Velocity profile behind a honeycomb straightener in a straight duct

The impact of the honeycomb straighteners on flow parameters was assessed using a test channel equipped with measurement devices, as shown in Figure 1. Honeycombs were manufactured with 3D print technology with polylactide acid (PLA) and placed in the straight channel 1000 mm behind the axial fan (Soler&Palau TD-250) controlled by a Soler&Palau REB-1 speed controller. The fan acted as a turbulence generator. To evaluate the effect of straighteners on the flow parameters, the velocity profile in the channel was measured using a MiniCTA 55T30 hot-wire anemometer (HWA) with a 55P16 single-wire probe and a NI9215 data acquisition device. Velocity profiles were measured 1000 mm downstream of the honeycomb. The anemometer was calibrated for velocity measurements ranging from 1.5 to 26 m/s. Temperature correction was applied, and the velocity measurement accuracy was within ±6% of the reading. The HWA probe was placed 1 mm behind the channel outlet, and positioning was performed using a micrometer screw. The diameter of the channels was 𝐷=100 mm. The pressure drop on the honeycomb was measured with the differential pressure probe Delta OHM TP705-10MBD (the measurement range was 1000 Pa, the accuracy was ±0.5% of full scale, and the measurement resolution was 1 Pa) connected to Delta OHM DH 2124.2 pressure meter. The pressure drop was measured at a distance of 1000 mm, as shown in Figure 1. Mean velocity was determined using an Airflow LCA501 air velocity meter (measurements range: 0.25−30 m/s, accuracy: ±1% of reading) placed 1500 mm upstream of the fan.