共查询到19条相似文献,搜索用时 171 毫秒
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随着进口燃气温度的不断增大和燃烧室出口温度的均匀化,燃气涡轮端壁承受极高的热负荷。涡轮端壁处的复杂流动结构使端壁部分区域冷却困难,容易造成端壁烧蚀从而降低涡轮气动性能且威胁涡轮的安全运行。为了提高涡轮的冷却和气动性能,需要深入分析端壁附近的流动结构和传热冷却特性。本文以端壁冷却为出发点,对燃气涡轮的气动传热和冷却技术的发展进行总结分析,结合实验和数值计算结果,对端壁流动传热和冷却相关的先进实验和数值研究结果进行分析讨论。在此基础上,对涡轮端壁的先进冷却技术和非轴对称端壁下冷却结构优化进行了展望。 相似文献
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为解决燃气轮机涡轮在端区二次流动造成的流动损失,对叶身/端壁融合(Blended Blade and End Wall,BBEW)技术在涡轮气动优化中的有效性进行研究,以E3模型高压涡轮第一级叶栅为研究对象,对涡轮叶片吸力面下端壁进行不同形式的叶身/端壁融合造型。设置入口总温为709 K,总压为344.74 kPa。通过数值模拟研究叶身/端壁融合技术在降低端壁气动损失及提高涡轮级效率和做功能力方面的贡献。研究结果表明:融合技术的应用能够有效减少端区局部流动损失,提升涡轮级做功能力,但同时会增加最大融合圆角半径位置处的流动损失;当静叶最大融合圆角相对半径和相对轴向弦长位置分别为0.16和0.47时,涡轮得到最佳的整体提升效果,此时等熵效率提高了0.010 %,比功率提升了0.141%。 相似文献
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应用数值方法研究了单级涡轮轮缘泄漏对动叶非轴对称端壁端部二次流损失及冷却效果的影响,得到了不同封严冷气质量流量比(MFR)下的叶栅内部流场特征,并与轴对称端壁模型进行对比。结果表明:轮缘泄漏吹扫使得非轴对称端壁对气流偏转的改善作用削弱;当冷气量从0.4%增大到1%时,相比于轴对称端壁模型,应用非轴对称端壁所产生的轴向涡量减小量从11.02%下降到了5.65%,非轴对称端壁的效果明显减弱;封严气流在动叶非轴对称端壁表面形成了三角形的气膜冷却区域,但绝热气膜有效度在流动的周向以及轴向方向上较轴对称端壁均有一定程度的减小,主要发生在叶片吸力面角区以及压力面侧马蹄涡的偏转路径上。 相似文献
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应用热线测量和颗粒图像测速(PIV)技术,测量平端壁叶栅(FEW)和非轴对称端壁叶栅(CEW)的二次流动。基于叶栅内的涡结构和剪切应力,分析非轴对称端壁降低二次流损失的流动机理。实验结果表明:二次流在叶片吸力面的边界层分离导致壁面涡与主流流体的剪切掺混,这是叶栅二次流损失的主要来源;非轴对称端壁通过降低端壁横向压力梯度推迟二次流分离的发生,使壁面涡与主流区产生剪切掺混的范围缩小,并使端壁二次流的流向速度提高、壁面涡的强度降低,在上述两方面作用下叶栅内的剪切应力减小,叶栅二次流损失降低。 相似文献
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基于Langston叶型的数值模拟结果,分析了叶栅前缘端区的流动特征,建立并优化了一种新型端壁造型。对比评估了新模型与原始模型的流动现象并对两者的流动机理进行分析。结果表明:新型端壁造型能够疏导前缘位置的低能流体并消除鞍点与分离线的产生;新型端壁造型能够减小马蹄涡及下游的通道涡强度,并使得叶栅出口总压损失系数下降6.831%。 相似文献
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为了研究端壁射流对端区二次流动的控制效果及作用机理,以GE-E~3高压涡轮为研究对象,采用数值模拟的方法,在涡轮进口总温为711 K、总压为345 951 Pa、出口静压为89 177 Pa和动叶转速为8 279 r/min的条件下,分析射流位置、角度及射流比等参数对控制效果的影响。结果表明:端壁射流能够有效组织涡轮内部三维流场,阻断二次流之间的相互掺混,削弱二次流强度;射流位置对控制效果的影响最大,在30%轴向弦长位置处,射流比为1.06%的情况下,可提高涡轮级效率约1.24%;当射流比大于0.057%时,效率随着射流比的增大而线性增加;射流角度影响射流流向分量的大小,因此随着射流角的增大,控制效果递减。 相似文献
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The current paper presents experimental and computational results to assess the effectiveness of non-axisymmetric endwall contouring in a compressor linear cascade. The endwall was designed by an endwall design optimization platform at 0° incidence(design condition). The optimization method is based on a genetic algorithm. The design objective was to minimize the total pressure losses. The experiments were carried out in a compressor cascade at a low-speed test facility with a Mach number of 0.15. Four nominal inlet flow angles were chosen to test the performance of non-axisymmetric Contoured Endwall(CEW). A five-hole pressure probe with a head diameter of 2 mm was used to traverse the downstream flow fields of the flat-endwall(FEW) and CEW cascades.Both the measured and predicted results indicated that the implementation of CEW results in smaller corner stall,and reduction of total pressure losses. The CEW gets 15.6% total pressure loss coefficient reduction at design condition, and 22.6% at off-design condition(+7° incidence). And the mechanism of the improvement of CEW based on both measured and calculated results is that the adverse pressure gradient(APG) has been reduced through the groove configuration near the leading edge(LE) of the suction surface(SS). 相似文献
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The major source of loss in modem compressors is the secondary loss. Non-axisymmetric endwall profile contouring is now a well established design methodology in axial flow turbines. However, flow development in axial compressors is differ from turbines, the effects of non-axisymmetric endwall to axial compressors requires flow analysis in detail. This paper presents both experimental and numerical data to deal with the application of a non-axisymmetric hub endwall in a high-subsonic axial-flow compressor. The aims of the experiment here were to make sure the numerically obtained flow fields is the physical mechanism responsible for the improvement in efficiency, due to the non-axisymmetric hub endwall. The computational results were first compared with avail- able measured data of axisymmetric hub endwall. The results agreed well with the experimental data for estima- tion of the global performance. The coupled flow of the compressor rotor with non-axisymmetric hub endwall was simulated by a state-of-the-art multi-block flow solver. The non-axisymmetric hub endwall was designed for a subsonic compressor rotor with the help of sine and cosine functions. This type of non-axisymmetric hub end- wall was found to have a significant improvement in efficiency of 0.45% approximately and a slightly increase for the total pressure ratio. The fundamental mechanisms of non-axisymmetric hub endwall and their effects on the subsonic axial-flow compressor endwall flow field were analyzed in detail. It is concluded that the non-axisymmetric endwall profiling, though not optimum, can mitigate the secondary flow in the vicinity of the hub endwall, resulting in the improvement of aerodynamic performance of the compressor rotor. 相似文献
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设计研制了具有亚音速透平高压级气动特性的一级半轴流式试验透平,采用试验方法对时序效应、叶栅壁面非定常静压幅频特性以及动叶出口非定常速度场进行了研究。结果表明:时序效应具有改善轴流式透平气动性能的潜力;动、静叶排压力有势场干涉引发的基频信号和上游静叶尾迹片段引发的两阶倍频信号,构成了第二列静叶壁面静压非定常分量的基本频率特征,其间还伴随高达六阶的倍频信号,主要由动叶尾缘高频脱落的涡街扰动产生;尚未完成掺混的第一列静叶尾迹片段出现在动叶出口,由其引发的负射流显著改变了动叶出口局部位置处的气流偏转角。 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