基于ANSYS的某型四缸内燃机曲轴模态分析

曲轴是内燃机的重要零部件,它对内燃机的动态特性影响很大。本文用ANSYS软件对曲轴进行自由模态分析,求出了曲轴在的前10阶模态的固有频率和振型。首先对曲轴进行简化,利用Pro/E建立曲轴的三维模型;然后导入ANSYS中进行有限元网格划分;最后对曲轴进行自由模态分析,得出曲轴的固有频率和振型,为发动机曲轴的优化设计和动力学分析提供了有价值的理论依据。     

基于Ansys的6110柴油机曲轴有限元分析

对6110柴油机整体曲轴运用Pro/e建立了符合实际情况的三维模型,导入Ansys对其进行了有限元分析,分析了整体曲轴的受力,并且对曲轴单拐有限元模型的应力状态进行了研究.最后对整体曲轴进行了自由模态分析,为曲轴的优化设计提供一定的参考依据.     

曲轴断裂失效影响因素与影响机制研究

以生命期的视角,对断裂曲轴进行研究,发现了曲轴生命期中设计、制造、使用三个阶段和材料对曲轴断裂的相关影响因素,并试图建立曲轴断裂影响因素全集,对三个阶段和材料对曲轴断裂的主要影响因素和影响机制进行了分析,为改善曲轴生命期质量提出了建议。     

1P68F曲轴强度有限元分析

本文利用UGNX2.0软件对通用小型汽油机1P68F曲轴进行了精确建模,采用大型通用有限元软件ANSYS对曲轴在最大受拉、受压两个工况下进行了强度分析,研究了曲轴的变形和应力状态,校核了其强度,同时对曲轴的疲劳强度进行了分析,为指导曲轴设计提供了有力的依据.     

基于动力学仿真和有限元分析的曲轴疲劳寿命计算

在对某型六缸汽车发动机曲轴系动态仿真和对曲轴进行静态有限元分析基础上对曲轴的疲劳寿命进行了计算。首先对曲轴系进行动态仿真，得到曲轴连杆颈处的载荷和载荷谱，载荷作为曲轴有限元分析的力边界条件，而栽荷谱经过简化，得到计算曲轴疲劳寿命的载荷谱，同时利用弹簧单元对主轴颈处的弹性支撑实际状况进行了模拟，也考虑了相邻拐的影响，然后在有限元分析的基础上分别利用S—N和局部应变法计算了曲轴的疲劳寿命，得到的结果说明传统的计算过于保守，这不但对曲轴的设计和优化有一定的意义;也说明再制造发动机时直接利用曲轴其寿命是可靠的，足以维持下一个生命周期。     

12V190天然气发动机的曲轴强度有限元分析

使用有限元分析软件对12V190天然气发动机的曲轴进行强度分析,校核了该曲轴的强度,同时对曲轴的疲劳安全系数进行了分析,为以后曲轴设计提供有力的依据。     

7FDL-16型柴油机曲轴的修复

对7FDL 16型柴油机曲轴的受力情况及常见故障进行了分析,重点对曲轴裂断原因进行分析,同时提出了曲轴的修复方法。     

柴油机曲轴静动特性的三维有限元分析

采用有限单元法，对4190柴油机曲轴进行了符合实际情况的三维建模，研究了整体曲轴的变形和应力状态，校核了曲轴在交变载荷下的疲劳强度，探讨了目前曲轴应力有限元计算中广泛采用的单拐力学模型的可靠性，并对曲轴进行了模态分析，为柴油机改进设计提供了有价值的理论依据。     

计及曲轴强度的曲轴轴承优化设计

以某4冲程4缸内燃机曲轴一轴承系统为研究对象,在计及曲轴强度下进行曲轴轴承优化设计,研究轴承优化设计中考虑曲轴强度的必要性.在建立轴承优化设计模型中,将曲轴强度作为约束条件之一,采用粒子群算法进行优化计算.结果表明,相比于原机轴承设计,在满足曲轴强度要求的情况下,通过曲轴轴承优化设计轴承总平均摩擦功耗降低了14.21%.同时进行了不考虑对曲轴影响的曲轴轴承优化设计计算,此时虽然轴承总平均摩擦功耗有明显降低,但曲轴强度已不能满足使用要求.因此,合理的曲轴轴承优化设计应从曲轴-轴承系统整体出发,计及对曲轴强度的影响,以获得满足系统要求的最优解.     

基于ABAQUS的发动机曲轴模态试验分析

以柴油机发动机曲轴为研究对象,运用CATIA建立发动机曲轴三维几何模型,并运用ABAQUS有限元分析软件对发动机曲轴进行了自由模态分析。再对曲轴的细节特征和约束进行了简化,求出了曲轴自由约束条件下前七阶模态的固有频率和振型。运用实验对比分析方法,通过模态实验可获得曲轴各阶的模态频率和振型,为动力分析提供技术参数,同时也为进一步发动机高速运转时曲轴振动中危险各区域提供了理论依据。     

A maximum torque per ampere control strategy for induction motordrives

In this paper, a new control strategy is proposed which is simple in structure and has the straightforward goal of minimizing the stator current amplitude for a given load torque. It is shown that the resulting induction motor efficiency is reasonably close to optimal and that the approach is insensitive to variations in rotor resistance. Although the torque response is not as fast as in field-oriented (FO) control strategies, the response is reasonably fast. In fact, if the mechanical time constant is large relative to the rotor time constant, which is frequently the case, the sacrifice in dynamic performance is insignificant relative to FO strategies     

脱硫系统对锅炉内爆影响的模拟试验研究

模拟带有脱硫系统电站锅炉的烟风系统,建立了燃气试验炉。试验从4个典型工况来进行,模拟研究脱硫系统对锅炉内爆的影响规律。试验结果表明:快速切断燃料后,炉膛而非引风机入口产生内爆的可能性最大,加装脱硫系统后,使得这一可能性更大;主燃料跳闸后,切断一次风,进气量减少,加大炉膛产生内爆的几率,加装脱硫系统后内爆的几率更大;延时断燃料,炉膛产生的最大负压减少,增设脱硫系统后,必须用更长的时间断燃料才能降低内爆产生的可能性;低负荷下熄火,炉膛产生内爆的可能性降低,增设脱硫系统使得低负荷下内爆可能性增大。     

NUMERICAL SOLUTION OF NAVIER-STOKES EQUATIONS WITH NONSTAGGERED GRIDS USING FINITE ANALYTIC METHOD

A new method referred to here as the momentum weighted interpolation method (MWIM) is introduced to solve the incompressible Navier-Stokes equations with nonstaggered grids. This new method is compared to other methods that employ nonstaggered and staggered grids, in terms of computational effort, number of iterations, and accuracy. It is found that MWIM with nonstaggered grids is as accurate as the staggered grid methods, is easier to implement, and is computationally more efficient. The finite analytic method is used to discretize the governing equations of the fluid flow.     

控旋风次序对角动量流率的影响

针对目前大型切向燃烧锅炉反切中存在的一些问题，在四角燃烧受控涡量燃烧模式的基础上，用数值模拟的方法对之进行了研究，探讨了一些基本规律。重点研讨了利用不同层二次风控旋时，角动量流率的变化规律。认为因气流贴壁的影响，不同层二次风控旋的效果是不同的，起旋风的大小及合理配置对维持气流旋转方向极其重要。图8表2参3     

催化肋片对微燃烧室内燃烧特性的影响

针对带有催化肋片的微燃烧室内部的氢氧预混合燃烧过程,利用CFD计算软件建立数值模型,在实验验证的基础上进行了模拟计算。结果表明:不同流速下,燃烧室内布置催化肋片能提高燃烧室外壁面平均温度以及燃烧效率。在低流速时催化肋片布置越靠近入口,表面催化反应对气相反应的抑制程度越大;肋片位置越靠近出口,燃烧室外壁面平均温度越高。在高流速下,催化肋片位置越靠近出口,表面催化反应对气相反应的促进作用越明显,使得燃烧室外壁面温度分布越均匀、燃烧室出口截面温度越高。     

一种柴油机排气微粒喷油助燃再生装置设计与试验研究

设计了一种柴油机排气加热装置.该装置的创新点在于从柴油机涡轮增压器取出新鲜二次空气供给燃烧器燃烧,加热排气.以BJ493ZQ3增压发动机为试验用发动机,将该装置加装在柴油机排气管尾端,应用于微粒捕集器喷油助燃再生中,对该装置应用的可行性进行了论证,对其加热能力进行了试验研究.试验表明,该排气加热装置能在发动机较大工况范围内快速加热排气到500℃以上,有效燃烧微粒使捕集器可靠再生,同时易于车载,较好解决了微粒捕集器热再生存在的问题.     

Uncertainty analysis and robust control of fuel delivery systems considering nitrogen crossover phenomenon

In this paper, the fuel delivery subsystem (FDS) with hydrogen recirculation and anode bleeding is applied in proton exchange membrane fuel cell (PEMFC) system, which is utilized to supply hydrogen to the anode of stack and recirculate fuel back to the supply line. As the diffusion of nitrogen from cathode to anode is inevitable in a real PEMFC during long-term operation. To prevent system performance decline due to nitrogen accumulation. Therefore, this paper firstly develops a control-oriented nonlinear dynamic FDS model involving gas diffusion. Additionally, the FDS is very sensitive to operating environment, uncontrolled operation conditions may cause stack degradation. Specifically, a method based on Monte Carlo simulation is proposed to identify the key parameter boundaries. Then the gas distribution in FDS due to nitrogen crossover is analyzed in detail. After this, a hybrid robust methodology based on sliding mode algorithm is also proposed to maintain adequate hydrogen pressure supply, suitable hydrogen and nitrogen content in the system in presence of nitrogen crossover and renewed uncertainties. Finally, the performance of the presented controller is compared with nonlinear PID (NPID) control and nonlinear multi-input-multi-output (NMIMO) control through a hardware-in-the-loop test bench. Experimental results show that the hybrid controller is accurate and suitable for control purpose, the nitrogen content is restricted to the given range and the variation of output voltage is limited to the desired boundaries, the feasibility and effectiveness are validated.     

Daylighting performance of optical rods

A novel tubular daylighting device, the light rod, is shown to have high transmittance throughout the day in Singapore. Constructed of an optical quality polymer and clad by air, the light rod is intended for use in buildings where fabric constraints prevent the use of larger daylighting devices. Maximum measured output is around 360 lm per rod and peak output is expected to be around 400 lm. Bending of light rods by up to 90° to accommodate corners is found to reduce output by less than 20% and modification of light emission is straightforward and aesthetically pleasing. An equation is used to describe light rod transmittance and used to predict performance at high aspect ratios, which is found to far exceed transmittance by light pipes of similar aspect ratio. Light rods of small diameter are expected to transmit light effectively at lengths greater than 4 m. The compact size of the light rods is expected to allow installation in locations previously without access to natural light.     

THE TRANSMISSION PROBLEM FOR THERMOELASTIC BEAMS

We study the transmission problem for a partially thermoelastic beam, that is, a beam that is composed of two components. One of them is thermoelastic and the other is not sensitive to the difference of temperature; the thermoelastic part of the beam is small. Our objective is to show that thermoelastic dissipation over part of the material, no matter how small this part, is sufficient to stabilize, in time, the whole beam.     

A coupling study of ignition position on fuel-air mixing and diffusion of a linear hydrogen engine

Linear hydrogen engine (LHE) is a new technology of hydrogen energy utilization due to its flexible compression ratio coupling with ignition, fuel-air mixing, and combustion to optimize thermal efficiency. Fuel-air mixing in LHE is expected to be promoted by using ignition, which differs with conventional engine. This paper develops a full-cycle model which couples with dynamics, hydrogen-air mixing and combustion to describe the effect of ignition position, meanwhile a loop iterative calculation method is proposed to solve the coupling model for hydrogen-air mixing predication. The results show that ignition position variation can cause the piston trajectory to change significantly, and the higher equivalent speed is obtained in the medium ignition position. Besides, the higher equivalent speed in the injection stage is conducive to the diffusion of hydrogen, but the higher equivalent speed is not conducive to diffusion and mixing in the diffusion stage. More importantly, the equivalence ratio distribution at the ignition position is more uniform for the later ignition position due to the longer mixing stroke, and the mixture uniformity index at the ignition position is inversely proportional to the advance of the ignition position. Therefore, the late ignition is recommended to obtain a uniform hydrogen mixture.