Elbow flow analysis and optimal exhaust port profile design

In this study, the exhaust port profile of a diesel engine was numerically analyzed and optimized. First, the elbow profile results show that the separation loss of lower profile plays the main role in overall separation loss, it decreases sharply and then slowly with an increase of r lower / d . Within the range of 0 ≤ r lower / d ≤ 5, the total secondary flow loss increases sharply and then slowly with an increase of r lower / d . Under the same condition of relative pressure difference and lower profile, the elbow discharge coefficient increases with an increase of d mid / r upper and remains almost constant when d mid / r upper > 1. The maximum discharge coefficient under a certain r lower condition increases with an increase of r lower . Afterwards, the applicability of elbow profile results to exhaust port were verified and an exhaust port profile design method was established based on a circular arc profile. Finally the feasibility of exhaust port profile design method was verified experimentally.