Producing a bubble flow in multi-orifice plate downstream (MOPD) is a basic condition for the exhaust absorber with multi-orifice plates to achieve a satisfied absorption capacity. In this paper

a visualization experiment on the flow pattern of gas-liquid two-phase flowing through a multi-orifice plate in a horizontal pipe was conducted using the air and water as the gas and liquid phase

respectively. Four multi-orifice plates with the orifice diameter of 2

3

4 and 5 mm were tested in a horizontal plexiglass pipe with the inner diameter of 98.5 mm by using a high speed camcorder to record the air-water flow

thus the effects of orifice diameter

air flow rate and water flow rate on the flow pattern in the multi-orifice plate downstream were obtained. The results show that the stratified/plug flow transition in MOPD shift to an increased water flow rate while the plug/bubble flow transition shift to a decreased water flow rate in comparison with the flow pattern transition in horizontal pipes. The flow pattern in MOPD is inclined to a bubble flow with the decrease of air flow rate or the increase of water flow rate. Meanwhile

an important dependence on the orifice diameter is found for the flow pattern in MOPD. With the decrease of orifice diameter

the plug/bubble flow transition shift to an increased air flow rate and a decreased water flow rate

meaning that an increased flow range is obtained to form bubble flow. In addition

as the orifice diameter decreasing

the flow pattern in MOPD is inclined to transfer from wavy stratified flow to bubble flow directly without an occurrence of plug flow. To achieve a satisfied flow pattern and absorption capacity for the exhaust absorber with multi-orifice plates

it is recommended to choose the orifice diameter not larger than 3 mm.