直喷式柴油机复杂形状燃烧室内空气运动的数值模拟和实验研究

摘要

With the SIMPLE algorithm and body-fitted curvilinear orthogonal mesh, the multidimenonal numerical modeling of the air motion in combustion chambers of complex shape such as square chamber and quadram chamber etc for D.I. diesel engines was completed. The results are compared with that of the traditional cylindrical chamber and the results from the square chamber are verified by LDA measurement. In order to overcome the difficulty to apply Laser-Doppler Anemometry to the detail study of the air motion in a combustion chamber due to the effect of reflection and refraction of laser beams at the inner surfaces of the chamber, the technique of Refractive Index Matching is used in our test rig. That is, the replicas of the cylinder, piston and combustion chamber in the rig are constructed from transparent perspex and the working medium is a liquid having the same refractive index as the perspex. Whereby, the laser beams no longer suffer deflection at the inner walls of the combustion chamber and the measuring volume can be located at any desired position in the chamber even having a complex configuration and the detail information of the flow field can be obtained.%本文用SIMPLE算法在适体正交曲线坐标网格下对直喷式柴油机复杂形状燃烧室(如方形,四角形等)中的空气运动进行了多维数值模拟计算,并与传统中圆柱形燃烧室内流动进行了对比.其中方形燃烧室的结果还与激光多普勒测量结果进行了对比.在试验装置中,为了克服激光束在燃烧室内表面的反射和折射造成的困难,作者采用了折射率匹配技术--工作介质是一种液体,它的折射率与制成气缸、活塞和燃烧室形状的有机玻璃的折射率完全相同.这样,激光束在燃烧室壁处不再受到折射和反射,测量体可置于燃烧室内任意位置,从而可以获得复杂形状燃烧室内流场的详细信息.