APPLICATION OF INVERSE ANALYSIS TO OBTAIN THE PARAMETERS OF THE WEIGHTED-MULTI-POINT-SOURCE MODEL FOR FREE FLAMES
Rodrigo Brenner Miguel1; Isaías Mortari Machado1; Fernando Marcelo Pereira1; Francis Henrique Ramos França1; Paulo R. Pagot2
1 Depertament of Mechanical Engineering - Federal University of Rio Grande do Sul - UFRGS; 2 CENPES/ PDEP/ TPP - PETROBRAS-Petroleo Brasileiro S.A.
doi:10.20906/CPS/COB-2015-0875
Resumo
Thermal radiation is responsible for a substantial portion of the heat release in a flame. Radiative characteristics of jet fires are usually expressed through the use of the fraction of heat radiated. Detailed flame simulations provide useful information but can be prohibitive for practical applications due to the significant computational resources required. The weighted-multi-point-source model use point sources with different weights to simulate the contribution of each discretized portion of flame. While previous studies used the trial-and-error approach to determine the sources weight, this paper proposes a method to obtain the weight of each source by inverse analysis. In the analysis, the experimental measured radiation heat flux distribution is the input data, while the weights of the sources and the fraction of heat radiated are the output data. The inverse problem is formulated as an optimization problem, which is solved by the generalized extremal optimization. The present study analyzes the influence of the number of sources and the length that the sources should be distributed on model results. Using seven sources uniformly distributed over 1.75 times the flame visible length, the maximum deviation between experimental radiation heat flux and results for all points of twelve flames were kept less than 5%. As will be show in the paper, the inverse method is capable of recovering the sources weight for the model that generates satisfactory results.
Palavras-chave: Inverse analysis; weighted-multi-point-source model; open flame; optimization methods