针对喷油器针阀体各部分传热方式的不同，将针阀体分为3个区域，分析了各区域的传热方式和传热边界条件确定方法。基于流体体积法建立了喷孔内部流动模型，计算分析了喷孔内部速度分布情况，确定了针阀体内表面的传热边界条件。建立了柴油机三维燃烧模型，计算分析了针阀体顶端外表面处的热流密度，确定了针阀体顶端外表面的传热边界条件。基于流固耦合的方法，计算了某型柴油机最大扭矩点和标定工况点的针阀体温度分布，计算结果表明：针阀体从上到下温度逐渐增大，最高温度出现在针阀体顶端；喷孔内部从进口到出口温度逐渐增大，喷孔出口温度最高；针阀体外表面喷孔下侧温度高于喷孔上侧；喷孔内部出口侧以及针阀体外表面喷孔处的温度均达到了积炭形成的最低温度；标定工况点针阀体温度高于最大扭矩点。结合针阀体实际积炭分布特点可知：在针阀体温度和缸内高温燃气的共同作用下，积炭不断产生并积累在喷孔出口周围。

According to different ways of heat transfer, the needle valve body was divided into three areas. The way of heat transfer and the determination method of boundary conditions were analyzed. The internal flow model of nozzle hole was established based on the fluid volume method. The internal velocity distribution of nozzle hole was calculated and analyzed and the heat transfer boundary condition for the inner surface of needle valve body was determined. Then three-dimensional combustion model of diesel engine was established, the heat flux for the outside surface of the top end of needle valve body was calculated and analyzed and its heat transfer boundary condition was determined. The temperature distribution of needle valve body at maximum torque point and rated condition point was finally calculated through the fluid-solid coupling method. The results show that the temperature of needle valve body gradually increases from the top to the bottom and the temperature at the top is the highest. The temperature of nozzle hole gradually increases from inlet to outlet and the nozzle outlet temperature is the highest. The temperature of lower side is higher than that of top side for nozzle hole on the outside surface of needle valve body, which is equal to or higher than the temperature of carbon deposit formation like the nozzle outlet temperature. The temperature of needle valve body at the rated condition point is higher than that at the maximum torque point. It is known that carbon deposits form, increase and aggregate continuously at the outlet of nozzle hole under the mutual action of the needle valve body temperature and the high-temperature gas inside cylinder according to the actual distribution characteristics of carbon deposit in the needle valve body.