身管内膛镀铬性能检测研究

目的对内膛表面强化层性能进行定量评估,给后续镀铬层的优化及新型内膛表面强化层技术的优选提供试验方法。方法以成熟度最高、应用最广泛的内膛表面镀铬技术为依据,开展强化层检测研究,主要包括硬度、厚度及微观缺陷、结合性能、抗烧蚀性能、抗磨损性能等研究。量化镀铬层抗烧蚀、抗磨损性能,实现实验室对内膛镀铬层性能的综合评估。结果铬层硬度约为521.8HV,高于基体硬度。铬层裂纹初始宽度约为300 nm,多数裂纹未连接成“网状”。铬层与基体结合力约为67.2 N。相同条件下,相比基体,镀铬层的烧蚀量和磨损量始终较小。结论镀铬层综合性能优于基体材料。     

增压风机入口烟道磨损优化分析

冲刷磨损是目前工业系统运行的主要问题之一。本文通过对电厂增压风机前的一段双入口烟道进行了CFD分析,通过增加导流板来减小系统的压力不平衡性,改善颗粒对烟道的磨损,考察了不同粒径的灰分颗粒对烟道和导流板磨损趋势,为实际工程中的防磨措施制定提供参考。     

某高速船用齿轮箱油泵连接套失效机理研究

目的掌握工作油泵连接套微观运行机理,增加齿轮箱的可靠性。方法从齿轮箱系统角度,对工作油泵连接套的结构进行分析,从齿轮箱动态运行、连接套微观磨损等方面的失效机理进行深入研究。结果通过分析和验证,机带泵端面键的间隙范围在0.05~1.5 mm左右为最佳,长期运行后端面的磨损程度可通过增加端面键硬度和润滑、减少齿轮箱的轴系扰动等措施减缓与控制。由于本齿轮箱的结构特点,端面键的寿命在1.5万小时内。在此基础上,对齿轮箱中连接套与油泵的连接方式进行了优化,在油泵的一端采用渐开线花键连接,可有效减小其磨损程度。结论某高速船用齿轮箱油泵连接套失效是由端面键的间隙、端面键动态运转时蠕动磨损、齿轮箱的轴系扰动等引起的,可通过合理设计端面键的间隙、增加端面键硬度和润滑,减小轴系扰动或优化为渐开线花键等措施预防。     

Ignition advancement study for optimized characteristics of a raw biogas operated spark ignition engine

In the current investigation, raw biogas obtained from rural sectors was used as the alternative to gasoline fuel in the spark ignition (SI) engine. The performance and efficiency are mainly dependent on the combustion phasing for which “ignition timing” is an effective tool in a SI engine. Hence, the objective of the present work is to understand the effect of “variable ignition timing” for a biogas-fueled SI engine. For this purpose, a single cylinder, 4-stroke, SI engine of rated power 4.5 kW was operated with raw biogas at a compression ratio (CR) of 10. By maintaining a speed of 1650 rpm, the engine was operated in wide open (WOT) and part throttle (PT) mode with an equivalence ratio of 0.81 and 0.83, respectively. It was observed that the biogas fueled SI engine was found to be operative only within the ignition advance (IA) range of 33–47° CA bTDC both in WOT and PT conditions. The results showed optimal brake power (BP), brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) are achieved at 45° CA bTDC. The average peak cylinder pressure, neat heat release rate (NHRR) and mean gas temperature (MGT) are also observed to be maximum while CO and HC emission at this point of IA were found to be minimum. Due to controlled and complete combustion, CO₂ and NO_x concentration in the exhaust emission were found to be higher at this point of ignition timing.     

电梯制动器机械装置提起（或释放）验证的研究

为确保电梯制动器检测开关能够准确检测电梯制动器机械装置提起（或释放）的异常,消除异常造成的危险情况,结合电梯制动器的型式和检测开关的动作原理,对各种检测开关接线方式进行分析,针对制动器的型式提出了合理的制动器检测开关接线方式。研究结果表明:直压式制动器可用1个通断状态的检测开关对其机械装置的提起（或释放）进行验证,但应在电梯的主板上设置2个检测点;杠杆式鼓式制动器应用具备2个通断状态的检测开关对其机械装置的提起（或释放）进行验证,且应采用常开并联或常闭串联的方式检测制动器机械装置的释放,采用常闭并联和常开串联的方式检测制动器机械装置的提起。     

发动机非正常磨损的机理探析

阐述了汽车发动机非正常磨损的机理、特征，以及预防非正常磨损的对策。     

Potential of Pteris vittata L. for phytoremediation of sites co-contaminated with cadmium and arsenic： The tolerance and accumulation

Field investigation and greenhouse experiments were conducted to study the tolerance of Pteris vittata L. （Chinese brake） to cadmium （Cd） and its feasibility for remediating sites co-contaminated with Cd and arsenic （As）. The results showed that P. vittata could survive in pot soils spiked with 80 mg/kg of Cd and tolerated as great as 301 mg/kg of total Cd and 26.8 mg/kg of diethyltriaminepenta acetic acid （DTPA）-extractable Cd under field conditions. The highest concentration of Cd in fronds was 186 mg/kg under a total soil concentration of 920 mg As/kg and 98.6 mg Cd/kg in the field, whereas just 2.6 mg/kg under greenhouse conditions. Ecotypes of P. vittata were differentiated in tolerance and accumulation of Cd, and some of them could not only tolerate high concentrations of soil Cd, but also accumulated high concentrations of Cd in their fronds. Arsenic uptake and transportation by P. vittata was not inhibited at lower levels （〈20 mg/kg） of Cd addition. Compared to the treatment without addition of Cd, the frond As concentration was increased by 103.8% at 20 mg Cd/kg, with the highest level of 6434 mg/kg. The results suggested that the Cd-tolerant ecotype of P. vittata extracted effectively As and Cd from the site co-contaminated with Cd and As, and might be used to remediate and revegetate this type of site.     

高耐磨化学复合镀层的研究

为了改善化学镀Ni-P合金镀层的耐磨性能,提高化学镀Ni-P合金镀层的使用寿命,实验中分别在化学镀液中加入了硬质相SiC粒子、Al2O3粒子以及具有自润滑性能的PTFE粒子,使它们与Ni-P合金一起共沉积,从而制备出具有特殊功效的高耐磨复合镀层.实验结果表明:化学镀Ni-P-SiC以及Ni-P-Al2O3复合镀层由于硬质粒子的加入使镀层的耐磨性比Ni-P镀层提高了6倍左右;Ni-P-PTFE复合镀层的摩擦系数可达0.063,远小于Ni-P镀层0.2的摩擦系数,同时耐磨性能也比Ni-P合金镀层有了较为明显的提高.     

基于CFD仿真的炮口制退器性能影响因素研究

目的 在降低火炮后坐力的同时,保证炮手区域超压和温度符合要求。方法 利用流体仿真软件进行炮口流场的数值模拟,对制退器性能影响因素进行仿真分析。根据分析结果,得到改进后的制退器模型,并进行仿真和试验对比。结果 加装侧孔外反射挡板和侧孔倾斜对制退器性能的影响较大,并随角度的变化而变化,加装吹孔能有效降低炮后超压和温度。改进后,制退器的效率提升8.33%,炮后超压值平均降低44.10 kPa,炮后温度值平均降低358.28 K。结论 改进后的制退器具有更高的制退效率以及较低的炮后超压值和温度值。     

模拟界面污染条件下的电接触性能及磨损研究

目的 模拟有机物挥发的气氛环境,研究载荷对界面污染条件下电接触性能的影响.方法 选用铜作为基底,将其置于有机气氛环境中进行贮存.将初始表面与贮存后的表面作为待试验表面,将两者置于大气及有机气氛2种环境中进行电接触试验.通过摩擦系数和接触阻值分析其电接触性能,结合磨痕形貌、截面轮廓及成分,揭示其磨损机理.结果 有机气氛环...