共查询到19条相似文献,搜索用时 187 毫秒
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针对存在动叶顶部间隙泄漏流的一级半透平级非定常流场,应用全三维黏性非定常数值模拟方法详细研究了动叶顶部间隙泄漏流气动特性,旨在揭示泄漏流与下游静叶栅的非定常干涉作用.结果表明:动叶顶部间隙泄漏流引发第二列静叶前缘85%叶展位置处静压波动;受相邻叶排间势干涉作用,第二列静叶50%叶展位置处的静压波动集中于流道中部;在第二列静叶出口截面,动叶顶部泄漏流引发的泄漏涡,其强度及空间分布并未随时间发生明显变化;汽封内的泄漏流静压随时间周期性波动,压力值的更新首先出现于下游并朝向上游流发展. 相似文献
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为有效改善和提升有机工质向心透平的效率和性能,对10 kW向心透平进行热力设计和模拟计算,分析了静叶栅和动叶轮内部各种涡系的形成机理和表现形式,给出了静叶栅不同截面静压利用系数的分布以及动叶内部截面的总压分布。结果表明:静叶栅内存在压力面到吸力面的横向流动,在前缘和尾缘分别存在马蹄涡和尾迹涡,但并未捕捉到通道涡,马蹄涡的压力面分支会在1/2弦长位置到达吸力面;动叶轮中的涡系主要由前缘压力涡、通道涡以及泄漏涡组成,在动叶前缘压力侧轮毂面形成的涡与端部发展起来的通道涡相互交汇,加剧了此处的流动损失;0.6倍动叶叶高截面的流动状况最佳,由于动叶顶部泄漏涡与通道涡的相互掺混,使叶顶附近截面的流线分布较为复杂。 相似文献
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以某汽轮机高压级动叶为研究对象,采用κ-ε湍流模型,应用SIMPLEC算法对在相同叶顶间隙高度下的常规扭叶片和正弯扭叶片的叶顶间隙流动进行了数值模拟。研究结果表明:与常规扭叶片相比,叶片正弯提高了汽流在叶顶区的最低压力值,减小了叶顶压力边与吸力边的横向压力梯度;汽流在正弯扭叶片吸力面附近形成的泄漏涡的影响范围和对通道主流的扰动弱于在常规扭叶片内形成的影响;正弯扭叶片使汽流在吸力面和压力面上形成了叶顶部正径向压力梯度、叶根部负径向压力梯度的"C"型压力分布,同时降低了叶片上端部附近的总压损失。叶片正弯既降低了叶顶泄漏损失,又降低了叶栅通道内的掺混损失。 相似文献
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为了分析叶顶间隙泄漏涡的影响范围、运行轨迹和强度的变化规律,以某汽轮机高压级为研究对象,采用SSTκ-ω湍流模型,应用PISO算法对叶项间隙内的非定常流动进行了数值模拟.结果表明:叶顶间隙泄漏流是有规律的周期性的非定常流动,泄漏涡的影响范围、运行轨迹和强度随时间和叶顶间隙的变化而变化;泄漏流对主流的影响呈现出从弱到强、再从强到弱的周期性变化规律;叶顶间隙泄漏涡在丁/4时刻的强度和影响范围均达到最大,在T/2时刻,静叶脱落涡和动叶吸力面前部的泄漏涡混合形成新的涡系,而动叶吸力面后部的泄漏涡却与其边界层的脱涡混合,离开吸力面. 相似文献
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轴流透平机械通流部分泄漏流动及控制技术研究进展 总被引:2,自引:0,他引:2
综述了轴流透平机械通流部分泄漏流动及控制技术的研究进展,首先详细介绍了轴流透平机械特别是汽轮机通流部分的泄漏流动特性及其对通流效率的影响,接着介绍了透平机械动叶顶部间隙泄漏流动特性及其对透平级气动性能的影响的研究,讨论了考虑间隙泄漏流动对某四级工业汽轮机气动性能的影响,研究了某汽轮机高压缸平衡孔对透平级气动性能的影响及其作用机制。论文简介了透平机械流动控制技术及其研究进展,最后给出了对透平机械泄漏流动及控制技术的研究展望。 相似文献
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应用拓扑学原理分析了叶顶相对间隙为0.036的涡轮直叶栅与正、反弯叶栅的壁面流谱,发现正弯叶片栅与直叶片、反弯叶片栅吸力面上半叶展的拓扑结构明显不同,探讨了差别形成的机理及其对相对漏气量与总流动损失的影响。 相似文献
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This paper describes the numerical investigations of flow and heat transfer in an unshrouded turbine rotor blade of a heavy duty gas turbine with four tip configurations. By comparing the calculated contours of heat transfer coefficients on the flat tip of the HP turbine rotor blade in the GE-E3 aircraft engine with the corresponding experimental data, the κ-ω turbulence model was chosen for the present numerical simulations. The inlet and outlet boundary conditions for the turbine rotor blade are specified as the real gas turbine, which were obtained from the 3D full stage simulations. The rotor blade and the hub endwall are rotary and the casing is stationary. The influences of tip configurations on the tip leakage flow and blade tip heat transfer were discussed. It’s showed that the different tip configurations changed the leakage flow patterns and the pressure distributions on the suction surface near the blade tip. Compared with the flat tip, the total pressure loss caused by the leakage flow was decreased for the full squealer tip and pressure side squealer tip, while increased for the suction side squealer tip. The suction side squealer tip results in the lowest averaged heat transfer coefficient on the blade tip compared to the other tip configurations. 相似文献
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This paper focuses on the effects of five different passive turbine tip clearance flow control methods on the tip clearance flow physics, which consists of a partial suction side squealer tip, a double squealer tip, a pressure side tip shelf with inclined squealer tip on a double squealer tip, a tip platform extension edge in pressure side and in suction side respectively. A pressure-correction based, 3D Reynolds-averaged Navier-Stokes equations CFD code with Reynolds Stress Model was adopted. The variable specific heat was considered. The detailed tip clearance flow field with different squealer rims was described with the streamline and the velocity vector. Accordingly, the mechanisms of five passive controls were elucidated; the effects of the passive controls on turbine efficiency and tip clearance flow field were illuminated. The results showed that the secondary flow loss near the outer casing including the tip leakage losses and the passage vortex losses could be reduced in all the five passive control methods. The turbine efficiency could be increased via the rational passive turbine tip clearance flow control. The Improved PS Squealer had the best effect on turbine efficiency, and the efficiency increased by 0.215%. 相似文献
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This study examines how the complex flow structure within a gas turbine rotor affects aerodynamic loss. An unshrouded linear turbine cascade was built, and velocity and pressure fields were measured using a 5-hole probe. In order to elucidate the effect of tip clearance, the overall aerodynamic loss was evaluated by varying the tip clearance and examining the total pressure field for each case. The tip clearance was varied from 0% to 4.2% of blade span and the chord length based Reynolds number was fixed at 2×105. For the case without tip clearance, a wake downstream of the blade trailing edge is observed, along with hub and tip passage vortices. These flow structures result in profile loss at the center of the blade span, and passage vortex related losses towards the hub and tip. As the tip clearance increases, a tip leakage vortex is formed, and it becomes stronger and eventually alters the tip passage vortex. Because of the interference of the secondary tip leakage flow with the main flow, the streamwise velocity decreases while the total pressure loss increases significantly by tenfold in the last 30% blade span region towards the tip for the 4.2% tip clearance case. It was additionally observed that the overall aerodynamic loss increases linearly with tip clearance. 相似文献
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为研究间隙变化对轴流压气机转子近失速工况下叶顶流场结构的影响,以轴流压气机转子Rotor37为研究对象,对其叶顶流场进行定常和非定常的数值模拟。计算结果表明:随着叶顶间隙的减小,压气机的总压比和等熵效率均有所提高,稳定运行范围扩大;2倍设计间隙下,叶尖泄漏涡经激波作用后发生膨胀破碎,堵塞来流通道,诱发压气机堵塞失速;0.5倍设计间隙下,吸力面流动分离加剧,发生回流,部分回流与来流在压力面前缘上游发生干涉,进口堵塞加剧,致使部分来流从前缘溢出,导致压气机叶尖失速;不同间隙下压气机失速过程的主导因素不同,大间隙下失速由叶尖泄漏涡破碎的非定常波动引起,小间隙下失速主要由流动分离引发的周期性前缘溢流所主导。 相似文献
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为了有效抑制叶顶泄漏流的发展,降低叶顶泄漏损失,针对两级动叶可调轴流风机提出在吸力面构造叶顶小翼并开设斜槽的新型叶顶改型方案。采用Fluent数值模拟了5种叶顶改型方案对风机性能和流场特征的影响,分析了不同方案下流场、叶顶静压、叶顶泄漏量和动叶区做功能力的变化。结果表明:吸力面小翼可有效降低叶顶损失,小翼上开设顺流向斜槽可进一步提高风机性能,逆流向斜槽会使性能略有降低;顺流向单斜槽为最佳改型方案,在设计流量下全压和效率分别提升166 Pa和0.942%;叶顶间隙处产生额外的涡流,叶顶泄漏流得到抑制,动叶区做功能力得以提升。 相似文献
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带小翼肋条的涡轮叶尖泄漏流场的数值模拟 总被引:1,自引:0,他引:1
对叶尖吸力面带小翼肋条的某一轴流转子叶尖间隙泄漏流场进行了数值研究,分析了在不同肋条宽度下泄漏流场细节,并对涡轮效率进行了计算.结果表明:涡轮叶尖单吸力边小翼肋条总体上减小叶尖表面压差,使得吸力面后半部分泄漏流速度减小,从而减小泄漏流动损失,但会增大通道内流动损失,使涡轮转子效率下降;小翼肋条宽度有一个最佳值,小间隙下增大肋条宽度使得涡轮转子效率降低,大间隙下增大肋条宽度却使得涡轮转子效率提高;吸力边小翼肋条改变了叶尖吸力边附近的流场,对压力边附近泄漏流动结构影响不大. 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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Huitao Yang Hamn-Ching Chen Je-Chin Han Hee-Koo Moon 《International Journal of Heat and Mass Transfer》2008,51(11-12):3066-3081
Numerical simulations were performed to predict the film cooling effectiveness and the associated heat transfer coefficient in a 1-1/2 turbine stage. The leading edge of the rotor blade is film cooled with three rows of film cooling holes. The rotor tip leakage has been investigated for a clearance of 0.8% of blade span. Sliding grid is used for the rotor domain, and interface technique is employed to exchange information between stator and rotor domains. Simulations were carried out for both design and off-design conditions to investigate the effects of the stator–rotor interaction on the film cooling characteristics. The commercial code FLUENT with Reynolds stress model is used in the prediction. It is found that the tilted stagnation line on the rotor leading edge moves from the pressure side to the suction side, and the instantaneous coolant streamlines shift from the suction side to the pressure side with the increasing rotating speed. For the fixed inlet/outlet pressure ratio of turbine stage, the high rpm reduces the heat transfer coefficient on the rotor due to the low rotor relative velocity, and increases the “sweet spot” on the rotor tip. These trends are well supported by the experimental results. 相似文献