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Ling L.,Tianjin Internal Combustion Engine Research Institute | Wang C.-Y.,China Automotive Technology and Research Center | Gao J.-H.,China Automotive Technology and Research Center
Neiranji Gongcheng/Chinese Internal Combustion Engine Engineering | Year: 2014

A China-Vdiesel engine was tested in the CVS bench according to ESC and ETC to measure its load characteristics and full load speed characteristics fueled with State III, IV and V diesel oil respectively. Results show that on the full load speed characteristics, max. power of State V is less than other fuels. With fuel quality drop, NOx and PM emissions under ESC and ETC increase. Through extracting and chemical analysis for PM emissioms in the ESC and ETC, it is concluded that the latter PAHs value is 2~3 times for the former and the PAHs emissions of State III diesel is far more than state IV and V diesels in any conditions. ©, 2014, Chinese Society for Internal Combustion Engines. All right reserved. Source

Sun C.,Tianjin University | Du Q.,Tianjin University | Yin Y.,Tianjin University | Jia B.,Tianjin Internal Combustion Engine Research Institute
Advanced Materials Research | Year: 2013

The performance of proton exchange membrane fuel cell is greatly influenced by the presence, distribution and transport of liquid water in the gas diffusion layer (GDL). In this study, air-water flow in a 3D GDL microstructure along the in-plane direction is studied numerically by using the volume of fluid (VOF) method. The GDL microstructure is considered initially filled with water, air flows into the structure under the driving force of a set pressure drop and the flow is supported by the capillary pressure due to the hydrophobic nature of the GDL structure. It is found that water removal can be accelerated by improving pressure drop. Pressure drop has little influence on the state-steady water volume fraction when the pressure drop is over a critical value. © (2013) Trans Tech Publications, Switzerland. Source

Bai F.,Tianjin University | Bai F.,Tianjin Internal Combustion Engine Research Institute | Diao H.,Tianjin University | Zhang M.,Xian Aerospace Propulsion Institute | And 3 more authors.
Fluid Dynamics Research | Year: 2014

The breakup characteristics of the shear-thinning power-law liquid sheets formed by two impinging jets have been investigated with the shadowgraph technique. This paper focuses on the effects of spray parameters (jet velocity), physical parameters (viscosity) and geometry parameters (impinging angle and nozzle cross-sectional shape) on the breakup behaviors of liquid sheets. The breakup mode, sheet length and expansion angle of the sheet are extracted from the spray images obtained by a high speed camera. Impinging angle and Weber number play the similar roles in promoting the breakup of liquid sheets. With the increase of jet velocity, five different breakup modes are observed and the expansion angle increases consistently after the closed-rim mode while the sheet length first increases and then decreases. But there exists a concave consisting of a fierce drop and a second rising process on the sheet length curve for the fluid with smaller viscosity. Different nozzle cross-sectional shapes emphasize significant effects on the sheet length and expansion angle of liquid sheets. At a fixed Weber number, the liquid sheet with greater viscosity has a greater sheet length and a smaller expansion angle due to the damping effect of viscosity. © 2014 The Japan Society of Fluid Mechanics and IOP Publishing Ltd. Source

Zhang J.,Tianjin University | Gao H.,Tianjin University | Gao H.,Tianjin Internal Combustion Engine Research Institute | Ni G.,Tianjin University
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2011

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 ring-cylinder. In the study of the energy equation, the oil viscosity-temperature properties, adsorption layer characteristics are usually not considered. So the theoretical research is different from the actual situation of engineering. The lubrication of piston ring-cylinder liner system in internal combustion (IC) engines is studied here based on the theory of thermal flow. An 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 model. While 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 considered. Finite 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 system. The 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 research. It is more helpful to guide the practical application of engineering to improve the accuracy of forecasting the minimum film thickness. On the other hand, distribution of the minimum oil film thickness shows a nonlinear property if the thickness of piston rings and cylinder liner adsorbent layer are involved in the analysis. It may be feasible to increase the minimum oil film thickness by varying surface roughness and material properties of piston rings and cylinder liner. © 2011 Chinese Journal of Mechanical Engineering. Source

Sun Y.,Tianjin Internal Combustion Engine Research Institute | Sun Y.,Tianjin University | Lu H.,Tianjin University | Yang W.,Shijiazhuang Bearing Equipment Company Ltd | Li G.,Shijiazhuang Bearing Equipment Company Ltd
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2011

TI worm gearing consists of involute helical gear and its enveloping hourglass worm. According to the previous research result of the parameter choice method of the worm gearing design, the design parameters for TI worm gearing are given. By utilizing a grinding wheel dresser and a special grinding head, the grinding process for TI worm tooth surface is realized on gear-hobbing machine. The hardened TI worm gearbox reducer is made with steel wheel teeth. Experimental research for testing transmission performance is carried out with two kinds of industrial lubricating oil. The input and output torques, box oil temperature, driving time and box vibration are measured. The worm transmission efficiency and its effect factors are analyzed. Test results show that the TI worm gearing reducer with hardened teeth has good transmission performance while the load is in low condition, the tooth friction wear becomes severe and transmission stability declines with the increase of load, and the lubricating oil with extreme pressure additive has good lubricating effect on the hardened TI worm gearing. © 2011 Journal of Mechanical Engineering. Source

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