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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Numerical analysis of flow and cavitation characteristics in a pilot-control globe valve with different valve core displacements

Abstract: The pilot-control globe valve (PCGV) is a novel globe valve with a piston-type valve core and a small pilot valve. It can utilize a pressure difference to control the state of the main valve by the pilot valve. In this paper, a mathematical model of PCGV is established and a computational fluid dynamics (CFD) method is used to numerically simulate its flow and cavitation characteristics. Analysis of the pressure difference between the upside and downside of the valve core and comparison with similar previous work increase the reliability of the simulation. Then an analysis of flow and cavitation characteristics is carried out with three comparisons: a comparison between opened and closed states, a comparison between different inlet velocities, and a comparison between different valve core displacements. The results demonstrate that the vapor volume fraction reaches its peak point at the valve seat near the outlet tube, and that a higher inlet velocity or smaller valve core displacement can cause greater cavitation damage. This study can help further design work for optimization and engineering applications of PCGV.

Key words: Computational fluid dynamics (CFD), Pilot-control globe valve (PCGV), Valve core displacement, Cavitation

Chinese Summary  <52> 先导式截止阀在不同阀芯位置下流动和汽蚀特性的数值分析

目的:先导式截止阀可通过一个先导阀,利用流体在阀门前后自身的压差控制主阀的启闭,是一种新型节能型截止阀。本文探讨该阀在开启和关闭状态下、不同入口速度情况下和不同阀芯位置下的流动和汽蚀特性,为后期结构优化提供设计建议。
创新点:1. 分析先导式截止阀的阀芯上下表面压差的变化情况,验证其可行性和模型准确性;2. 建立数值模型,对先导式截止阀在不同启闭状态和不同阀芯位移情况下进行流动和汽蚀分析。
方法:1. 通过数值模拟,分析阀芯上下表面的压差,并与现有文献进行比较,验证模型的准确性(图3);2. 建立开启和关闭条件下的阀门模型,比较两种状态下该阀的流动和汽蚀特性(图4和5);3. 建立不同入口速度条件下的阀门模型,比较分析速度对该阀的汽蚀情况的影响(图6);4. 建立不同阀芯位置的阀门模型,比较分析不同阀芯位置下的速度和压力情况,进一步验证该阀的可行性,并分析阀芯位置对阀门汽蚀的影响(图7)。
结论:1. 在开启和关闭状态下,流速和汽含率在阀座底部靠近出口处达到峰值;2. 入口速度更高的情况下,阀的开启速度更快,但汽含率并不一定同步上升;3. 当阀芯处于低位置时,虽然对阀门出口处影响位置较小,但其压力梯度较大、汽含率较高,选取合适的弹簧刚度非常重要。

关键词组:计算流体动力学;先导式截止阀;阀芯位移; 汽蚀


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DOI:

10.1631/jzus.A1500228

CLC number:

TH161.12

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On-line Access:

2016-01-06

Received:

2015-08-17

Revision Accepted:

2015-09-29

Crosschecked:

2015-12-11

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