恒定微压下微小流量的非定常流测量方法

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1、第45卷第5期机械工程学报VO1．45NO．52009年5月JOURNALOFMECHANICALENGINEERINGMay2009DoI：10．3901／JME．2009．05．204恒定微压下微小流量的非定常流测量方法木魏列江冀宏李少年强彦魏中英2(1．兰州理工大学流体动力与控制学院兰、I,I730050；2．兰州兰飞医疗器械有限公司兰州730070)摘要：为了精确测量微小流道中的微小流量，提出了用非定常流等效定常流进行恒定微压下微小流量测量的新方法，推导出了非定常流等效定常流进行微小流量测量时的水头适用条件。利用流体力学拉格朗曰积分建立非定常流的非线性微分方程，用Matla

2、b软件对非线性微分方程进行了数值解析，得出该测量方法的理论误差，数值结果表明在不考虑测试管段沿程阻力的条件下，被测试件过流面积与测试管断面积比值越小，非定常流与定常流条件下的测量结果差别越小。依据所提出的测量方法建立微小流量非定常流测量装置，实测结果与理论计算结果吻合良好。计算和试验表明：在满足水头适用条件且被测试件过流面积与测试管断面积比值小于3．422％时，非定常流测量方法测试精度可保证在2．27％以内。关键词：微小流量微压非定常流测量方法精度中图分类号：TB937Non—steadyFlowMethodforMeasuringtheMicroFlowatConstantMic

3、ropressureWEILiejiangJIHongLIShaonianQIANGYanWEIZhongying(1．CollegeofFlowPowerandControlEngineering，LanzhouUniversityofTechnology,Lanzhou730050；2．LanzhouLanfeiMedicalInstrumentCo．Ltd．，Lanzhou730070)Abstract：Inordertomeasurethemicroflowinmicrochannelpreciselyandeasily,anewmeasuringmethodbasedon

4、theideaofutilizingnon—steadyflowstatetObeequivalenttosteadyflowstateusedintraditionalmeasurementisproposed．Theapplicableconditionofpressureheadforthenewmeasuringmethodisderived．BasedonLagrangeintegralprincipleinfluiddynamics，amathematicmodelinformofnon—lineardiferentialequationisbuiltandanalyz

5、ednumericallybyusingMATLABsoftware，SOthetheoreticalerroroftheproposedmethodisobtained．Thenumericalresultsrevealthatthediferencebetweenmeasurementresultunderthenon—steadyflowstateandthatunderthesteadyflowstatereduceswiththedecreasingoftheratiooftheareasofthemicrochannelandthetubeinupperstreamwh

6、enthepressurelossinthetubeisomitted．Then，anapparatusformeasuringthemicroflowisestablishedaccordingtotheproposedmethod．Themeasuredresultsfromtheapparatusagreewellwiththetheoreticalcalculationresults．Bothresultsshowthatthemeasuringerorislowerthan2．27％whentheapplicableconditionofpressureheadissat

7、isfiedandtheratioofcrosssectionalareasofthemicrochannelandthetubeinupperstreamissmallerthan3．422％．Keywords：MicroflowMicropressrueNon—steadyflowMeasurementmethodPrecision比如，人工心脏瓣膜的返流量测试lIj要求测量瓣膜0前言关闭、跨瓣压差为10．67~-．16．00kPa时流过瓣膜微小间隙(其过流面积不