scholarly journals Nitrogen as an environmentally friendly suppression agent for aircraft cargo fire safety

2021 ◽  
pp. 073490412110344
Author(s):  
Michail Diakostefanis ◽  
Suresh Sampath ◽  
Akhil Dinesh ◽  
Rainer Beuermann ◽  
Areti Malkogianni
Keyword(s):  
Fire Suppression ◽  
Environmentally Friendly ◽  
Montreal Protocol ◽  
Performance Standard ◽  
Small Scale ◽  
Average Temperature ◽  
Surface Burning ◽  
Additional Qualification ◽  
Bulk Load ◽  
Minimum Performance

Fire suppression systems in cargo compartments are a certification requirement for commercial aircraft safety. Halon production was banned and usage ends in 2040 according to Montreal Protocol for environmental reasons. This necessitates an alternative environmentally friendly agent. Quantitative analysis of nitrogen as agent established suitability of the suppression system. The Minimum Performance Standards specifies the qualification procedure of an agent through four scenarios – bulk load; containerised load; surface burning; and aerosol can explosion. Empirical sources from Airbus, independent computational fluid dynamics studies and small-scale cup-burner tests indicate suitability of nitrogen specific to aircraft cargo fire suppression. The nitrogen delivery system and the experimental apparatus are presented. Extensive commissioning tests verified instrumentation reliability. All the four scenarios were conducted at Cranfield University, in a replica of a wide-body aircraft cargo compartment. In a reduced oxygen environment (11%) obtained with nitrogen discharge, the aerosol can explosion tests were performed without any evidence of explosion or pressure increase beyond the expected baseline value. The surface burning scenario was completed successfully and passed the Minimum Performance Standard criteria. The maximum average temperature was found to be 220°C (limit – 293°C). All the scenarios passed the Minimum Performance Standard criteria for indicating successful prevention of Class B fire re-ignition. Similarly, the containerised and bulk-load scenarios obtained results that passed the Minimum Performance Standard criteria for successfully maintaining continued fire suppression for a specified period of time. The maximum average temperature in containerised-load fire scenario was found to be 210°C (limit – 343°C) and in bulk-load scenario was 255°C (limit – 377°C). Additional qualification criteria and system design are presented in this article according to the Minimum Performance Standard format. This work can be extended to introduce standard testing for safety critical systems, such as engine bay and lithium-ion fires.

scholarly journals Numerical assessment for aircraft cargo compartment fire suppression system safety

2021 ◽  
pp. 073490412110032
Author(s):  
Yifang Xiong ◽  
Michail Diakostefanis ◽  
Akhil Dinesh ◽  
Suresh Sampath ◽  
Theoklis Nikolaidis
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fire Suppression ◽  
Montreal Protocol ◽  
Performance Standard ◽  
Numerical Code ◽  
Potential Candidate ◽  
System Safety ◽  
Halon 1301 ◽  
Surface Burning

Fire on board an aircraft cargo compartment can lead to catastrophic consequences. Therefore, fire safety is one of the most important considerations during aircraft design and certification. Conventionally, Halon-based agents were used for fire suppression in such cases. However, an international agreement under the Montreal Protocol of 1994 banned further production of Halon and several other halocarbons considered harmful to the environment. There is therefore a requirement for new suppression agents, along with suitable system design and certification. This article aims to describe the creation of a mechanism to validate a preliminary design for fire suppression systems using Computational Fluid Dynamics and provide further guidance for fire suppression experiments in aircraft cargo compartments. Investigations were performed for the surface burning fire, one of the fire testing scenarios specified in the Minimum Performance Standard, using the numerical code Fire Dynamics Simulator. This study investigated the use and performance of nitrogen, a potential replacement for Halon 1301, as an environmentally friendly agent for cargo fire suppression. Benchmark fires using the pyrolysis model and fire design model were built for the surface-burning fire scenario. Compared with experiment results, the two Computational Fluid Dynamics models captured the suppression process with high accuracy and displayed similar temperature and gas concentration profiles. Fire consequences in response to system uncertainties were studied using fire curves with various fire growth rates. The results suggested that using nitrogen as a fire suppression agent could achieve a lower post-suppression temperature compared to a Halon 1301-based system. It can therefore be considered as a potential candidate for aircraft cargo fire suppression. Such work will feed directly into system safety assessments during the early design stages, where analyses must precede testing. Future work proposed for the application of this model can be extended to other fire scenarios such as buildings, shipping, and surface transport vehicles.

scholarly journals Research of the Photo-Optical Method Application for Measuring Selected Data on the Movement of a Parachute for Type M-282

2021 ◽  
Vol 11 (12) ◽  
pp. 5637
Author(s):  
Peter Kaľavský ◽  
Róbert Rozenberg ◽  
Peter Korba ◽  
Martin Kelemen ◽  
Matej Antoško ◽  
...  
Keyword(s):  
Optical Method ◽  
Training Programs ◽  
Performance Standard ◽  
Motion Data ◽  
Innovative Methods ◽  
Measurement Results ◽  
Different Types ◽  
Vertical Speed ◽  
Individualized Training ◽  
Minimum Performance

Testing in the field of parachute technology provides space for the application of new and innovative methods of measuring operating and functional parameters. The main aim of the paper is to present the results of research for the verification of the photo-optical method of measuring the vertical speed of the M-282 parachutes, and for its use in testing, collecting, and investigating motion data in parachuting. As part of this measuring technology, twelve jumps were performed. It was verified that the experiment was completed for the M-282 parachute according to the regulation of SAE AS 8015B “Minimum Performance Standard Parachute Assemblies and Components”. An analysis of the influencing factors and quantification of their influence on the uncertainty of the measurement results was also performed. The results of the measurement achieved by using the photo-optical method were compared with the measurement with the electronic variometer FLYTEC 4030. The vertical speed of the M-282 parachute (4.655 m·s−1) defined by the photo-optical method is significantly similar to the vertical speed of the M-282 parachute (4.662 m·s−1) defined by FLYTEC 4030. We can state that the process of identifying the vertical speed of the parachute by the photo-optical method was correct. This is a suitable method of evaluating motion data in the operation of M-282 type parachutes. In the following research for generalization of the methodology, we assume the performance of more than 60 experimental jumps using different types of parachutes, digital sensors (cameras), and a photo-optical method to examine motion data and formulate recommendations for testing, investigative applications, individualized training programs, and aspects of parachuting injury prevention.

Experimental Investigation of Lab-Scale, Heat Exchanger Prototypes Designed to Provide Refugia for Trout

2021 ◽  
Author(s):  
Rajib Uddin Rony ◽  
Adam Gladen ◽  
Sarah LaVallie ◽  
Jeremy Kientz
Keyword(s):  
Heat Exchanger ◽  
Temperature Difference ◽  
Large Scale ◽  
Cold Water ◽  
Cooling System ◽  
Tube Bundle ◽  
Small Scale ◽  
Scaled Model ◽  
Average Temperature ◽  
Average Temperature Difference

Abstract In recent years Spring Creek in South Dakota, a popular fishing location, has been experiencing higher surface water temperatures, which negatively impact cold-water trout species. One potential solution is to provide localized refugia of colder water produced via active cooling. The present work focuses on the design and testing of a small-scale prototype heat exchanger, for such a cooling system. Various prototypes of the heat exchanger were tested in a 1/10th-scaled model of a section of the creek. A staggered, tube-bundle heat exchanger was used. The prototypes consisted of just the heat exchanger placed directly in the scaled-stream model and of the heat exchanger placed inside an enclosure with an aperture. The results show that, without the enclosure, the average temperature difference is 0.64 °C, with a corresponding heat transfer requirement of 1.63 kW/°C of cooling. However, with an enclosure, the average temperature difference is 1.95 °C, which required 0.59 kW/°C of cooling. Modifications to the enclosure decrease the average temperature difference but also decrease the standard deviation of the temperature difference. Thus, the cooling effect is more evenly spread throughout the water in the enclosure. This indicates that the enclosure design can be used to balance the requirements of obtaining a desired temperature difference with a relatively low spatial variation in that temperature difference. These results will be used to guide the design of the large-scale heat exchanger prototype.

Design and Analysis of Small Scale Horizontal Archimedean Screw for Electric Power Generation

2017 ◽  
Author(s):  
Paul E. Slaboch ◽  
Jillian Coday
Keyword(s):  
Power Generation ◽  
Electric Power ◽  
Environmentally Friendly ◽  
Small Scale ◽  
Aquatic Environments ◽  
Efficient Design ◽  
Electric Power Generation ◽  
Aquatic Life ◽  
Overall Efficiency ◽  
Pass Through

A small scale horizontal Archimedean screw was designed, built, and tested for small-scale electric power generation. The small-scale device is suitable for deployment in shallow waterways and rivers. The design of the screw is environmentally friendly and allows for fish and other aquatic life to pass through harmlessly. A series of horizontal screws were designed over a range of blade pitch and tip conditions to determine the most efficient configuration of the device. The tip conditions included straight, flanged, and open. The device was placed both inside and outside of a duct to control tip conditions. The flanged condition added material to the tip of the device to simulate a partially ducted screw. Preliminary studies have shown that the straight bladed screw is the most efficient design. Preliminary data also show that the addition of a duct reduced the overall efficiency of the device. The flange feature on the screw was shown to be ineffective as well. However, the design was environmentally friendly and would provide electric power on a small scale without harm to local aquatic environments.

Burn Chamber Test of Ex Situ Thermal Impulse Sensors

2020 ◽  
Vol 74 (5) ◽  
pp. 515-524
Author(s):  
Benjamin R. Anderson ◽  
Natalie Gese ◽  
Ray Gunawidjaja ◽  
Hergen Eilers
Keyword(s):  
Research Laboratory ◽  
Large Scale ◽  
Current Method ◽  
Ex Situ ◽  
Small Scale ◽  
Average Temperature ◽  
Current Test ◽  
Oxide Precursor ◽  
The Us ◽  
Lab Test

Recently, we reported on a novel ex situ thermal impulse sensing technique (based on lanthanide-doped oxide precursor nanoparticles) for use in structural fire forensics and demonstrated its functionality in small-scale lab-based tests. As a next step we have now performed a large-scale lab test at the US Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) Fire Research Laboratory using a burn chamber with three sand burners. In this test we demonstrate our technique’s ability to determine the average temperature experienced by surfaces during the fire. While we successfully demonstrate our techniques accuracy, we also discover several previously unknown vulnerabilities. Namely, we find that: (1) our current method of embedding sensors in paint results in our sensor particles being difficult to recover (due to a large quantity of debris), (2) the current test panels have poor survivability, (3) debris from the fire tests interferes with excitation of dopant Dy ions (limiting our sensors’ functionality), and (4) dispersal in paint results in suppression of the (metastable)tetragonal-to-monoclinic phase transition of ZrO2. To overcome these vulnerabilities we are evaluating new panel materials, paints, and lanthanide-dopants.

scholarly journals Prediction of a Small-Scale Pool Fire with FireFoam

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Camilo Andrés Sedano ◽  
Omar Darío López ◽  
Alexander Ladino ◽  
Felipe Muñoz
Keyword(s):  
Numerical Results ◽  
Pool Fire ◽  
Flame Height ◽  
Combustion Model ◽  
Small Scale ◽  
Average Temperature ◽  
Eddy Simulation ◽  
Fire Experiment ◽  
Large Eddy ◽  
Good Agreement

A computational model using Large Eddy Simulation (LES) for turbulence modelling was implemented, by means of the Eddy Dissipation Concept (EDC) combustion model using the fireFoam solver. A small methanol pool fire experiment was simulated in order to validate and compare the numerical results, hence trying to validate the effectiveness of the solver. A detailed convergence analysis is performed showing that a mesh of approximately two million elements is sufficient to achieve satisfactory numerical results (including chemical kinetics). A good agreement was achieved with some of the experimental and previous computational results, especially in the prediction of the flame height and the average temperature contours.

Study on the Thermal Effect of Adding Coal Cinder to the LCZ of Solar Pond

2010 ◽  
Vol 42 ◽  
pp. 294-298
Author(s):  
Hua Wang ◽  
Jun Li Liu ◽  
Jia Ning Zou
Keyword(s):  
Normal Modes ◽  
Temperature Evolution ◽  
Small Scale ◽  
Large Area ◽  
Solar Ponds ◽  
Average Temperature ◽  
Solar Pond ◽  
Salt Gradient ◽  
Increasing Temperature

In this study, adding coal cinder to bottom of solar pond as a means of increasing temperature of the solar pond is presented. A series of small-scale tests are conducted in the simple mini solar ponds. These small-scale tests include the temperature evolution comparisons of this mode with other normal modes; the comparisons of the material added to LCZ and the comparisons of the different soaking times for coal cinder. In addition, a numerical calculation on predicting temperature evolution in large area of salt gradient solar pond is also given. Both of the experimental and numerical results suggest that adding porous media with low thermal diffusivity (e.g. coal cinder) could significantly increase the temperature in the vicinity of the bottom of the pond. From the view of long-term, this effect is supposed to enhance the average temperature of the solar pond.

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