Numerical investigation of a DI diesel spray flame using a detailed chemical reaction mechanism

Emission standards have grown increasingly stricter, consequently triggering greater interest in issues surrounding environmental pollution. In particular, soot and NOx released from DI diesel vehicles is considered to be the main source of air pollution in urban environments. However, the mechanics of fuel spray formation and the influence of the operating parameters on the resulting spray flame are not yet fully understood. In this study, the original KIVA code was modified to incorporate a detailed chemical reaction mechanism involving various species and multiple reaction steps to better understand the spray characteristics. n-Heptane, C₇H₁₆, was used as the representative fuel for diesel fuel, and the reaction mechanism for this fuel was composed of 66 species and 274 elementary reaction steps. The accuracy of the predicted results was demonstrated primarily by a comparison with experimental results. The numerical prediction of a specific operating condition for the parametric investigation correlates well with the experimental results.     

Roof strength performance improvement enablers

Before 2009, rollover in vehicle accidents had not been significantly studied not only because its rate is lower than other types of accidents but also because it had been easy to meet the rollover regulation, the FMVSS 216 Roof Crush Resistance target. The regulation only requires that the strength-to-weight ratio (SWR) be 1.5, i.e., it was acceptable when the roof could withstand a force of only 1.5 times the vehicle??s weight. In other words, rollover is not considered an important safety factor. However, presently, the situation has completely changed. Rollover is now considered a key safety factor. Recently, the number of rollover incidences has been increasing, reaching as much as the number of front, side and rear accidents. Furthermore, the IIHS has begun to require that the roof must withstand a force of 4.0 times the vehicle??s weight, a more severe restriction than FMVSS. To satisfy this requirement, many manufacturers, universities and institutes are studying the topic. This paper focuses on changing the body structure to minimize injury to the occupant when rollover occurs and help rollover safety performance become excellent. This paper draws on a simple analysis that is based on general factors: changes in the material, the addition of welds and additional reinforcements. The best result will be determined, as described by this paper.     

Computational study on the effects of volume ratio of DOC/DPF and catalyst loading on the PM and NOx emission control for heavy-duty diesel engines

The use of a diesel particulate filter (DPF) in a diesel aftertreatment system has proven to be an effective and efficient method for removing particulate matter (PM) in order to meet more stringent emission regulations without hurting engine performance. One of the favorable PM regeneration technologies is the NO₂-assisted regeneration method due to the capability of continuous regeneration of PM under a much lower temperature than that of thermal regeneration. In the present study, the thermal behavior of the monolith during regeneration and the conversion efficiency of NO₂ from NO with an integrated exhaust system of a diesel oxidation catalyst (DOC) and DPF have been predicted by one-channel numerical simulation. The simulation results of the DOC, DPF, and integrated DOC-DPF models are compared with experimental data to verify the accuracy of the present model for the integrated DOC and DPF modeling. The effects of catalyst loading inside the DOC and the volume ratio between the DOC and DPF on the pressure drop, the conversion efficiency, and the oxidation rate of PM, have been numerically investigated. The results indicate that the case of the volume ratio of ‘DOC/DPF=1.5’ within the same diameter of both monoliths produced close to the maximum conversion efficiency and oxidation rate of PM. Under the engine operating condition of 175 kW at 2200 rpm, 100% load with a displacement of 8.1, approximately 55 g/ft³ of catalyst (Pt) loading inside the DOC with the active Pt surface of 5.3 m²/g_pt was enough to maximize the conversion efficiency and oxidation rate of PM.     

计量模型在“十五”四川省 交通运输量预测中的应用

在阐述科学预测交通运输量的意义的基础上,利用计量经济模型对四川省的“十五”交通运输量进行了预测,并给出了一般性的模型检验流程.     

CONSTRUCTING POLYCOMPETITOR CDNAS FOR QUANTITATIVE PCR

ＣＯＮＳＴＲＵＣＴＩＮＧＰＯＬＹＣＯＭＰＥＴＩＴＯＲＣＤＮＡＳＦＯＲＱＵＡＮＴＩＴＡＴＩＶＥＰＣＲＳ．Ｌ．Ｒｅｉｎｅｒ，Ｚｈｅｎｇ，Ｓｈｉｃｈｕｎ；Ｄ．Ｂ．Ｃｏｒｒｙ，Ｒ．Ｍ．Ｌｏｃｋｓｌｅｙ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｄｉｃｉｎｅａｎｄＭｉｃｒｏ...     

Structural optimization of a circumferential friction disk brake with consideration of thermoelastic instability

This research suggests a new disk brake design using circumferential friction on the disk of a front-wheel-drive passenger car. The paper compares mechanical performance between the conventional and suggested disk brakes under dynamic braking conditions. Thermoelastic instability is considered in simulation of the test condition. An optimization technique using a metamodel is introduced to minimize the weight of the suggested disk brake. To achieve this goal, the response defined in the optimization formulation is expressed in a mathematically explicit form with respect to the design variables by using a kriging surrogate model, resulting in a simple optimization problem. Then, the simulated annealing algorithm is utilized to find the global optimum. The design results obtained by the kriging method are compared with those obtained from ANSYS analysis.     

沥青混凝土罩面对水泥混凝土路面裂缝的影响

耐久裂缝（Ｄ裂缝）是普通水泥混凝土（ＰＣＣ）损坏产生的,而且通常引起的原因是冬季的冻融循环。为了较好地研究Ｄ裂缝,ＰＣＣ配合比应采用良好级配的粗骨料。对ＰＣＣ路面上Ｄ裂缝维修的方法,大多是在ＰＣＣ上用沥青混凝土（ＡＣ）罩面,这样可使路表的使用功能重新恢复。但是有关ＡＣ罩面对开裂路面的长期作用的效果,人们却很少了解。对裂缝影响最主要的气候因素反映在湿度和温度方面。采用计算机模拟的有限差分瞬间流动的温     

轻轨车辆噪声评价标准初探

根据轻轨车辆噪声的现状及特点,本文认为轻轨车辆的噪声仍以A声级评价为宜,但需规定容许的倍频程带声压值,以抑制低频噪声对人体的影响,同时提出了轻轨车辆噪声的控制标准。最后还指出了A声级评价总体的缺陷,建议应以人体工程学为基础,综合考虑噪声对人体的多方面危害,以制定出更完善的轻轨车辆噪声评价标准。     

A Numerical Model Coupling Electromagnetism and Thermomechanics Application to Induction Heating Modeling

Introduction-TheinductionheatingprocessInductionheatingiswide1yusedinindustrialProcessesinvolvingmetallurgyheattreatthentsuchasquenching,hardening,brasing,Preheatinforforgillgoperations,sdsecoatinormeltnginelectromagneticcrucibles[DAV].ThemainadVatapesofinductionheatngProcessesarethefastheatinrate,greatPrecisionintheheatinlocalisation(suPefficialheatngedhighfrequencypowersuPpliesforschcetreatmentProcess),instarestart/top(nowimuPrequlredforeachcycle)andagoodreProducibilityThebasicinducton…     

Numerical Study of the Plastic Behaviour of a Low Alloy Steel during Phase Transformation

IntroductionItiswellknownthaphasetrapsformationsplayanimPortantroleontheresidualstressesandstrainsinducedbythermalprocessessuchasweldingandquenching.lnthispaPer,wefocusourattentiononthebehaviourofsteelsduringphasetransformations.AtheoreticalaPproachhasbeenachievedbyLeblondetal[1]andhasledtOamacroscopicmodelinthecaseofideal-plasticphases[2][3].Thenthemodelhasbeengeneralizedtotakestrainhardeningphenomenaintoaccount[4].ThetheoreticalaPproachhasbeenassessedandcompletedusingflniteelementsimulati…