Questions regarding the calculation of air volume for centrifugal fans
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There is a centrifugal blower controlled by an inverter, with a flow rate parameter of 15,000 m3/h； Total pressure: 20,000 Pa, spindle speed: 2,900 rpm, specific volume of the medium: 1.2 ； Inlet temperature: 20°C. Motor parameter nominal current 235A ； Power: 132kw ； Three-phase 380V ； Frequency: 50HZ; Constant torque frequency range: 30-50HZ ； Variable torque frequency range: 5-50HZ ； CoSφ0.92 ； Under operating conditions, the frequency is 40 Hz, the current is 126 A, the voltage is 380 V, the inlet temperature is 20 degrees Celsius, and the wind pressure is 8700 Pa. The outlet pipe of the fan is DN600. Everything else is calculated under standard conditions. How can I calculate the air volume under operating conditions?
The profile of each fan is different, and calculations must be done in conjunction with the performance curve. It can’t be calculated directly. The actual boost pressure is currently set at 8700 Pa. According to the principle that pressure is proportional to the square of the rotation speed, at 50 Hz, the corresponding pressure for 8700 Pa is 13594 Pa. You should check the performance curve to find out what air volume corresponds to a pressure increase of 13,594 Pa at 50 Hz; for example, if it’s Q, then the actual air volume will be 4Q/5
Manufacturers usually provide performance curves; just ask them!