Development and experimental validation of a new one-dimensional valve boundary condition based on the method of characteristics

作者：Brejaud P^*; Higelin P; Charlet A; Chamaillard Y

来源：Proceedings of the Institution of Mechanical Engineers - Part D: Journal of Automobile Engineering , 2011, 225(D12): 1614-1632.

DOI：10.1177/0954407011409653

• one-dimensional simulation
• valve boundary condition
• method of characteristics
• unsteady gas dynamics
• computational fluid dynamics

One-dimensional (1D) engine gas dynamic simulations are necessary in order to develop control laws for specific valve systems such as variable valve timing or the pneumatic hybrid engine. The keystone of 1D engine models is the valve boundary condition, where the pressure wave phenomenon into a pipe is created and the in-cylinder mass flowrate is determined. Most commercial or research simulation codes embed the method of characteristics (MOC) constant-pressure valve boundary condition from Benson. This constant-pressure model in its original form provides good results in most cases, but this paper shows that it does not converge for low valve opening and pressure ratio values, for which the characteristic lines become vertical. A solution to this problem cannot be found in the literature. The current paper presents a new MOC-based valve boundary condition that obviates convergence problems. The computational time of the proposed model is evaluated and compared with that of Benson's model. The new valve boundary condition is validated experimentally on a valve gas dynamics test bench and compared with the original constant-pressure model. The study shows that results obtained with the proposed model are similar to data from both experiments and Benson's model.

• 出版日期2011