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This paper develops an exhaust manifold pressure estimation method for a Diesel engine equipped with a variable geometry turbine (VGT) turbocharger. Extrapolated VGT data-maps are used directly for the estimation of the exhaust pressure using a non-iterative Newton-Raphson based method suitable for real-time applications. This approach can give more accurate estimations than traditional methods because it takes into account the turbine speed effect on the turbine mass flow rate. All this without increasing the calculation load significantly. The proposed exhaust manifold estimation can be used to relieve the exhaust manifold pressure physical sensor during engine operating conditions where its reliability is low. The estimator is evaluated in transient with two different engine cycles using a engine model validated in a benchmark as a reference.

A complete non-homentropic boundary resolution method for a flow upstream and downstream an intra-pipe restriction is considered in this article. The method is capable of introducing more predictable quasi-steady restriction models into the boundary problem resolution without adding artificial discharge coefficients. The traditional hypothesis of isentropic contraction, typically considered for the boundary resolution, is replaced by an entropy corrected method of characteristics (MOC) in order to be consistent with a non-homentropic formulation. The boundary resolution method is designed independently of the quasi-steady restriction models which allows obtaining a greater modeling flexibility when compared with traditional methods. An experimental validation at unsteady conditions is presented using different restriction quasi-steady models to illustrate the effectiveness of the proposed boundary resolution method in terms of predictability as well as flexibility.