The effect of surface regression on the downward flame spread over a solid fuel in a quiescent ambient

Mohammad Ayani, Javad Esfahani, Antonio Sousa
2007 Thermal Science  
The pres ent work is ad dressed to the nu mer i cal study of the tran sient lam inar op posed-flow flame spread over a solid fuel in a qui es cent am bi ent. The tran sient gov ern ing equa tions -full Navier-Stokes, en ergy, and spe cies (oxy gen and volatiles) for the gas phase, and con ti nu ity and en ergy equa tions for the solid phase (fuel) with prim i tive vari ables are discretized in a staggered grid by a con trol vol ume ap proach. The sec ond-or der Arrhenius kinet ics law is used
more » ... t ics law is used to de ter mine the rate of con sump tion of volatiles due to com bus tion, and the zero-or der Arrhenius ki net ics law is used to de ter mine the rate of deg ra da tion of solid fuel. The equa tions for the fluid and solid phases are solved si mul ta neously us ing a seg re gated tech nique. The phys ical and thermo-phys i cal prop er ties of the fluid (air) such as den sity, ther mal con duc tiv ity, and vis cos ity vary with tem per a ture. The sur face re gres sion of the solid fuel is mod eled nu mer i cally us ing a dis crete for mu la tion, and the ef fect upon the re sults is an a lyzed. The sur face re gres sion of the solid fuel as shown af fects on the fuel sur face and gas tem per a ture, mass flux and ve locity of volatiles on the top sur face of fuel, to tal en ergy trans ferred to the solid phase, etc. It seems the re sults to be re al is tic.
doi:10.2298/tsci0702067a fatcat:ji2sb3inb5c5jcd6qwiacxqwzy