Analysis of particulate size distribution and concentrations from simulated jet engine bleed air incidents

Abstract

Engine oil migrating into the bleed air stream of aircraft environmental control systems occurs with enough frequency and deleterious effects to generate significant public interest. While previous work has explored the chemical makeup of the contaminants in the aircraft cabin during these events, little is known about the characteristics of the aerosol resulting from oil contamination of bleed air. This article presents particle counter data (giving both size distributions and concentration information) of the oil droplets from simulated jet engine bleed air. Four particle counters—a scanning mobility analyzer, an aerodynamic particle-sizer, an optical particle counter, and a water-based condensation particle counter—were used in the study encompassing a size range from 13 nm to 20 μm. The aerosol characterization is given for different bleed air temperatures and pressures. The data show a substantial increase of ultrafine particles as the temperature is increased to the maximum temperatures expected during normal aircraft operation. This increase in ultrafine particles is consistent with smoke generated from the oil. The pressure of the bleed air had little discernible effect on the particle size and concentration.

Additional information

Funding

This research was funded by the U.S. Federal Aviation Administration (FAA) Office of Aerospace Medicine through the National Air Transportation Center of Excellence for Research in the Intermodal Transport Environment under Cooperative Agreement 07-C-RITE-KSU. Although the FAA has sponsored this project, it neither endorses nor rejects the findings of this research. Presentation of this information is in the interest of invoking technical community comment on the results and conclusions of the research.