The KCS Container Ship executing zigzag and turning circle maneuvers in shallow water is studied numerically with CFD simulation.Different factors affecting the accuracy of the numerical prediction such as grid densit...The KCS Container Ship executing zigzag and turning circle maneuvers in shallow water is studied numerically with CFD simulation.Different factors affecting the accuracy of the numerical prediction such as grid density,overset discretization,propeller model,turbulence modeling and setup condition have been carefully investigated.Numerical predictions for port side and starboard side turning circle maneuvers and 3 different zigzag maneuvers are compared with experimental data obtained by Flanders Hydraulics(FH)for the KCS ship model at scale 1/52.66 with Froude number Fr=0.095 and water depth to draft ratio h/T=1.2 in tank conditions.To better assess the accuracy of the numerical prediction,simulations have been performed both with a non-confined and confined configuration.展开更多
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 gasolin...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.展开更多
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, autom...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.展开更多
This paper is devoted to the assessment of ship maneuvering simulation using different propeller models with the focus on a simplified propeller model that represents the action of the propeller by body force and uses...This paper is devoted to the assessment of ship maneuvering simulation using different propeller models with the focus on a simplified propeller model that represents the action of the propeller by body force and uses propeller performance curve to determine propeller loading during ship maneuvering.Simulations are also performed with an actual propeller approach with which the propeller rotation is simulated directly with the Reynolds averaged Navier-Stokes equation(RANSE)solver.Both time accurate simulations using sliding grid and rotating frame approximations have been performed for comparison.The zigzag and turning circle maneuvers in calm water have been simulated for two different ship models,namely the ONR tumblehome(ONRT)test case and the KRISO(Korea Research Institute of Ship and Ocean)Container Ship(KCS)test case.Predicted ship motion is compared with measurement data to assess the accuracy of the numerical prediction using RANSE computations with different propeller models.展开更多
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 ex...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.展开更多
文摘The KCS Container Ship executing zigzag and turning circle maneuvers in shallow water is studied numerically with CFD simulation.Different factors affecting the accuracy of the numerical prediction such as grid density,overset discretization,propeller model,turbulence modeling and setup condition have been carefully investigated.Numerical predictions for port side and starboard side turning circle maneuvers and 3 different zigzag maneuvers are compared with experimental data obtained by Flanders Hydraulics(FH)for the KCS ship model at scale 1/52.66 with Froude number Fr=0.095 and water depth to draft ratio h/T=1.2 in tank conditions.To better assess the accuracy of the numerical prediction,simulations have been performed both with a non-confined and confined configuration.
文摘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.
文摘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.
基金This work was made possible thanks to granted access to the HPC resources of CINES and IDRIS computing centers under the allocation A0072A01308 made by Grand Equipement National de Calcul Intensif(GENCI).
文摘This paper is devoted to the assessment of ship maneuvering simulation using different propeller models with the focus on a simplified propeller model that represents the action of the propeller by body force and uses propeller performance curve to determine propeller loading during ship maneuvering.Simulations are also performed with an actual propeller approach with which the propeller rotation is simulated directly with the Reynolds averaged Navier-Stokes equation(RANSE)solver.Both time accurate simulations using sliding grid and rotating frame approximations have been performed for comparison.The zigzag and turning circle maneuvers in calm water have been simulated for two different ship models,namely the ONR tumblehome(ONRT)test case and the KRISO(Korea Research Institute of Ship and Ocean)Container Ship(KCS)test case.Predicted ship motion is compared with measurement data to assess the accuracy of the numerical prediction using RANSE computations with different propeller models.
文摘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.
