为了提高发光二极管（LED）的散热性能，基于烟囱效应原理，设计了一种特殊的直筒式烟囱结构的LED冷却用散热器。通过Solidworks软件构建三维模型，利用其插件Flow Simulation对构建的模型进行热仿真。研究了不同烟囱高度、通风口形状和大小对烟囱效应散热效果的影响。研究结果表明：烟囱效应有效地提高了散热器的对流散热性能。当烟囱高度为50 mm、通风口等效直径为8 mm、通风口形状为梯形时，LED最高温度为61.60 ℃，比优化前降低了6.54 ℃。与传统散热器对比，LED最高温度降低了8.89 ℃。实验中4个监测点的实际温度与仿真所得温度的平均误差为4.0%，在允许范围内，验证了以上研究的正确性。所设计的散热器可以很好地满足自然对流条件下LED的工作要求。

In order to improve the heat dissipation performance of light emitting diode (LED), based on the principle of the chimney effect, a special cooling radiator with straight chimney structure for LED is designed. The three-dimensional model is built by Solidworks software, and the model is simulated by its plug-in called Flow Simulation. The effects of various heights, vent shapes and sizes on the heat dissipation of chimney effect are studied. Studies show that chimney effect effectively improves the convection cooling performance of the radiator. When the height of chimney is 50 mm and the equivalent diameter of trapezoidal vent is 8 mm, the highest temperature of the LED is 61.6 ℃， which is 6.54 ℃ lower than the original model. Compared with the traditional radiator, the highest temperature of LED reduces 8.89 ℃. Through experiments, the average error between the actual temperature of the 4 monitoring points and the simulated temperature is 4.0%, and the average error is in the allowable range. It confirms the correctness of the simulation steps. In conclusion, the designed radiator can better satisfy the working requirements under the nature convection conditions.