Flow Characteristics in Compact Thermal Spray Coating Systems with Minimum Length Nozzle

作     者：Seung-Hyun KIM Youn-Jea KIM 

作者机构：School of Mechanical EngineeringSungkyunkwan University 

出 版 物：《Plasma Science and Technology》 (等离子体科学和技术（英文版）)

年 卷 期：2009年第11卷第5期

页      面：550-554页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 0702[理学-物理学] 080201[工学-机械制造及其自动化] 

基　　金：support by the Center of Excellency Program of the Korea Science and Engineering Foundation (KOSEF)and Ministry of Science and Technology (MOST)(No.R11-2000-086-0000-0)through the Center for Advanced Plasma Surface Technology (CAPST)at the Sungkyunkwan University 

主　　题：minimum length nozzle HVOF equivalence ratio 

摘      要：In this study, numerical analysis is performed to adopt the equivalence ratio on the high velocity oxygen fuel （HVOF） thermal spray coating systems equipped with a minimum length nozzle. The analysis is applied to investigate the axisymmetric, steady-state, turbulent, and chemically combusting flow both within the torch and in a free jet region between the torch and the substrate to be coated. The combustion is modeled using a single-step and eddy-dissipation model which assumes that the reaction rate is limited by the turbulent mixing rate of the fuel and oxidant. As the diameter of the nozzle throat is increased, the location of the Mach shock disc moves backward from the nozzle exit. As the throat diameter and the divergent portion are 6 mm and 8 mm, respectively, the pressure in the HVOF system is the lowest at the chamber and the expanding gas is steadily maintained with both high velocity and high temperature for different equivalence ratios. Thus, relatively minor amendments of the equivalence ratio and the geometry of HVOF can lead to improved control over coating characteristics.