign. The mass spectrometer was placed 3m from the exhaust plane of the engine. Measurements were done as a function of engine power in six steps from idle (50%) to military power (100%). Since the exhaust velocity changes with power, this also corresponds to a time evolution for ion growth. At 100% power most of the ions are HSO"4^- with minor amounts of HSO"4^-(H"2O)"n. With decreasing engine power the degree of hydration increases. In addition, ions with a 139-amu core dominate the spectra at lower engine power. The chemical identity of this ion is unknown. Observation of a small amount of NO"3^- core ions in the high-power spectra allows the determination of H"2SO"4 concentrations, which turn out to be a fraction-of-a-percent of the total sulfur in the fuel. Combining the present data with several previous composition measurements allows one to observe ion evolution from bare ions to ions with masses >8000amu. Ion densities are derived and appear consistent with previous measurements used in modeling studies indicating that ion nucleation is a probable mechanism for volatile aerosol formation.
Description:
Measurements of negative-ion composition and density have been made in the exhaust of a J85-GE-5H turbojet, at ground level, as part of the NASA-EXCAVATE campaign. The mass spectrometer was placed 3m from the exhaust plane of the engine. Measurements were done as a function of engine power in six steps from idle (50%) to military power (100%). Since the exhaust velocity changes with power, this also corresponds to a time evolution for ion growth. At 100% power most of the ions are HSO"4^- with minor amounts of HSO"4^-(H"2O)"n. With decreasing engine power the degree of hydration increases. In addition, ions with a 139-amu core dominate the spectra at lower engine power. The chemical identity of this ion is unknown. Observation of a small amount of NO"3^- core ions in the high-power spectra allows the determination of H"2SO"4 concentrations, which turn out to be a fraction-of-a-percent of the total sulfur in the fuel. Combining the present data with several previous composition measurements allows one to observe ion evolution from bare ions to ions with masses >8000amu. Ion densities are derived and appear consistent with previous measurements used in modeling studies indicating that ion nucleation is a probable mechanism for volatile aerosol formation.
