This article presents the fluid mechanics of a ventilation system formed by a momentum source and buoyancy sources. We investigate the interaction between plumes and a non-isothermal air jet for separate sources of buoyancy produced by the plume and the momentum of the air jet. The mathematical model represents the situation in which a plume rises from two heat sources causing buoyancy. The model is used to discuss the interactions involved. The effects of parameters such as the power of the source and the air-flow volume used in the mathematical-physical model are also discussed. An expression is deduced for the trajectory of the non-isothermal air jet penetrated by plumes. Experiments were also carried out to illustrate the effect on the flow of the air jet and to validate the theoretical work. The results show that the buoyancy source's efforts to baffle the descent of the cold air have even been effective in reversing the direction of the trajectory. However, increasing the distance between the plumes can reduce the effect of the plumes on the jet curve. And it is apparent that when the velocity of the air supply increases, the interference caused by the plumes can be reduced.

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If high-power machines are used and a large number of people are present, a significant amount of heat will be generated, which forms an upward thermal plume. The interaction problem occurs when the cold jet and the thermal plume meet. This article presents the interaction mechanism between a momentum source and a buoyancy source and deduces the interaction parameter b to investigate the effects of parameters such as the power of the source, the air-supply velocity, plume spacing, and nozzle spacing height. Experiments were carried out to investigate the flow field of the air jet affected by the plume and to validate the theoretical work.