Multi nozzle air flow table

Why does the auxiliary fan of the multi nozzle air volume testing system use a centrifugal fan

1、 The core requirement for multi nozzle wind chamber testing Shanghai Hanchao

Multi nozzle wind chamber（GB/T 1236, ISO 5801, AMCA 210 standards) are used for precise measurement of fan/outlet airflow, with core requirements:

· Stable wind pressureOvercoming the resistance of wind chambers, nozzles, pipelines, and rectifiers

· Stable under wide operating conditions: Covering small flow (high pressure)High flow (low pressure) full curve

· Uniform airflowReduce turbulence and eddies to ensure a straight flow field in front of the nozzle

· Anti surgeDo not oscillate, lose pressure, or exceed power during changes in operating conditions

2、 CentrifugeVS Axial Flow: Key Performance Comparison (Adapted Test Bench)

1. Wind pressure and resistance adaptation

· centrifugal fan

o High static pressure（1000–3000 Pa）， Can stably overcome resistance from nozzles, air chambers, and pipelines

o performance curvesteep dropResistance changes, air volume remains stable, and test repeatability is good

o Smooth power curve: small flow (high pressure) is not easily overloaded

· axial flow fan

o Low wind pressure（<500 Pa）， Sudden drop in air volume under high resistance, inaccurate testing

o The curve isSaddle shapedEasy to stall/Surge, flow oscillation, data jump

o When the wind volume is low, the power increases dramatically and the motor is prone to burning

2. Traffic stability and testing accuracy

· centrifugationStable airflow and uniform flow field under all operating conditions, suitable for high-precision calibration

· axial flowHigh pressure zone fluctuates greatly, eddy currents are strong, and the pressure difference before and after the nozzle is chaotic, resulting in large errors

3. Structure and Installation

· centrifugation: Spiral shell+Impeller, airflow turning 90 °, easy to match with noise reduction/rectification, noise controllable

· axial flowCylindrical direct connection, small footprint, cheap, butLarge airflow disturbance and strong low-frequency noise

3、 Selection Decision Table

table

4、 Why do almost all test benches use centrifugation

1. Resistance matching: Nozzle+The total resistance of rectification, filter, and pipeline is often greater than 500 Pa, and the axial flow cannot withstand it

2. stabilityCentrifugal airflow fluctuation in high-pressure zone<± 2%, axial flow can reach ± 10%+

3. Standard adaptation：GB/T 1236 and AMCA 210 both use centrifugal fans as the main auxiliary fan scheme

4. safetyLow flow rate without exceeding power, reliable long-term continuous operation

5、 Very few cases where axial flow can be used

· wind chamberMinimalismNo unnecessary resistance components

· Only testHigh flow low pressureSection, not measuring low flow high pressure section

· Extremely low budget, relaxed precision requirements (such as teaching demonstrations)

6、 Selection suggestions

·shou xuan：Rear curved blade centrifugal fan(Efficient, stable, overload resistant, noise voice actor)

· Wind pressure reserve:Calculate resistance ×1.3–1.5(including nozzle switching and aging allowance)

· Control: Equipped with variable frequency drive to achieveSmooth and stepless speed regulation, covering all working conditions