双测试区GTEM室设计

吉赫兹横电波室(GTEM室)是一种重要的电磁兼容试验设备,与传统的开阔场及微波暗室相比,GTEM室具有场强大、能量利用率高等优点。本文设计了一个用于电磁辐射敏感度测试的GTEM室,有主、副两个测试区域,其工作频率为DC-4GHz,可产生超过400V/m的场强。     

舰载机发动机腐蚀敏感性试验

为验证某航空涡扇发动机抗腐蚀能力,基于腐蚀敏感性试车台,设计了盐雾发生系统,制定了试验方案,完成了航空涡扇发动机腐蚀敏感性试验。结果表明,试验系统设计合理,试验方法可行,可为其他发动机开展腐蚀敏感性试验提供借鉴。试验后发动机主要零部件和成附件未发现明显腐蚀痕迹,主要流道件表面有不同程度的盐雾结晶附着。试验后发动机在相同换算推力下换算排气温度上升约 5.5%,性能衰减幅度较大,建议其他发动机开展腐 蚀敏感性试验时进行流道清洗以恢复发动机性能。     

Hot Tearing Behavior of Mg-Gd-Y-X Alloys

Mg-Gd-Y-Zr alloy castings are widely used in the aerospace field owing to their high strength and excellent creep resistance. The castability of these alloys is also an important consideration for engineering application. Thus， the hot tearing susceptibilities (HTSs) of Mg-10Gd-1Y-1Zn-0.5Zr (VW91) alloy and Mg-10Gd-2Y-1Zn-0.5Zr (VW92) alloy are investigated with a constrained rod casting (CRC) mold. The microstructures and fracture surface are characterized by optical microscope and scanning electron microscope. The results unveil that the HTS of VW92 alloy is lower than that of VW91 alloy. The microstructures indicate that obvious tears can be observed in VW91 alloy， while the tears in VW92 alloy are tiny. The tear feeding and healing by eutectic are also observed in VW91 and VW92 alloys. Therefore， the lower hot tearing susceptibility of VW92 alloy is mainly attributed to the high amount of eutectic which feeds and heals tears. Besides， the effects of the coefficient of thermal expansion (CTE) and the fluidity of VW91 and VW92 alloys on their HTSs are discussed.