浅析导流板与蝶阀对中低压连通管内流场的影响

采用数值模拟的方法对某大型机组中低压连通管内的流场作了详细分析,研究了导流板附近流场及蝶阀开度对中压缸排汽管道和低压缸进汽管道蒸汽流量分配、压力损失及速度场的影响,以减少蝶阀对机组运行的不良影响。     

汽轮机中低压缸连通管变形分析与优化设计

汽轮机中低压缸连通管在运行时会产生很大的应力直接传递到汽缸上,引起汽缸变形,造成低压缸漏汽。针对这一问题,利用有限元技术对现有连通管的应力分布及变形情况进行了模拟分析,模拟的结果与电厂低压缸连通管测量的变形实验数据有较好的一致性,验证了有限元分析结果的有效性。重新对连通管的结构进行优化设计,取消了膨胀节,并进行了有限元分析。研究结果表明,改进后的连通管在设计工况下的应力及变形量相较于改进前的连通管大大减少了,这为大型高温高压设备的优化设计提供了一种新思路。     

汽轮机中低压缸连通管变形分析与优化设计

汽轮机中低压缸连通管在运行时会产生很大的应力直接传递到汽缸上,引起汽缸变形,造成低压缸漏汽。针对这一问题,利用有限元技术对现有连通管的应力分布及变形情况进行了模拟分析,模拟的结果与电厂低压缸连通管测量的变形实验数据有较好的一致性,验证了有限元分析结果的有效性。重新对连通管的结构进行优化设计,取消了膨胀节,并进行了有限元分析。研究结果表明,改进后的连通管在设计工况下的应力及变形量相较于改进前的连通管大大减少了,这为大型高温高压设备的优化设计提供了一种新思路。     

异径弯管的无力矩环向应力解析解

提出以异径管单位高度（长度）的直径变化程度作为反映异径管结构特征的无因次量，并定义为异径系数。根据异径弯管横截面管径随经向弯角而变化及其锥形结构的两个特点，推导了内压作用下异径弯管无力矩环向应力武，最大环向应力位于大端内侧。该武可以作为工程中常见回转壳无力矩环向应力式的任意条件式，等径弯管、直管及异径直管的环向应力公式均是异径弯管环向应力武的一个特定条件的特例，本质上这些公式均是环向应力的薄膜解。计算环向薄膜应力时，一般来说．工程中各种鼻径管与连接直管之间的边缘应力可以忽略。     

汽轮机低压缸漏汽的原因分析与研究

目前国产300MW、600MW汽轮机的低压汽缸中分面在运行中普遍存在着漏汽,从而导致机组运行经济性下降.本文以300MW机组低压汽缸作为研究对象,对其结构利用有限元分析软件ANSYS进行实体建模,根据内缸的实际特点,分析汽缸的应力与温度分布,计算低压汽缸膨胀变形量,并计算出低压连通管的冷拉值,根据低压连通管的冷拉值选择最佳性能补偿器来解决低压缸的漏汽现象.     

巴西350MW机组通流优化设计

哈汽为巴西卡迪奥塔火电厂设计的350MW汽轮机,其转速为3600r/min,高中压缸采用合缸结构,低压缸采用1017mm末级长叶片双分流结构。机组通流部分进行全三维优化设计,使机组具有较高的运行效率。文中重点介绍了巴西350MW机组高中压缸及低压缸通流部分的设计特点。     

多壳体凝汽器在非对称传热工况下的背压计算方法研究

基于凝汽器的传热原理和蒸汽流动的阻力特性,建立了求解多壳体凝汽器在非对称传热工况下的背压计算方法,以某核电机组三壳体凝汽器为例,计算了无连通管和有连通管两种情况下的各台凝汽器的背压,并详细讨论了连通管直径、海水温度以及热负荷对背压差的影响。     

弯管中性线与内外拱间的面积压力差及其经向等效弯矩

对于内压作用下的任何弯管,因为弯管中线上径向向外的管壁表面积均要比中线上径向向内的管壁表面积大,两者面积之差在同一内压作用下产生面积压力差。整体环壳存在的面积压力差能整体自平衡,但是局部环壳的面积压力差能产生开弯效应,与相连工程管线之间为了平衡而引起经向等效弯矩,等效弯矩的计算模型与其两端面的边界条件有关。弯管的内壁表面积压力差的大小与管截面内径及内压有关。经向等效弯矩只与管截面圆内半径、弯曲半径、经向弯角及内压有关。     

催化裂化装置蒸汽轮机转子的在线清洗

催化装置富气压缩机组转速出现下滑、不可调节现象,蒸汽轮机运行参数出现变化,判定蒸汽轮机转子已经结垢,利用低压饱和湿蒸汽对蒸汽轮机转子进行了在线清洗,通过对凝结水中SiO23-含量和Na+含量的分析数据及清洗后机组的运行状态来看,此次清洗的效果较好,达到了预期目标。     

扩压叶栅最佳弯叶片生成线与稠度的关系

为了研究亚声速扩压叶栅最佳弯叶片参数与叶栅稠度的关系,在8个不同叶栅稠度下对7组共56个方案进行数值模拟,计算出每个方案下的最佳弯叶片弯高和弯角。计算结果表明:在所选积叠线形式下,在同一个弯角下弯叶片总压损失系数随弯高的增大而减小,弯高为50%时损失最小,最佳弯叶片生成线的弯高为50%;在同一弯高下,弯叶片损失随弯角增大呈现类似抛物线的形式的变化规律,存在最佳弯角(αopt)使叶栅损失最小。在不同的叶栅稠度下,最佳弯角随叶栅稠度增加呈先减小后增大的趋势,弯叶片收益随稠度增大也是先减小再增大的。叶栅稠度对最佳弯角的影响取决于叶栅负荷,叶栅负荷大时影响较大,叶栅负荷较小时影响很小,甚至可以忽略。     

使用照相法测量汽轮机湿蒸汽中水滴尺寸的研究

为了蒸汽轮机的运行安全，准确可靠地测量蒸汽轮机中湿蒸汽水滴的粒径分布，利用图像测量的方法对湿蒸汽特征进行分析，采用Canny边缘检测算子准确检测水滴的边缘，然后根据水滴图片的放大倍数计算出水滴的实际尺寸，最后根据水滴的尺寸分布估计湿蒸汽的湿度及湿蒸汽的危害程度并发出报警信息。     

一种新的旋转叶片-机匣碰摩表征模型

基于机械能守恒定律,推导了旋转叶片-机匣的碰摩表征模型。该模型不仅考虑了碰摩过程中叶片的弯曲变形,同时也考虑了由于碰撞导致的机匣变形,在表征模型中引入了机匣当量刚度。模型除可以对直板叶片-机匣之间的碰摩进行表征,还可应用于锥形叶片-机匣之间的碰摩。并且,该模型还考虑叶片的运行情况,即转速、摩擦因数等参数的影响,讨论碰摩力与各参数之间的关系。通过叶片-机匣碰摩试验得到的碰摩力数据,对该模型进行试验验证。通过分析发现新模型与试验结果吻合较好,并与现有模型对比,证明了新模型能更好地描述旋转叶片与机匣的之间的碰摩力。     

Damage prevention design of the branch pipe under pressure pulsation transmitted from main steam header

Vibration has severely increased at the branch pipe of the main steam header since the beginning of commercial operation of nuclear power plants. Intense broadband disturbance flow at a discontinuous region such as elbows, valves or headers generates an acoustical pulsation which is propagated through the piping system. The pulsation becomes the source of low frequency vibration at the piping system. If it coincides with the natural frequency of the pipe system, excessive vibration results. High-level vibration due to the pressure pulsation related to high dynamic stress, and ultimately, to failure probability fatally affects the reliability and confidence of the plant piping system. This paper discusses steady-state high vibrations appearing in the branch piping system due to the effect of acoustical pulsations transmitted from the large main steam header by broadband turbulence in a 700 MW power plant. The excitation sources and response of the piping system are investigated by using on-site measurements and analytical approaches. Energy absorbing restraints with additional stiffness and damping factor were designed and installed to reduce vibration damage.     

Study of corrosive fatigue and life enhancement of low pressure steam turbine blade using friction dampers

The paper investigates the causes of failure of low pressure steam turbine blade of the last stage and suggests few techniques to overcome the failure causes is presented in this paper. The blade under investigation is made of chrome alloy steel. The fracture occurred at the airfoil region of the blade. The investigation included visual inspection, micro structural characterization, SEM-EDS microanalysis and spectroscopy test to identify the causes of failure. The paper also suggests the methods to reduce the blade fatigue subsequently through computation and to enhance the fatigue strength of the steam turbine blade. In order to reduce the blade fatigue susceptibility and to enhance the fatigue life of the steam turbine blade, the wedge shape friction damper is proposed.     

Some aspects of wet steam flow in turbine cross-over pipes

Deposition and agglomeration in cross-over pipe flows of wet steam, preceding the external moisture separators in a nuclear turbine, have usually been ignored when designing separators. These flows are discussed, with the emphasis on inertial deposition in bends and turbulent impaction. Results are presented which show the possibility of the pipes making a large contribution to separation via these two processes. The paper indicates those areas requiring further investigation in order to produce data on which a pipe layout design optimised for water separation might be based.     

机匣处理对轴流风机性能影响的数值研究

为研究机匣处理对通风机气动性能的影响,以OB-84型动叶可调轴流风机为对象,基于Fluent对不同机匣处理方案下的风机性能进行了三维定常数值模拟。研究表明:不同机匣处理方案对风机性能均有明显影响,设计工况及大流量下全压和效率均有所提升,小流量下则与之相反;机匣处理改变了吸力面与压力面的静压分布,叶顶泄漏流减轻,叶片中上部通流能力增强,做功能力增加;对比各种开槽结构,圆形槽结构提升风机性能最为明显。     

COMPARISON OF TWO METHODS TO INCREASE TIP CLEARANCE AND ITS EFFECT ON PERFORMANCE OF TURBOCHARGER CENTRIFUGAL COMPRESSOR STAGE

Tip clearance between the blade tip and casing of a centrifugal compressor can be varied through two methods:by changing the blade height(M1)or by changing the casing diameter(M2). Numerical simulations are carried out to compare these two methods and their effect on the stage and impeller performance.The impeller and diffuser are connected through rotor stator boundary using frozen rotor approach.Overall stage performance and the flow configuration have been investigated for nine tip clearance levels from no gap to 1 mm.Impeller and diffuser performances are also pre- sented separately.It has been found that the overall and impeller performance are comparatively better for M1 below tip clearance of 0.5 mm whereas M2 is found advantageous above 0.5 mm of tip clear- ance.Both M1 and M2 show performance degradation with the increase in tip clearance.Two models have been proposed for the stage total pressure ratio and efficiency,which are found to be in agree- ment with experimental results.The impeller efficiency and the pressure ratio are found to be maxi- mum at tip clearance of 0.1 mm for both the cases however minimum diffuser effectiveness is also observed at the same clearance level.Diffuser effectiveness is found to be maximum at zero gap for both cases.As it is practically impossible to have zero gap for unshrouded impellers so it is concluded that the optimum thickness is 0.5 mm onwards for M1 and 0.5 mm for M2 in terms of diffuser effec- tiveness.Mass averaged flow parameters,entropy,blade loading diagram and relative pressure fields are presented,showing the loss production within the impeller passage with tip clearance.     

UNSTEADY FLOW ANALYSIS IN A CROSS-FLOW FAN WITH A CASING

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主蒸汽阀噪声原因分析及处理

通过对噪声产生机理的分析，确定了主蒸汽阀噪声的生成原因，介绍了几种降噪措施及其效果，对电厂管道设计和阀门选型具有借鉴意义。     

叶片检验样板的数控加工工艺设计

汽轮机叶片制造中,叶片叶型的内弧、背弧形状通常是使用样板来检验的。本文以432叶片内弧样板工艺设计为例,通过分析叶片检验样板的技术要求,介绍了采用数控磨削改进加工工艺的方法。