CAJ | 학술논문

通过混流式水轮机定常和非定常流动计算,研究混流式水轮机在不同开度下的流动特点,阐述非定常流动分析结果.非定常流动计算结果表明:开度α_(12)时,转轮出口靠近上冠处压力脉动不显著,中间流线和下环处脉动较为强烈;尾水管中涡带主要集中于直锥段,呈螺旋型,在肘管处逐渐变小消失.尾水管内部压力脉动主要集中在直锥段和肘管,频率为低频,是转频的0.233倍;其中直锥段脉动幅值较大,内外两侧压力脉动频率基本一致.开度α_(24)时,转轮出口靠近上冠处没有回流,脉动小,中间流线和下环处压力脉动更为剧烈,脉动频率为转轮频率与叶片数乘积的倍数;尾水管涡带在直锥段水流形成的呈柱状涡,在肘管变成较小的螺旋型涡带,其结果是长的涡带在尾部形成像钻机式的切削作用,对水轮机效率和稳定性产生严重的影响,涡带的长度为研究混流式水轮机尾水管深度和优化设计提供理论依据.
통과혼류식수륜궤정상화비정상류동계산,연구혼류식수륜궤재불동개도하적류동특점,천술비정상류동분석결과.비정상류동계산결과표명:개도α_(12)시,전륜출구고근상관처압력맥동불현저,중간류선화하배처맥동교위강렬;미수관중와대주요집중우직추단,정라선형,재주관처축점변소소실.미수관내부압력맥동주요집중재직추단화주관,빈솔위저빈,시전빈적0.233배;기중직추단맥동폭치교대,내외량측압력맥동빈솔기본일치.개도α_(24)시,전륜출구고근상관처몰유회류,맥동소,중간류선화하배처압력맥동경위극렬,맥동빈솔위전륜빈솔여협편수승적적배수;미수관와대재직추단수류형성적정주상와,재주관변성교소적라선형와대,기결과시장적와대재미부형성상찬궤식적절삭작용,대수륜궤효솔화은정성산생엄중적영향,와대적장도위연구혼류식수륜궤미수관심도화우화설계제공이론의거.
The flow features are presented on different openings in Francis turbine by unsteady numerical simulation.The unsteady flow results are as follows:when the opening is 12 mm,pressure fluctuation at runner outlet near hub is not obvious and pressure fluctuation amplitudes near midstream and shroud are bigger.Helical vortex is situated on conical tube on opening 12 mm.It will disappear at the elbow tube.Pressure fluctuation of low frequency in draft tube is mainly located at conical and elbow tube.The frequency of helical vortex is low and is about 0.233 times that of runner frequency.And pressure fluctuation amplitudes in conical tube is higher.Frequencies of two points on the same measurement section are almost equivalent.But when the opening is 24 mm,there is no back flow region at iunner outlet near hub and pressure fluctuation amplitude is smaller.And the ones near midstream and shroud are greatly higher.The frequency is several times that ofproduct ofrunner frequency and blade number.The columnar vortex formed in conical tube will become small helical vortex in the elbow tube.The result is that the long vortex rope forms the cutting effect like drilling rig on the empennage.It will have serious effect on the tubine efficiency and stability.The length of vortex rope provides the theoretical basis for studying the depth of Francis turbine draft tube and optimization design.