简介:Generallyspeaking,mainflowpathofgasturbineisassumedtobeperfectforstandard3Dcomputation.Butinrealengine,theturbineannulusgeometryisnotcompletelysmoothforthepresenceoftheshroudandassociatedcavityneartheendwall.Besides,shroudleakageflowisoneofthedominantsourcesofsecondaryflowinturbomachinery,whichnotonlycausesadeteriorationofusefulworkbutalsoapenaltyonturbineefficiency.Ithasbeenfoundthatneglectshroudleakageflowmakesthecomputedvelocityprofilesandlossdistributionsignificantlydifferenttothosemeasured.Evenso,theinfluenceofshroudleakageflowisseldomtakenintoconsiderationduringtheroutineofturbinedesignduetoinsufficientunderstandingofitsimpactonendwallflowsandturbineperformance.Inordertoevaluatetheimpactoftipshroudgeometryonturbineperformance,a3Dcomputationalinvestigationfor1.5-stageturbinewithshroudedbladeswasperformedinthispaper.Thefollowinggeometryparameterswerevariedrespectively:-Inletcavitylengthandexitcavitylength,-Shroudoverhangupstreamoftherotorleadingedgeanddownstreamofthetrailingedge,-Shroudradialtipclearance,Theaimofthispaperistoisolatetheinfluenceofshroudandcavitygeometrymodificationsonturbineaerodynamicperformanceandtoobtaincleartrendsofefficiencychangescausedbydifferenttipshroudgeometry.Moreover,interactionbetweenleakageflowandmainstreamfordifferentshroudconfigurationisalsohighlightedinordertopenetrateintothephysicalmechanismsproducingthem.Duetothelimitationsofthemodelselectedinthispaper,theaimofresearchisnottoputforwardthedesignrulesofturbineshroud.However,theresultsobtainedfromthisworkwillbeusefultotheintegrateddesignandoptimizationofturbinewithshroudedblades.
简介:La1.5Mg17Ni0.5hydrogenstoragematerialswerepreparedbyhydridingcombustionsynthesis(HCS)andmechanicalalloying(MA)methodrespectively.TheexperimentalresultsshowthatthehydrogenabsorptionpropertiesofLa1.5Mg17Nio.5preparedbyMAarebetterthanthatbyHCS.La1.5Mg17Nio.5preparedbyMAcanabsorb6.73mass%hydrogenat523Kwithin1min,and4.92mass%hydrogenat423K.TheimprovementofhydridingpropertiesofLa1.5Mg17Ni0.5alloypreparedbyMAcanbeascribedtotheformationofnano-crystallineanddefectsduringthemechanicalalloying.
简介:摘要目的研究磁共振全景矩阵成像(panoramicmatriximaging)技术全脊柱成像在诊断脊柱及脊髓病变中的临床应用价值。方法采用国产联影uMR650型1.5T超导磁共振成像系统,头颈联合线圈--16和脊柱线圈--24,自动移床及无缝拼接技术,对1200例可疑脊柱及脊髓病变患者行全脊柱扫描。结果所有1200例检查患者中除67例因为病情,年龄等原因出现少量运动伪影,余1133例患者均获得了清晰、直观、完整椎体、椎管、脊髓及周围韧带的连续全脊柱MR图像。1200例患者全脊柱成像显示未见异常患者129例,173例脊柱椎体病变,89例脊髓病变,809例椎间盘韧带病变。结论联影1.5TMR全景矩阵全脊柱成像明显缩短了传统颈、胸、腰椎扫描时间,扫描范围宽,图像质量好,可以直观的全方位的观察脊柱及脊髓多发性、弥漫性病变。
简介:【摘要】目的:探析1.5T核磁共振技术诊断膝关节损伤的效果。方法:随机选取我院2020.01~2020.12内收治的150例膝关节损伤患者为本次研究对象,所有研究对象均采用1.5T核磁共振技术和CT扫描技术进行临床诊断,统计对比两种诊断技术的确诊率。结果:核磁共振技术的诊断准确率显著高于CT扫描技术(χ2=14.685、P<0.05)。结论:在膝关节损伤患者的临床诊断中实施1.5T核磁共振技术进行临床诊断,其诊断确诊率较高,具有较佳精确性,可为患者的临床治疗提供可行性参考。
简介:【摘要】目的:研究女性盆腔肿瘤疾病引进CT联合1.5T磁共振的诊断有效性。方法:时间入选为2021年5月-8月,入选对象为78例患者,这些患者均达到盆腔肿瘤诊断标准,对78例患者均实施CT检查和1.5T磁共振检查,比较两种方式诊断的结果。结果:78例女性患者,45属于良性病变盆腔肿瘤有例(27例子宫肌瘤与18例卵巢囊肿)、33属于恶性病变盆腔肿瘤有例(14例宫颈癌与19例卵巢癌);CT检查中:良性病变盆腔肿瘤33例、恶性病变盆腔肿瘤29例,总62例,占比79.5%;1.5T磁共振检查中:良性病变盆腔肿瘤32例、恶性病变盆腔肿瘤31例,总63例,占比80.8%;CT与1.5T磁共振检查中;良性病变盆腔肿瘤44例、恶性病变盆腔肿瘤30例,总74例,占比95.0%,互相对比之下,CT与1.5T磁共振检查检出率更高,p
简介:摘要:在现代建筑行业中,施工过程成本管控是企业实现利润最大化、提升竞争力的关键环节。以工程造价结算管理为中心,构建一套科学、严谨、高效的施工过程成本管控体系,对于确保项目的经济效益和社会效益具有重要意义。