Evolution of Combustion-Generated Particles at Tropospheric Conditions

Abstract

This paper describes particle evolution measurements taken in the Particulate Aerosol Laboratory (PAL). The PAL consists of a burner capable of burning jet fuel that exhausts into an altitude chamber that can simulate temperature and pressure conditions up to 13,700 m. After presenting results from initial temperature distributions inside the chamber, particle count data measured in the altitude chamber are shown. Initial particle count data show that the sampling system can have a significant effect on the measured particle distribution: both the value of particle number concentration and the shape of the radial distribution of the particle number concentration depend on whether the measurement probe is heated or unheated.

Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime

“…In our model, a semi-empirical correlation describing the mixing of an axisymmetric jet in a co-flowing ambient fluid (Nickels and Perry, 1996) was used to evaluate the plume's centerline properties. The calculated exhaust plume's centerline temperature, velocity, and dilution ratio as a function of downstream distance were found to be consistent with experimental data collected in the chamber (Tacina and Heath, 2010). The contribution of microphysical processes is further divided into contributions of (1) homogeneous nucleation of new liquid particles, (2) coagulation between liquid particles, (3) activation of hydrophobic soot surfaces, (4) condensational growth of water vapor on soot particles, and (5) heterogeneous freezing of liquid coated soot particles: In our model, homogeneous nucleation of new liquid particles is described by the kinetic quasi-unary nucleation theory developed by Yu (2005Yu ( , 2006Yu ( , 2007.…”

“…The exhaust temperature at the nozzle tip (T ex ) was set at 350 K and the chamber background temperatures (T b ) were set to the values listed in Table 1. This scaling law was found to be robust in laboratory buoyant jets in coflowing fluids, and our previous experimental work showed that it is valid in the PAL chamber (Tacina and Heath, 2010). Following Eq.…”

“…The background nitrogen and combustion products exit the chamber through an exhaust duct located on top; the exhaust, in turn, is connected to a high-flow vacuum source to maintain the chamber at pressures simulating upper tropospheric conditions. More details on chamber operation, including background temperature and pressure profiles, can be found in the paper by Tacina and Heath (2010).…”

“…This paper discusses results from our coupled laboratory and modeling investigation of the effects of water and soot emissions and ambient conditions on the near-field formation of contrail ice particles. The Particle Aerosol Laboratory (PAL) at the NASA Glenn Research Center (Tacina and Heath, 2010) was employed to simulate a broad range of conditions that bracket those found in the exhaust from aircraft engines at cruise altitudes. The Aerodyne microphysical parcel model for contrail ice particle formation (Wong and Miake-Lye, 2010) was used to guide experimental design and analyze experimental results.…”

Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the formation of contrail ice particles in the jet regime

“…This paper discusses results from our coupled laboratory and modeling investigation of the effects of water and soot emissions and ambient conditions on the near-field formation of contrail ice particles. The Particle Aerosol Laboratory (PAL) at the NASA Glenn Research Center (Tacina and Heath, 2010) was employed to simulate a broad range of conditions that bracket those found in the exhaust from aircraft engines at cruise altitudes. The Aerodyne microphysical parcel model for contrail ice particle formation (Wong and Miake-Lye, 2010) was used to guide experimental de-sign and analyze experimental results.…”