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INTRoDUCTIONThestructuralfailureofturbotalsbytorsionalvibrationisoneofthemostimPortantproblemsthect-ingthesafetyoftheturbomachineryoperation-Inthepasttime,researchesonthecauseofthetorsionalvibrationofturboaxishavebeenfocusedonelectricalandmechanicalfields(D.Lambrecht,1982.H.DikenandI.G.Tadjbakhsh,1989.IEEEWorkingGroupInterimReport,l982).Butasafluidmachinerystea-mturbinemayexperienceintensetorsionalvibrationin-ducedbyfluid.Thisphenomenonissimilartotheflutterinsofarasbothoftheminvolve… 相似文献
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Tadeusz Opara 《热科学学报(英文版)》1997,6(4):298-306
INTRODUCTIONMeasurementofthedropletdiameteroffuelaerosolisverydifficult,becauseofthefastchangeofitssize,whichiscausedbyevaporationandassociation.Itisalsoverydifficulttogetaknowledgeofaerosolstreamsinthecourseofconstructionofnewtypeoffuelburn-ersanddiagnosticprocessaswell.Diffractionmethodisoneofthemostusefulmea-suringproceduresinthiscase.Thedropletsizeofmonodispersivemediumiseasytorecognise.Analy-sisofadiffeactionpatternofpolydispersivemediumisconsiderablymoredifficult.Thisworkpresentsam… 相似文献
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D84710 扩充地热规划( Geothermal ProjectOutreach, Laurie Maclenahan and Curtis Williams, GRC Bulletin, Vol. 34. No. 1. Jan./Feb.2005,23-26 );D84711 50年地热生涯谈勘探(A Strange Brecd of Cat, Carl F. Austin, GRC Bulletin, Vol.34 ,No. 1 ,Jan./Feb. 2005,27-29 );D84712 示踪剂试验分析的系统方法(A Systematic Method An Alternative Tracer Test Analysis Using Beowawe Data, G. Michael Shook,GRC Bulletion, Vol. 34. No. 1. Jan./Feb. 2005,31-35 );D84713可再生能源能帮助重建天然气市场平衡吗?( Can Renewable Energy Help? Restoring Equilibrium to Natural Gas Markets, Ryan Wiser and Mark Bolinger, GRC Bulletin, Vol. 34.No. 1 Jan./Feb. 2005,37-39 );D84714 注入低温流体诱发的热弹性提高与破碎渗透性的效果及其实验室验证(Thermoelastically-induced Fracture Permeability Enhance-ment Associated With Cold Fluid Injection andits Laboratory Verification, 伊藤高敏、渡边恒、Daniel Swenson、林一夫,日本地热学会蒜。Vol.27.No.2(2005),101—113);…… 相似文献
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本实验对微尺度燃烧器内部使用电热丝向反应物加热,提高其温度,减少散热影响,从而实现微尺度火焰稳燃.燃烧器为石英直圆管,长82.mm,通流面积3.33.mm2.氢气/空气混合气体流量为0.12.L/min、0.2.L/min、0.4.L/min,电热功率分别为0.W、1.05.W4、.70.W.实验结果显示,提高电热功率抑制熄火;提升燃料混合气体总流量也有助于抑制熄火;但高流量同时带来吹脱问题.测量燃烧器壁面温度,结合数值模拟研究内部燃烧过程.结果显示,随电热功率上升,反应温度和OH质量分数上升,证明电加热强化反应,抑制了热熄火.比较壁面散热,电热功率0.W,流量由0.12.L/min上升到0.2.L/min时,壁面散热占总能量份额由84.8%降低至81.1%.因此,在一定范围内提升燃料流量亦可抑制热熄火. 相似文献
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《锅炉技术》2014,(6)
正1.参考文献按正文部分标注的序号依次列出,并在序号中加[]。2.对于常见的各类参考文献标注方法如下:1)著作:作者姓名,题名[M].出版地:出版者,出版年.2)期刊论文:作者姓名.题名[J].期刊名称,年,卷(期):页码.3)会议论文集:作者姓名.题名[C]//论文集名称,会议地点,会议日期.4)学位论文:作者姓名.题名[D].出版地:出版者,出版年.5)专利文献:专利申请者或所有者姓名.专利题名.专利国别.专利号[P].公告日期或公开日期.获取路径.6)电子文献:作者姓名.题名[文献类型标志(含文献载体标志)见其它].出版地:出版者,出版年(更新或修改日期),获取路径.7)报告:作者姓名.题名[R].出版地:出版者,出版年. 相似文献
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INTRoDUCTI0NThetipleakaeflowisnowrecognizedasanimpor-tantsourceoflossesinbothcompressorsandturbines,asasourceofcoolingprobleminturbinesandasourceofinstabilityincomPressorsandfans.Manyturbo-maChinimPellersarenotshroudedandtheleakaeflowthroughthetipgaPofthebladeisanunavoidablefaCtorwhichdeterioratestheperformance.Den-tonandCumpsty[1]melltionedabouttwodistinctandequallyimportantaspects.tothetipclearanceflows.First,thereisareducti0ninthebladeforce,there-fore,theworkdone.Thisoccursbecausethe… 相似文献
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INTRoDUCTIoNRecentlysignificantattentionhasbeengiventothefinestructurewithintheflowfieldofturbomachinery.Ingeneral,thestudyofthisproblemcontainstwoas-pects.Thefirstistovisualizethesolidsurfaceflowandtopologicallyanalyzethesingularpointstoinves-tigatetheirnumbers,typesandlocationsandtheskinfrictionlinepatternsintheflowfie1dnearesttothewall.Thisaspectaimsatobtainingacertainamountofwallflowinformation.Thesecondaspect,ontheotherhand,carriesoutdetailedflowfieldmeasure-mentsandvisualizationstoac… 相似文献
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Determination of Effective Thermal Conductivity ForReal Porous Media Using Fractal Theory 总被引:1,自引:0,他引:1
INTRODUCTIONPorousmediaisacompositemediathatincludessolidframeandfluidandexistedwidelyintheeajrthbiosphere.Heatandmasstransferinporousmediaisbothanaturalphenomenoninearthbiosphereandaphysicalchemistryprocessinindustries,agricultureandhumanlife.Thusthestudyonheatandmasstransferinporousmediahasbecomeanimportanttasktoscielltistsandengineers.Heatandmasstransferinporousmediaisaverycomplexobject.Therearestillmanydifficultiestodescribethecoupledheatandmasstransferphenomena.Amongthesedifficultie… 相似文献
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为获得全气膜气冷涡轮叶栅的损失特性,采用试验及数值仿真方法,研究了不同冷气流量、不同叶栅出口马赫数条件下冷气射流对叶栅损失的影响。通过叶栅槽道静压云图及叶片表面压力分布等试验及数值仿真结果对比,验证了通冷气叶栅性能仿真分析方法的准确性。结果表明:同一冷气流量比下,通冷气叶栅能量损失系数随着马赫数的增大先减小后增大,在设计马赫数附近损失最低;通冷气叶栅能量损失系数随着冷气流量的增大而增大,且前后腔均通冷气时能量损失系数最大,前腔单独通冷气时能量损失系数最小;通冷气叶栅能量损失系数随着冷气与主流温比增大而增大。 相似文献
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Based on the method to change blade loading type along blade height, that is, applying aft-loading at both end zones of cascade while applying fore-loading in the mid zone of cascade, HTC (Harbin Turbine Company) de- signed a twisted and bowed stationary cascade with low aspect ratio and large enthalpy drop. To verify the aero- dynamic performance of such cascade, firstly, low-speed wind tunnel tests were conducted to validate the calcula- tion results of commercial software CFX, and then numerical simulations were made for the aerodynamic per- formance of the cascade at different Mach numbers. The simulation results show that the large enthalpy drop sta- tionary cascade designed by HTC can offer good aerodynamic performance while keeping its high-load charac- teristics in the change range of outlet Mach number as stated in this paper. 相似文献
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To explore the effects of airfoil-probe tubes and its installment position on the flow field of the compressor cascade,and find out the mechanism that how the airfoil-probes affect the aerodynamic characteristics of the compressor cascade,this paper performed both numerical and experimental works on the same compressor cascade.The experiment mainly focused on the cases of low Mach number (Ma =0.1),and cases with different Mach numbers (0.1,0.3,0.7) and different incidence angles (-5,0,5) are investigated by the numerical method.The case without the airfoil-probe tube was referenced as the baseline,and other three cases with the airfoil-probe tubes installed in different chordwis positions (30%,50%,70% of the chord length) were studied.The diameter of the airfoil-probe tube is 3ram,which is configured as 300% amplification of some particular airfoil-probe according to the geometrical similarity principle.The results show that the airfoil-probe tubes have a negative influence on the flow capacity of the cascade at all investigation points.The separations and the large scale streamwise vortices that induced by the airfoil-probe tube on the pressure side cause most the losses at the high Mach number.The influence of the airfoil-probe tube on the flow field in the vicinity of the pressure side surface is local separation at the low Mach number.The airfoil-probe tubes also have a clearly effect on the leakage flow.It decreases the mass flow of the leakage flow and weakens the intensity of the leakage vortex,but enlarges the influence area.The total pressure loss of the case that the tube is installed at the half chordwise position is generally lower than other cases especially at the high Mach number,it can even decrease the losses compared with the basic case. 相似文献
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圆柱型两孔探针通过旋转使用可获得三维流场特征,其本质与四孔针原理相同。本文系统地阐述了圆柱型两孔针的工作原理,重点进行了数据处理方法的研究,提出了二阶拉格朗日插值马赫数迭代方法,并对高斯最小二乘拟合方法进行了优化处理。比较两种处理方法,两者都可以直接求解不同马赫数条件下的三维流场特征参数,高斯最小二乘拟合法可以给出数据处理方法的精度,对准确描述整个测试系统误差具有重要的意义,而二阶拉格朗日插值马赫数迭代方法更适用于两孔针校准特性。 相似文献
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Sheng ZHOU Hongbin WU Xinqian ZHENG National Key Laboratory of Aircraft Engine Beijing University of Aeronautics Astronautics Beijing P.R. China 《热科学学报(英文版)》2004,13(3):207-212
Numerical simulations are carried out for unsteady flow field of certain kind of 3D compressor cascade. Emphasis is laid on vortex shedding and frequency analysis in a compressor cascade. Numerical simulations using unsteady Reynolds-averaged viscous turbulent equations are carried out. The results show that the flows in separated areas and wake areas are characterized as periodic or quasi-periodic vortex shedding and the frequencies of vortex shedding vary with incidences and Mach number. At the same Mach number, the frequency of vortex shedding will decrease as the incidence increases. Yet, the frequency will increase as the Mach number increases at the same incidence. In the same computation case, the frequency of vortex shedding will vary along the span of blade. The frequency is smaller at the middle of the span than that at the hub. 相似文献
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基于定常RANS方程,采用Spalart-Allmaras(S-A)湍流模型,数值模拟某跨音速导叶尾缘劈缝射流的定常流动结构,分析尾缘劈缝射流对尾缘激波结构、尾迹流动特性及叶栅气动性能的影响。研究表明:开缝射流显著降低尾缘压力面侧燕尾波强度,并使激波在相邻叶片吸力面入射点向上游移动;当叶栅出口马赫数小于1.35时射流使吸力面燕尾波强度减弱,而达到1.35后射流使该侧激波强度增大;在不同出口马赫数下射流均能降低叶栅动能损失。 相似文献
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通过数值求解基于雷诺时均的三维定常粘性N-S方程,结合RNGk-ε湍流模型和非平衡壁面函数,对一种超微型向心涡轮动叶栅内的流动情况进行了数值模拟。揭示了具有极低展弦比动叶栅叶顶间隙对流场参数分布和气动损失的影响,为超微涡轮的设计和改进提供了理论依据。模拟结果表明,叶顶间隙的大小对通道内马赫数分布有重要影响,其中顶部间隙射流所引发的泄漏涡与主流的掺混是主流马赫数降低的重要原因;叶顶间隙的存在使得总压损失系数均匀化,即近壁区和主流区的总压损失都较高;动叶栅在叶展方向上的载荷分布均匀,弦向载荷主要由接近尾缘的弧段承担;模拟中还解析出三维的尾迹涡,这主要是动叶栅尾缘过厚所导致,应进行叶型改进。 相似文献
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The supersonic multi-hole probe is an essential test tool for wind tunnel experiments, which is necessary to develop the basic research of improving the measurement accuracy and expanding the application of the probes. 相似文献