In order to investigate the combustion gas in a small scale furnace, the experiment on visualization and characteristics of temperature of natural convection flow is made in a model room and the numerical calculation is conducted. In the experiment on flow visualization and temperature in fluid, water is used as the working fluid. Flow pattern is obtained by means of the aluminum powder method. The numerical calculation based on the stream function(ψ)-vorticity(ω) method is conducted in the case of laminar flow. In the case of turbulent flow the k-ε method is applied. The similarity between the room and the practical furnace is not always established because the latter has premixed burners and around which there are some of secondary air flows. However, the fundamental feature of flow patterns is observed. The clockwise and counter clockwise circulation flow is observed alternately in the model room, and the bend of streamlines around burners is obtained as a result of the numerical simulation.
