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41.
基于光滑粒子流体动力学方法,构建齿轮泵壳体及内部流体的粒子模型,对内啮合齿轮泵在不同工况下的流量特性进行数值模拟。首先设置了均匀分布的油泵出入口压强,计算得到的流量结果与试验结果吻合,且在中低转速下流量与转速呈线性关系;针对高转速下油泵流量降低的问题,通过适当减小周期模型内部的流体粒子数反映流量降低,获得了与试验值相吻合的连续转速流量的模拟结果;针对影响齿轮泵性能的间隙和空化现象,结合模型特点给出了相应的近似处理方法。通过以上研究,将SPH方法成功地应用于滑油泵问题的分析计算。 相似文献
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43.
Construction of a Chemical Kinetic Model of Five-Component Gasoline Surrogates under Lean Conditions
The requirements for improving the efficiency of internal combustion engines and reducing emissions have promoted the development of new combustion technologies under extreme operating conditions (e.g., lean combustion), and the ignition and combustion characteristics of fuels are increasingly becoming important. A chemical kinetic reduced mechanism consisting of 115 species and 414 elementary reactions is developed for the prediction of ignition and combustion behaviors of gasoline surrogate fuels composed of five components, namely, isooctane, n-heptane, toluene, diisobutylene, and cyclohexane (CHX). The CHX sub-mechanism is obtained by simplifying the JetSurF2.0 mechanism using direct relationship graph error propagating, rate of production analysis, and temperature sensitivity analysis and CHX is mainly consumed through ring-opening reactions, continuous dehydrogenation, and oxygenation reactions. In addition, kinetic parameter corrections were made for key reactions R14 and R391 based on the accuracy of the ignition delay time and laminar flame velocity predictions. Under a wide range of conditions, the mechanism’s ignition delay time, laminar flame speed, and the experimental and calculated results of multi-component gasoline surrogate fuel and real gasoline are compared. The proposed mechanism can accurately reproduce the combustion and oxidation of each component of the gasoline-surrogate fuel mixture and real gasoline. 相似文献
44.
In this paper, the aeroelastic analyses of a rectangular cantilever plate of varying aspect ratio is presented. The classical plate theory has been selected as the structural model. The main point that distinguishes this study from previously reported research is employing Peters’ theory to model aerodynamic effect which is not straightforward. The Peters’ aerodynamic model was originally developed to provide lift and moment, which is only applicable to the structural model based on the beam theories. In this study, using the basic concept of the Peters’ aerodynamic model in addition to utilizing the Fourier series, the pressure distribution is derived, which makes Peters’ model applicable to structural models based on plate theory. This combination provides a much simpler state–space aeroelastic model for plates in comparison to the prevalent panel methods, which could lead to a significant reduction in computational time. In addition, the aeroelastic response of the plate with respect to changes in the structural model from the beam theory to the plate theory is evaluated. By using data from an experiment carried out at Duke University, the theoretical results are evaluated. Furthermore, the differences in structural models obtained from the plate and beam theories can be divided into two distinct parts, which are responsible for differences in bending and torsional behaviors of the structure, separately. This approach enables us to measure the effects of differences of each behavior separately, which could provide with a new insight into the problem. It has been determined that the flutter speeds obtained from the beam and plate aeroelastic models are little affected by the difference in bending behavior, but rather is mainly caused by the difference in torsional frequencies. 相似文献
45.
Laminar flame speed (LFS) is one of the most important physicochemical properties of a combustible mixture. At normal and elevated temperatures and pressures, LFS can be measured using propagating spherical flames in a closed chamber. LFS is also used in certain turbulent premixed flame modelling for combustion in spark ignition engines. Inside the closed chamber or engine, transient pressure rise occurs during the premixed flame propagation. The effects of pressure rise rate (PRR) on LFS are examined numerically in this study. One-dimensional simulations are conducted for spherical flame propagation in a closed chamber. Detailed chemistry and transport are considered. Different values of PRR at the same temperature and pressure are achieved through changing the spherical chamber size. It is found that the effect of PRR on LFS is negligible under the normal and engine-relevant conditions considered in this study. This observation is then explained through the comparison between the unsteady and convection terms in the energy equation for a premixed flame. 相似文献
46.
47.
应用高速逆流色谱法对同分异构体的分离纯化进行研究。实验结果表明,以正己烷-乙酸乙酯-水(体积比为1∶10∶10)为两相溶剂系统,上相为固定相,下相为流动相,进行二次高速逆流色谱分离,可从茶多酚中分离出g级的儿茶素同分异构体——(-)-表没食子儿茶素没食子酸酯(EGCG)和(-)-没食子儿茶素没食子酸酯(GCG),其高效液相色谱纯度均在98%以上。选择四氯化碳-氯仿-甲醇-水(体积比为7∶3∶7∶3)为溶剂系统,下相为固定相,上相为流动相,经一次高速逆流色谱即可将药物中间体溴代苯胺同分异构体进行有效的分离。 相似文献
48.
制备型高速逆流色谱分离纯化香菇多糖 总被引:2,自引:0,他引:2
利用高速逆流色谱仪,研究了双水相系统对香菇多糖的分离.溶剂系统为w(PEG1000):w(K2HPO4):w(KH2PO4):w(H2O)=0.5:1.25:1.25:7.0,在转速为500 r/min,流速为1.5 mL/min的条件下,成功分离了香菇多糖粗品(700 mg),得到LenⅠ(95 mg)、LenⅡ(45 mg)两个组分.用Sephadex G-100凝胶色谱柱检测纯度,结果显示:LenⅡ为单一峰,凝胶渗透色谱法测定; LenⅡ分子量为293 kDa;经酸水解后液相色谱分析表明,其单糖组成为葡萄糖和甘露糖,摩尔比为2.7:1; 红外光谱显示其具有多糖类的特征吸收峰. 相似文献
49.
高速逆流色谱分离金果榄中巴马亭 总被引:6,自引:0,他引:6
用高速逆流色谱分离金果榄中巴马亭,以氯仿∶甲醇∶0.2mol·L-1盐酸(2∶1∶1)溶剂体系,上相为固定相,下相为移动相,流速2ml·min-1,仪器转速800r·min-1,进样量100mg,2h后分离出了16.8mg巴马亭(组分Ⅱ),并经HPLC测定,组分纯度>99.6%,并由UV、IR、MS和1H NMR确定结构。 相似文献
50.
TiB2增强Al2O3陶瓷刀具高速干切削摩擦磨损性能 总被引:6,自引:2,他引:6
采用TiB2增强Al2O3陶瓷刀具对淬硬钢进行高速干切削试验,利用切削高温作用下的摩擦化学反应,在刀具表面原位生成具有润滑作用的反应膜,从而实现Al2O3/TiB2陶瓷刀具的自润滑.结果表明:低速干切削时,Al2O3/TiB2陶瓷刀具的磨损机制主要表现为粘着磨损和磨料磨损;而在高速干切削时,刀具的磨损机制主要表现为氧化磨损,刀具表面经由氧化反应生成具有润滑作用的反应膜而起到固体润滑作用,从而使刀具的耐磨性能提高,随着TiB2含量和切削速度的增加,反应膜的减摩抗磨作用增强;而在切削区通入氮气时,由于刀具表面氧化膜形成受阻,刀具的抗磨能力有所降低. 相似文献