Numerical Simulation Of The Stack Effect And The Combinations Of The Wind Pressure Analysis On Super High-Rise Building

In recent years, with the rapid development of the super high-rise buildings, problems such as elevator door sticking, whistle in the shaft as well as difficulty in opening and closing doors which caused by stack effect have become increasingly highlighted. In order to avoid such serious problems, analysis and evaluation of stack effect is necessary in construction drawing design stage. Stack effect is mainly caused by the temperature difference between indoor and outdoor, and its negative effects often appear in cold and hot weather. Elevator door sticking and whistle in the shaft is likely to happen when the pressure difference across the elevator door exceeds 25 Pa and the flow rate exceeds 100L/s. Similarly, a man will open and close a typical door with difficulty if the pressure difference across it exceeds more than 130 Pa.Thus, these values can be used to be the intuitive criterion of evaluating the severity of stack effect.Wind will make the distribution of the pressure and air infiltration due to stack effect more complex. However at present, the study of the combinations of the stack effect and the wind pressure on super high-rise buildings is quite lacking.In this paper, stack effect in super high-rise buildings is analyzed numerically by multizone net model, and the wind tunnel test and the numerical simulation are used to get the wind pressure boundary conditions. Mechanism of the influence of wind on the stack effect is studied preliminary with an ideal open type super high-rise building, furthermore, the distribution of the pressure and air infiltration due to the combinations of stack effect and the wind pressure on an actual super high-rise building is studied and effective measures are taken to ease the problem.The research in this paper mainly draws the following conclusions:Firstly, air flow into or out of indoor and the elevator shaft follows the flow conservation law. The wind pressure changes the interior and exterior pressure, then, the pressure difference and air flow across the curtain wall and the elevator doors change with it.Secondly, there are several functional areas which are partitioned by the refuge floors in typical super high-rise buildings, what’s more, the elevators and stairs are arranged complex, all of these lead to more than one NPL and complex airflow. In winter, the NPL rise up at windward side but fall down at leeward side due to wind pressure; however, the NPL move in the opposite direction in the summer, what’s more, there will be no NPL when the wind speed exceeds a certain value.Finally, the exterior curtain wall with good air tightness can play an important role to control stack effect, but at the same time,the pressure difference at normal entrance doors rises, therefore, setting elevator front room or improving the air tightness of front room doors is more appropriate if problems appear only in the individual floors. the exterior sliding doors in the ground floor keep open in periods of peak demand which will lead to a lot of air infiltration and a sharp rise of pressure difference across elevator doors, so it’s necessary to take measures such as installing a revolving door in the main entrance to relieve the problem.The research in this paper mainly provide a certain valuable reference for the analysis and evaluation of stack effect in super high-rise buildings as well as the optimization of the design of super high-rise building.