Influence of Exhaust Valve Lift on Flow Capacity of Exhaust Port
RUI Jingmin1,XU Yang2
Author information+
(1.College of Automotive Engineering,Beijing Polytechnic,Beijing 100176,China;
2.School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100081,China)
The exhaust port model was established by AVL-Fire software and was checked and verified. Based on the verified model, the influence of exhaust valve lift on the flow capacity of exhaust port was studied. The results show that the discharge coefficient of exhaust port is only related to the loss coefficient. Under the samevalve lift and diameter ratio, the discharge coefficient of exhaust port only depends on the relative pressure difference. It means that the discharge coefficient will become the same if the relative pressure difference is the same for different exhaust back pressures. Under the certain relative pressure difference, the discharge coefficient of exhaust port increases rapidly and then slowly with the increase of valve lift and diameter ratio. Under the same valve lift and diameter ratio, the discharge coefficient of exhaust port increases with the increase of relative pressure difference. The optimal valve lift and diameter ratio keeps constant no matter how the relative pressure difference changes. Accordingly, the design method of maximum exhaust valve lift was put forward.
