Mach number analysis on multi-stage perforated plates in high pressure reducing valve

• Mach number on multi-stage perforated plates in HPRV is investigated.
• Design method of multi-stage perforated plates for HPRV is proposed.
• Influence area of the last perforated plate is larger under higher pressure ratio.
• Energy loss of the perforated plate is larger than the valve core.
• There is a limited pressure ratio of every perforated plate expect the last one.

High pressure reducing valve (HPRV) is a key device for the pressure control of high temperature and pressure steam in industrial processes. Perforated plate is used as the throttling element to ensure the suitable pressure of steam and reduce aerodynamic noise inside HPRV and the linked pipelines. Mach number is the parameter to reflect the compressibility of steam flow. Higher Mach number may cause serious aerodynamic noise of steams flow, waste large amount of energy and do harm to the valves and pipelines. In this paper, Mach number on multi-stage perforated plates inside a novel HPRV and the linked pipelines is investigated. Mach number in reversible isentropic process is analyzed and the design method of multi-stage perforated plates in HPRV is proposed. Then, the RNG k–ε model combining with compressible gas is established, and the Mach number simulation of single perforated plate and multi-stage perforated plates is carried out in software Fluent 6.3. Meanwhile, Mach number inside HPRV is also presented, and the pressure ratio of perforated plate is also investigated. It can be found that under higher pressure ratio, the influence area of the last perforated plate becomes larger, and the energy loss in perforated plate is larger than the valve core. Furthermore, there exists a limited pressure ratio of every stage perforated plate, and it is better to keep the pressure ratio of every stage perforated plate larger than 0.5. This work presents the function of perforated plates in HPRV for throttling and reducing aerodynamic noises, and it can benefit the researchers who are dealing with multi-stage perforated plates design for valves and pipelines.