缸盖鼻梁区水腔内沸腾气泡演化行为试验
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摘要
针对内燃机缸盖鼻梁区严重的热负荷问题,以一款高强化增压水冷式柴油机为研究对象,借助内窥式高速摄像技术,搭建了缸盖水腔内鼻梁区沸腾换热试验系统.在不同柴油机运行工况下分别获得了不同进口过冷度及进口流速下沸腾气泡演化行为图像.图像分析结果表明:在标定工况下,随着冷却液过冷度的下降,沸腾气泡数量增多,尺寸增长加快,气泡滑移速度增加;在最大转矩工况下,沸腾气泡当量直径比低速大负荷工况时增大20%,左右,气泡滑移速度比低速大负荷工况时提高近2倍.
Thermal load in the bridge zone of cylinder head is generally a serious issue in internal combustion engines.Based on a water-cooled diesel engine with high turbocharging boost ratio,an experiment of boiling heat transfer in the bridge zone of cylinder head was conducted by means of endoscopic high-speed photography technology.Under different operating conditions of the diesel engine,the evolution behaviour of boiling bubbles at different subcoolings and inlet velocities was obtained.The results of image analysis show that there is a significant increase in bubble numbers,bubble sizes and bubble slip velocity with the decrease of coolant subcooling under the rated power condition.The bubble equivalent diameter under the maximum torque condition is about 20% larger than that under low-speed and high-load operations.The bubble slip velocity is nearly 2 times higher than that under lowspeed and high-load operations.
Thermal load in the bridge zone of cylinder head is generally a serious issue in internal combustion engines.Based on a water-cooled diesel engine with high turbocharging boost ratio,an experiment of boiling heat transfer in the bridge zone of cylinder head was conducted by means of endoscopic high-speed photography technology.Under different operating conditions of the diesel engine,the evolution behaviour of boiling bubbles at different subcoolings and inlet velocities was obtained.The results of image analysis show that there is a significant increase in bubble numbers,bubble sizes and bubble slip velocity with the decrease of coolant subcooling under the rated power condition.The bubble equivalent diameter under the maximum torque condition is about 20% larger than that under low-speed and high-load operations.The bubble slip velocity is nearly 2 times higher than that under lowspeed and high-load operations.
引文
[1]李智.天然气发动机气缸盖热负荷及冷却水腔内沸腾换热研究[D].武汉:华中科技大学能动学院,2012.
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[13]徐建军,卓文彬,谢添舟,等.矩形窄缝通道近壁汽泡滑移和浮升可视化实验研究[J].核动力工程,2013,34(4):73-78.
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[16]何联格,左正兴,向建华.气泡尺寸气缸盖沸腾换热的影响[J].内燃机学报,2013,31(1):70-80.
[17]董非,郭晨海,范秦寅,等.发动机冷却水腔内沸腾传热的模拟研究[J].内燃机工程,2011,32(4):76-82.
[18]董非,龚伟,张威望,等.内燃机缸盖水腔内气/液流动可化与传热试验研究[J].内燃机学报,2015,33(5):466-471.
[2]Steiner H,Brenn G,Ramstorfer F,et al.Increased cooling power with nucleate boiling flow in automotive engine applications[C]//Chiaberge M New Trends and Developments in Automotive System Engineering,Italy,2011:249-273.
[3]Zavaragh G,Alir?za Kaleli H,Afshari F,et al.Optimization of heat transfer and efficiency of engine via air bubble injection inside engine cooling system[J].Applied Thermal Engineering,2017,123:390-402.
[4]Torregrosa A J,Broatch A,Olmeda P,et al.Experiments on subcooled flow boiling in IC engine-like conditions at low flow velocities[J].Experimental Thermal and Fluid Science,2014,52:347-354.
[5]Torregrosa A J,Broatch A,Olmeda P,et al.A note on bubble sizes in subcooled flow boiling at low velocities in internal combustion engine-like conditions[J].Journal of Applied Fluid Mechanics,2016,9(5):2321-2332.
[6]花仕洋,黄荣华,陈琳,等.发动机缸盖模拟冷却通道内过冷沸腾传热特性[J].内燃机学报,2015,33(2):171-177.
[7]Castiglione T,Pizzonia F,Piccione R,et al.Detecting the onset of nucleate boiling in internal combustion engines[J].Applied Energy,2016,164:332-340.
[8]Hua S Y,Huang R H,Li Z,et al.Experimental study on the heat transfer characteristics of subcooled flow boiling with cast iron heating surface[J].Applied Thermal Engineering,2015,77:180-191.
[9]Puenkar H,Das S.Numerical simulation of subcooled nucleate boiling in cooling jacket of IC engine[C]//SAE Paper.Detroit,MI,USA,2013,2013-01-1651.
[10]He L G,Zuo Z X,Xiang J H.Simulation of two phase flow boiling heat transfer in cylinder head cooling water jacket[J].Journal of Xian Jiaotong University,2013,47(1):20-27.
[11]刘永丰,王龙飞,花仕洋,等.矩形通道内过冷流动沸腾传热特性试验研究[J].内燃机工程,2016,37(2):111-115.
[12]郑强,高璞珍,许超,等.窄矩形通道内汽泡聚合行为研究[J].原子能科学技术,2014,48(6):1015-1019.
[13]徐建军,卓文彬,谢添舟,等.矩形窄缝通道近壁汽泡滑移和浮升可视化实验研究[J].核动力工程,2013,34(4):73-78.
[14]张体恩.基于气泡行为的缸盖沸腾冷却应用研究[D].北京:北京理工大学机械与车辆学院,2014.
[15]Hong G,Yan X,Yang Y H,et al.Experimental study on onset of nucleate boiling in narrow rectangular channel under static and heaving conditions[J].Annals of Nuclear Energy,2012,39(1):26-34.
[16]何联格,左正兴,向建华.气泡尺寸气缸盖沸腾换热的影响[J].内燃机学报,2013,31(1):70-80.
[17]董非,郭晨海,范秦寅,等.发动机冷却水腔内沸腾传热的模拟研究[J].内燃机工程,2011,32(4):76-82.
[18]董非,龚伟,张威望,等.内燃机缸盖水腔内气/液流动可化与传热试验研究[J].内燃机学报,2015,33(5):466-471.