Design and Verification for Dual⁃mode CDFS and High⁃Load Compressor with a Large Flow Regulation Range

This paper presents the design and verification of the dual-mode core driven fan stage(CDFS)and high-load compressor with a large flow regulation range.In view of the characteristics of large flow regulation range of the two modes and high average stage load coefficient,this paper investigates the design technology of the dual-mode high-efficiency compressor with a large flow regulation range and high-load compressor with an average stage load coefficient of 0.504.Building upon this research,the design of the dual-mode CDFS and four-stage compressor is completed,and three-dimensional numerical simulation of the two modes is carried out.Finally,performance experiment is conducted to verify the result of three-dimensional numerical simulation.The experiment results show that the compressor performance is improved for the whole working conditions by using the new design method,which realizes the complete fusion design of the CDFS and high-pressure compressor(HPC).The matching mechanism of stage characteristics of single and double bypass modes and the variation rule of different adjustment angles on performance are studied comprehensively.Furthermore,it effectively reduces the length and weight of compressor,and breaks through the key technologies such as high-load compressor with the average load factor of 0.504.These findings provide valuable data and a methodological foundation for the development of the next generation aeroengine.

苏州生态涵养区农业土壤中农药残留的分布特征及风险评估

为评价苏州生态涵养发展实验区农业土壤中农药的污染状况与潜在风险,运用气相色谱-质谱法(GC-MS)检测了苏州生态涵养区63个位点的农业土壤中46种农药的残留水平,结合非度量多维尺度分析其时空分布特征,并以风险商法评估其生态风险。结果显示:土壤样品中共检出有机氯、有机磷、噻二嗪及拟除虫菊酯4类农药,其平均浓度分别为31.8、56.9、109.8μg·kg-1和71.9μg·kg^(-1)。p′p-DDE检出范围最广(检出率91%~100%),噻嗪酮检出浓度最高(1061.1μg·kg^(-1))。生态风险评估显示,27%的土壤样点存在潜在生态高风险,风险来自p,p′-DDE、噻嗪酮、水胺硫磷、联苯菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯7种农药。

气相色谱-质谱法测定水-沉积物系统中39种农药残留

建立了气相色谱-质谱(GC-MS)同时测定水体和沉积物中39种农药残留的检测方法。水体样品由乙酸乙酯萃取,无水硫酸钠干燥;沉积物样品经乙腈超声提取,采用N-丙基乙二胺(PSA)和石墨化碳黑(GCB)净化,选择离子监测模式(SIM)进行检测,外标法定量。结果表明:39种农药在10~1000μg/L范围内线性关系良好,决定系数(R^(2))均大于0.9950。空白水样在0.25、0.5、5.0μg/L 3个添加水平下的平均回收率在72%~111%之间,相对标准偏差(RSD,n=5)在1.1%~10%之间,检出限(LOD)为0.02~0.06μg/L,定量限(LOQ)为0.04~0.18μg/L;空白沉积物在5.0、20.0、100.0μg/kg 3个添加水平下的回收率在65%~119%之间,RSD(n=5)在2.1%~12%之间,LOD为0.7~1.5μg/kg,LOQ为2.1~4.3μg/kg。该方法灵敏、准确,结果可靠,可满足水体和沉积物中39种目标农药的残留分析要求。

苏州生态涵养区地表水和沉积物中农药污染特征及生态风险评价

于2021年3月(枯水期)和8月(丰水期)分别对苏州生态涵养区29个监测点位进行地表水和沉积物采样,测定了38种不易降解的农药(包括8种有机氯农药、9种有机磷农药、9种拟除虫菊酯农药、11种三嗪类农药和噻嗪酮),分析它们的污染特征和生态风险。结果表明,苏州生态涵养区地表水中只检出1种农药(扑草净),质量浓度为108.7~746.9 ng/L,枯水期平均为194.7 ng/L,丰水期平均为128.2 ng/L,生态风险总体处于中风险水平。沉积物中共检出7种农药(p,p’-滴滴伊、p,p’-滴滴滴、联苯菊酯、氯菊酯、高效氯氟氰菊酯、噻嗪酮、扑草净),总质量浓度为2.27~99.92 ng/g,枯水期平均为19.75 ng/g,丰水期平均为17.65 ng/g,检出率较高的p,p’-滴滴伊、噻嗪酮、联苯菊酯和毒性较强的p,p’-滴滴滴生态风险总体处于低风险水平。

航空发动机压气机旋转不稳定现象研究进展

旋转不稳定现象是航空发动机压气机内一种复杂的流动不稳定现象,常常导致叶尖气动噪声增加或诱发叶片高幅值的流致振动问题。随着压气机气动负荷不断提高和整体叶盘叶片阻尼下降,国内外主要发动机公司在新型发动机研制过程中,都遭遇过旋转不稳定现象诱发的叶片流致振动问题,且预测在未来高性能航空发动机研制过程中必将面临更严峻的挑战。首先,回顾了过去80年压气机流动失稳研究的发展历程;随后,梳理和总结了国内外近30年压气机旋转不稳定现象的研究进展,包括压气机旋转不稳定现象、数值模拟方法、实验测试技术、产生机制、影响因素和控制方法等,旨在扩展压气机旋转不稳定方面的基础理论认知;最后,对压气机旋转不稳定现象进行了思考及未来研究展望。