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1.
《International Journal of Hydrogen Energy》2019,44(11):5538-5542
The research of hydrogen fuel internal combustion engine (HICE) had great significance facing the challenges of energy and environmental problems. Based on the detailed hydrogen-air reaction mechanism, the pre-mix model of CHEMKIN-Pro software was selected to simplify the detailed mechanism GRI-3.0. The most important elements and reactions was chose to construct framework mechanism firstly based on the sensitivity coefficient for H2O and NO formation, and additional elements and reactions were added to framework mechanism for complementing the oxidation path of N2 and H2. A simplified mechanism including 24-step elementary reaction was obtained and the laminar burning velocity calculated by this simplified mechanism matches well with the detailed mechanism in a wide range. This simplified mechanism was also applied in a CFD model which predicted the cylinder instantaneous pressure and NOx emission accurately within a large range of fuel air equivalent ratio. Showing that this mechanism has good applicability. 相似文献
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茂名石化 30万吨水泥厂共有 10座现浇钢筋混凝土筒壁式结构的水泥库 ,在施工中采用了附着式三角架倒模施工技术 ,利用已浇混凝土支承待浇混凝土自重 ,用对拉螺栓支承施工荷载 ,用附着式三角架固定模板、支撑操作平台 ,模板互相利用倒替上升 ,安全、经济、快速地完成了施工任务。 相似文献
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本提出了以摩擦副的(pυ)应力模型和应力一强度干涉模型为基础,建立轴向柱塞泵缸体一配流盘这对关键摩擦副可靠性设计模型,并以XB40型轴向柱塞泵为实例,作了缸体一配流盘的耐磨可靠性设计。 相似文献
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采用交变磁场测量的圆柱体表面缺陷的ANSYS仿真,以各向同性铝圆柱体为试件,采用柱坐标系及矩形激励线圈,电流流向为圆柱体轴向.将圆柱体体划分后再对各分体局部网格划分.划分较密的缺陷部分向周围划分较疏部分过渡时,采用四面体自由划分衔接.对带有表面周向缺陷的圆柱体网格划分后,产生的单元类型为四面体与六面体的混合.其仿真采用波前求解器.仿真路径为激励线圈沿缺陷长度方向、经过缺陷中心点进行周向移动. 相似文献
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结合万家寨引黄工程实例,详细地介绍了PCCP管道的制作,从沟槽开挖、管道安装、管道回填等方面探讨了PCCP管道的安装,以便使预应力钢筒混凝土管更好地服务于引黄北干线工程建设及国内大型管道引水工程和给排水工程。 相似文献
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Musculoskeletal disorders of the hand are mostly due to repeated or awkward manual tasks in the work environment and are considered a public health issue. To prevent their development, it is necessary to understand and investigate the biomechanical behavior of the musculoskeletal system during the movement. In this study a biomechanical analysis of the upper extremity during a cylinder grasping task is conducted by using a parameterized musculoskeletal model of the hand and forearm. The proposed model is composed of 21 segments, 28 musculotendon units, and 20 joints providing 24 degrees of freedom. Boundary conditions of the model are defined by the three-dimensional coordinates of 43 external markers fixed to bony landmarks of the hand and forearm and tracked with an optoelectronic motion capture system. External marker positions from five healthy participants were used to test the model. A task consisting of closing and opening fingers around a cylinder 25 mm in diameter was investigated. Based on experimental kinematic data, an inverse dynamics process was performed to calculate output data of the model (joint angles, musculotendon unit shortening and lengthening patterns). Finally, based on an optimization procedure, joint loads and musculotendon forces were computed in a forward dynamics simulation. Results of this study assessed reproducibility and consistency of the biomechanical behavior of the musculoskeletal hand system. 相似文献
10.
《Measurement》2016
Analysis of measured in-cylinder pressure data provides various parameters that characterize engine combustion process. Advanced engine control technologies use cylinder pressure based combustion parameters for closed loop control. Four step signal processing (i) absolute pressure correction, (ii) crank angle position referencing, (iii) cycle averaging and (iv) filtering is typically applied to get sufficiently accurate cylinder pressure data for an engine cycle. This paper focuses on cycle averaging and filtering of in-cylinder pressure signal from a conventional compression ignition (CI) engine. Experiments are conducted at different engine load and compression ratios at 1500 rpm. The in-cylinder pressure trace of 2500 consecutive engine cycles is recorded and analyzed. Effect of in-cylinder pressure signal noise and cyclic variation on combustion analysis is investigated. A method based on standard deviation of pressure and pressure rise rate is used to find sufficient minimum number of engine cycles to be recorded for averaging to get reasonably accurate pressure data independent of cyclic variability. 相似文献