According to the theory of hydrodynamics, the flow process of gas will be accompanied by loss. For example, after the gas flows through the throttling device, the pressure of the air flow will be reduced accordingly, that is, they lose the active work of the fan. Because all this happens in the process of gas conveying by the fan, that is, the energy of the fan is wasted.

风机工况点是风机在某一转速下的性能曲线与管网阻力特性线的交点。风机实际运行时，并非永远停留在设计工况点上。它将随用户的需求或外界条件的变化而变化，也就是风机实际上处于变工况下工作。要想使风机的风压或风量达到某一目标值，就需要对风机或管网进行为人为地控制，亦称调节。通过有效地调节，实现在保证风机能够稳定工作的条件下，既要满足生产对流量或压力的要求，又能限度地。简言之，调节的目的就是满足性能要求，扩大（稳定）工况，实现，防止喘振。

The operating point of the fan is the intersection of the performance curve of the fan at a certain speed and the resistance characteristic line of the pipe network. During the actual operation of the fan, it does not always stay at the design working condition point. It will change with the needs of users or changes in external conditions, that is, the fan actually works under variable working conditions. In order to make the air pressure or air volume of the fan reach a certain target value, it is necessary to artificially control the fan or pipe network, also known as regulation. Through effective regulation, it can not only meet the requirements of production for flow or pressure, but also save energy to a certain extent under the condition that the fan can work stably. In short, the purpose of regulation is to meet the performance requirements, expand (stabilize) working conditions, save energy and prevent surge.

风机采用不同的调节方式都可达到同一目的，但效果各不相同。

Different adjustment methods of fan can achieve the same purpose, but the energy-saving effects are different.

根据理论分析及实践证明，可得出如下4个方面的结论。

According to theoretical analysis and practical proof, the following four conclusions can be drawn.

⑴对于鼓风机和压缩机，出口节流调节方式耗功多。尽管相对流量Qr（实际流量Q与设计流量Q0之比）减少时，功率亦相应减少。如当Q=0.65Q0时，所对应的功率减少到原来的80%左右，但与其它调节方式相比，耗能仍居重要位置。

(1) for blowers and compressors, the outlet throttling regulation mode consumes the most power. Although the relative flow QR (the ratio of actual flow Q to design flow Q0) decreases, the power also decreases accordingly. For example, when q = 0.65q0, the corresponding power is reduced to about 80%, but compared with other regulation methods, energy consumption still occupies an important position.

⑵如果相对流量变化不大时（或称调节深度小时），几种调节方式耗功差别不大。即调节方式对效果影响不大，甚不仅不，反而因调节装置的存在多耗功（如液力耦合器）。

(2) if the relative flow changes little (or the regulation depth is small), there is little difference in power consumption among several regulation modes. That is, the regulation mode has little impact on the energy-saving effect, or even does not save energy, but consumes more power due to the existence of the regulation device (such as hydraulic coupler).

⑶一般来说，调节深度越大，效果越显著。因此，要慎重选择调节方式，以期获得效益。

(3) generally speaking, the greater the adjustment depth, the more significant the energy-saving effect. Therefore, we should carefully choose the regulation mode in order to obtain benefits.

⑷变速调节曲线接近理想曲线。所以，变速调节方式优越，特别是采用变频电动机调速的方案为好，但需要增设变频装置。对于中小容量的变频调速建议积极试用；由于大容量高电压变频调速装置较高，应结合具体情况，综合比较，决定取舍。总之，既要考虑调节性能，也要考虑设备初投资、可靠性及经济性等，全 面评价调节方式的优劣。

(4) the speed regulation curve is close to the ideal curve. Therefore, the variable speed regulation mode is superior, especially the energy-saving scheme of variable frequency motor speed regulation is better, but the variable frequency device needs to be added. It is recommended to actively try out frequency conversion speed regulation with small and medium capacity; Due to the high price of high-capacity and high-voltage variable frequency speed regulation device, the choice should be determined by comprehensive comparison in combination with specific conditions. In short, we should not only consider the regulation performance, but also consider the initial investment, reliability and economy of the equipment, and comprehensively evaluate the advantages and disadvantages of the regulation mode.