CFD Simulation On Natural Ventilation Assisted By Wind In Connected Rooms

Much attention had been paid on the building natural ventilation. Scholars internal and abroad had done many researches on the single natural ventilation room. However, it was still necessary to give many studies on the heating exchange and air distribution in the connected natural ventilation rooms. This article established displacement natural ventilation model caused by point heat source of two joined rooms. The room vertical temperature profile was simplified as two uniform zones. Leaded into dimensionless temperature λ considered the thermal radiation between heat source and floor, ceiling, and consequently the influence on the lower level room temperature. The position of the interface hf, flow rate Q, lower and upper level temperature T₂ and T₁ were investigated with thermal plume theory in the case of buoyancy force and buoyancy force assisted by wind. In addition, in the case of buoyancy force, in order to obtain fine air distribution, the critical relations among the effective vents area, the position of the intermediate level vent and the ratio of the effective vents area were analyzed with neutral theory. In the case of buoyancy force assisted by wind, the difference of natural ventilation efficiency between the single room and the connected rooms was analyzed.Leading into the dimensionless temperature λ, the position of the interface hf, the ventilation airflow rate Q, lower and upper level temperature T₂ and T₁ could be forecasted accurately. The influence of the dimensionless temperature λ on the lower level temperature T\ are more noticeable than the position of the interface h_f. In the case of buoyancy force, in order to obtain fine air distribution, it is necessary to adjust the vents area, the ratio of vents and the height of intermediate vent. On the situation of constant effective vents area A₁^* and ratio of effective vent area γ, there were critical lower limit value of the height of intermediate vent;On the situation of constant effective vent area y and the height of intermediate vent h₂, there were critical upper limit value of the effective vents area A₁^* . In the case of buoyancy force assisted by wind, the wind force increased the height of interface and the natural ventilation airflow rate, decreased the lower and upper level temperature efficiently. Partition structure decreased the natural ventilation efficiency of the connected rooms compared with the single room. Simultaneously, the applications of the model on the design of building natural ventilation were carried off.