Affiliations: Precision and Intelligence Laboratory, Tokyo Institute
of Technology, R2-45,4259 Nagatuta, Midori-Ku, Yokohama, 226-8503, Japan.
E-mail: [email protected] | Department of Civil and Environmental Engineering,
Tokyo Institute of Technology, M1-1, 2-12-1, O-okayama, Meguro-ku, Tokyo,
152-8552, Japan. E-mail: [email protected]
Abstract: Pressure reducing valves are widely used to maintain the pressure of
gas reservoirs to specific values. In a normal valve, supply pressure is
decompressed with an orifice structure. When compressed air passes through the
orifice structure, considerable noise occurs at the downstream side. In this
paper, we have developed a radial slit structure that can reduce pressure
without noise. The noise is reduced by changing the orifice structure into the
radial slit structure. The radial slit structure valve reduces pressure without
noise by suppressing the generation of turbulence and shock wave at the
downstream. The analysis of the flow in radial slit structure was achieved by
CFD2000 software. The flow rate and pressure distribution were simulated and
compared with the experimental result. To confirm the generation of shock wave,
the flow of orifice and radial slit structure at the downstream was visualized
by Schlieren photography method. A shock wave was generated in the orifice
structure, but no shock wave was generated in the radial slit structure. Noise
reduction efficiency was investigated by the experiment. The experiment
apparatus was set up to JIS standards. The experimental results indicated that
the noise level decreased by approximately 40 dB in the slit structure. It is
confirmed that the radial slit structure has effectiveness for low noise in the
pressure reducing flow. And, it is expected that it can be applied to various
kinds of industrial fields.
