The characteristics of ¦lm cooling in a CH 4 /O 2 subscale chamber with multiinjector elements and two kinds of ¦lm cooling slot dimensions are investigated using a calorimeter chamber in experiments and simulations, in which the ¦nite rate chemistry with a reduced CH 4 /O 2 reaction mechanism is taken into account. The computed wall heat §ux and pressure distributions are compared to the experimental results, which overall show good agreement. A large slot dimension is shown to induce mixing with core §ow. This mixing causes a low heat- §ux distribution near face plate along with high combustion e©ciency.