백드래프트에 영향을 미치는 질량유량 및 구획실 형상에 대한 전산해석 연구

Abstract

A computational study is performed for effects of mass flow rate, compartment size, and different opening geometries on backdraft using FDS. The prediction performance of the Large Eddy Simulation (LES) with Mixing-Controlled Fast Chemistry (MCFC) and Eddy Dissipation Concept (EDC) 1-step was evaluated for backdraft before the simulation on backdraft. A LES adopting EDC 1-step was successfully performed for backdraft phenomena. The prediction of the EDC 1-step model was similar to that of the MCFC model and backdraft study proceed using MCFC that computational cost is efficient. At first, theoretical and FDS analysis for the evaluation of inflowing air mass flow rate in a compartment among factors on backdraft. Predictions of FDS is the most similar and predictions of stratified case showed a reasonable trend with the experimental results. As the size of compartment increased, the gravity current time was delayed and backdraft intensity tended to increase. However, it is difficult to investigate the increasing volume of compartment since the volume of the compartment and the opening increase together. Opening geometries influence on mixing characteristics consequently the fuel and oxygen were the best mixed for the SlotU case while the fuel and oxygen were not well mixed in relatively separated to layers for the SlotL case. The peak pressure during backdraft was the highest for the SlotU case, a well mixed condition of fuel and oxygen, and backdraft was not found for the SlotL where the pressure rise was not so high due to the mixing status.