共查询到19条相似文献,搜索用时 171 毫秒
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为了进一步认识匹配应用迷宫汽封和平衡孔对透平级气动性能的影响,采用商用软件CFX,数值仿真了某汽轮机高压一级半透平、堵住平衡孔的一级半透平内部的三维流场.通过对计算结果的比较分析发现,转子带凸台的高低齿迷宫式汽封,与转子外径相等、同压比的等齿高直通型迷宫汽封相比,泄漏流动的方向折转以及在汽封腔内形成的旋涡显著增多,因此强化了对泄漏流的阻抗及其动能的耗散,提高了汽封的封严性.对于低反动度透平级,气流对动叶栅的直接冲击是级内轴向力产生的主要原因.叶冠的径向高度远小于叶高,但是叶冠产生的轴向力在级轴向力中占有较大比例.平衡孔需要与前后静叶隔板汽封以及动叶前后轴向间隙汽封匹配设计,设计合理,能够消除泄漏流对主流的干扰,降低透平级的流动损失. 相似文献
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针对某600 MW机组高压缸冲动式级的模拟透平级在隔板汽封一定的条件下,通过改变平衡孔的孔径及总面积,对模拟透平级进行数值计算分析,研究平衡孔面积的变化对透平级效率和气动性能的影响,并与试验结果进行了分析比较.结果表明:叶轮上开平衡孔有利于改善级间根部流动,提高了透平级效率;与无平衡孔透平级相比,随着平衡孔面积的增大,级效率逐渐提高;但面积增大至一定值后,级效率变化不明显;在叶轮结构和强度许可的条件下,设计时平衡孔面积可尽量取大一些,以保证设计工况时级间根部保持不吸不漏或少量漏气状态;平衡孔面积较大,也有利于减小隔板漏气量增加对级效率的影响作用;对于反动度较小的冲动级,要获得最佳级间漏气工况(相对漏气量约-1%)是不太可能的. 相似文献
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《动力工程学报》2016,(5):352-359
采用耦合流场计算和共轭传热的方法,研究了超超临界汽轮机合缸轴端(过桥)汽封漏汽量(即轴端漏汽量)对中压第1级动叶及叶轮冷却性能的影响,对无蒸汽冷却、蒸汽冷却和轴端漏汽时中压第1级透平级的冷却性能进行了对比,并分析了3种轴端漏汽量时中压第1级透平级的冷却效果.结果表明:随着轴端漏汽量的增大,中压第1级透平级效率逐渐下降;当轴端漏汽量为9.68kg/s时,相比于无轴端漏汽时透平级效率降低了0.68%;轴端漏汽对中压第1级部件的冷却机理与冷却蒸汽相同,二者冷却效果的不同主要是由于其流量和温度不同;与蒸汽冷却相比,随着轴端漏汽量的增大,冷却蒸汽与轴端漏汽的混合蒸汽对叶根的冷却效果减弱,导致叶根温度整体上升,但温度梯度减小. 相似文献
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在3级空气透平试验台上,开展了变平衡孔面积对透平气动性能影响的试验研究。同时对试验透平级进行数值计算分析,研究了透平级性能随平衡孔面积变化的规律,并与试验结果进行了对比。结果表明:无平衡孔时透平效率最低,平衡孔直径小于25 mm,效率随平衡孔直径的增大而逐渐提高,但之后逐渐降低。计算得到的效率变化规律与试验结果吻合良好,平衡孔与隔板汽封漏气面积比为2~3时,效率最优。 相似文献
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文章通过CFD三维气动模拟,计算了某典型高压级次通流不同隔板汽封间隙、动叶根部齿间隙、轮盘漏汽间隙下,轮盘上进出汽侧的压力分布.比较了各位置漏汽间隙变化对轮盘上压差的影响.结果表明,不同的隔板漏汽,轮盘漏汽面积对轮盘上压差存在较大影响,将导致轮盘上推力产生较大变化.动叶通流根部少量抽吸不仅有利于通流的经济性提升,而且有利于降低轮盘上的推力水平. 相似文献
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为了研究气流在涡轮枞树型叶根间隙内的流动特性,以及校核与优化现有叶根间隙流量计算关联式。以某型地面燃气轮机涡轮一级转子枞树型叶根间隙为对象,对其进行了流量试验与三维数值模拟研究。测量了进出口压比范围为1~2工况下通过叶根间隙的流量值,该流量值对应的流动雷诺数范围为1 700~16 500。并在ANSYS/CFX中对相同模型及进出口边界条件下叶根间隙内的流动进行数值模拟,获得叶根间隙截面流动结构,同时计算了长径比39~118范围内,不同压比工况下通过叶根间隙的流量。研究表明:随着压比增大,流过叶根间隙的流量增大趋势逐渐减小;随着长径比增大,流过叶根间隙流量逐渐减小;文献[10-11]提供的叶根间隙流量计算关联式的计算结果与试验测量值平均误差16.3%;与关联式流量计算值随压比变化趋势不同,试验测量值分布曲线随压比增大无明显转折;两端宽、中间窄的叶根间隙通道结构使得流道内层流与湍流共存,从而造成了上述偏差;针对上述偏差,根据试验与三维数值模拟结果拟合了新的叶根间隙流量计算关联式。 相似文献
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为了完成高速高载荷系列工业汽轮机的低压级扭叶片的设计和应用,以常规驱动汽轮机叶片为原型,对其末三级扭叶片组进行了全三维气动性能分析;利用自适应差分进化算法对末三级叶片的型线和积叠规律进行了优化设计;然后根据常规强度计算结果,选择合适的材料并选择松拉筋配枞树型叶根的结构;最后采用有限元仿真软件对其进行了强度振动和动应力及疲劳分析。结果表明:优化后末三级叶片的气动效率提升约1.61%且强度满足要求;设计末两级动叶片时,优先考虑可靠性,其余级因其强度振动问题相对容易解决,优先考虑气动效率;末级叶片材料可能需要选择钛合金,而枞树型叶根是更可靠的叶根形式;选择抗弯模量大、厚度小的叶型搭配松拉筋有利于增加叶片刚度、减小叶片重量,从而为不调频叶片的设计提供参考。 相似文献
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Numerical Investigations of the Influence of Unsteady Vane Trailing Edge Shock Wave on Film Cooling Effectiveness of Rotor Blade Leading Edge 总被引:1,自引:0,他引:1
Unsteady numerical simulations of a high-load transonic turbine stage have been carried out to study the influences of vane trailing edge outer-extending shockwave on rotor blade leading edge film cooling performance. The turbine stage used in this paper is composed of a vane section and a rotor one which are both near the root section of a transonic high-load turbine stage. The Mach number is 0.94 at vane outlet, and the relative Mach number is above 1.10 at rotor outlet. Various positions and oblique angles of film cooling holes were investigated in this research. Results show that the cooling efficiency on the blade surface of rotor near leading edge is significantly affected by vane trailing edge outer-extending shockwave in some cases. In the cases that film holes are close to leading edge, cooling performance suffers more from the sweeping vane trailing edge outer-extending shockwave. In addition, coolant flow ejected from oblique film holes is harder to separate from the blade surface of rotor, and can cover more blade area even under the effects of sweeping vane trailing edge shockwave. As a result, oblique film holes can provide better film cooling performance than vertical film holes do near the leading edge on turbine blade which is swept by shockwaves. 相似文献
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为量化评估工程应用的气冷低压涡轮带冠转子叶片的叶尖间距大小对涡轮气动性能的影响,综合现有涡轮部件试验能力,以单级轴流低压涡轮性能试验件为基础,通过控制圆度的机加方式磨削转子外环内壁以实现叶尖间距的变化,采用控制冷气流量比的方法,开展5次不同叶尖间距大小的涡轮级性能试验,得到多工况下涡轮效率、换算流量和换算功率等特性参数。采用加载冷气及考虑转子叶冠结构的数值模型进行三维仿真计算,并与试验结果对比分析。研究表明:叶尖间距由0.6 mm增加至3.2 mm,低压涡轮流通能力增大1%,叶冠泄漏量增多3.4%,但做功能力下降2.3%。涡轮效率变化与叶尖间距大小近似呈线性关系,叶尖间距每增加1 mm,效率约降低0.7%,同时,叶尖间距的增加导致了叶冠腔的旋涡结构、气流掺混及主流入侵强度逐渐增大,引起动叶总压损失的增大,叶尖间距增加至3.2 mm导致叶间位置总压损失由0.88增至2.3。 相似文献
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大容量冷凝机组的低压末级叶片的长度代表了汽轮机制造商的设计制造水平和能力,同时效率高、安全性能好、长度更大的叶片符合国家节能降耗的产业发展目标.本文采用平衡态计算模型对汽轮机低压末级叶片蒸汽流动状态进行数值模拟分析,根据不同叶高处极限流、载荷、熵的分布情况分析,表明在末级动叶根部存在去湿和涡流问题、末级静叶顶部存在涡流和摩擦损失.因此在今后的末级叶片优化时必须重点加以改进. 相似文献
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《热科学学报(英文版)》2019,(1)
To investigate the effect of bowed/leaned vane configurations on the aerodynamic performance and aerodynamic excitation in transonic high-pressure turbine, the full three-dimensional viscous unsteady numerical simulation was performed by solving N-S equations based on SAS SST method.The influence of bowed/leaned vanes on turbine efficiency and efficiency fluctuation was investigated. The action of vane modelling to the overall aerodynamic fluctuation level and the amplitude of each vane passing frequency were analyzed. By comparing instantaneous pressure fluctuation contours in the blade passage with space-time maps, the link of the pressure fluctuation on blade surface with flow distortions was achieved, which can reveal the mechanism of the impact of the vane modelling. As the results suggest, the turbine efficiency is promoted with positively leaned and bowed vane modelling, and the fluctuation of stage turbine efficiency is repressed, which contributes to the smooth running of the turbine stage. The blade aerodynamic excitation on the rotor blade is characterized by the motion of vane trailing edge shock system, and the vane configurations can reduce the fluctuation level on the rotor blade surface effectively. For the positively leaned vane configuration, the aerodynamic excitations at the root and tip region are affected by the impact of the amplitude of the first harmonic, whereas they are reduced with the decrease of the amplitude of the second and higher harmonics at midspan. For the positively bowed vane, aerodynamic excitation is repressed by reducing the amplitude of the third harmonic at the root region, and the first harmonic at the tip region, and the amplitude of each harmonic is reduced at the middle region. 相似文献
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Froude scaling is a generally reliable way to design models of floating wind turbines for wave basin testing. However, the resulting rotor thrust of the model is far lower than the Froude-scaled value of a full-size turbine, because the reduction in Reynolds number decreases the lift coefficients and increases the drag coefficients (the Reynolds number scaling effect). A 1/50th scale model wind turbine based on a NREL-5MW reference turbine is examined here. To mitigate the Reynolds number scaling effect in the model, the original aerofoils of the reference turbine (DU series and NACA 64-618) were replaced by an aerofoil at a low Reynolds number (NACA 4412). Such a model with aerofoil-adjusted blades was used in the mathematical optimization of rotor thrust. The design objective was to guarantee that while the rotor thrust of the model equalled the Froude-scaled rotor thrust of the reference, the smallest chord lengths were achieved, considering the weight control in building the model blade. The distribution of chord lengths fitted a fourth-order polynomial curve, and the distribution of twist angles along the blade fitted a second-order polynomial curve. The eight coefficients of the two curves were chosen as optimization variables, and pattern search method was used to solve the optimization model. The model blade was designed at zero pitch angle and further tested in FAST, a fully coupled simulation tool. A model test was conducted using the optimized blade geometry in the State Key Laboratory of Ocean Engineering in Shanghai, China, and the thrusts were compared with the predicted values. 相似文献
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为研究静叶弯、扭、掠联合造型对流场结构的影响,以某高压透平首级叶片为研究对象,借助计算流体力学与正交优化方法,基于动静叶最佳匹配原则(即对于每种静叶构型,动叶都进行了相应的扭转规律变化,使得动静叶气动性能处于最佳匹配状态),研究了静叶不同复合构型方式对流场结构的影响。结果表明:在合理的静叶弯曲规律下,静叶扭转改型对透平性能有较大影响,掠改型对透平性能影响有限;在一定的扭转规律下,对静叶进行掠改型对轮周效率的影响较小,仅后掠改型会提高透平的轮周效率;对弯扭掠静叶匹配扭动叶进行联合优化,得到的最佳透平的轮周效率为87.12%,与原始透平相比,轮周效率提高了2.09%。 相似文献