scholarly journals Surface Fouling in Aviation Fuels: An Isothermal Chemical Study

1995 ◽  
Author(s):  
E. Grant Jones ◽  
Walter J. Balster ◽  
James M. Pickard
Keyword(s):  
Experimental Test ◽  
Chemical Study ◽  
Aviation Fuel ◽  
Test Time ◽  
Tubular Heat Exchanger ◽  
Surface Deposition ◽  
Test Conditions ◽  
Aircraft Fuel ◽  
Dynamic Experiments ◽  
Selection Of

Surface fouling in aircraft fuel lines that results from autoxidation of aviation fuel remains a serious and very complicated problem. This area has been studied using two Jet-A fuels, POSF-2827 and POSF-2980. The results of a series of dynamic experiments conducted in a single-pass, tubular heat exchanger operated at very slow flow rates under near-isothermal conditions are reported herein. Such studies, by minimizing complications resulting from fluid dynamics and heat flow, constitute a simpler global approach to the chemistry of fouling. The basis for the selection of experimental test conditions is discussed, and data from measurements of dissolved oxygen and surface deposition as a function of fuel stress duration are presented. The effects of parameters such as reaction temperature, tube diameter, experimental test time, and fuel dopants are considered.

Surface Fouling in Aviation Fuels: An Isothermal Chemical Study

1996 ◽  
Vol 118 (2) ◽  
pp. 286-291 ◽  
Author(s):  
E. G. Jones ◽  
W. J. Balster ◽  
J. M. Pickard
Keyword(s):  
Experimental Test ◽  
Chemical Study ◽  
Aviation Fuel ◽  
Test Time ◽  
Tubular Heat Exchanger ◽  
Surface Deposition ◽  
Test Conditions ◽  
Aircraft Fuel ◽  
Dynamic Experiments ◽  
Selection Of

Surface fouling in aircraft fuel lines that results from autoxidation of aviation fuel remains a serious and very complicated problem. This area has been studied using two Jet-A fuels, POSF-2827 and POSF-2980. The results of a series of dynamic experiments conducted in a single-pass, tubular heat exchanger operated at very slow flow rates under near-isothermal conditions are reported herein. Such studies, by minimizing complications resulting from fluid dynamics and heat flow, constitute a simpler global approach to the chemistry of fouling. The basis for the selection of experimental test conditions is discussed, and data from measurements of dissolved oxygen and surface deposition as a function of fuel stress duration are presented. The effects of parameters such as reaction temperature, tube diameter, experimental test time, and fuel dopants are considered.

scholarly journals Evaluation of the Effectiveness of a Metal Deactivator and Other Additives in Reducing Insolubles in Aviation Fuels

1996 ◽  
Author(s):  
E. Grant Jones ◽  
Walter J. Balster ◽  
Lori M. Balster
Keyword(s):  
Surface Passivation ◽  
Aviation Fuel ◽  
Jet Fuels ◽  
Dissolved Metals ◽  
Radical Initiation ◽  
Tubular Heat Exchanger ◽  
Advantages And Disadvantages ◽  
Fundamental Information ◽  
Aircraft Fuel ◽  
Free Radical Initiation

Surface fouling in aircraft fuel lines resulting from autoxidation of aviation fuel leads to reduced efficiency as deposits collect on heat exchangers, nozzles, and servocontrols and may ultimately lead to system failure. Metal surfaces and trace quantities of metals dissolved in the fuel exacerbate the surface-fouling problem because they can catalyze free-radical initiation, thereby accelerating autoxidation. Additives and additive packages containing antioxidants, dispersants, and metal deactivators (MDA) have been shown to reduce insolubles in some fuels. Because of metal chelation and possible metal-surface passivation, MDA has been proposed as an additive component to be included in all fuels, even those without dissolved metals. The goal of the present study was to obtain fundamental information on the behavior of MDA under conditions where surface-passivation effects are minimal. Experiments have been conducted to 1) study the effects of adding MDA to fuels containing a significant concentration of dissolved metals (i.e., chelation) and to those containing minor concentrations of dissolved metals and 2) investigate interactions when MDA is used in conjunction with an antioxidant and a dispersant. Simple fuel-line-fouling simulations with a single-pass tubular heat exchanger operated under near-isothermal conditions have been conducted to study the thermal behavior at 185°C of several neat and MDA-treated jet fuels as well as fuels treated with MDA plus other additives. Comparison of neat and treated fuels is based on several criteria: 1) dependence of autoxidation on stress duration, 2) dependence of surface deposition on stress duration, and 3) quantity of total insolubles (bulk filterables and surface deposits). Potential advantages and disadvantages of using MDA alone and in combination are discussed.

Evaluation of the Effectiveness of a Metal Deactivator and Other Additives in Reducing Insolubles in Aviation Fuels

1997 ◽  
Vol 119 (4) ◽  
pp. 830-835 ◽  
Author(s):  
E. G. Jones ◽  
W. J. Balster ◽  
L. M. Balster
Keyword(s):  
Surface Passivation ◽  
Aviation Fuel ◽  
Jet Fuels ◽  
Dissolved Metals ◽  
Radical Initiation ◽  
Tubular Heat Exchanger ◽  
Advantages And Disadvantages ◽  
Fundamental Information ◽  
Aircraft Fuel ◽  
Free Radical Initiation

Surface fouling in aircraft fuel lines resulting from autoxidation of aviation fuel leads to reduced efficiency as deposits collect on heat exchangers, nozzles, and servocontrols and may ultimately lead to system failure. Metal surfaces and trace quantities of metals dissolved in the fuel exacerbate the surface-fouling problem because they can catalyze free-radical initiation, thereby accelerating autoxidation. Additives and additive packages containing antioxidants, dispersants, and metal deactivators (MDA) have been shown to reduce insolubles in some fuels. Because of metal chelation and possible metal-surface passivation, MDA has been proposed as an additive component to be included in all fuels, even those without dissolved metals. The goal of the present study was to obtain fundamental information on the behavior of MDA under conditions where surface-passivation effects are minimal. Experiments have been conducted to (1) study the effects of adding MDA to fuels containing a significant concentration of dissolved metals (i.e., chelation) and to those containing minor concentrations of dissolved metals and (2) investigate interactions when MDA is used in conjunction with an antioxidant and a dispersant. Simple fuel-line-fouling simulations with a single-pass tubular heat exchanger operated under near-isothermal conditions have been conducted to study the thermal behavior at 185°C of several neat and MDA-treated jet fuels as well as fuels treated with MDA plus other additives. Comparison of neat and treated fuels is based on several criteria: (1) dependence of autoxidation on stress duration, (2) dependence of surface deposition on stress duration, and (3) quantity of total insolubles (bulk filterables and surface deposits). Potential advantages and disadvantages of using MDA alone and in combination are discussed.

Design of an experimental test loop for fast spectrum test conditions

2021 ◽  
pp. 108438
Author(s):  
Daniel LaBrier ◽  
Ben Lilley ◽  
Anton Higgins ◽  
Ryan Stewart ◽  
Todd Palmer ◽  
...  
Keyword(s):  
Experimental Test ◽  
Test Conditions ◽  
Test Loop

scholarly journals The Thermal Stability of Aviation Fuel

1984 ◽  
Author(s):  
J. S. Mills ◽  
F. R. Edwards
Keyword(s):  
Thermal Stability ◽  
Research Tool ◽  
Aviation Fuel ◽  
Engine Oil ◽  
Thermally Stable ◽  
Fuel System ◽  
Flow Rates ◽  
Aircraft Fuel ◽  
Oil Cooler ◽  
Thermal Stability Of

The propensity of aviation turbine fuels to produce deposits in the oil-cooler and filter sections of aircraft fuel systems has been examined using a rig that simulates the fuel system of an aircraft and which employs realistic flow rates. All the fuels examined were found to be thermally stable up to temperatures in excess of those currently attained in engine oil coolers. Comparison with results obtained with the JFTOT indicates that this is not suited for use as a research tool.

scholarly journals The investigation on the middle period dephosphorization in 70t converter

2020 ◽  
Vol 39 (1) ◽  
pp. 567-575
Author(s):  
Deng Nanyang ◽  
Wang Haijun ◽  
Ling Haitao ◽  
Wang Jianjun
Keyword(s):  
Theoretical Calculation ◽  
Experimental Test ◽  
Limiting Factor ◽  
Molten Bath ◽  
Large Margin ◽  
Test Conditions ◽  
Middle Period ◽  
Slag Conditions ◽  
Dephosphorization Rate ◽  
Lance Position

AbstractAn experimental test is carried out on the 70t converter in Masteel to study the law of middle period dephosphorization in the smelting period. It is found that the dephosphorization rate is slow in the early and middle period of smelting and the content of the final P in steel cannot reach the standard due to the low oxidation of slag. The content of the final P in steel can be controlled within 0.02% by adding ore to the molten bath in the middle period and raising the lance position. The experimental test shows that the dephosphorization can still be achieved by a large margin if appropriate slag conditions are maintained in the middle period when the C and O reactions are strong. By theoretical calculation, it is concluded that the slag content should be controlled between 15 and 23%, and the basicity of slag should be between 2.5 and 2.8 in the middle period of production. Through the observation of experimental slag by SEM, it is found that the limiting factor of dephosphorization in the middle period under the test conditions is that the dephosphorization speed is too slow due to the low oxidation, rather than the solidification of phosphorus.

Experimental and Analytical Characterization of Alternative Aviation Fuel Sprays Under Realistic Operating Conditions

2018 ◽  
Author(s):  
Andrew Corber ◽  
Nader Rizk ◽  
Wajid Ali Chishty
Keyword(s):  
Experimental Data ◽  
Alternative Fuels ◽  
Laser Sheet ◽  
National Research Council ◽  
Diagnostic System ◽  
Operating Conditions ◽  
Aviation Fuel ◽  
Injection System ◽  
Test Time

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities.

scholarly journals Critical appraisal of speech in noise tests: a systematic review and survey

2016 ◽  
Vol 5 (1) ◽  
pp. 13 ◽  
Author(s):  
Suhani Sharma ◽  
Rajesh Tripathy ◽  
Udit Saxena
Keyword(s):  
Critical Appraisal ◽  
Measurement Model ◽  
Test Time ◽  
Hearing Research ◽  
Speech In Noise ◽  
Hearing In Noise ◽  
Instrument Bias ◽  
Noise Test ◽  
Time Required ◽  
Selection Of

Speech in noise tests that measure the perception of speech in presence of noise are now an important part of audiologic tests battery and hearing research as well. There are various tests available to estimate the perception of speech in presence of noise, for example, connected sentence test, hearing in noise test, words in noise, quick speech-in-noise test, bamford-kowal-bench speech-in-noise test, and listening in spatialized noise-sentences. All these tests are different in terms of target age, measure, procedure, speech material, noise, normative, etc. Because of the variety of tests available to estimate speech-in-noise abilities, audiologists often select tests based on their availability, ease to administer the test, time required in running the test, age of the patient, hearing status, type of hearing disorder and type of amplification device if using. A critical appraisal of these speech-in-noise tests is required for the evidence based selection and to be used in audiology clinics. In this article speech-in-noise tests were critically appraised for their conceptual model, measurement model, normatives, reliability, validity, responsiveness, item/instrument bias, respondent burden and administrative burden. Selection of a standard speech-in-noise test based on this critical appraisal will also allow an easy comparison of speech-in-noise ability of any hearing impaired individual or group across audiology clinics and research centers. This article also describes the survey which was done to grade the speech in noise tests on the various appraisal characteristics.

scholarly journals Measuring Sound-Processor Thresholds for Pediatric Cochlear Implant Recipients Using Visual Reinforcement Audiometry via Telepractice

2018 ◽  
Vol 61 (8) ◽  
pp. 2115-2125 ◽  
Author(s):  
Michelle L. Hughes ◽  
Jenny L. Goehring ◽  
Joshua D. Sevier ◽  
Sangsook Choi
Keyword(s):  
Young Children ◽  
Success Rate ◽  
Outcome Measures ◽  
Test Session ◽  
Test Time ◽  
Visual Reinforcement ◽  
Behavioral Thresholds ◽  
Test Conditions ◽  
Significant Difference ◽  
Caregiver Questionnaire

Purpose The goal of this study was to test the feasibility of using telepractice for measuring behavioral thresholds (T levels) in young children with cochlear implants (CIs) using visual reinforcement audiometry (VRA). Specifically, we examined whether there were significant differences in T levels, test time, or measurement success rate between in-person and remote test conditions. Method Data were collected for 17 children, aged 1.1–3.4 years. A within-subject AB-BA (A, in-person; B, remote) study design was used, with data collection typically occurring over 2 visits. T levels were measured during each test session using VRA for one basal, middle, and apical electrode. Two additional outcome measures included test time and response success rate, the latter of which was calculated as the ratio of the number of electrode thresholds successfully measured versus attempted. All 3 outcome measures were compared between the in-person and remote sessions. Last, a parent/caregiver questionnaire was administered at the end of the study to evaluate subjective aspects of remote versus traditional CI programming. Results Results showed no significant difference in T levels between in-person and remote test conditions. There were also no significant differences in test time or measurement success rate between the two conditions. The questionnaires indicated that 82% of parents or caregivers would use telepractice for routine CI programming visits some or all of the time if the option was available. Conclusion Results from this study suggest that telepractice can be used successfully to set T levels for young children with CIs using VRA.

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