吉林大学学报(工学版) ›› 2022, Vol. 52 ›› Issue (3): 504-514.doi: 10.13229/j.cnki.jdxbgxb20200857

• 车辆工程·机械工程 • 上一篇    

二/四冲程可变柴油机燃烧室热负荷的改善

张岩1(),刘玮1,张树勇1,裴毅强2(),董蒙蒙2,秦静2,3   

  1. 1.中国北方发动机研究所 柴油机增压技术重点实验室,天津 300072
    2.天津大学 内燃机燃烧学国家重点实验室,天津 300072
    3.天津大学 内燃机研究所,天津 300072
  • 收稿日期:2020-11-06 出版日期:2022-03-01 发布日期:2022-03-08
  • 通讯作者: 裴毅强 E-mail:tjuzhangyan@163.com;peiyq@tju.edu.cn
  • 作者简介:张岩(1981-),男,研究员,博士. 研究方向:发动机燃烧及动力循环. E-mail:tjuzhangyan@163.com
  • 基金资助:
    国家自然科学基金项目(51606175)

Optimization on thermal load of combustion chamber on two/four⁃stroke switchable diesel engine

Yan ZHANG1(),Wei LIU1,Shu-yong ZHANG1,Yi-qiang PEI2(),Meng-meng DONG2,Jing QIN2,3   

  1. 1.National Key Laboratory of Diesel Engine Turbocharging,China North Engine Research Institute,Tianjin 300072,China
    2.State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China
    3.Internal Combustion Engine Research Institute,Tianjin University,Tianjin 300072,China
  • Received:2020-11-06 Online:2022-03-01 Published:2022-03-08
  • Contact: Yi-qiang PEI E-mail:tjuzhangyan@163.com;peiyq@tju.edu.cn

摘要:

采用计算流体动力学(CFD)方法对一台二/四冲程可变柴油机在二冲程工作模式下活塞烧蚀的现象进行了研究,分析发现气流运动导致混合气在活塞碗沿处发生燃烧,从而产生了局部高温和局部过高热负荷。设计了两种燃烧室结构形式,通过调整油-气-室的配合以改善燃烧状况,研究发现,增大燃烧室碗口直径可以减少向活塞碗沿上方扩散的混合气,增大混合气在燃烧室内部的扩散空间,从而避免了在活塞碗沿处产生过高热负荷;增大燃烧室凹坑直径则有助于在凹坑内产生涡流,促进混合气的形成,缩短燃烧持续期。模拟计算结果显示,相比于原机,在2800 r/min@46 kW工况下两种优化设计的燃烧室在活塞碗沿上的热负荷得到明显改善,功率分别提高了4.11%和1.96%。加工设计一方案并在相同工况下进行对比试验,结果表明,相对于原机,优化设计后的柴油机油耗降低了6.93%,排气温度降低了21.1 K,活塞表面状态良好,无烧蚀发生。

关键词: 动力机械工程, 二/四冲程可变柴油机, 热负荷, 燃烧室设计

Abstract:

The in-cylinder combustion process of a two/four-stroke switchable diesel engine at high load conditions under two-stroke working mode was analyzed based on the three-dimensional CFD simulation. It was found that the movement of airflow causes the mixture to burn at the edge of the piston bowl, resulting in local high temperature and local excessive thermal load. Two optimized designs of combustion chambers were obtained to adjust the match of oil and gas with chamber to improve combustion. It was found that increasing the diameter of combustion chamber expands the diffusion space of the mixture and reduces the mixture diffused above the piston bowl edge, which can avoid excessive thermal load at the piston bowl edge. Increasing the diameter of the piston pit helps produce the vortex in the pit to promote the mixture formation and shorten the combustion duration. The thermal loads of the piston bowl edge of these two designs are significantly improved, and the combustion durations of the chamber Ⅰ and chamber Ⅱ increase the power by 4.11% and 1.96% respectively. The comparison test of the original machine and chamber Ⅰ was carried out under the ablation condition of the original machine at 2800 r/min@46 kW. Compared with the original machine, the fuel consumption of the chamber Ⅰ is reduced by 6.93%, exhaust temperature is decreased by 21.1 K and the piston surface is smooth without any ablation.

Key words: power machinery and engineering, two/four-stroke switchable diesel engine, thermal load, combustion chamber design

中图分类号: 

  • TK421.2

表1

发动机参数"

参数数值参数数值
缸径/mm110排气门定时/°CA102/230
冲程/mm110喷油时刻/°CA347
压缩比13.3喷油量/mg83.3
进气门定时/°CA135/270

图1

CONVERGE计算模型"

图2

喷雾贯穿距的模拟值与试验值对比"

图3

缸压的试验值与模拟值对比"

图4

试验烧蚀位置与模拟中热通量的分布对比"

图5

16 ATDC时刻活塞仰视图中的温度等值面(K)分布(右侧为排气门侧)"

图6

喷雾发展过程(左侧为排气门侧,单位为m)"

图7

原机Y截面当量比场及温度场(左侧为排气门侧,温度单位为K)"

图8

原机Z截面当量比场及速度场分布(左侧为排气门侧)"

图9

燃烧室结构参数示意图"

图10

设计燃烧室与原机结构对比"

表2

燃烧室结构参数对比"

参数原机设计一设计二
燃烧室口径Dk/mm72.076.881.2
燃烧室深度H/mm14.313.312.5
凹坑直径d/mm8.920.014.9
燃烧室宽度Dl/mm75.077.283.0

表3

原机与设计燃烧室的燃烧性能对比"

参数原机设计一设计二
单循环放热/J3750.453683.353638.98
平均有效压力/MPa1.451.511.48
燃烧持续期/°CA51.4044.7046.80
有效功率/kW48.4750.4749.43
燃烧室传热/J203.94171.18182.24

图11

原机与设计燃烧室放热率对比"

图12

原机与设计燃烧室的混合气当量比对比"

图13

设计燃烧室与原机的活塞顶面在燃烧过程中的热通量(W/m2)分布对比"

图14

原机与设计燃烧室的湍动能(m2/s2)对比(左侧为排气门侧)"

图15

观察截面"

图16

原机与设计燃烧室在观察截面的当量比场及速度场对比"

图17

原机与设计燃烧室在观察截面的温度分布对比"

图18

试验台架示意图"

表4

试验参数对比"

参数原机设计一
燃油消耗量/(kg·h-114.0413.13
进气温度/K322.40323.80
进气压力/kPa273.00278.10
进气流量/(kg·h-1415.00396.80
排气温度/K688.50667.40

图19

原机与设计一方案在相同工况下的缸压对比"

图20

原机与设计一试验后活塞顶面状态对比"

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