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Characteristics of the Main Journal Bearings of an engine Based on Non-linear Dynamics

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Chinese Journal of Mechanical engineering 2009年第5期22卷 755-759页

作者： NI Guangjian ZHANG Junhong CHENG Xiaoming State Key Laboratory of engine Tianjin University Tianjin 300072 China Tianjin internal combustion engine Research institute Tianjin 300072 China

Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.

关键词： non-linear dynamics engine main journal bearings

Piston-ring and Cylinder-liner Lubrication in internal combustion engines Based on Thermo-hydrodynamic

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Chinese Journal of Mechanical engineering 2011年第6期24卷 971-975页

作者： ZHANG Junhong GAO Hongge NI Guangjian State Key Laboratory of engine Tianjin UniversityTianjin 300072China Tianjin internal combustion engine Research institute Tianjin 300072China

Currently the extruded effect,roughness to the lubricant shear thinning,temperature changes and other factors or some combination of a single factor mainly considered in the lubrication study of piston *** the study of the energy equation,the oil viscosity-temperature properties,adsorption layer characteristics are usually not *** the theoretical research is different from the actual situation of *** lubrication of piston ring-cylinder liner system in internal combustion(IC) engines is studied here based on the theory of thermal *** unsteady and compressible hydrodynamic lubrication model with an equivalent viscosity based on shear and extruded flow factor is derived by employing the viscosity-temperature relationship,meanwhile,characteristics such as lubricating oil’s density varying with pressure and temperature,thickness of adsorbent layer and oil film’s geometry are also considered in this *** setting up the energy equation,the effect of lubricating oil’s volume expansion and viscous dissipation on temperature,the heat conduction along oil film’s thickness direction are *** difference equation is formed by using a first-order difference scheme in time scale and second-order difference scheme in space scale.A common diesel engine is introduced as an instance to predict the distribution of the minimum oil film thickness in the piston ring-cylinder liner *** results of simulation calculation show that the minimum oil film thickness will decrease especially around the top dead center when the oil’s volume expansion,viscous dissipation and heat conduction are considered,which implies that:it is essential to take the thermal flow idea into account during investigating piston ring-cylinder liner system’s lubrication.A more complete piston ring-cylinder liner lubrication theory was established according to thermal fluids from the perspective of *** is more helpful to guide the practical applicat

关键词： thermal flow piston ring-cylinder liner adsorbent layer viscosity-temperature revision

Fuel design real-time to control HCCI combustion

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Chinese Science Bulletin 2006年第21期51卷 2673-2680页

作者： HOU Yuchun HUANG Zhen LU Xingcai FANG Junhuan ZU Linlin institute of internal combustion engine Shanghai Jiao Tong UniversityShanghai 200030 China

In order to achieve lower emissions and extensive load in the homogeneous charge com- pression ignition (HCCI) engine system, a novel fuel design concept that high-octane number fuel and high-cetane number fuel are mixed real-time to con- trol HCCI combustion is proposed in this study. HCCI combustion fueled with iso-octane/n-heptane mix- tures controlled real-time on a single-cylinder HCCI combustion engine is studied. The test results show that the equivalence ratio of n-heptane in mixtures decides ignition and controls the combustion phase of HCCI combustion. The addition of iso-octane ex- tends knocking limit in equivalence ratio somewhat, but knocking occurrence mainly depends on the total concentration of mixture. Although operating range in equivalence ratio becomes narrow with the increas- ing proportion of iso-octane, the maximum load of HCCI combustion fueled with iso-octane/n-heptane mixtures controlled real-time is increased about 80% more than that of pure n-heptane. When iso-octane/ n-heptane mixtures are controlled in optimized method, it is proved that the load of HCCI combustion can be fully extended and emissions can be de- creased remarkably, while at the same time the higher indicated thermal efficiencies are obtained over the extensive operation range.

关键词： HCCI 燃料设计实时控制正庚烷异辛烷

Simulation of Turbulent combustion Flame Feature Based on Fractal Theory for SI engines

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Transactions of Tianjin University 2010年第4期16卷 256-261页

作者：张军杜青宋东先杨延相 internal combustion engine Research institute Tianjin University State Key Laboratory of engines Tianjin University

The flame structure of gasoline engine is complicated and has the characteristic of fractal geometry. A fractal combustion model was used to simulate the engine working cycle. Based on this model, the fractal dimension and laminar flame surface area of turbulent premixed flames were studied under different working conditions. The experimental system mainly includes an optical engine and a set of photography equipment used to shoot the images of turbulent flame of spark-ignition engine. The difference box-counting method was used to process 2D combustion images. In contrast to the experimental results, the computational results show that the fractal combustion model is an effective method of simulating the engine combustion process. The study provides a better understanding for flame structure and its propagation.

关键词： turbulent combustiom fractal simulation optical engine

Influence of Diesel Nozzle Geometry on Cavitation Using Eulerian Multi-Fluid Method

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Transactions of Tianjin University 2010年第1期16卷 33-39页

作者：张军杜青杨延相 internal combustion engine Research institute Tianjin University State Key Laboratory of engines Tianjin University

Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid *** diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor *** that both of them are fully coupled and interpenetrated, sepa...

关键词： diesel injection cavitation nozzle geometry multi-phase flow numerical simulation

Dynamic Response of Functional Virtual Prototyping of Motorcycle under Combined Excitations

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Transactions of Tianjin University 2013年第4期19卷 279-286页

作者：孙立星舒歌群卫海桥 internal combustion engine Research institute Tianjin University State Key Laboratory of engines Tianjin University

This paper developed 3D product models of motorcycle and engine by UGNX as well as virtual prototyping by ADAMS program with road roughness generated by MATLAB. Under the straight-line running condition, the dynamic responses of motorcycle multibody system to both road and engine excitations were compared with those to only road excitation in terms of vertical acceleration response, amplitude frequency response and power spectral density. The comparisons of simulation data showed that the response due to flat road excitation was around 20 Hz, while that to the combined excitations was in a wide frequency band, of which the major components focused on 10 Hz, 15 Hz, 35 Hz ,70 Hz, 100 Hz and even higher frequencies, reflecting the characteristics of engine excitation based on its unbalanced inertia force and torque. It is concluded that the high fidelity virtual prototyping can simulate the dynamics of motorcycle product well in investigating the vibration and ride comfort performance.

关键词： multibody dynamics engine excitation road excitation motorcycle dynamic response

Experimental Investigation of the Influence of Fuel Viscosity on the Spray Characteristics of Diesel Nozzle

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Journal of Shanghai Jiaotong university(Science) 2007年第1期12卷 61-65页

作者：吕兴才乔信起陈剑黄震 Inst.of internal combustion engine Shanghai Jiaotong Univ.

This paper presented an investigation of atomization characteristics including the velocity vector field and the mean droplet sizes for different percentages of DMM-diesel blended fuels using a phase doppler anemometry (PDA) analyzer system. Based on the fuel design concept, an oxygenated fuel named dimethoxy methane (DMM), which has lower viscosity, surface tension, and boiling point, was used to blend with diesel. The experiments were carried out under atmospheric conditions on a single-hole type diesel nozzle, liquid conditions comprise a temperature of 298 K under the needle valve opening pressure of 6 MPa. The results show that the sauter mean diameter (SMD) and spray cone angle of blended fuels decrease with the increase of DMM content; the axial mean velocity in the centerline increases with the increase of DMM. However, the spray behavior of blended fuel in which DMM exceeds 75% is virtually identical to that of neat DMM. The measurement also reveals the existence of an "S" shape in the radial mean velocity variations with radial distance.

关键词： spray characteristics phase doppler anemometry (PDA) fuel design concept dimethoxy methane(DMM) kinetic viscosity

Test on Evaluation Method for Biodegradability of Lubricants

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Transactions of Tianjin University 2008年第1期14卷 61-65页

作者：杨礼河朱勇范国琛孙玉德解世文 internal combustion engine Research institute Tianjin University School of Chemical engineering and Technology Tianjin University

Using carbon tetrachloride （CCl4） as extraction agent, the activated sludge from Tianjin Jizhuangzi Sewage Treatment Plant as inoculum, the test study on biodegradability of lubricants was carried out. The test flasks containing the mineral medium, the test oil and the inoculum were placed in incubation together with flasks containing poisoned blanks for periods of 0 and 21 days, respectively. Flasks containing the reference materials in place of the test oil were run in parallel. At the end of the incubation period, the contents of the flasks were subjected to sonic vibration, and were acidified and extracted by using CCI4. The extracts were then analysed by infra-red （IR） spectrometer to measure the maximum absorption of the C-H stretch of CH2-CH3 band at wavelength of 2 930 cm^-1. The absorption values were used to calculate the residual oil contents of the poisoned and test flasks. Consequently the biodegradability of the test oil was calculated. The test results indicate that the differences in the biodegradability of test materials in different tests are within 5.5%, and consistent with the data described in Coordinating European Council （CEC） L-33- A-93. The biodegradability of lubricants can be evaluated by this method effectively.

关键词： biodegradability lubricant evaluating test CEC L-33-A-93

Study the ethanol SI/HCCI combustion mode transition by using the fast thermal management system

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Chinese Science Bulletin 2007年第19期52卷 2731-2736页

作者： PENG YaPing TAN ManZhi GUO Liang LIU FaFa LI Hua GUO YingNan Department of internal combustion engine Campus Nanling Jilin University Changchun 130022 China

In this paper the ethanol homogeneous charge compression ignition (HCCI) is achieved in a modified single cylinder engine by means of a self-developed fast thermal management system (FTMS), and the ethanol SI/HCCI operation regions are defined. It can be concluded that the thermal efficiency is higher and the NOx emission is lower in the HCCI operation region. In addition, the maximum NOx emission drops by 98%. The ethanol SI/HCCI combustion mode transition is conducted in different conditions near the SI/HCCI operation boundaries. It is likely to realize the transition by the utilization of FTMS. However, it is impossible to complete the transition within one operating cycle under current operation conditions. There are fluctuations in engine speed and brake mean effective pressure during the transition process. In order to reduce the fluctuations during the transition, the initial work concerning the effects of the spark ignition on the transition smoothness is carried out and the investigation indicates that the engine speed and brake mean effective pressure fluctuations cannot be eradicated only through spark ignition. Therefore, the control strategies combined with other factors should be further optimized.

关键词：电荷压缩点火乙醇燃烧模型火花