Fluid dynamic modeling of junctions in internal combustion engine inlet and exhaust systems

The modeling of inlet and exhaust systems of internal combustion engine is very important in order to evaluate the engine performance.This paper presents new pressure losses models which can be included in a one dimensional engine simulation code.In a first part,a CFD analysis is made in order to show the importance of the density in the modeling approach.Then,the CFD code is used,as a numerical test bench,for the pressure losses models development.These coefficients depend on the geometrical characteristics of the junction and an experimental validation is made with the use of a shock tube test bench.All the models are then included in the engine simulation code of the laboratory.The numerical calculation of unsteady compressible flow,in each pipe of the inlet and exhaust systems,is made and the calculated engine torque is compared with experimental measurements.

A new modeling approach of pressure waves at the inlet of internal combustion engines

This paper presents a new model used to describe the propagation of pressure waves at the inlet systems of internal combustion engine. In the first part, an analogy is made between the compressible air in a pipe and a mechanical ideal mass damper spring system. A new model is then presented and the parameters of this model are determined by the use of an experimental setup (shock tube test bench). With this model, a transfer function is defined in order to link directly the pressure and the air mass flow rate. In the second part, the model is included into an internal combustion engine simulation code. The results obtained with this code are compared to experimental ones which are measured on a one-cylinder engine test bench. This last one is driven by an electric motor in order to study only the effect of the pressure waves on the engine behavior. A good agreement is obtained between the experimental results and the numerical ones and the new approach is an alternative method for modeling the pressure wave phenomena in an internal combustion engine manifold.

Oil Strategies Benefits over Different Driving Cycles using Numerical Simulation

95 g/kin is the allowed quantity of CO2 emission normalized to NEDC to be set in 2020. In addition, NEDC will be replaced by more severe driving cycles and will be united worldwide. To respond to those criteria, automotive industries are working on every possible field. Thermal management has been proved to be effective in reducing fuel consumption. Cold start is a primordial reason of ovcrconsumption, as the engine highest efficiency is at its optimal temperature. At cold start, the engine＇s oil is at its lowest temperature and thus its higher viscosity level. A high viscosity oil generates more friction, which is one of the most important heat losses in the engine. In th/s paper, hot oil storage is studied. Numerical simulations on GT-suite model were done. The model consists of a 4-cylinder turbocharged Diesel engine using a storage volume of 1 liter of hot oil. Ambient temperature vari- ation were taken into consideration as well as different driving cycles. Furthermore, different configurations of the thermal strategy （multifunction oil sump） were proposed and evaluated. Lubricant temperature and viscosity profiles are presented in the article as well as fuel consumption savings for different configurations, driving cycles and ambient temperatures.

Characterization of Particle Emissions of Turbocharged Direct Injection Gasoline Engine in Transients and Hot Start Conditions

Reducing pollutant emissions,particularly soot particles emitted by internal combustion engines,is a major challenge for car manufacturers.In this paper,the experimental setup is a turbocharged three-cylinders gasoline direct injection engine installed on a HORIBA dynamic test driven by a HORIBA STARS computer.The particle-measuring device is a Pegasor Particles Sensor that measures the current carried by previously electrically charged particles.The hot engine stabilized tests,with lambda parameter lower or equal to one,have very low emission levels,unlike dynamic tests.As a consequence,the present paper deals with experiments in transient conditions.Unlike diesel engine,cycle tests show that particulate emissions vary widely.To understand the phenomenon,a simple transient was created and reproduced a hundred times in order to obtain enough data to analyze and compare these different tests.This transient starts from idle to reach the speed of 2000 r/min and 60 N·m in 5 s.To reach this point,it is necessary to stay in full load for about 3 s.The maximum deviations of particles reaches 85%with the standard deviationσ=18%.The cylinder pressure sensor shows significant variations at the very beginning of each transient,i.e.,during the first 500 ms.This kind of result was observed for Worldwide harmonized Light vehicles Test Cycles(WLTC)with a maximum deviations of particles reaching 75%withσ=30%,on Real Drive Emissions Cycle(RDE)with a maximum deviations of particles reaching 45%withσ=22%and for a 300 s Mini-Cycle with a maximum deviations of particles reaching 70%withσ=17%.The Mini-cycle is made up of the five largest accelerations of the WLTP cycle.A complete analysis highlights the importance of filling the first engine cycles.This depends on the opening speed of the throttle,the position of the crankshaft at the beginning of the transient,and the acceleration of the first cycles.But,the NO_(x) sensor shows very slight variations between each test.As a consequence,it appears that the variation of particles emissions is not only related to variation of equivalence ratio but with another setting,which may be the oil consumption.Finally,from these results,it is possible to determine a particle characterization function.It consists of two functions.The first one is the average of the emitted particles level which depends on the engine speed,engine acceleration,engine torque and torque acceleration.The second function,which corresponds to dynamic variations in emissions,mainly depends on oil consumption in the cylinder and on the combustion quality of the first transient engine cycles.

New 0D/1D Physical Approach for Modelling the Gas Dynamics Behavior Inside the Intake System of an Engine

The competition among carmakers to introduce the most innovative solutions is growing day by day. Since few years, simulation is being used widely in automotive industries. Instead of building costly prototypes and expending fuel for doing tests on a real engine, simulation became a good solution before taking new decisions. Concerning the study of gas dynamics and pressure wave's propagation in the intake system of an internal combustion engine, a precise modelling is needed in order to obtain good results. Unfortunately, the computational time for these simulations is considered as high compared to the real time. The main objective of the new approach presented in this paper, is to reduce simulation time of models in the internal combustion engine simulation code, allowing them to accomplish many engine simulations faster than one-dimensional non-linear approach. A transfer function is defined to link directly the relative pressure and the air mass flow rate. In a second time, the model is included into an internal combustion engine simulation code. The results obtained with this code are compared to experimental ones which are measured on a one-cylinder engine test bench. A good agreement is obtained between the experimental results and the numerical one. The model was improved by adding a transfer function for temperature evolution. The convergence time is then reduced as well as the global simulation time of the model.