For centrifugal fans, why does the air volume decrease when the resistance increases? !
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The rotation speed hasn’t changed – why has the air volume decreased? ! Please give me some advice!
It is equivalent to using an outlet valve for flow regulation
The air volume of a fan is proportional to its rotational speed; if the speed remains unchanged, why would the air volume decrease?
Has there been any change in the opening degree of the inlet and outlet valves? If nothing else changes, temperature variations will also affect the air volume.
There’s no change. This is the basic characteristic of a centrifugal fan; its characteristic curve is like this.
Air volume is related to rotational speed as well as to outlet pressure. The increase in resistance is due to a reduction in the flow area of the pipeline, which results in a decrease in the natural flow rate. The relationship is as follows: 1. As the fan speed increases, the air volume increases by a factor of one more ； 2. As the fan speed increases, the wind pressure increases by a factor of two squared ； 3. As the fan speed increases, the current increases by a factor of three ；
Bro, that’s not right; the usable area stays the same. Besides, even if the flow area decreases, the flow rate doesn’t necessarily go down either; it’s just that the resistance increases.
High resistance is equivalent to the outlet valve controlling the flow rate, resulting in a very low flow rate
Even if the outlet valve is reduced in size, it only increases the resistance; the flow rate does not necessarily decrease!
The reason for the increased resistance must be a reduction in the flow area, that is, the outlet valve is closed tighter or there is an obstruction somewhere downstream at the outlet! As the flow area decreases and the outlet pressure increases, the flow rate must also decrease.
An increase in resistance does not necessarily lead to a decrease in flow rate. The outlet resistance of the Roots blower increases, but the flow rate does not decrease.