共查询到20条相似文献,搜索用时 125 毫秒
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论述了325MW空冷汽轮机低压第6级(末级)动叶片结构新颖的Z型拉筋凸台及凸台拉筋孔的加工工艺。文章从分析该叶片汽道内、背弧面上的拉筋凸台及拉筋孔的结构人手,结合东汽实际情况,分别对叶片内、背弧拉筋凸台的型线、凸台端面以及拉筋孔的加工进行了分析,提出了切实可行的加工工艺方案。 相似文献
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对某超临界500MW汽轮机低压末级960mm叶片在工作转速及超速转速下的离心应力进行三维有限元分析,计算考虑了叶片大变形时几何非线性的影响。结果表明:该叶片有着较高的离心应力水平;围带自锁状态下内弧表面的最大离心应力发生在外拉筋孔截面的拉筋孔靠进汽侧处;拉筋孔特别是外拉筋孔处的离心应力对围带的状态较为敏感。 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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针对应用三维有限元法计算大型汽轮发电机组转子-末级叶片耦合系统扭转振动时存在自由度多和难以实现等问题,在模态综合法(CMS)的基础上,推导了计算转子-末级叶片耦合系统振动的分层二重CMS法的基本方程,给出了降阶的思路和原理.采用该方法对某1 000 MW汽轮发电机组的转子、末级和次末级叶片组成的耦合系统进行了扭转振动特性计算和分析,与不考虑末级、次末级叶片实际结构影响的固有振动特性进行了对比.结果表明:如果不考虑末级叶片的实际结构,会漏掉一些重要的振动模态,给转子和叶片的安全带来隐患;降阶前系统的自由度达到1.5亿,而降阶后系统的广义自由度仅为原自由度的0.07%;分层二重CMS法可用于大功率机组转子、末级、次末级耦合系统的扭转振动分析. 相似文献
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据《Электрические станции》2006年7月号报道,ВТИ(全俄热工研究所)制定了在不用拆卸转子叶片,其中包括不用打开汽轮机组汽缸盖(通过冷凝器),利用电火花熔合的方法强化并修复汽轮机末级工作叶片的工艺过程,允许在转子不同位置的叶片上形成涂层。 相似文献
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一、引言 30万千瓦汽轮机转子使用两根整锻转子,即高中转子和低压转子,高中压转子工作温度高达508℃,而且高压部分和中压部分合并为一个转子。为保证轴系合适的临界转速,转子的长度就受到限制,所以高中压转子的强度校核是个重要问题;低压转子需承受1米长叶片等的巨大离心力,末级叶轮的强度校核亦成为更突出的问题。在设计转子过程中除了采用常规的二次计算法和轴身加载法来计算转子的应力外,还运用有限元方法来计算高中压转子的稳定温度场、热应力及离心应力和低压转子的离心应力。 相似文献
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提出用围带或凸肩接触面上的法向作用力来表征叶片相邻围带或凸肩的接触关系,并通过迭代计算接触法向力从0转变为正的临界转速值(即接触转速).迭代计算中,接触面上的法向作用力由三维接触有限元分析获得,并取上一次有限元分析结果作为本次有限元分析的初始值来提高收敛速度.应用该方法对工作转速为3000r/min的某200MW汽轮机组末级叶片相邻围带、凸肩的接触转速进行了计算.结果表明:迭代7次后接触转速的计算误差小于11.7r/min;该叶片围带、凸肩接触法向力随转速的加快而增大,且在工作转速下达到最大值. 相似文献
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Kaiqiang Jin Qiangling Duan Jiayan Chen K.M. Liew Liang Gong Jinhua Sun 《International Journal of Hydrogen Energy》2017,42(21):14809-14820
Hydrogen, which is considered to be a promising clean energy source, has been studied and applied extensively in industries. In order to improve the safety of hydrogen energy application, an experimental study on the influence of multi-layer wire mesh on dynamics of premixed hydrogen-air flame propagation in a closed duct is conducted. Four different kinds of wire mesh with 40, 45, and 50 layers are chosen in the experiments. High speed schlieren photography is applied to capture the flame shape changes and determine the flame tip speed. Pressure transducer is used to measure the pressure transient. It is found that flame quenches in the cases of adding wire mesh of 60, 80, and 100 mesh with 45 and 50 layers, while for the wire mesh of 40 mesh, 50 layers cannot even quench the flame. Moreover, the multi-layer wire mesh can effectively suppress the flame tip speed, maximum pressure, and sound waves during premixed hydrogen-air flame propagation in the duct. The attenuated maximum pressure reaches approximately 78.6% in the case of adding wire mesh of 100 mesh-50 layers. 相似文献
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Ishant Jain 《亚洲传热研究》2017,46(2):111-133
The strength in a high carbon wire is attributed to the pearlitic microstructure, which is required for ease of wire drawing. During cold drawing of high carbon steel wires, residual stress develops which has to be relieved in order to obtain the desired mechanical properties. To achieve this, the wire is passed through a closed loop online an induction furnace at a particular speed in order to heat it to a uniform temperature range. This research work presents the electromagnetic‐thermal modeling of the induction heating of a moving wire based on the finite element method using the software package, COMSOL MultiphysicsTM. The furnace had a complicated geometry for the coils and this is, perhaps, for the first time an exhaustive study which is being reported. A unique grid generation technique was developed considering the skin effect. This work is aimed at enabling modeling of the process and will in turn be useful when defining individual parameters affecting the temperature distribution in a component, subjected to induction heating. The temperature distribution in the work piece depends primarily on parameters like coil position, line speed, frequency of the current, thermal and magnetic properties of the work piece, and so on. The impact of power supply frequency and line speed were studied during the heating of the moving wire (workpiece). An in‐situ customized furnace of lower capacity was developed to carry out the validation experiments. The present modeling results are validated with online plant trial data and found to be in good agreement. Finally, the desired mechanical property achieved during trials was confirmed through tensile testing. 相似文献
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This article presents the use of a wire mesh in optimising the performance of two volumetric solar receivers that use oil as a heat transfer fluid. Computational fluid dynamics models have been used to optimise the receivers. Varied parameters (including the use of a wire mesh) of the receiver models were changed in the optimisation process. Based on the models, prototype receivers were developed and tested. After that, the models were validated against experiments and the results compare well. The results indicate that the use of a wire mesh placed inside a receiver improves its performance. An optimal wire mesh porosity was found as ≈0.95 mainly because the efficiency is increased without inducing an adverse pressure drop inside the receiver. 相似文献
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M.A. Akhavan-Behabadi M.R. Salimpour V.A. Pazouki 《International Communications in Heat and Mass Transfer》2008
An experimental study was performed to investigate the increment of the pressure drop during condensation of R-134 a vapor inside a horizontal tube with different coiled wire inserts. A double-pipe counter-flow heat exchanger of 1040-mm length was used as the test condenser while, the refrigerant flowed inside the inner tube and the coolant flowed in the annulus. Four coiled wires of 10.0-mm pitch and different diameters of 0.5, 0.7, 1.0 and 1.5-mm and also four springs of 1.0-mm diameter and different pitches of 5, 8, 10 and 13-mm were inserted on the refrigerant side of the test condenser. Data were recorded for different mass flow rates in plain tube and each coiled wire inserted tube. Investigating the results for the coiled wire inserted tubes revealed that inserting the springs increased the pressure drop in a range of 260 to 1600% in comparison with that for a plain tube. Also, influence of coiled wire geometry on the pressure drop was investigated. Based on the collected data, an empirical correlation was developed to predict the pressure drop during the condensation inside a horizontal tube in the presence of a spring insert. Finally, the performance evaluation of the coiled wire inserted condensers was done. 相似文献