- Author
-
Tatem, P. A.
|
Williams, F. W.
|
White, D. A.
|
Beyler, C. L.
- Title
- Modeling Missile Propellant Fires in Shipboard Compartments.
- Coporate
- Naval Research Laboratory, Washington, DC
Hughes Associates, Inc., Baltimore, MD
- Report
-
NRL/MR/6180-00-8446,
March 30, 2000,
50 p.
- Keywords
-
shipboard fires
|
fire models
|
large scale fire tests
|
ignition
|
computer models
|
compartments
|
burning rates
- Identifiers
- class A materials; China Lake test descriptions; HULVUL test description; FAST; CFAST (Consolidated Fire growth And Smoke Transport)
- Abstract
- Concerns regarding the likelihood and severity of propellant initiated fires have given rise to a test program to characterize this class of tires. This test program was very successful in identifying the basic character of these fires and the important phenomenology which govern the ultimate results. Several phenomena unique to propellant-initiated fires have been identified, including overpressures which result from the propellant burn and the dependence of Class A material ignition upon the interplay of temperature and oxygen concentration at the end of the propellant burn. Missile propellant fires result in interesting phenomena which have been observed during the experiments. The fire growth rate associated with the ignition of the missile propellant results in a jump to tens of megawatts in a matter of seconds. A measurable overpressure surge pushes the compartment air, with normal oxygen content, out as it is filled with expanding combustion gases from the burning missite propellant. As the missile propellant continues to burn, the compartment is assaulted with high radiant heat fluxes and gas temperatures which can globally exceed peak values of 1200 to 1400 deg C. This severe thermal exposure only lasts for approximately a minute which corresponds to the propellant burning duration. The heating of the compartment and its contents occurs in the brief window of time where the oxygen content of the compartment environment is significantly depressed. As fresh air with normal oxygen content begins to re-enter the compartment, the combustible items which were only briefly heated, have begun to cool. Thus, an interplay of the surface temperatures of combustible items and the local oxygen concentrations determines the possibility of ignition. As is often the case, it is not feasible to test all combinations of parameters which may be expected in practice, and it can be difficult to extrapolate the results from this test series to the broad range of ship compartments and burn scenarios of interest within the U.S. Navy Fleet. In order to consolidate the findings from the experimental program and facilitate the application of the results to a broad range of ship compartments and scenarios, a model capable of simulating the impact of these fires was developed. The focus of this project was an evaluation of the feasibility of modeling propellant-initiated ties by attempting to predict the results of the HULVUL tests without prior examination of the experimental results. The test results of the China Lake series were used to guide model development. The goal of the work has been to develop a tool with sufficient capabilities to characterize the fire environment in the compartment with burning missile propellant. No attempt has been made to predict conditions in compartments other than the compartment of fire origin.