内燃机缸内传热过程的探讨及其进展

本文论述了目前内燃机缸内传热研究的发展。对缸内传热的研究方法,主要是对表面温度法进行了探讨,并将缸内传热模型的发展划分为三个阶段。文中综合介绍了利用表面温度法对缸内传热所进行的实验研究,并用无损方法测量了内燃机燃烧室陶瓷隔热表面的瞬态温度。实验结果表明,用氧化锆隔热,取得了减少传热的明显效果。作者还对内燃机缸内传热研究中的某些问题进行了较为深入的讨论。     

车用内燃机冷却系统动态传热模型

提出了一个基于集总参数法的车用内燃机冷却系统动态传热模型。考虑了内燃机燃烧室、散热器和水泵的传热和冷却系统的工作,建立了机体、散热器、水泵与冷却介质之间的热耦合计算公式。对一台单缸柴油机冷却系的稳态及动态温度进行了计算,结果证实该模型可用于内燃机冷却系统的动态传热特性研究。     

车用内燃机冷却系的流动与传热仿真

本提出了车用内燃机冷却系的流动与传热仿真方法。采用一维的方法研究了车用内燃机冷却系的流动问题；采用集总参数法研究了车用内燃机冷却系的传热问题；将车用内燃机冷却系的流动问题与传热问题耦合起来作为一个系统，进行整体研究，建立了内燃机冷却系的流动与传热问题的整体模型。编制了计算程序。对某型坦克内燃机冷却系的流动与传热进行了实例计算，仿真结果与试验值符合较好。     

基于集总参数法的车用内燃机传热计算机仿真研究

针对车用内燃机某些部件不能直接应用集总参数法研究传热的问题，根据集总参数法的限制条件，提出了将集总参数法用于内燃机所有部件研究传热问题的方法。将车用内燃机的流动问题与传热问题耦合起来作为一个系统，建立了车用内燃机的流动与传热问题的综合模型，编制了计算程序。对某型坦克内燃机的传热进行了实例计算。计算结果表明，坦克内燃机传热不但与内燃机的工况有关，还与外界环境中的大气压力与大气温度有关，文中给出了坦克内燃机传热随外界环境中大气压力与大气温度的变化规律，并将计算结果与实验值作了比较，其结果吻合较好。     

车用内燃机润滑系统传热仿真

提出了履带车辆动力装置润滑系的传热仿真方法。采用集总参数法研究了车用内燃机润滑系的传热问题，并建立了润滑系各部件的传热教学模型，编制了计算程序。对某型坦克内燃机润滑系的传热进行了实例计算。仿真结果与试验值符合较好。     

燃烧室部件耦合系统过渡工况传热全仿真模拟研究

内燃机的起动、停车、加载等运行工况发生急剧变化（过渡工况）过程中,其燃烧室部位外于强烈地被加热或被冷却状态。这种热冲击增加了部件的动态疲劳热应力,给内燃机的可靠性带来严重恶果,是导致燃烧室部位破裂的主要原因之一。燃烧室部件的传热研究是热负荷计算和评定的基础,对内燃机的可靠性设计具有重要意义。作对燃烧室部件活塞组气缸套耦合系统在过渡工况下的耦合传热关系进行了较深入的研究,建立了描述这一传热过程的数学模型;并利用该模型,模拟了125风冷柴油机在各种过渡工况下的传热情况。     

沸腾对柴油机冷却系统数值模拟的影响

计算对比了不考虑沸腾和考虑沸腾2种冷却系统数值模拟计算,得出结论:考虑沸腾传热对内燃机冷却水腔内流动与压力的分布影响不明显,而对冷却水腔内传热过程的影响是很大的。若只考虑纯对流传热,计算结果可能与实际情况存在很大的差异。因此,在对强化内燃机进行流动与传热问题的研究时必须考虑沸腾传热的因素,以获得更为真实、准确的结果。     

用热线风速仪测量内燃机气缸内的空气流速

用定温式热线风速仪测量内燃机气缸内空气流速时,由于空气温度、压力和补充热线传热损失的变化,必须对热线风速仪的输出进行修正。热线的传热损失依靠供给热线顶端的热量来补充。在内燃机气缸内,供给热线顶端的热量随曲柄转角而变化。前文已经介绍了稳定流动状态下,随空气温度和热线传热损失变化的一种实际修正方法。本文研究压力对空气和补充传热损失之间的对流传热损失的作用。此外还研究了内燃机气缸内供给热线的热量的情况。根据这个研究结果,提出了一种随空气温度、压力及补充热线的热损失的变化而对热线风速仪输出进行补偿的实际方法。     

内燃机缸内零件系统传热的计算机模拟进展

本文综合介绍了内燃机缸内零件系统传热计算机模拟的国际和国内现状，并介绍了作者目前正在进行的缸内耦合三维零件系统传热的研究情况。由于缸内零件传热的计算机模拟是未来内燃机虚拟设计的关键技术，因而有必要对缸内零件的分析历史和现状进行综合探讨。     

活塞环摩擦热对燃烧室部件耦合系统的传热影响模拟研究

在内燃机传热全仿真模拟研究中考虑了环组摩擦热的影响,建立了一整套有关环组摩擦热处理子模型：1）活塞环－气缸厌的混合润滑模型;2）摩擦热计算模型;3）摩擦热在活塞组和气缸厌间的分配模型;4）摩擦热在活塞组和气缸套上的分布模型。利用这些模型,模拟了125风冷柴油机环组摩擦热对活塞组－气缸套耦合系统的传热影响。     

内燃机冷却系统中应用纳米流体强化传热研究综述

内燃机工作时依赖冷却系统将多余热量及时带走以保证燃烧室核心部件及润滑油膜的正常工作温度。常规内燃机冷却介质导热系数偏低,而新一代强化传热工质纳米流体具有明显提升的传热性能,应用于内燃机冷却系统有利于强化内燃机传热及提高热管理性能。且由于纳米流体的传热性能受纳米粒子的种类、大小、浓度、形状等因素影响,可以通过改变这些因素控制内燃机冷却水腔的传热量。综述了国内外研究者针对纳米流体导热系数与对流换热性能开展的试验测试、理论分析和计算机模拟研究工作,以及纳米流体应用于内燃机冷却系统中强化传热的进展,最后指出当前研究工作的不足及未来工作方向。     

Numerical study of heat transfer of hydrogen combustion in noble gases atmosphere in compression ignition engine

The high energy content of hydrogen and zero carbon emission from hydrogen combustion is very important for compression ignition engine development. Hydrogen requires a very high auto-ignition temperature, which encourages replacing nitrogen with noble gases with higher specific heat ratio during compression process. In noble gases-hydrogen combustion, higher combustion temperature potentially leading to a higher heat loss. This paper aims to investigate the effect of hydrogen combustion in various noble gases on heat distribution and heat transfer on the cylinder wall. Converge CFD software was used to simulate a Yanmar NF19SK direct injection compression ignition engine. The local heat flux was measured at different locations of cylinder wall and piston head. The heat transfer of hydrogen combustion in various noble gases at different intake temperatures was studied using the numerical approach. As a result, hydrogen combustion in light noble gases such as helium produces faster combustion progress and higher heat temperature. The hydrogen combustion that experienced detonation, which happened in neon at 340 K and argon at 380 K, recorded a very high local heat flux at the cylinder head and piston due to the rapid combustion, which should be avoided in the engine operation. At a higher intake temperature, the rate of heat transfer on the cylinder wall is increased. In conclusion, helium was found as the best working gas for controlling combustion and heat transfer. Overall, the heat transfer data gained in this paper can be used to construct the future engine hydrogen in noble gases.     

燃煤气单元玻璃熔窑火焰空间数值模拟

通过建立火焰空间三维数学模型来模拟燃煤气单元玻璃熔窑火焰空间内的流动、燃烧、传热等过程。针对煤气的燃烧特点，单元窑的火焰特征等进行了较深入的研究。结果表明，该三维数学模型能够比较全面地反映火焰空间速度场、温度场分布的规律；模型具有通用性好，不易受环境波动影响的优点，具有一定的实用意义。     

棉秆循环流化床稀相区传热系数的试验研究

在热功率0.5 MW棉秆循环流化床试验装置上对稀相区传热系数进行了测定,研究了不同参数对传热系数的影响,结果表明:环形区颗粒浓度和床温对传热系数的影响较大,且随着颗粒浓度和床温的增加而增加;一次风率和过量空气系数对不同床高的传热系数也有一定影响,传热系数随一次风率的增加而增加,但一次风率过大时,传热系数会有所下降;为了得到较高的传热系数,过量空气系数存在一个最佳值;循环倍率对传热系数的影响也很明显,在一定的范围内,传热系数随循环倍率的增加而增加;当循环倍率太大时,床温有所降低,使传热系数减小.     

Research on Marine Boiler''''s Pressurized Combustion and Heat Transfer

The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable and the method is applicable to combustion and heat transfer of the marine supercharged boiler.     

Research on Marine Boiler＇s Pressurized Combustion and Heat Transfer

The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable and the method is applicable to combustion and heat transfer of the marine supercharged boiler.     

P型蓄热式辐射管设计与数值模拟

开发了P型蓄热式辐射管。在开发设计过程中,应用CFD技术,对设计方案进行三维流动、传热与燃烧过程的数值模拟。根据模拟结果,改进和优化设计方案,大大减少了实验次数。实践表明,CFD技术是提高燃烧设备开发设计水平和增强技术创新能力的有效工具。     

Effect of concentration of bed materials on combustion efficiency during incineration

The concentration of bed materials in a fluidized bed incinerator influences the reaction time, mass and heat transfer efficiency. These parameters significantly affect the combustion efficiency and the generation of pollutants in the waste incineration. This research studied the effect of concentration of bed materials on combustion efficiency during waste incineration. The size of bed materials, combustion temperature, and excess air factor were controlled to assess the concentration of carbon monoxide. The pressure drop was measured to evaluate the bed expansion and calculate the concentration of bed materials. Experimental results indicated that the concentration of carbon monoxide did not decrease with the decrease of residence time and increase of excess air factor. With higher heat transfer efficiency, the combustion time could be reduced and the combustion efficiency would be improved. The concentration of carbon monoxide at 700 °C was higher than that at 800 and 900 °C. The influence of heat transfer efficiency on combustion efficiency was significant as the operating temperature was higher than 700 °C. The concentration of carbon monoxide decreased with increasing static bed height. In addition, the size of bed materials affected the mixing and heat transfer efficiency in the sand bed. According to the result of experiment, the best particle size of bed materials was 770 μm.     

Estimation of instantaneous local heat transfer coefficient in spark-ignition engines

Optimizing heat transfer for internal combustion engines requires application of advanced development tools. In addition to experimental method, numerical 3D-CFD calculations are needed in order to obtain an insight into the complex phenomenas in-cylinder processes. In this context, fluid flow and heat transfer inside a four-valve engine cylinder is modeled and effects of changing engine speed on dimensionless parameters, instantaneous local Nusselt number and Reynolds number near the surface of combustion chamber are studied. Based on the numerical simulation new correlations for instantaneous local heat transfer on the combustion chamber of SI engines are derived. Results for several engine speeds are compared for total heat transfer coefficient of the cylinder engine with available correlation proposed by experimental measurements and a close agreement is observed. It is found that the local value of heat transfer coefficient varies considerably in different parts of the cylinder, but it has equivalent trend with crank angle position.