Effects of Flow Passage Expansion or Contraction on Jet-Fuel Surface Deposition

A quartz crystal microbalance (QCM)/Parr bomb system with a headspace oxygen sensor is used to measure oxidation and deposition during thermal oxidative stressing of jet fuel. The advantages of the oxygen sensor technique in monitoring fuel oxidation is demonstrated. Simultaneous measurement of deposition using the QCM shows a strong correlation between oxidation and deposition in jet fuels. Studies performed over the temperature range 140 to 180°C show that surface deposition peaks at an intermediate temperature, while bulk deposition increases with temperature, in studies of jet fuel antioxidants, we find that rapid increases in oxidation rate occur upon consumption of the antioxidant. The antioxidant appears to be consumed by reaction with alkylperoxy radicals. In studies of metal deactivator (MDA) additives, we find that MDA is consumed during thermal stressing, and this consumption results in large increases in the oxidation rate of metal containing fuels. Mechanisms of MDA consumption are hypothesized.

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Hot Surface Deposition of Jet Fuel Containing Various Fatty Acids or Esters

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.78.1620 ◽

2012 ◽

Vol 78 (793) ◽

pp. 1620-1629

Author(s):

Masahito HATTA ◽

Takeshi OHMORI ◽

Yoshio ZAMA ◽

Tomohiko FURUHATA ◽

Masataka ARAI

Keyword(s):

Fatty Acids ◽

Jet Fuel ◽

Surface Deposition ◽

Hot Surface

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One-Dimensional Simulations of Jet Fuel Thermal-Oxidative Degradation and Deposit Formation Within Cylindrical Passages

Journal of Energy Resources Technology ◽

10.1115/1.1326915 ◽

2000 ◽

Vol 122 (4) ◽

pp. 229-238 ◽

Cited By ~ 3

Author(s):

J. S. Ervin ◽

S. Zabarnick ◽

T. F. Williams

Keyword(s):

Fluid Dynamics ◽

Jet Fuel ◽

Thermal Oxidative Degradation ◽

Fuel System ◽

Flow Conditions ◽

Surface Deposition ◽

Deposition Rates ◽

Fuel Oxidation ◽

One Dimensional ◽

Dissolved O2

Flowing aviation fuel is used as a coolant in military aircraft. Dissolved O2 reacts with the heated fuel to form undesirable surface deposits which disrupt the normal flow. For purposes of aircraft design, it is important to understand and predict jet fuel oxidation and the resulting surface deposition. Detailed multi-dimensional numerical simulations are useful in understanding interactions between the fluid dynamics and fuel chemistry. Unfortunately, the detailed simulation of an entire fuel system is impractical. One-dimensional and lumped parameter models of fluid dynamics and chemistry can provide the simultaneous simulation of all components which comprise a complex fuel system. In this work, a simplified one-dimensional model of jet fuel oxidation and surface deposition within cylindrical passages is developed. Both global and pseudo-detailed chemical kinetic mechanisms are used to model fuel oxidation, while a global chemistry model alone is used to model surface deposition. Dissolved O2 concentration profiles and surface deposition rates are calculated for nearly isothermal and nonisothermal flow conditions. Flowing experiments are performed using straight-run jet fuels, and the predicted dissolved O2 concentrations and surface deposition rates agree reasonably well with measurements over a wide range of temperature and flow conditions. The new model is computationally inexpensive and represents a practical alternative to detailed multi-dimensional calculations of the flow in cylindrical passages. [S0195-0738(00)01204-8]

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Computational Study on the Effect of Local Expansion and Contraction Upon Surface Deposition in a Heated Fuel Injector

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2011-46265 ◽

2011 ◽

Cited By ~ 1

Author(s):

Ehsan Alborzi ◽

Renato Piazzolla ◽

Christopher Wilson

Keyword(s):

Fuel Injection ◽

Computational Study ◽

Fluid Dynamic ◽

Jet Fuel ◽

Injection System ◽

Data Sampling ◽

Fuel Injector ◽

Chemical Kinetic Model ◽

Surface Deposition ◽

Local Expansion

A preliminary numerical analysis was carried out to examine the effect of local expansion and contraction on surface deposition rate for two series of geometries. These geometries correspond to the new geometrical features found in jet fuel injection system. For this simulation, commercial computational fluid dynamic package, Fluent 6.3.26, was used. Fluid flow, energy, and turbulence equations were solved coupled with a pseudo-detailed chemical kinetic model for jet fuel thermal degradation and the subsequent surface deposition sub model. The model results indicate that the highest deposition rates occur at intermediate expansion ratios and for a bigger inlet diameter due to a lower convective heat transfer. It was also shown that high expansion ratios are recommended to be used for short injector lengths. These simulated results are used for the experimental work in progress. The most susceptible locations to surface deposition are those with the highest rates; these are the best indicative points for data sampling.

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Aspects of Jet Fuel Oxidation

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2818177 ◽

1998 ◽

Vol 120 (3) ◽

pp. 519-525 ◽

Cited By ~ 5

Author(s):

S. Zabarnick ◽

S. D. Whitacre

Keyword(s):

Oxidation Rate ◽

Oxygen Sensor ◽

Jet Fuel ◽

Jet Fuels ◽

Surface Deposition ◽

Fuel Oxidation ◽

Headspace Oxygen ◽

Sensor Technique ◽

Metal Deactivator ◽

Alkylperoxy Radicals

A quartz crystal microbalance (QCM)/Parr bomb system with a headspace oxygen sensor is used to measure oxidation and deposition during thermal oxidative stressing of jet fuel. The advantages of the oxygen sensor technique in monitoring fuel oxidation is demonstrated. Simultaneous measurement of deposition using the QCM shows a strong correlation between oxidation and deposition in jet fuels. Studies performed over the temperature range 140 to 180°C show that surface deposition peaks at an intermediate temperature, while bulk deposition increases with temperature. In studies of jet fuel antioxidants, we find that rapid increases in oxidation rate occur upon consumption of the antioxidant. The antioxidant appears to be consumed by reaction with alkylperoxy radicals. In studies of metal deactivator (MDA) additives, we find that MDA is consumed during thermal stressing, and this consumption results in large increases in the oxidation rate of metal containing fuels. Mechanisms of MDA consumption are hypothesized.

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