﻿ 柴油机烟道导流板设计模拟与实验研究
 舰船科学技术  2018, Vol. 40 Issue (6): 73-78 PDF

Simulation and experimental study on design of diesel engine flue guide plate
DU Jun, ZHANG Yan, SHI Hong
Jiangsu University of Science and Technology, Zhenjiang 212003, China
Abstract: In response to the injection system of the NH3, which is injected into the flue, the gas is mixed along the flue, and it is easy to form a large gas vortex through the path of the flue, which is the problem of the high velocity difference. Flue is presented in this paper the second corner, in view of different flue structure and gas flow rate and composition of different parameters, such as, based on the diagonal type flue design six kinds of guide plate arrangement, changes in flow rate and pressure loss analysis system, to obtain optimized layout scheme. At the same time, the relevant optimization scheme is verified by experiment. According to the experiment and simulation results, it is concluded that in the inclined type flue, the flow of the same guide plate is the best when it is arranged in a column, and the lowest value of the exit velocity is the lowest, and the pressure loss is the lowest. The results of this study provide a reference for diesel engine flue design.
Key words: selective catalytic reduction     diesel engine     flue gas     velocity     guide plate
0 引　言

1 模型建立 1.1 结构模型

 图 1 SCR催化反应系统简化图 Fig. 1 Simplified diagram of SCR catalytic reaction system

1.2 理论模型 1.2.1 湍流模型

 ${\rm div}(\rho {\overline \mu _k}) = {\rm div}\left[ {\left( {\mu 0 + \frac{{{\mu _t}}}{{{\sigma _k}}}} \right){\rm grad}(k)} \right] + {G_k} - {\rho _\varepsilon }\text{，}$ (1)
 ${\rm div}(\rho {\overline \mu _\varepsilon }) = {\rm div}\left[ {\left( {{\mu _0} + \frac{{{\mu _t}}}{{{\sigma _\varepsilon }}}} \right){\rm grad}(\varepsilon )} \right] + \frac{\varepsilon }{k}\left( {{C_{1\varepsilon }}{G_k} - {C_{2\varepsilon }}{\rho _\varepsilon }} \right)\text{。}$ (2)

 $\frac{{\partial \left( {\rho \phi } \right)}}{{\partial {t}}} + {\rm div}\left( {\rho \mu \phi } \right) = {\rm div}\left( {\Gamma \text{·} {\rm grad}\phi } \right) + S\text{。}$ (3)

1.2.2 组分输运模型

 $\frac{\partial }{{\partial t}}\left( {\rho {Y_i}} \right) + \nabla \cdot \left( {\rho v{Y_i}} \right) = - \nabla {J_i} + {R_i} + {S_i}\text{。}$ (4)

2 方案设计

 图 2 斜型烟道拐弯处模型图 Fig. 2 A model diagram of inclined type flue and arc type flue and the exit velocity position

3 斜板形烟道模拟结果及分析 3.1 无导流板模拟分析

 图 3 无导流板时烟道的速度分布图 Fig. 3 The velocity distirbution of the flue gas in the non-deflector plate

 图 4 无导流板时烟道出口速度曲线图 Fig. 4 A graph of the exit velocity of a flue without a deflector

3.2 添加导流板后的模拟结果

 图 5 不同导流板布置方案的速度场分布图 Fig. 5 The velocity field profile of the different deflector plates

 图 6 不同导流板布置方案出口速度曲线图 Fig. 6 The velocity diagram of the exit velocity of different guide plate is given

3.3 各方案系统压损对比分析

 图 7 不同设计方案烟道压力损失 Fig. 7 Different design scheme of smoke pressure loss

4 模拟与实验结果对比分析

 图 10 数值模拟与实验所得压力损失对比图 Fig. 10 Numerical simulation and comparison of the pressure loss of experiment

 图 9 斜型烟道数值模拟与实验出口速度分布图 Fig. 9 Outlet velocity of the flue gas in test

 图 8 实验台简化模型图 Fig. 8 Simplified model diagram

5 结　语

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