排风系统管路局部阻力的数值探究

Numerical Study of Local Resistance of Exhaust System Piping

通风空调系统中,经设计选型的送、排风系统在现场调试时会出现如下问题,风机压头相同的同一系统,送风工况容易调节出设计风量,而排风工况则可能难以调节到该状态,这表明较送风系统,排风系统除受到常见的沿程和局部阻力外,可能还受到其它局部阻力的影响。本文通过数值手段研究发现,排风系统由于受到吸入空气扰动等因素影响,导致其遭受更大的局部压力损失,造成理论计算的排风工况压头不足,难以调试出设计风量。

In ventilation and air conditioning systems, the air supply and exhaust system which are designed according to hydraulic calculation occur that in the construction site commissioning： for the same ventilation pipe system, using the same fan pressure, the air supply system can be easily adjusted the designed air volume, while the exhaust system is difficult to be debugged the designed air volume. It shows that the resistance is different when we compared exhaust system with the air supply system. In addition to the general resistance along the way, local resistance, the exhaust system may be also influenced by other local resistance. Air supply/exhaust system flow field are studied in this paper by means of numerical methods, which has found that flow field of the exhaust system, because of factors external intake air exhaust vents and other disturbances, causing the exhaust system from a greater local pressure loss, and ultimately making that the fan pressure of exhaust system is less than the theoretical pressure and it leads to debug the design air volume difficultly.