共查询到18条相似文献,搜索用时 171 毫秒
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随着超超临界汽轮机的发展,机组蒸汽参数不断提高,蒸汽管道内壁氧化产生的氧化物会加剧剥落,氧化铁粒子随着主蒸汽进入汽轮机通道,对叶片产生严重的冲蚀破坏。同时随着我国电力消费结构的变化,电昼夜峰谷差逐渐增大,风电、光伏等新能源发电迅速发展,新能源发电的消纳成为关键问题,超超临界机组也面临承担电网调峰的任务。对于高参数、大容量的机组,其发电量和经济性得以提高,然而新的技术问题又摆到了面前,即固体颗粒冲蚀问题,解决固体颗粒冲蚀问题至关重要。从粒子冲蚀行为的影响因素出发,主要包括粒子撞击速度、粒子撞击角度、粒子尺寸、粒子形状等角度出发,从根本上来分析粒子的冲蚀行为及冲蚀机理。针对动静叶片分析了粒子的冲蚀程度及冲蚀区域,指出调节级喷嘴所受冲蚀程度较动叶严重,随着长时间的粒子冲蚀,叶片会产生严重的缺口,机组经济性降低的同时安全性也大大降低。同时从表面涂层技术的应用、叶栅型线的改变、粒子分离方面来探究解决或降低冲蚀破坏的方法。在此基础上,对汽轮机固体颗粒冲蚀问题的研究前景做出了展望。 相似文献
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混合粒径固体颗粒对滑套球座冲蚀磨损的影响 总被引:2,自引:0,他引:2
随着超长水平井施工排量和加砂量的不断增加,滑套球座冲蚀磨损日益严重。目前对液固两相流冲蚀磨损的研究较多,但均未考虑混合粒径固体颗粒对冲蚀磨损的影响。研究不同粒径混合的支撑剂对球座的冲蚀磨损,基于欧拉双流体理论,运用Fluent软件对混合粒径固体颗粒对滑套球座的冲蚀磨损进行数值模拟。结果表明:混合粒径固体颗粒与单一粒径固体颗粒对球座冲蚀磨损规律有所不同,单一粒径固体颗粒对球座冲蚀磨损速率随着粒径的增大而减小;混合粒径固体颗粒对球座冲蚀磨损速率不仅和支撑剂粒径有关,而且和不同粒径固体颗粒的比例有关,即冲蚀磨损速率随混合固体颗粒中小粒径固体颗粒比例的增大而表现出先减小后增大的趋势。模拟结果为水平井分段压裂材料的选择提供了依据。 相似文献
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高原、沙漠和沿海等服役环境中不同粒径的砂粒不可避免地对涡轴发动机压气机叶片造成冲蚀磨损,破坏叶片叶型和动力学特性,严重危及涡轴发动机使用寿命和直升机飞行安全。基于Finnie冲蚀磨损理论推导了颗粒对金属表面的磨损率表达式,分析颗粒粒径对材料冲蚀磨损率的影响,以某型涡轴发动机压气机动叶和静叶为研究对象,设计搭建砂粒冲击速度测试装置和钛合金冲蚀磨损实验装置,通过典型砂粒粒径下冲蚀磨损实验获取磨损率表达式中与靶材材料和冲击速度相关的关键参数,结合气固两相流动力学分析开展砂粒粒径对压气机动叶和静叶冲蚀磨损的影响研究。结果表明:砂粒粒径与冲击速度存在内在关联,材料冲蚀磨损率与砂粒冲击速度呈幂函数关系。实验条件下,砂粒粒径由177 μm增至423 μm时,其冲击速度平均降低约17%。压气机动叶和静叶的磨损集中区域不随砂粒粒径的改变而变化,但磨损程度差异明显,其中177 μm砂粒对动叶和静叶造成的最大冲蚀磨损率浓度值相比423μm砂粒分别增加91%和131%。研究结果为涡轴发动机压气机叶片抗磨损设计提供了理论参考。 相似文献
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为解决超临界汽轮机日益突出的固体颗粒侵蚀问题,研究超临界汽轮机调节级喷嘴内的固体颗粒运动特性,由固体颗粒撞击位置、速度与角度以及材料抗冲蚀性能三方面对喷嘴的侵蚀机理进行了综合分析,提出了采用改进叶型设计、表面强化处理与运行工况优化等对策,以降低汽轮机固体颗粒侵蚀问题。 相似文献
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应用流体计算软件Fluent对某600MW大型火电机组配套的SAF两级动叶可调轴流引风机的内流特征及运行特性进行模拟分析。研究表明:正常状态下风机内静压沿轴向先增大后减小,动压仅在扩压器区及集流器区出现较大变化,动叶轮的升力作用主要转化为流体静压,全压的增加则主要来自静压的增大;风机动叶出口截面总压呈现高压区与低压区交替出现的周向对称性分布,但第二级动叶出口总压分布的对称性要比第一级的差;叶片压力面与吸力面间的静压差沿叶高方向逐渐增大,表明叶片中上部的做功能力较强;相同流量下随着动叶安装角的减小,叶片压力面与吸力面速度变化梯度减小,做功能力减弱,风机的全压升逐渐减小。 相似文献
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采用多种叶片材质对应的反弹恢复系数,结合气固双向耦合颗粒随机轨道模型,对双级烟气透平内颗粒与叶片碰撞形成的冲蚀行为进行数值试验,分析叶片材质对其冲蚀率和冲蚀分布的不同影响程度,并预测叶片自振频率因冲蚀而发生的变化。数值分析表明,不同反弹恢复系数,叶片内弧近中径的冲蚀率会有明显差异,较大的反弹恢复系数,冲蚀率数值较大,而反弹恢复系数的变化对叶片自振频率的变化影响却不明显。研究结果将为叶片材质、表面处理工艺、涂层等选用,实现冲蚀率和冲蚀分布控制提供依据。 相似文献
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动静干涉下低压涡轮非定常气动载荷研究 总被引:1,自引:0,他引:1
为研究动静干涉下轴向间距和尾缘锯齿结构对低压涡轮叶片非定常气动载荷的控制作用,对高效节能发动机(energy efficient engine,简称E3)低压涡轮最后一级的内部流场进行了数值仿真,研究了不同轴向间距和静叶尾缘锯齿结构两种情况下,下游动叶表面非定常气动载荷的变化规律。研究发现:增大轴向间距可以加强尾迹与主流的掺混,消除气流不均匀性,削弱下游动叶表面的非定常气动载荷;静叶采用尾缘锯齿结构不仅可以加强尾迹与主流的掺混,同时还会改变尾缘处的涡结构,对下游动叶前缘产生破坏性干涉效应,使其最大载荷波动降低约30%,减少静叶尾迹速度亏损75.7 m/s,还能适当提升涡轮的流通能力和时均效率。与采用直尾缘静叶的模型相比,采用锯齿尾缘静叶不仅能大幅度地改善涡轮的转静干涉效应和气动性能,还能在不影响涡轮效率的前提下,将涡轮轴向间距缩短10%。 相似文献
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To evaluate the accurate performance and characteristics of turbomachinery, it is important to measure the unsteady flow phenomena
downstream of the rotating blades. This paper presents the development of a fast-response total pressure probe for the measurement
of the total pressure field at the exit of blades. The result of measurement in a one-stage axial turbine is also presented.
The fast-response total pressure probe is fabricated by installing a fast-response pressure sensor in the cylindrical head
of the probe. In terms of simplicity of the measurement system and data reduction method, this method is more competitive
over established methods that use more than four sensors. The probe is applied to the one-stage axial turbine in order to
measure the instantaneous total pressure downstream of rotor blades. The measured instantaneous signal is decomposed to obtain
the blade-to-blade pressure distribution. The pressure distribution due to blade passing is clearly captured. Due to the loss
generation in the casing region, the total pressure and its amplitude of fluctuation by the blade passing are lower in the
shroud and hub region than in mid-span. The total pressure distribution at the exit of the rotor blade is found to be slightly
different from blade to blade due to the geometric difference and the different relative positions of the rotor blades and
stator vanes. The developed probe successfully measures the accurate total pressure distribution at the rotor exit, and allows
the evaluation of the loss distribution and the accurate performance of turbomachinery. 相似文献
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Young-Seok Kang Jae-Chun Yoo Shin-Hyoung Kang 《Journal of Mechanical Science and Technology》2006,20(7):1077-1088
This paper describes a numerical investigation on the performance deteriorations of a low speed, single-stage axial turbine
due to use of rough blades. Numerical calculations have been carried out with a commercial CFD code, CFX-Tascflow, by using
a modified wall function to implement rough surfaces on the stator vane and rotor blade. To assess the stage performance variations
corresponding to 5 equivalent sand-grain roughness heights from a transitionally rough regime to a fully rough regime, stage
work coefficient and total to static efficiency were chosen. Numerical results showed that both work coefficient and stage
efficiency reduced as roughness height increased. Higher surface roughness induced higher blade loading both on the stator
and rotor which in turn resulted in higher deviation angles and corresponding work coefficient reductions. Although, deviation
angle changes were small, a simple sensitivity analysis suggested that their contributions on work coefficient reductions
were substantial. Higher profile loss coefficients were predicted by higher roughness heights, especially on the suction surface
of the stator and rotor. Furthermore sensitivity analysis similar to the above, suggested that additional profile loss generations
due to roughness were accountable for efficiency reductions. 相似文献
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Water droplet erosion is one of major concerns in the design of modern large fossil steam turbines because it causes serious
operational problems such as performance degradation and reduction of service life. A new erosion model has been developed
in the present study for the prediction of water droplet erosion of rotor blades operated in wet steam conditions. The major
four erosion parameter ; impact velocity, impacting droplet flow rate, droplet size and hardness of target are involved in
the model so that it can also be used for engineering purpose at the design stage of rotor blades. Comparison of the predicted
erosion rate with the measured data obtained from the practical steam turbine operated for more than 90.000 hours shows good
agreement. 相似文献
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