涡流对于中、小型柴油机内混合气的形成有重要作用，各缸涡流比的不均匀会使发动机性能下降。通过对CA498柴油机送气歧管出口流速进行了测量。试验结果表明：气流的旋向与气道走向相同，会加强涡流，否则会减弱涡流；气道外侧流量越高则涡流越强，流量越低涡流越弱。气缸内流速的不均匀是由歧管内气流的旋转和流量分布的不均匀共同造成的。 Eddy current plays an important role in the formation of mixed gas in medium and small-sized diesel engines. The inhomogeneity of the vortex ratio of each cylinder will lead to the decline of the engine performance. The outlet flow rate of the CA498 diesel engine exhaust manifold was measured. The results show that the direction of the airflow is the same as that of the airway, which will intensify the vortex, otherwise the vortex will be weakened. The higher the airflow outside, the stronger the vortex and the lower the vortex. The non-uniform flow velocity in the cylinder is caused by the rotation of the air flow in the manifold and the non-uniform flow distribution.