2. Experimental setup

The schematic diagram for observing the flow patterns is shown in Fig. 2. The apparatus is made of transparent acrylic resin to allow observation of the flow pattern. The experiments are conducted at room temperature and standard atmospheric pressure, and the air-water system is chosen in this experiment. The gas and liquid phase are transported to the spray box by a magnetic pump and blower, respectively. The liquid and gas phases flow through the channel of the blade unit. The guide plate eliminates the outside interferences. The sieve plate unit is positioned at the end of the baffle. The bottom of the unit is connected to the central bulkhead of the barrel section, which extends to the bottom of the water tank, dividing the tank into two parts. The rotational and perforated fluid are separated through a central separator. The swirling liquid enters the swirling separation chamber. The gas phase flows out through the left stoma outlet, and the perforated liquid flows into the perforated flow separation chamber. The perforated gas flows out through stoma outlet2. Heightsh 1r and h 2p of the rotating flow and perforated flow can be read from the two separation chambers, and a hot-wire anemometer is located at the gas phase exits to measure the gas flow rate, u gr andu gp. The exit aperture is the same and known; therefore, the corresponding gas flow volume can be calculated based on the velocity. The pressure measuring points are set at 20 mm on both sides of the unit, and the pressure changes can be measured by the differential pressure sensor in real-time.
The liquid phase distribution is uneven on the unit surface owing to the liquid distributor when the liquid density is small, thereby disagreeing with the actual working conditions. Therefore, the overflow method of liquid distribution is adapted. As shown in Fig. 2b, the spray box is replaced by the overflow box. The liquid phase passes the box through two overflows and flows along the guide plate connected to the box after stabilization. The liquid phase flows to the upper edge of the blade unit in the form of falling film flow (as shown in Fig. 2b inside the ellipse). Then, the liquid phase is evenly laid on the surface of the unit, and the gas-phase inlets and other experimental conditions remain unchanged.
In this experiment, the diameter of the blade unit is 140 mm; the axial height is 50 mm; the overall height of the device is 1.2 m. The diameter of the cylinder section where the unit is located is 150 mm. The structure parameters and shematic of the blade unit are listed and shown in Table 1 and Fig. 3.