Experimental Aircraft Fuel Tank Vapour/Air Explosions Using Jet A and Jet A / Gasoline Blend Fuels

The potential of a fuel tank explosion is a well-known hazard in the aircraft industry. In this study, an investigation of a lab scale aircraft fuel tank in a flight situation at varying initial pressures of 400 - 1,000 mbar (equivalent to altitudes of 0 - 22,300 ft) and at variable temperatures was conducted in a 100-litre cylindrical test rig. A standard Jet A fuel and with a type Jet B fuel (which in this case was a Jet A with 10% of gasoline by mass) were used. Their flashpoints were measured to be 45oC (Jet A) and 20 oC (Jet B). In the simulated fuel tank explosions ignition occurred when the fuel liquid temperature was much higher than the flash point - 71 – 107 oC depending on initial pressure (altitude) for Jet A and 57 – 95 oC for the more volatile Jet B. The resulting maximum explosion overpressures were high, ranging from 0.7 to 5.8 bar, much higher than typical design strengths of aircraft fuel tanks, and much stronger than anticipated overpressures on the basis of ignition at or close to the lower flammability limit (LFL). It is postulated that these pressures are due to the distance between the liquid fuel surface and the ignition point and the formation of a vapour cloud with decreasing concentration with height above the fuel (being at LFL at the ignition point) and hence an overall concentration much higher than LFL. This demonstrated that severe explosions are fuel tanks are likely and the assumption that the explosion will be a near lean limit event is not safe. The work also provided explosion severity index data which can be used in design of suppression and venting systems for the mitigation of aircraft fuel tank explosions and provided other quantitative data to help manage this explosion risk appropriately.

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Analytical Algorithm for Oxygen Concentration of Aircraft Fuel Tank in Various Inerting Stages

Applied Sciences ◽

10.3390/app11167698 ◽

2021 ◽

Vol 11 (16) ◽

pp. 7698

Author(s):

Yuhao Wei ◽

Yang Pei ◽

Yuxue Ge

Keyword(s):

Differential Equations ◽

Oxygen Concentration ◽

Fuel Tank ◽

Conventional Model ◽

Aircraft Fuel ◽

Proposed Model ◽

Fuel Tanks ◽

Analytical Algorithm ◽

Fire And Explosion ◽

Derivatives Of

Ullage washing is an efficient inerting method to keep the ullage oxygen concentration under the safe value, thus reducing the hazard and loss of fire and explosion of aircraft fuel tanks. In the conventional model of ullage washing, the initial derivatives of oxygen concentration that are used to solve the differential equations are selected subjectively by researchers and the empirical select influences the accuracy of the result. Therefore, this paper proposes an analytical algorithm that can calculate the ullage oxygen concentration without selecting any initial derivative value. The algorithm is based on a fuel tank ullage washing model regarding various inerting stages. It has been experimentally validated with an average relative error of 5.781%. Moreover, sensitive analyses carried out on the proposed model show that ground-based inerting can effectively reduce the ullage oxygen, concentration in the climb phase. Increasing 5 min of pre-takeoff inerting duration can shorten the time of decreasing the ullage oxygen concentration to 9% after takeoff by 2.1 min.

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Elementary Computer Modeling Applied to TWA800 Fuel Tank Forensic Issues

Volume 6: 18th Computers in Engineering Conference ◽

10.1115/detc98/cie-6021 ◽

1998 ◽

Author(s):

Floyd A. Wyczalek

Keyword(s):

Jet Fuel ◽

Combustible Mixture ◽

Scientific Data ◽

Fuel Tank ◽

Critical Conditions ◽

Jet Fuels ◽

Potential Hazard ◽

Minimum Ignition Energy ◽

Aircraft Fuel ◽

Fuel Tanks

Abstract The specific mission was to identify the conditions of atmospheric pressure and ambient temperature under which a so-called empty-Boeing model 747-131 fixed wing jet aircraft center wing tank (CWT), containing a residual fuel loading of about 3 kg/m3, less than 100 gallons of aviation kerosene (JetA Athens refinery commercial jet fuel), could form hazardous air/fuel mixtures. The issues are limited to explosion safety concerns relating to certificated fixed wing jet aircraft in regularly scheduled commercial passenger service. It is certain that a combustible mixture does not exist in a fuel tank containing Jet-A type fuel at ambient temperatures below 38°C (100°F), which is the lean limit flash point (LFP) for commercial jet fuel at sea level. Never the less, although not included in this paper, the original study reported by Wyczalek and Suh (1997), identified six highly unlikely, but rationally possible critical conditions which can occur in a combination which may permit a combustible mixture to exist within a jet aircraft fuel tank and pose a potential hazard. The scope of this paper is limited to mathematical modeling concerns related to fixed wing jet aircraft fuel tanks and commercial jet fuels combustible air-fuel mixture ratios. It was further limited to a historical review of the scientific literature in the public domain from 1950 to the present time, which defined the thermodynamic and minimum ignition energy properties of aviation gasoline and commercial jet fuels; and, to comparisons with new thermodynamic data for JetA Athens flight test samples, released by the National Transportation Safety Board (NTSB) during public hearings on the TWA800 event in Baltimore, Maryland in December 1997. The original work reported by Wyczalek and Suh (1997) conclusively demonstrated that the USAF Wright Air Development Center and the US Bureau of Mines conducted and published comprehensive evaluations of the potential hazards relating to jet aircraft fuel tanks as early as 1952. This historical scientific data and the mathematical models for the new jetA and Athens refinery jetA in this paper, are relevant to pending TWA800 related litigation, and to the future implementation of NTSB recommendations resulting from the TWA800 event.

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Dimensional modelling of the fuel outgassing phenomenon: Improving flammability assessment of aircraft fuel tanks

The Aeronautical Journal ◽

10.1017/s0001924000006291 ◽

2011 ◽

Vol 115 (1172) ◽

pp. 605-614 ◽

Cited By ~ 4

Author(s):

A. P. Harris ◽

N. M. Ratcliffe

Keyword(s):

Oxygen Evolution ◽

Oxygen Transfer Rate ◽

Fuel Tank ◽

Aviation Fuel ◽

Evolution Rate ◽

Time Constants ◽

Oxygen Evolution Rate ◽

Aircraft Fuel ◽

Wide Range ◽

Fuel Tanks

Abstract Fuel outgassing (oxygen evolution) within aircraft fuel tanks presents a serious flammability hazard. Time constants representing oxygen transfer rate, from the fuel into a tank’s ullage, are used to model the effect of outgassing on tank flammability. These time constants are specific to a single aircraft type and flight envelope and may not accurately represent fuel outgassing behaviour for other aircraft types with differing fuel tank configurations and flight envelopes. To improve current modelling practice for more accurate flammability analysis dimensional modelling has been used to determine the rate of oxygen evolution from Jet A-1 fuel in an aircraft fuel tank. Measurements of oxygen evolution rate, made on a dimensionally similar model, have been projected to an A320 aircraft. The evolution of oxygen from the fuel was found to increase monotonically with time. Fitting the test data with an inverse-exponential function enabled oxygen release rate and its associated time constant (τ) to be determined. Dimensional modelling of aviation fuel outgassing using model fuel tanks will enable oxygen evolution rate from aviation fuel to be determined for a wide range of aircraft fuel tank configurations and environments without the need for flight testing. In turn the accuracy of flammability assessment of aircraft fuel tanks will be improved and significant cost savings made.

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Fibrous polyamide material for use as an explosion suppressant and as a baffle material in aircraft fuel tanks. Test methods

10.3403/30115937 ◽

2005 ◽

Keyword(s):

Test Methods ◽

Aircraft Fuel ◽

Fuel Tanks

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Fibrous polyamide material for use as an explosion suppressant and as a baffle material in aircraft fuel tanks. Specification

10.3403/30115935 ◽

2005 ◽

Keyword(s):

Aircraft Fuel ◽

Fuel Tanks

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Multiple microbending optical-fibre sensors for measurement of fuel quantity in aircraft fuel tanks

Sensors and Actuators A Physical ◽

10.1016/s0924-4247(98)00030-2 ◽

1998 ◽

Vol 68 (1-3) ◽

pp. 320-323 ◽

Cited By ~ 31

Author(s):

S.F. Knowles ◽

B.E. Jones ◽

S. Purdy ◽

C.M. France

Keyword(s):

Optical Fibre ◽

Optical Fibre Sensors ◽

Aircraft Fuel ◽

Fuel Tanks

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Fuel Leaking Analysis of Fuel Tank by Projectiles Impact with Mechanical Properties of Projectiles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.644.203 ◽

2013 ◽

Vol 644 ◽

pp. 203-206

Author(s):

Hai Liang Cai ◽

Bi Feng Song ◽

Yang Pei ◽

Shuai Shi

Keyword(s):

High Speed ◽

Drop Size ◽

Fuel Tank ◽

Size Distributions ◽

Sauter Mean Diameter ◽

Fuel Droplets ◽

High Speed Impact ◽

Fuel Tanks ◽

Rigid Projectile ◽

Drop Size Distributions

For making sure the dry bay ignition and fire, it’s necessary to calculate the number and the sizes of the droplets and determine the mass flow rate of the fuel induced by high-speed impact and penetration of a rigid projectile into fuel tank. An analytical model is founded and the method for calculating the initial leaking velocity of the fuel is determined. It gives the equation for calculating the drop size distributions of fuel and the Sauter mean diameter (SMD) of droplets, through the Maximum Entropy Theory and the conservation for mass. Using the Harmon’s equation for SMD,the fuel droplets SMD can be calculated. Results shows that the initial leaking velocity of the fuel is about linearly increasing with the velocity of the projectile, the SMD of fuel droplets increases with the hole size of the fuel tank which induced by the penetration of the projectile and linearly decreases with the velocity of the projectile. The results can be used for the ignition and fire analysis of the dry bay adjacent to fuel tanks.

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Totalizing contents of aircraft fuel tanks

Electrical Engineering ◽

10.1109/ee.1944.6440728 ◽

1944 ◽

Vol 63 (12) ◽

pp. 1419-1419

Keyword(s):

Aircraft Fuel ◽

Fuel Tanks

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Updated Fuel Tank Puncture Survey: 1995-2020

2021 Joint Rail Conference ◽

10.1115/jrc2021-58520 ◽

2021 ◽

Author(s):

Karina Jacobsen

Keyword(s):

Fuel Tank ◽

Technical Data ◽

Passenger Rail ◽

Blunt Impact ◽

Field Investigations ◽

Fuel Tanks ◽

Serious Injury ◽

Conducting Research ◽

Railroad System ◽

General Operation

Abstract The Federal Railroad Administration’s Office of Research, Development and Technology has been conducting research into passenger fuel tank crashworthiness. The occurrence of a fuel tank puncture during passenger rail collisions and derailments increases the potential of serious injury and fatality for crew and passengers due to the possibility of fire. The purpose of the FRA research is to help support regulatory and standard development with technical data. In the last decade, the research has focused on understanding how fuel tanks are punctured during an impact and how various tank designs respond to common types of loading in collisions, derailments and general operation. Throughout the research, surveys have been conducted to determine the most likely scenarios that are causing fuel tank punctures. A previous FRA survey found that fuel tank punctures occur under two types of loading conditions: a blunt impact or a raking impact. A limited number of accident/incidents were evaluated in this survey. These incidents showed that fuel tanks are punctured on any side that is not protected or shielded. The purpose of this paper is to report on a recently conducted fuel tank puncture survey updated to include the last decade. This paper identifies and describes accidents and incidents that led to breached fuel tanks in freight and passenger trains traveling on the general railroad system in the U.S. between 2008 and 2020. The results include data from the FRA’s Railroad Accident/Incident Reporting System (RAIRS), queried from 1995 to 2020. This data include the number of recorded accidents/incidents and other trends like fuel spillage, operating authority and cause of accident/incident. RAIRS data showed accidents/incidents with fuel tank puncture ranging from 10 to 55 accidents/incidents per year. Additionally, more detailed results are shared from field investigations recently conducted by the FRA or Volpe Center. These more detailed investigations provide additional insight into the types of loading that may lead to a fuel tank puncture. This survey supplements the RAIRS data with more detailed information from field investigations. The paper finally discusses the conditions that lead to fire and the associated hazards.

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