Fast cook-off test with a sand bed burner: Evaluation of the heating process with LPG compared to Jet A1
Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
Many modern munitions are designed to be insensitive to outside influences. To classify a munition as insensitive certain tests must be accomplished. One of these tests is a fast cook-off test to simulate the munitions behavior in an intense fire. According to the NATO standard, STANAG 4240, the test must be performed with jet fuel, for example Jet A1. Due to high testing costs and the environmental impact of the standard test, attempts have been made to replace jet fuel with alternative fuels. The aim of this report is to construct a sand bed burner based on propane and compare the heating process with a Jet A1 pool fire. The report also presents an alternative measurement method to ensure the same thermal impact as in a Jet A1 pool fire. The sand bed burner is based on letting propane diffuse through a sand bed. This will make the combustion result in flames with a higher radiation than premixed flames. A probe measuring steel surface temperature and gas temperature was constructed to make the comparison possible. The steel temperature was then approximated as the adiabatic surface temperature. Three different tests were made; with the sand bed burner, with a Jet A1 pool fire and with the existing Bofors Test Center (BTC) gas burner. The results were then analyzed by comparing the thermal impact in each direction.The result shows some differences in the heating pattern. Jet A1 provides the most even heating but the maximum gas temperatures are lower than with the other methods. The BTC gas burner shows the most uneven heating, with over 400 ˚C difference from the lower to the upper point. The sand bed burner is somewhere between the other two methods.The two main problems were identified during the tests with the sand bed burner. No combustion occurred in the middle of the burner and the gas supply varied due to cooling of the tubes when the LPG evaporated.Based on the results from the test carried out it can be assumed that with a slightly modified sand burner and an adequate gas supply further test in larger test are likely to be successful in terms of yielding similar thermal exposure as the test specified in the standard STANAG 4240.
Place, publisher, year, edition, pages
2013. , 78 p.
Teknik, Insensitive munitions, IM, IM-testing, fast cook-off test, FCO, adiabatic surface temperature, TAST, sand bed burner, propane, LPG, Jet A1, STANAG 4240, AOP-39
IdentifiersURN: urn:nbn:se:ltu:diva-44512Local ID: 24f84a13-927a-4575-8319-65dd794de19eOAI: oai:DiVA.org:ltu-44512DiVA: diva2:1017791
Subject / course
Student thesis, at least 15 credits
Fire Protection Engineer, bachelor's level
Validerat; 20130609 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved