不同结构燃烧室内流场的三维模拟

利用AVL Fire软件对105柴油机进气、压缩过程进行三维瞬态数值模拟,模拟结果给出了两种形状燃烧室详细的流场结构.在压缩上止点之前,A型燃烧室(直口ω形)内挤流速度明显低于B型燃烧室(缩口ω形),压缩上止点后B型燃烧室逆挤流强度大,持续时间长,说明缩小燃烧室开口直径能有效增强挤流和逆挤流;B型燃烧室的湍流强度明显高于A型燃烧室,B型燃烧室最大湍动能约为A型燃烧室的两倍.

Three-Dimensional Transient Numerical Simulation of In-Cylinder Flow Field for Different Combustion Chamber Geometry

To obtain the detailed in-cylinder flow field structure, this paper simulates a diesel engine of two different combustion chamber geometries respectively, under condition of intake and compressed stroke. The result shows that before TDC the squash velocity in chamber A is far lower than that in chamber B whose open cave is contracted; and after TDC the counter squash flow in chamber B influences larger area and lasts for longer time than chamber A. This indicates that contracted open cave can strengthen the squash flow. Turbulence flow in chamber B is also intensified and the maximum TKE is nearly twice as big as that in chamber A.