船用增压器系统模态分析及优化

为提升船用增压器系统的可靠性,以零部件的固有模态属性为基础,利用Abaqus软件对现有某6缸中速柴油机的增压器及相关零部件模型进行仿真模态分析,并通过试验对仿真结果进行校验。结果表明:基于仿真的模态分析满足精度要求,增压器系统一阶模态频率为67.36 Hz,低于设计要求的90 Hz,且转速为1150～1300 r/min时,共振倾向明显。根据仿真模态分析结果提出相应的优化解决方案,通过优化增压器支架结构形式,增加整个增压器及相关零部件的支撑刚度。试验结果表明:增压器系统的一阶模态频率提高到90.8 Hz,避免增压器系统在发动机运行区间内发生共振,提升了柴油机整机的运行可靠性,优化方案满足设计要求。     

基于CFD分析的某轻型卡车发动机舱热保护研究

基于计算流体动力学(computational fluid dynamics, CFD)模拟仿真与热平衡试验,对某轻型卡车的整车温度场进行分析,发现蓄电池、排气歧管与涡轮增压器附近线束的表面温度较高,出现热害现象。根据热害发生位置,对高温部件使用隔热罩削弱热辐射,使蓄电池与线束在热浸状态与发动机最大扭矩(转速为1300 r/min)工况下,温度始终低于其许用最高温度,避免零部件的高温失效甚至自燃;并根据隔热罩厚度与隔热效果的关系,在不影响隔热效果的同时,降低隔热罩厚度,实现轻量化设计。     

复合隔热组合活塞结构设计及优化

提出一种采用空气和隔热衬垫复合隔热的钢顶铝裙活塞,其中活塞顶、隔热衬垫和铝裙通过4个对称螺栓连接.为了解该活塞结构特性,开展组合活塞热边界分析,并进行活塞温度场仿真与试验测试对比,揭示空气隔热腔及隔热衬垫对整体活塞温度场的影响.结果表明:经活塞环槽区输出的热流减小约为20%,后续进行组合活塞机械应力及接触面压对比分析,验证了仿真模型的有效性.在此基础上进一步开展活塞热机应力分析,针对隔热衬垫与活塞顶接触面应力状态较差的部位,通过组合活塞结构匹配优化降低了结构应力幅值、改善了应力分布,其中应力幅值降低约为50%,据此最终完成复合隔热组合活塞设计.     

某柴油机附件支架仿真优化与试验

利用ABAQUS与FEMFAT软件对柴油机附件支架进行结构应力、接触面滑移、结构模态以及高周疲劳分析.根据分析结果,对支架不满足限值项进行优化并再次仿真分析,直到满足设计要求.为验证仿真分析结果,对支架进行了柴油机台架试验,测试支架上各个测点的振动加速度.将支架上各个测点的振动加速度整理为X,Y,Z方向的colormap图进行了分析,试验结果表明,附件支架测试最大加速度为12.45 g低于仿真分析边界载荷15 g;模态一阶频率仿真分析结果为141 Hz,样件试验结果为130 Hz,误差为7.7％,测试结果进一步验证了仿真分析的可靠性.     

基于CAE的某发动机增压器故障分析及优化

某增压直喷发动机在进行发动机台架可靠性试验过程中,涡轮增压器由于中间体和蜗壳连接抱箍松脱造成失效,通过采用CAE仿真分析手段结合试验测试,对涡轮增压器模态和振动分析并进行发动机台架涡轮增压器振动测试,结果表明涡轮增压器中间体抱箍松脱是由于涡轮增压器模态低引起共振造成的。通过对涡轮增压器和排气系统进行优化设计,整改后通过了可靠性试验。     

相继增压柴油机燃气阀性能试验研究

针对某型相继增压柴油设计了一种新型的燃气阀。新型燃气阀采用了挡板蝶阀,密封材料采用石墨材料。在柴油机上新型燃气阀与原用燃气阀进行了性能对比试验,测量和对比了相继增压柴油机在不同负荷,不同增压器数下的油耗、涡轮前温度以及增压器的工作状态的一致性。结果表明,采用所设计的燃气阀后油耗最高降低了2 410mg/(kW·h),涡轮前温度降低10K以上,同时基本增压器和受控增压器的工作状态一致性得到了大幅度的改善,最大的转速差仅为600r/min。验证了新型燃气阀对柴油机性能有明显的改善。     

基于GT-Power的车用柴油机增压器匹配模拟分析

本文对一种现有六缸柴油机进行废气涡轮增压器优化匹配的模拟分析.首先在GT-Power软件中基于基础机发动机模型,建立了增压器模型,并通过仿真结果与试验数据的对比,验证了此模型以及标定方法的可行性.然后通过备选增压器方案给出柴油机性能仿真分析,得出增压器匹配的最佳方案.     

增压器对排气管噪声频率特性的影响

测量了增压和非增压6-135柴油机排气管噪声的特征参数。通过对测试结果进行对比分析,得出了增压器对柴油机排气管噪声频率特性的影响规律,并从气体动力噪声和辐射噪声两方面分析了增压器对噪声频率特性的影响。结果表明:与非增压柴油机相比,增压柴油机排气管噪声的频谱主要由一次谐波和一次谐波的多次分量构成,主频频率等于基频频率。     

基于dSPACE柴油机电子调速系统硬件在环仿真研究

跟据平均值原理建立了增压柴油机进气系统、增压器、扭矩计算、喷油泵、柴油机动力学和排气系统的数学模型,根据所建立的数学模型,应用Tesis DYNAware建立了增压柴油机参数化仿真模型。利用所建立的仿真模型、dSPACE仿真平台、接口设备、真实的柴油机电子调速系统和真实的执行器设计,实现了柴油机电子调速系统硬件在环仿真平台,并进行了起动、调速功能验证,仿真结果与配机实验值的比较,结果表明仿真测试平台精度高、实时性好、测试工况完整、功能完备、通用性强。     

某中速柴油机底座刚度对整机模态影响分析

某型中速柴油机在试车台测试时振动偏大,初步判定系柴油机底座刚度不足引起.对柴油机底座进行改进设计,在此基础上对不同方案的底座进行刚度计算和模态分析,然后对不同底座方案整机进行模态计算,得到底座刚度与整机振动模态间的关系.同时分析了采用不同垫板对整机模态的影响,为柴油机底座的选型设计提供参考.     

Numerical Study on Some Improvements in the Passive Cooling System of a Radio Base Station

Passive cooling schemes, such as natural convection, are the most safe heat dissipation mode of electronic equipment. Some times the highest temperature of the PCB, rather than the highest of chips, is very much a concern due to technological reasons. In order to reduce the maximum PCB temperature, this article discusses various improvement methods via numerical simulation. These include optimization of fin number of heat sink, structure improvement of sun shield, and creation of insulation cavity in the base plate of heat sink. Taking the PCB of an RBS as an example, numerical simulation results show that by integrating these methods the maximum PCB temperature can be appreciably reduced. This article provides an example that by using a careful numerical thermal design, a passive cooling mode can sometimes meet the cooling requirement of a PCB with high power input in some extent.     

The research applications of new heat insulation composite material in automobiles

With the rapid development of its unique advantages, nonwoven fabric has become the leading material of automotive textiles. Nonwoven fabric has become an ideal material for automobiles and replaced traditional textiles and plastic products. This paper takes a car as the research model. A DRL‐2B thermal conductivity tester was used to test thermal conductivity of the material based on the plate method. Material systems and structures of new types of heat insulation composite materials were determined according to test results and the theory of heat transfer. Then, the final new type of heat insulation material was determined by calculating and comparing average heat transfer coefficients and heat transfer between traditional insulation materials and new types of heat insulation materials. The calculated results were verified by experiments in this paper. All the test results show that the new type of composite insulation material is significantly better than traditional insulation materials, and the test results match the calculated results.     

面向对象的柴油机多功能仿真软件开发与应用

提出了一种发动机通用性能仿真软件的开发思路,并基于此完成了软件开发工作。基于C++语言,设计了一种面向对象的通用程序框架,可以实现多种仿真计算功能,包括稳态下的一维详细计算、容积法计算、实时计算及瞬态计算。气缸、进排气道、管接头、涡轮增压器等主要组件包含多种计算模型,可以根据建模需求进行选择。针对某型中速柴油机,详细介绍了软件性能计算的操作流程,并将计算结果与试验数据进行对比。结果表明,软件有较高的计算精度,而且实时计算功能完全能满足实时分析的要求,实时率可以达到3.92。     

柴油机混合涡轮增压系统的研制及试验研究

混合涡轮增压系统是在常规废气涡轮增压器转轴上集成一个既能电动又能发电的高速电机,介绍了研制这一新型增压系统的关键技术和样机在增压器试验台上的试验研究.等压气机流量试验结果显示:混合涡轮增压系统从功能上达到了电动/发电的设计要求,可以根据负荷调整高速电机的工作模式和功率.混合涡轮增压系统在小流量时电动的潜力大,而在大流量时发电功率大.其次,通过调整混合涡轮增压系统的高速电机功率能够拓宽涡轮膨胀比变化范围.另外,由于采用滚动轴承等措施,样机的机械效率高于常规废气涡轮增压器,试验时最高机械效率达到96%.加速特性试验结果表明:混合涡轮增压系统的加速时间比普通废气涡轮增压器缩短40%以上,并且高速电机的电动功率越大,改善涡轮滞后的效果越显著.     

Numerical and experimental investigation on the thermal insulation performance of low temperature cold box

A new modeling method with the discrete ordinate (DO) model and GKT model was proposed to simulate the thermal insulation performance of a low temperature cold box. Experimental data from the thermal insulation experiment of a cold box were used to validate the model. The thermal insulation performance and the coupled radiation and conduction heat transfer were analyzed at various pressures, shield numbers and shield positions. The results confirmed that the thermal insulation performance can be significantly improved by the addition of a thermal insulation shield. It was found that the effects of shield position on the thermal insulation performance are different at lower pressure (<3 × 10^− 2 Pa) from higher pressure. A practical application was presented by the usage of the new model in analyzing the performance of the cold box in a cold neutron source. A composite thermal insulation method was proposed to reduce the cold loss by 18.3% and 9% respectively compared with those with the aluminum foil wrapping and shield insulating methods.     

基于正交试验的低速机增压器涡轮排气壳性能优化研究

为提升船用低速机涡轮增压器性能,对增压器涡轮排气壳底部流道结构进行参数化,设计并开展了以效率为优化目标的四因素三水平正交试验优化设计和增压器整机性能试验。首先,采用CFD数值模拟方法对不同参数组合的涡轮气动性能进行了计算,然后对涡轮排气壳底部流道结构参数开展了灵敏度分析,同时针对不同参数组结构开展了内部流场对比分析,明确结构因素对流动的影响机理;在此基础上对优化后方案开展了涡轮特性分析,最后在低速双燃料机平台上开展增压器整机试验验证。分析研究表明：在涡轮进气壳、喷嘴环和涡轮叶片等通流部件结构不变的前提下,涡轮排气壳排气方向轴向长度对涡轮整级效率的影响最大,优化后效率明显提升,设计点总压损失系数降低0.3874,静压恢复系数提升0.537,总静效率提升1.85%,其余工况总静效率最大提升2.4%。试验结果表明：优化后涡轮增压器整机效率在主机燃油模式和燃气模式下的全工况范围内效率均有提升,最大提升幅度分别达到1.4%和2.1%,涡轮性能和增压器整机性能改善明显。     

Cooling effect analysis on para-ortho hydrogen conversion coupled in vapor-cooled shield

The conversion process from parahydrogen to orthohydrogen accompanies an endothermic effect. Embedment of a para-ortho hydrogen converter into the thermal insulation could enhance the thermal protection of a liquid hydrogen storage tank. A physical model was proposed to simulate the heat transfer behavior of the insulation structure that integrates a polyurethane foam, a blanket of multilayer insulation, a vapor-cooled shield, and a para-ortho hydrogen converter. The effect of the para-ortho conversion process was considered. The model was validated by experimental data and then used to investigate how the para-ortho hydrogen conversion influences the temperature distribution inside the composite insulation. It was found that a single converter improves the cooling performance most effectively if it is placed at the middle length of the venting pipe mounted on the vapor-cooled shield. Either incorporating more converters or extending the length of the vapor-cooled shield pipes brings limited further improvement. The optimum position of the vapor-cooled shield inside the multilayer insulation moves towards the cold boundary in the presence of para-ortho conversion, compared to conventional vapor-cooled shield and multilayer insulation structures. A net heat flux reduction of over 10% could be achieved when the para-ortho conversion is located at the optimal position inside the vapor-cooled shield.     

Insulation System Using High-Temperature Fibrous Insulation Materials

ABSTRACT

In this study, we performed a preliminary research on an insulated sandwich structure using high-temperature fibrous insulation materials. Two types of fibrous materials, Saffil alumina and KCC cerakwool insulation materials, were selected. A sandwich specimen was invented to test the heat-shielding performance of the fibrous materials which were sandwiched by an Inconel plate and a titanium plate. The insulated sandwich structure was heated to 800°C for 2,000 seconds. The temperature profiles of the back side of the titanium plate were measured to compare the heat-shielding performance of the fibrous insulation materials. The microstructure of insulation materials, such as the fiber diameter, fiber orientation, and the parent materials of the fiber, was studied to understand how those characteristics influence the radiative properties of the fiber. The difference in microstructural parameters caused a difference in thermal resistance in the fibrous materials. The Saffil alumina insulation had a better performance than KCC cerakwool insulation because of its small fiber diameter and in-plane fiber orientation. The experimental results confirmed the heat transfer simulation results for fibrous materials done by other researchers. In addition, the reusability of high-temperature fibrous insulation, one of the important issues in real applications, was tested.     

涡轮增压器轴向力分析与止推轴承承载力评估

为研究涡轮增压器止推轴承评估及选用方法,利用数值模拟建立某型号涡轮增压器的有限元模型,使用NUMECA软件对涡轮增压器轴向力进行分析,将轴向力结果输入DyRoBeS,计算止推轴承不同油楔面下的油膜厚度,选择承载能力满足要求的止推轴承,并进行压气机性能试验。结果表明:压比的仿真计算与试验结果基本一致,在低速工况下重合性较好,高速工况下最大误差小于1%;效率的仿真计算结果较试验略低,误差范围为0.5%-2.0%,但仿真与试验的总体趋势一致,在小流量范围内误差更小。该方法能够在增压器初步配试阶段较精确地选择止推轴承,提高整机可靠性。     

高压比增压器转子轴承系统振动性能改进

针对我国铁路运用的大功率交流传动内燃机车研发了一款新型增压器,其压比和流量较现有产品大幅提高;由于压气机叶轮线速度和转子质量提高,现有的叶轮与主轴的连接方式不能满足新研发增压器的要求,研发了一种新型的压气机叶轮与主轴连接方式,并设计了新型轴承。对改进前后的转子轴承系统进行了临界转速、稳定性、瞬态响应和转子轴心轨迹分析,并进行试验测试,验证了新转子轴承系统完全达到要求。目前,改进转子结构后的增压器已经完成了平台型式试验、装车运用考核试验,实现批产。