2015全球民用航空维修市场预览

<正>各种预测显示2015年全球航空维修市场十分可观,预计市值将达到563亿美元,尽管各地区的维修需求有所不同,但整体上呈现出十大发展趋势。在具体业务方面,主要亮点包括"客舱改装开始由宽体飞机的头等舱和商务舱转向窄体飞机的经济舱"、"新一代宽体飞机进入维修期"、"北美地区的宽体飞机重维修业务开始重回故里"、"CFM56和V2500发动机的维修需求将持续增长",以及"燃油成本下降和新机型不断投入运营带来的航电设备市场变化"等。     

Grinding temperature and energy ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different vegetable oils as base oil

Vegetable oil can be used as a base oil in minimal quantity of lubrication(MQL). This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force,and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grinding temperature, and energy ratio coefficient of MQL grinding were compared among the seven vegetable oil types. Results revealed that(1) castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient;(2) palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient;(3) MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil;(4) viscosity significantly influences grinding force and grinding temperature to a greater extent than fatty acid varieties and contents in vegetable oils;(5) although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less viscous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature;(6) saturated fatty acid is a more efficient lubricant than unsaturated fatty acid; and(7) a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force,87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7% energy ratio coefficient.     

维修业各方积极推动数字化维修记录的发展

目前,全球约90%的民航飞机维修记录均采用纸质文档,但由于纸质文档具有易丢失、难保存、无法检索等弊端,导致飞机维修履历的管理难度增大,而数字化维修记录则可有效解决这一问题。目前,维修业从传统纸质文档到电子文档的变革仍处于早期发展阶段,面临着数据标准化、数据存储与访问、信息安全等多方面问题。     

山特维克可乐满CoroPak08.2新品亮相CIMES 2008

山特维克可乐满是山特维克集团旗下最大的金属切削刀具公司,是全球金属切削行业的领导品牌。作为全球排名第一的金属切削业刀具制造和供应商,山特维克可乐满始终致力于提升制造业的综合实力,并为客户不断提供创新的高效率金属切削刀具和解决方案。金秋9月新鲜     

An equivalent ground thermal test method for single-phase fluid loop space radiator

Thermal vacuum test is widely used for the ground validation of spacecraft thermal control system. However, the conduction and convection can be simulated in normal ground pressure environment completely. By the employment of pumped fluid loops’ thermal control technology on spacecraft, conduction and convection become the main heat transfer behavior between radiator and inside cabin. As long as the heat transfer behavior between radiator and outer space can be equivalently simulated in normal pressure, the thermal vacuum test can be substituted by the normal ground pressure thermal test. In this paper, an equivalent normal pressure thermal test method for the spacecraft single-phase fluid loop radiator is proposed. The heat radiation between radiator and outer space has been equivalently simulated by combination of a group of refrigerators and thermal electrical cooler(TEC) array. By adjusting the heat rejection of each device, the relationship between heat flux and surface temperature of the radiator can be maintained. To verify this method,a validating system has been built up and the experiments have been carried out. The results indicate that the proposed equivalent ground thermal test method can simulate the heat rejection performance of radiator correctly and the temperature error between in-orbit theory value and experiment result of the radiator is less than 0.5 C, except for the equipment startup period. This provides a potential method for the thermal test of space systems especially for extra-large spacecraft which employs single-phase fluid loop radiator as thermal control approach.     

含激波的湍流流动高精度大涡数值模拟方法

针对采用亚格子模型进行含激波的湍流流动模拟时会面临激波附近的精度损失问题,考虑从通过亚格子模型以及数值模拟方法两方面的改进来实现湍流流动大涡模拟的精度提高.大涡模拟采用了Yee及Sj(o)green (2009)提出的高阶低耗散方法.该方法采用自适应的流场探测器以控制计算中所需区域的数值耗散,并考虑对动力学模型采用在激波位置使用Sagaut和Germano(2005)提出的单边亚格子过滤器和(或)直接禁用亚格子项等方法加以改进.对于标准的马赫数1.5和3条件下的激波-湍流干扰问题,上述新方法相较于全区域采用亚格子模型的方法均表现出了相似的精度提升.同时实现的数值精度改进方案采用了Harten的亚单元分辨过程来定位和锐化激波,并在精确激波位置附近的网格点处采用了单边测试滤波.     

STUDY ON THE SOLUTION OF DYNAMIC THERMOELASTICITY SYSTEM

ＳＴＵＤＹＯＮＴＨＥＳＯＬＵＴＩＯＮＯＦＤＹＮＡＭＩＣＴＨＥＲＭＯＥＬＡＳＴＩＣＩＴＹＳＹＳＴＥＭＧｅｎｇＺｈｅｎｗｅｎ（ＢａｓｉｃＤｅｐａｒｔｍｅｎｔ，ＺｈｏｎｇｚｈｏｕＵｎｉｖｅｒｓｉｔｙ５２Ｈａｎｇｈａｉｚｈｏｎｇｌｕ，Ｚｈｅｎｇｚｈｏｕ４５０...     

A PARALLEL IMAGINARY EBE METHOD FOR SOLVING POSITIVE DEFINITE LINEAR SYSTEMS

ＡＰＡＲＡＬＬＥＬＩＭＡＧＩＮＡＲＹＥＢＥＭＥＴＨＯＤＦＯＲＳＯＬＶＩＮＧＰＯＳＩＴＩＶＥＤＥＦＩＮＩＴＥＬＩＮＥＡＲＳＹＳＴＥＭＳＰａｎＸｉａｏｓｕ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＰｈｙｓｉｃｓａｎｄＭｅｃｈａｎｉｓ...     

ELECTRONIC CONTROL OF TURBINE POWER UNITS

ＥＬＥＣＴＲＯＮＩＣＣＯＮＴＲＯＬＯＦＴＵＲＢＩＮＥＰＯＷＥＲＵＮＩＴＳ￥ＷａｎｇＤａｏｂｏ（ＤｅｐａｒｔｍｅｎｔｏｆＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ，ＮＵＡＡ２９ＹｕｄａｏＳｔｒｅｅｔ，Ｎａｎｊｉｎｇ２１００１６，Ｐ．Ｒ．Ｃｈｉｎａ）Ａｂｓ...     

DATA PROCESSING ON LINEARIZATION OF HOT-WIRE ANEMOMETER

ＤＡＴＡＰＲＯＣＥＳＳＩＮＧＯＮＬＩＮＥＡＲＩＺＡＴＩＯＮＯＦＨＯＴ－ＷＩＲＥＡＮＥＭＯＭＥＴＥＲ￥ＬｉＳｕｆｅｎ（ＤｅｐａｒｔｍｅｎｔｏｆＰｏｗｅｒＥｎｇｉｎｅｅｒｉｎｇ，ＮＵＡＡ２９ＹｕｄａｏＳｔｒｅｅｔ，Ｎａｎｊｉｎｇ２１００１６，Ｐ．Ｒ．Ｃｈ...