Detonation is a type of premixed combustion, which propagates interacting with shock waves and combustion flames at supersonic speed. It is known in the early researches that DDT (Deflagration to Detonation Transition) in a channel is promoted by installing obstacles. This research investigates flame propagation and local explosions in channels filled with hydrogen/oxygen stoichiometric mixture and installed ten obstacles by using the two-dimensional simulation with a detailed reaction model. Furthermore, we estimate differences between the three-dimensional experiments performed in a past study and the present two-dimensional simulations. The simulations performed by changing the scale of the channel, grid width, and obstacle height. As a result, the flames did not transit to detonation under any conditions of the obstacle heights and channel sizes, unlike the experiments. Higher obstacles disturbed the flame propagation and induced the shock waves crossing the channel, which lead to the enhancement and acceleration of the combustion reaction. A small local explosion was observed near the eighth obstacle at one-tenth the size. The flame acceleration was faster in the experiment than in the numerical analysis.