Large eddy simulation of fuel injection and mixing process in a diesel engine

The large eddy simulation （LES） approach implemented in the KIVA-3V code and based on one-equation sub-grid turbulent kinetic energy model are employed for numerical computation of diesel sprays in a constant volume vessel and in a Caterpillar 3400 series diesel engine. Computational results are compared with those obtained by an RANS （RNG k-e） model as well as with experimental data. The sensitivity of the LES results to mesh resolution is also discussed. The results show that LES generally provides flow and spray characteristics in better agreement with experimental data than RANS; and that small-scale random vortical structures of the in-cylinder turbulent spray field can be captured by LES. Furthermore, the penetrations of fuel droplets and vapors calculated by LES are larger than the RANS result, and the sub-grid turbulent kinetic energy and sub-grid turbulent viscosity provided by the LES model are evidently less than those calculated by the RANS model. Finally, it is found that the initial swirl significantly affects the spray penetration and the distribution of fuel vapor within the combustion chamber.

INDUSTRIAL ENGINEERING AND VISUALISATION—A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very impo[tant role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.

STUDY ON SHIFT SCHEDULE AND SIMULATION OF AUTOMATIC TRANSMISSION

From the point of view of saving energy, a new shift schedule and auto-controlling strategy for automatic transmission are proposed. In order to verify this shift schedule, a simulation program using a software package of Matlab/ Simulink is developed. The simulation results show the shift schedule is correct. This shift schedule has enriched the theory of vehicle automatic maneuvering and will improve the efficiency of hydrodynanic drive system of the vehicle.

Control of surface wettability via strain engineering

Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sam- ple material and molecular dynamic simulations, we demon- strate that strain engineering can serve as an effective way to control the surface wettability. The contact angles 0 of water droplets on a graphene vary from 72.5° to 106° under biaxial strains ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface （at zero strain）, the variation of 0 upon the applied strains is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the strains. In light of the inherent dependence of the contact an- gle on liquid-solid interfacial energy, we develop an analytic model to show the cos 0 as a linear function of the adsorption energy Eads of a single water molecule over the substrate sur- face. This model agrees with our molecular dynamic results very well. Together with the linear dependence of Eads on bi- axial strains, we can thus understand the effect of strains on the surface wettability. Thanks to the ease of reversibly ap- plying mechanical strains in micro/nano-electromechanical systems, we believe that strain engineering can be a promis- ing means to achieve the reversibly control of surface wetta- bility.

APPLICATION OF CIRCUIT SIMULATION IN HARDWARE DESIGN FOR ELECTRONIC CONTROL HIGH PRESSURE COMMON-RAIL FUEL SYSTEM OF DIESEL ENGINE

By means of circuit simulation, hardware of electronic control unit （ECU） of high pressure common-rail electronic control fuel system for diesel engine is designed. According to the system requirements for hardware of ECU, signal-processing circuit of variable reluctance （VR） sensor, filter circuit for input signal, high voltage power circuit and driver and protection circuit of solenoid are simulated as emphases. Difficulties of wide scope of VR sensor output signal, efficiency of high voltage power and reliable and swift driver of solenoid are solved. The results of simulation show that the hardware meets the requirement of the fuel system. At the same time, circuit simulation can greatly increase quality of the design, alleviate design labor and shorten design time.

SIMULATION IN THERMAL DESIGN FOR ELECTRONIC CONTROL UNIT OF ELECTRONIC UNIT PUMP

The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation, the thermal design of ECU for electronic unit pump （EUP） fuel system is applied. The power dissipation model of each power component in the ECU is created and simulated. According to the analyses of simulation results, the factors which affect the power dissipation of components are analyzed. Then the ways for reducing the power dissipation of power components are carried out. The power dissipation of power components at different engine state is calculated and analyzed. The maximal power dissipation of each power component in all possible engine state is also carried out based on these simulations. A cooling system is designed based on these studies. The tests show that the maximum total power dissipation of ECU drops from 43.2 W to 33.84 W after these simulations and optimizations. These applications of simulations in thermal design of ECU can greatly increase the quality of the design, save the design cost and shorten design time

Practical Survey on Design and Testing of Flight Control Laws for Helicopter Engineering Simulators

A practical survey on engineering implementation of flight control laws on helicopter engineering simulators is proposed.Advances of helicopter engineering simulators are introduced.Practical flight control technologies are reviewed,with an emphasis on discussing the corresponding engineering simulation programs.Finally,the difficulties of implementing advanced control technologies are addressed,and the future development of helicopter engineering simulators are highlighted.

季节因素对二冲程船用柴油机性能参数及排放影响研究

In comparison to onshore facilities,ships,and their machinery are subjected to challenging external influences such as rolling,vibration,and continually changing air&cooling water temperatures in the marine environment.However,these factors are typically neglected,or their consequences are deemed to have little effect on machinery,the environment,or human life.In this study,seasonal air&seawater temperature effects on marine diesel engine performance parameters and emissions are investigated by using a full-mission engine room simulator.A tanker ship two-stroke main engine MAN B&W 6S50 MC-C with a power output of 8600 kW is employed during the simulation process.Furthermore,due to its diverse risks,the Marmara Region is chosen as the application area for real-time average temperature data.Based on the research findings,even minor variations in seasonal temperatures have a significant influence on certain key parameters of a ship’s main engine including scavenge pressure,exhaust temperatures,compression and combustion pressures,fuel consumption,power,and NOx-SOx-COx emissions.For instance,during the winter season,the cylinder compression pressure(pc)is recorded at 94 bar,while the maximum pressure(pz)reaches 110 bar.In the summer,pc experiences a decrease of 81 bar,while pz is measured at 101 bar.The emission of nitrogen oxides(NOx)exhibits a measurement of 784 parts per million(ppm)during winter and 744 in summer.The concentration of sulfur oxides(SOx)is recorded at 46 ppm in winter and 53 in summer.Given the current state of global warming and climate change,it is an undeniable fact that the impact of these phenomena will inevitably escalate.

Stability analysis of backflling in subsiding area and optimization of the stoping sequence

In underground mining by sublevel caving method, the deformation and damage of the surface induced by subsidence are the major challenging issues. The dynamic and soft backflling body increases the safety risks in the subsiding area. In this paper, taking Zhangfushan iron mine as an example, the ore body and the general layout are focused on the safety of backflling of mined-out area. Then, we use the ANSYS software to construct a three-dimensional(3D) model for the mining area in the Zhangfushan iron mine. According to the simulation results of the initial mining stages, the ore body is stoped step by step as suggested in the design. The stability of the backflling is back analyzed based on the monitored displacements, considering the stress distribution to optimize the stoping sequence. The simulations show that a reasonable stoping sequence can minimize the concentration of high compressive stress and ensure the safety of stoping of the ore body.

Analysis and Calibration of Internal Flow Force of EjectorPowered Engine Simulator System in Wind Tunnels

The ejector-powered engine simulator(EPES)system is an important piece of equipment in conducting an influence test of the intake and jet flow in low-speed wind tunnels.In this work,through the analysis of the structure and principle of EPES,three parts of the internal flow force were obtained,namely,the additional resistance before the inlet,the internal flow force in the inlet and the thrust produced by the ejector.On the assumption of one-dimensional isentropic adiabatic flow,the theoretical formulae for calculating the forces were derived according to the measured total pressure,static pressure and total temperature of the internal flow section.Subsequently,a calibration tank was used to calibrate the EPES system.On the basis of the characteristics of the EPES system,the process and method of its calibration were designed in detail,and the model installation interface of the calibration tank was reformed.By applying this method,the repeatability accuracy of the inlet flow rate calibration coefficient was less than0.05%,whereas that of the exhaust flow rate and velocity was less than 0.1%.Upon the application of the calibration coefficients to the correction of the wind tunnel experiment data,the results showed good agreement with the numerical simulation results in terms of regularity and magnitude before stall,which validates the reasonableness and feasibility of the calibration method.Analysis of the calibration data also demonstrated the consistency in the variation law and trend between the theoretical calculation and actual measurement of internal flow force,further reflecting the rationality and feasibility of the theoretical calculation.Nevertheless,the numerical difference was large and further widened with a higher ejection flow rate mainly because of the accuracy of flow measurement and the inhomogeneity of internal flow.The thrust deflection angle of EPES is an important factor in correcting this issue.In particular,the thrust deflection angle becomes larger with small ejection flow and becomes smaller with an increase in flow rate,essentially exhibiting a general change of less than 10°.

Numerical simulation of a rotary engine primary compressor impacted by bird

In order to examine the process of a rotary engine primary compressor impacted by bird, a finite element model of a bird impacted on plate is developed with the explicit code PAM-CRASH. The smooth particles hydrodynamic （SPH） method is used to simulate the bird because of the SPH method showing no signs of instability and correctly modeling the breaking-up of the bird into particles. Good agreement between the simulation results and experimental results indicates that the numerical method of bird strike used in the present paper is reasonable. Then a rotary engine primary compressor impacted by three different configurations bird named straight-ended cylinder bird, quadrangular bird, hemispherical-ended bird are investigated using the numerical simulation method. It is found that the whole process of bird strike sustained about 3.5 ms and the bird is slashed by blade during the strike. The geometry configuration of bird affected the displacement and von Mises stress of some blades severely, just because the breaking bird＇s mass is affected by the bird＇s configuration. In the event of bird striking on the site of＂up＂some blades may develop plastic deformation and it is very adverse for the safety work of the engine.

DESIGN AND IMPLEMENTATION OF REAL-TIME PHYSICS SIMULATION ENGINE FOR e-ENTERTAINMENT

We present our recent research results regarding the designing and implementation of real-time physics simulation engines,which aim at developing physics-inspired e-entertainment such as computer games,mobile applications,interactive TV and other smart media in Korea.Our real-time physics engine consists of three functional components:rigid body dynamics simulation,deformable body simulation,and data-driven physics simulation.The core simulation techniques to realize these simulation components include real-time collision detection and response,large-scale model simulation,and character model control.In this paper,we highlight these features and demonstrate their performances.We also showcase some of the gaming applications that we have integrated our physics engine into.

A spatially distributed,deterministic approach to modeling Typha domingensis(cattail)in an Everglades wetland

Introduction:The emergent wetland species Typha domingensis(cattail)is a native Florida Everglades monocotyledonous macrophyte.It has become invasive due to anthropogenic disturbances and is out-competing other vegetation in the region,especially in areas historically dominated by Cladium jamaicense(sawgrass).There is a need for a quantitative,deterministic model in order to accurately simulate the regional-scale cattail dynamics in the Everglades.Methods:The Regional Simulation Model(RSM),combined with the Transport and Reaction Simulation Engine(TARSE),was adapted to simulate ecology.This provides a framework for user-defineable equations and relationships and enables multiple theories with different levels of complexity to be tested simultaneously.Five models,or levels,of increasing complexity were used to simulate cattail dynamics across Water Conservation Area 2A(WCA2A),which is located just south of Lake Okeechobee,in Florida,USA.These levels of complexity were formulated to correspond with five hypotheses regarding the growth and spread of cattail.The first level of complexity assumed a logistic growth pattern to test whether cattail growth is density dependent.The second level of complexity built on the first and included a Habitat Suitability Index(HSI)factor influenced by water depth to test whether this might be an important factor for cattail expansion.The third level of complexity built on the second and included an HSI factor influenced by soil phosphorus concentration to test whether this is a contributing factor for cattail expansion.The fourth level of complexity built on the third and included an HSI factor influenced by(a level 1–simulated)sawgrass density to determine whether sawgrass density impacted the rate of cattail expansion.The fifth level of complexity built on the fourth and included a feedback mechanism whereby the cattail densities influenced the sawgrass densities to determine the impact of inter-species interactions on the cattail dynamics.Results:All the simulation results from the different levels of complexity were compared to observed data for the years 1995 and 2003.Their performance was analyzed using a number of different statistics that each represent a different perspective on the ecological dynamics of the system.These statistics include box-plots,abundance-area curves,Moran’s I,and classified difference.The statistics were summarized using the Nash-Sutcliffe coefficient.The results from all of these comparisons indicate that the more complex level 4 and level 5 models were able to simulate the observed data with a reasonable degree of accuracy.Conclusions:A user-defineable,quantitative,deterministic modeling framework was introduced and tested against various hypotheses.It was determined that the more complex models(levels 4 and 5)were able to adequately simulate the observed patterns of cattail densities within the WCA2A region.These models require testing for uncertainty and sensitivity of their various parameters in order to better understand them but could eventually be used to provide insight for management decisions concerning the WCA2A region and the Everglades in general.

Research of Virtual Experiment Based on Flex and XML

In this paper, the design of a virtual experiment system based on Flex and XML is described. The system adopts threelayer architecture and it is composed of four modules. Flex is used to design user interface, and XML is used as data format between layers or modules. Data services are used to store or retrieve the information of experiment components or experiment scenes. Principles for the design of simulation engine and simulation scheduler are discussed. The design of the simulation engine for ＂Digital Logic＂ course is described in detail. The system has been implemented in the experiment teaching of Digital Logic. Teaching results and the feedback from students demonstrate that the virtual experiment system can improve the effects of experiment teaching and arouse the learning interests of students.

Potential of secondary aerosol formation from Chinese gasoline engine exhaust

Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds（VOCs）. However,little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4–5 hr simulation, which was estimated to represent more than 10 days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol（SOA） production was 426 ± 85 mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China.