Fuel Property Effects Upon Exhaust Smoke and the Weak Extinction Characteristics of the Pratt &amp; Whitney PT6A-65 Engine

Sampath, P.; Gratton, M.; Kretschmer, D.; Odgers, J.

doi:10.1115/1.3239868

Cited by 11 publications

(9 citation statements)

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“…The differences in particulate emission characteristics observed between the fuels of different aromatic content are expected given the current understanding of soot formation and growth in gas turbine engines. Several studies have shown that the soot production is proportional to fuel aromatic and naphthalene content (Rosfjord, 1987;Chin and Lefebvre, 1990a, b) and inversely proportional to fuel hydrogen content (Sampath et al, 1986;Rosfjord, 1987). Based on the analysis Blend-1 FT-1 Fig.…”

Section: Direct Emissionsmentioning

confidence: 97%

Reductions in aircraft particulate emissions due to the use of Fischer–Tropsch fuels

et al. 2014

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Abstract. The use of alternative fuels for aviation is likely to increase due to concerns over fuel security, price stability, and the sustainability of fuel sources. Concurrent reductions in particulate emissions from these alternative fuels are expected because of changes in fuel composition including reduced sulfur and aromatic content. The NASA Alternative Aviation Fuel Experiment (AAFEX) was conducted in January–February 2009 to investigate the effects of synthetic fuels on gas-phase and particulate emissions. Standard petroleum JP-8 fuel, pure synthetic fuels produced from natural gas and coal feedstocks using the Fischer–Tropsch (FT) process, and 50% blends of both fuels were tested in the CFM-56 engines on a DC-8 aircraft. To examine plume chemistry and particle evolution with time, samples were drawn from inlet probes positioned 1, 30, and 145 m downstream of the aircraft engines. No significant alteration to engine performance was measured when burning the alternative fuels. However, leaks in the aircraft fuel system were detected when operated with the pure FT fuels as a result of the absence of aromatic compounds in the fuel. Dramatic reductions in soot emissions were measured for both the pure FT fuels (reductions in mass of 86% averaged over all powers) and blended fuels (66%) relative to the JP-8 baseline with the largest reductions at idle conditions. At 7% power, this corresponds to a reduction from 7.6 mg kg−1 for JP-8 to 1.2 mg kg−1 for the natural gas FT fuel. At full power, soot emissions were reduced from 103 to 24 mg kg−1 (JP-8 and natural gas FT, respectively). The alternative fuels also produced smaller soot (e.g., at 85% power, volume mean diameters were reduced from 78 nm for JP-8 to 51 nm for the natural gas FT fuel), which may reduce their ability to act as cloud condensation nuclei (CCN). The reductions in particulate emissions are expected for all alternative fuels with similar reductions in fuel sulfur and aromatic content regardless of the feedstock. As the plume cools downwind of the engine, nucleation-mode aerosols form. For the pure FT fuels, reductions (94% averaged over all powers) in downwind particle number emissions were similar to those measured at the exhaust plane (84%). However, the blended fuels had less of a reduction (reductions of 30–44%) than initially measured (64%). The likely explanation is that the reduced soot emissions in the blended fuel exhaust plume results in promotion of new particle formation microphysics, rather than coating on pre-existing soot particles, which is dominant in the JP-8 exhaust plume. Downwind particle volume emissions were reduced for both the pure (79 and 86% reductions) and blended FT fuels (36 and 46%) due to the large reductions in soot emissions. In addition, the alternative fuels had reduced particulate sulfate production (near zero for FT fuels) due to decreased fuel sulfur content. To study the formation of volatile aerosols (defined as any aerosol formed as the plume ages) in more detail, tests were performed at varying ambient temperatures (−4 to 20 °C). At idle, particle number and volume emissions were reduced linearly with increasing ambient temperature, with best fit slopes corresponding to −8 × 1014 particles (kg fuel)−1 °C−1 for particle number emissions and −10 mm3 (kg fuel)−1 °C−1 for particle volume emissions. The temperature dependency of aerosol formation can have large effects on local air quality surrounding airports in cold regions. Aircraft-produced aerosols in these regions will be much larger than levels expected based solely on measurements made directly at the engine exit plane. The majority (90% at idle) of the volatile aerosol mass formed as nucleation-mode aerosols, with a smaller fraction as a soot coating. Conversion efficiencies of up to 2.8% were measured for the partitioning of gas-phase precursors (unburned hydrocarbons and SO2) to form volatile aerosols. Highest conversion efficiencies were measured at 45% power.

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Section: Direct Emissionsmentioning

confidence: 97%

Reductions in aircraft particulate emissions due to the use of Fischer–Tropsch fuels

et al. 2014

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“…5 are only slightly below those in Table 3 for conventional combustors. However, the correlation of Odgers (17,18) was based on reflectance measurements and hence should be compared with the present reflectance results. This comparison shows that there is a reduction in black smoke of two orders of magnitude at the 0.65 equivalence ratio with an order of magnitude lower smoke at the richer mixtures.…”

Section: Influence Of Pressure Loss On Smokementioning

confidence: 99%

“…Odgers et al (17,18) have published a correlation equation for the smoke emission index of conventional combustors. This takes into account the air/fuel ratio, pressure, inlet temperature and hydrogen content of the fuel.…”

Section: Conventional Combustorsmentioning

confidence: 99%

“…The objective was to investigate relative effects such as the influence of equivalence ratio, pressure loss and stabiliser design. The smoke correlation of Odgers et al (17,18) was used to extrapolate the present results to higher pressures and to compare with conventional combustor smoke emissions at one bar pressure. Atmospheric pressure combustor tests are far less expensive to perform than test at high pressure and allow more variables to be studied.…”

Section: Introductionmentioning

confidence: 99%

“…However, to be representative of practical combustor aerodynamics and mixing rates it is important that the operating conditions of Mach number, inlet temperature and pressure loss are correctly simulated. Unfortunately, in some atmospheric investigation of gas turbine smoke formation this has not been done (17,18) and systems with unrepresentative fuel and air mixing rates have been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Smoke Emissions From Lean Well Mixed Gas Turbine Primary Zones

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1985

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels

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Smoke emissions for a Jet Mix flame stabiliser at lean gas turbine combustor primary zone conditions are reported at a 600K operating temperature and 1 bar pressure for kerosene. The influence of pressure loss was studied, this influences the fuel and air mixing and the liquid drop size and hence has an influence on smoke emissions. Two flame stabiliser designs were studied with different fuel and air mixing rates. The results show that even for lean well mixed situations factors that influence local fuel and mixing also influence smoke emissions.

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A study of jet fuel sooting tendency using the threshold sooting index (TSI) model

Yang

Boehman

Santoro

2007

Combustion and Flame

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Fuel Property Effects Upon Exhaust Smoke and the Weak Extinction Characteristics of the Pratt & Whitney PT6A-65 Engine

Cited by 11 publications

References 0 publications

Reductions in aircraft particulate emissions due to the use of Fischer–Tropsch fuels

Reductions in aircraft particulate emissions due to the use of Fischer–Tropsch fuels

Smoke Emissions From Lean Well Mixed Gas Turbine Primary Zones

A study of jet fuel sooting tendency using the threshold sooting index (TSI) model

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