Abstract: An object is to provide a decompression device including a plurality of stages of orifice plates disposed in a flow passage, which generates less noise in response to sonic feedback phenomenon and gas-column resonance. A decompression device 10A includes: an upstream orifice plate 14 disposed in a duct 12 forming a flow passage for a fluid F; and a downstream orifice plate 16 disposed in the flow passage and downstream of the upstream orifice plate 14. A jet-flow interference part 22A is disposed only partially on an outlet rim portion of an orifice 18 on the upstream orifice plate 14 and configured to interfere with a jet flow discharged from the orifice 18. Positions of Karman vortices e are differentiated in a duct axial direction between regions with and without the jet-flow interference part 22A to reduce generation of noise.

Abstract: An object is to provide a decompression device including a plurality of stages of orifice plates disposed in a flow passage, which generates less noise in response to sonic feedback phenomenon and gas-column resonance. A decompression device 10A includes: an upstream orifice plate 14 disposed in a duct 12 forming a flow passage for a fluid F; and a downstream orifice plate 16 disposed in the flow passage and downstream of the upstream orifice plate 14. A jet-flow interference part 22A is disposed only partially on an outlet rim portion of an orifice 18 on the upstream orifice plate 14 and configured to interfere with a jet flow discharged from the orifice 18. Positions of Karman vortices e are differentiated in a duct axial direction between regions with and without the jet-flow interference part 22A to reduce generation of noise.

Abstract: A multistage pressure reduction device (10) of the present invention includes a fuel pipe (1) forming a flow path (5), an upstream orifice plate (2) disposed in the flow path (5), and a downstream orifice plate (3) disposed downstream of the upstream orifice plate (2) in the flow path (5). The upstream orifice plate (2) is formed such that a jet flow (7-i) discharged from a hole (6-i) formed at the upstream orifice plate (2) contacts a certain target. With this multistage pressure reduction device (10), the jet flow (7-i) discharged from the upstream orifice plate (2) contacts the certain target to prevent air column resonance excited between the upstream orifice plate (2) and the downstream orifice plate (3). Noise due to the air column resonance can be reduced without providing a porous metal between the upstream orifice plate (2) and the downstream orifice plate (3).