Fluid Dynamic Analysis On Multi-Stage Perforated Plate In Obstacle Contained System (OCS) And Its Typical Industrial Applications

Perforated plate is used for pressure and flow adjustment, hydrodynamic cavitation and acoustic noise control in piping system, and it plays a significant role for ensuring the safety and efficiency of the equipment and the whole system under specific conditions. With the development and construction of national key projects, traditional piping system cannot meet the security and stability requirement. Perforated plate as an external component, can realize the above conditions especially under the background of international community concerns on energy saving and environmental protection. Therefore, to carry out the research work on perforated plate, combined with valves and heat exchangers about their fluid dynamic characteristics is of great scientific significance and economic value.This paper is supported by the Special Major Scientific Project from Science and Technology Department of Zhejiang Province through the No.2012C11018-1 and No. 2012C13009, and the Key Scientific and technological Innovation Team of Zhejiang Province through the No.2011R50005, to analyze the fluid dynamics of perforated plate and its typical industrial applications with numerical and experimental methods. The main research contexts and results are as follows:To begin with, build the Obstacle Contained System (OCS) model of perforated plates in piping system. From the system analysis view, undertake the analysis on spring sliding block system, DC circuit system, flow pressure drop system and the flat heat transfer system. Combined with Computational Fluid Dynamics, Field Synergy Analysis and experiment analysis, propose the OCS method, which is made up of Obstacle, Pass body and D-value. In this model, it can build the direct relationship of Obstacle and D-value.Secondly, establish the numerical model of single-stage perforated plate with single phase flow and two-phase flow analysis. Based on the model verification with the existing literature, this paper analyzes the effects of thickness porosity, center hole and the holes spacing on the pressure drop and cavitation characteristics. It shows that opening rate has sensitive effects on the pressure drop performance, while the center hole can reduce nearly 10% pressure drop level, and low outlet pressure turns out more cavitations. Meanwhile, based on the normal analysis work, OCS method is applied for optimization design work.Thirdly, establish the numerical model of multi-stage perforated plate to carry out pressure drop and aerodynamic characteristics. This paper analyzes the effects of two plates spacing, center holes eccentric and rotary displacement. It shows that, the pressure drop is no longer increasing when plate spacing increases to a certain degree; while under the same space, there is a linear relationship of the pressure drop and the inlet velocity, and the larger eccentricity produces larger Mach number.Based on the analysis of pressure drop and Mach number, OCS method is also applied for optimization design work.Finally, three typical applications of perforated plate structure are studied. (1) The orifice on the valve core in Pilot-Control Globe Valve is used for producing the pressure difference for driving the valve core. Experimental and numerical methods are both carried out to analyze the flow and cavitation characteristics. (2) Dimple Jacked Heat Exchanger in Chemical Post-Processing Integrated Equipment is used for the enhancement of heat transfer. The effect of the distribution of holes on the heat transfer and pressure drop characteristics in Dimple Jacked Heat Exchanger is presented. (3) Multi-stage perforated plate in Pressure and Temperature Reducing Device is used for pressure and flow adjustment. The pressure and Mach number of different stages of perforated plates are studied. Meanwhile, OCS method is applied for optimization design work of all the three typical applications. Moreover, two-stage perforated plates with hand wheel adjustment, screw dislocation typed two-stage perforated plate, perforated plate flange, and micro corrugated channel plate heat exchangers, these four novel devices are proposed, which can be pioneers for the applications of perforated plate in the nearly future.