Effects of Initial Condition and Opening Geometry of a Compartment on the Gravity Current in the Backdraft

Title & Authors
Effects of Initial Condition and Opening Geometry of a Compartment on the Gravity Current in the Backdraft
Park, Ji-Woong; Oh, Chang Bo; Han, Yong Shik; Do, Kyu Hyung;

Abstract
Computational study of a gravity current prior to the backdraft was conducted using fire dynamic simulator (FDS). Various initial conditions of mixture compositions and compartment temperature as well as four opening geometries (Horizontal, Door, Vertical, and Full opening) were considered to figure out their effects on the gravity current. The density difference ratio ($\small{{\beta}}$) between inside and outside of compartment, the gravity current time ($\small{t_{grav}}$) and velocity ($\small{v_{grav}}$), and non-dimensional velocity ($\small{v^*}$) were introduced to quantify the flow characteristics of the gravity current. Overall fluid structure of the gravity current at the fixed opening geometry showed similar development process for different $\small{{\beta}}$ conditions. However, $\small{t_{grav}}$ for entering air to reach the opposed wall to the opening geometry increased with $\small{{\beta}}$. Door, Vertical, and Horizontal openings where openings are attached on the ground showed similar development process of the gravity current except for Horizontal opening, which located on the middle of the opening wall. The magnitude of $\small{v_{grav}}$ at fixed $\small{{\beta}}$ was, from largest to smallest, Full > Vertical > Door > Horizontal, but it depended on both the size and location of the opening. On the other hand, $\small{v^*}$ was found to be independent to $\small{{\beta}}$, and only depended on the geometry of the opening.
Keywords
backdraft;fire dynamics simulator(FDS);gravity current;non-dimensional velocity;compartment fire;
Language
Korean
Cited by
1.
A Numerical Study of the Backdraft Behavior with the Variation of the Ignition Location and Time, Journal of the Korean Society of Safety, 2016, 31, 4, 1
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