共查询到19条相似文献,搜索用时 203 毫秒
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本文利用经过试验数据验证的RANS方法,针对高压涡轮导向器端壁双排气膜冷却结构,研究了顺向以及不同顺/逆向组合气膜孔下的端壁流动和气膜冷却特性,探索了逆向孔在涡轮端壁上应用的可行性。结果表明:端壁周向整排逆向孔出流与主流的强烈掺混增强了马蹄涡和通道涡强度并降低了冷气动量,使冷气无法到达下游区域;逆向孔布置在中部近吸力侧的顺/逆向组合方案对端壁涡系影响较小,可使端壁上游冷效明显增加且下游冷效降低较少;逆向孔角度减小,冷效增加,但提升幅度有限;本文提出的顺/逆向组合孔在MFR=1~3的范围内,明显改善了顺向孔对端壁上游冷却有限的问题,使端壁65%轴向弦长之前区域气膜冷效明显提升,且对尾缘冷效的影响较小。 相似文献
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攻角对端壁缝隙泄漏流气膜冷却的影响 总被引:1,自引:0,他引:1
本文中的实验在高压涡轮进口导叶平面叶栅中完成,叶栅端壁前缘开有模拟燃烧室涡轮连接处的缝隙。实验中采用GE-E~3高压涡轮进口导叶作为研究对象,缝隙与端壁表面夹角为30°。进口雷诺数(基于叶片轴向弦长和进口气流速度)为3.5×10~5,进口马赫数为0.1,泄漏流流量比为0.5%和2.0%。气膜有效度通过压力敏感漆(Pressure Sensitive Paint,PSP)进行测量。实验结果表明随泄漏流流量比的增加,端壁表面的平均气膜有效度有所增加;当来流攻角从i=+10°变化至i=-10°时,叶片前缘吸力面附近的端壁气膜有效度降低,但在整个端壁表面气膜有效度对攻角变化并不敏感。 相似文献
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采用三维非定常数值模拟计算某重型燃气轮机第一级透平的全气膜冷却特性,探讨级环境下静叶表面与静叶端壁及动叶表面与动叶平台的气膜非定常特性及泛冷却效应。燃气轮机泛冷却是指燃气轮机透平冷却气体出流在非设计位置所引起的附加效果。该部分工作包含两部分内容,其中第一部分关注级环境下静叶全气膜及燃烧室与静叶间的环缝密封出流在静叶端壁上的气膜覆盖,以及环缝密封出流在下游静叶栅中所形成的泛冷却效应。结果表明,在时均来流条件下,静叶表面及端壁气膜冷却效率分布非定常特征并不明显;燃烧室与静叶环缝密封出流在端壁上形成气膜覆盖,同时在静叶吸力面轴向Z/C>0.5和叶高S/H<10%区域形成泛冷却效应,且泛冷却效率随着环缝密封流量的增大而呈指数关系快速上升,设计工况下最大泛冷却效率达0.11。 相似文献
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《工程热物理学报》2021,42(9):2269-2274
受端区二次流的影响,叶片前缘和压力面根部角区端壁难以实现有效冷却。为了实现该区域的冷气覆盖,本文研究了新型冷却结构离散台阶缝的端区气膜冷却特性。离散台阶缝在叶片周向主要覆盖叶片前缘区域,能够集中冷气冷却换热恶劣的区域。本文研究了两种不同离散台阶缝轴向位置(AP1,AP2)和三种不同冷气量(MFR=0.43%,0.88%,1.33%),通过红外热像仪测量端区气膜冷却效率分布。结果表明,增加离散台阶缝与叶片的轴向距离,能够有效提高叶片上游区域的冷却效果,但在通道内部,结果相反。增加冷气量能够提高端壁的气膜冷却效果。此外,应用五孔探针测量叶栅通道喉部附近截面二次流流场特征,解释了通道冷却分布的机理。 相似文献
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基于频闪拍照和稳态液晶测温技术,实验研究了不同气膜孔出流角对旋转态整级涡轮叶片前缘外壁面的气膜冷却特性的影响。实验中,叶片前缘处的主流雷诺数为6.3378×104。实验转速为574 r/min,对应的旋转数为0.0018。平均吹风比从0.5变化到1.25。射流采用N2,其对应的密度比为1.04。结果表明:展向平均气膜冷效是随吹风比的增加而单调增加的,其中最佳吹风比为M=1.25。对于所有吹风比,在-4.3相似文献
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燃气轮机透平叶片气膜冷却性能受到吹风比、曲率、压力梯度等多种因素的影响。本文采用压力敏感漆(PSP)技术研究了燃气轮机静叶气膜冷却的冷却性能,实验测量了不同吹风比下全覆盖气膜的冷却有效度,并结合单排孔冷却的实验结果进行分析。结果表明:随吹风比增大,压力面冷却有效度递增,吸力面受曲率和压力梯度影响,冷却有效度先递增后递减;前缘射流在低吹风比下附壁效果较好,高吹风比下由于复合角造成冷气向中叶展汇聚;通过对比单排冷却的叠加结果与全覆盖实验结果的误差,研究了Sellers叠加模型在叶栅条件下的适用性。 相似文献
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The focus of this numerical study is to conceive a new basic film cooling configuration in order to increase film cooling effectiveness, especially at the leading edge zone between the injection holes where cooling is mostly needed. The new configuration, resulting from the tangential slot configuration and especially adapted to the leading edge of an asymmetrical blade, is compared to the uniform slot configuration. Three alternatives geometries were proposed and numerically tested to find the configuration that provides the best film cooling effectiveness. The simulation is conducted at a fixed density ratio of 1.0 and a blowing ratio of 0.7. A new parameter, Rc, is defined to measure the rate of blade coverage by the film cooling. The outcomes of the numerical results indicate that the three proposed configurations allow better thermal protection because of their higher film cooling coverage. At suction side, the new configurations provide a better film cooling coverage than the baseline case. The minimal improvement is at approximately 34%, with a light superiority of case 1. At pressure side, the use of the tangential slot is especially interesting for the allowed minimum adiabatic effectiveness values between 0.3 and 0.5. 相似文献
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The interaction between the film-cooling jet and vortex structures in the turbine passage plays an important role in the endwall cooling design. In this study, a simplified topology of a blunt body with a half-cylinder is introduced to simulate the formation of the leading-edge horseshoe vortex, where similarity compared with that in the turbine cascade is satisfied. The shaped cooling hole is located in the passage. With this specially designed model, the interaction mechanism between the cooling jet and the passage vortex can therefore be separated from the crossflow and the pressure gradient, which also affect the cooling jet. The loss-analysis method based on the entropy generation rate is introduced, which locates where losses of the cooling capacity occur and reveals the underlying mechanism during the mixing process. Results show that the cooling performance is sensitive to the hole location. The injection/passage vortex interaction can help enhance the coolant lateral coverage, thus improving the cooling performance when the hole is located at the downwash region. The coolant is able to conserve its structure in that, during the interaction process, the kidney vortex with the positive rotating direction can survive with the negative-rotating passage vortex, and the mixture is suppressed. However, the larger-scale passage vortex eats the negative leg of the kidney vortices when the cooling hole is at the upwash region. As a result, the coolant is fully entrained into the main flow. Changes in the blowing ratio alter the overall cooling effectiveness but have a negligible effect on the interaction mechanism. The optimum blowing ratio increases when the hole is located at the downwash region. 相似文献
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基于BP神经网络的多参数气膜冷却效率研究 总被引:1,自引:0,他引:1
气膜冷却作为当代燃机高温透平中必需的冷却手段,其冷却性能在多种参数的影响下表现复杂。采用BP神经网络模型对多种几何、流动参数变化下的气膜冷却系统的绝热气膜冷却效率进行预测。选择气膜冷却系统的吹风比、密度比、主流湍流度、面积比和长径比作为神经网络的输入参数,以燃气轮机透平叶片气膜冷却的实际运行工况为范围建立数据库。计算结果表明,采用贝叶斯归一化法训练后建立的气膜冷却神经网络模型在预测精度上要优于经验公式法,而且参数适用范围更广,具有良好的发展应用前景。 相似文献
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涡轮叶顶冷却布置对叶顶传热冷却性能的影响 总被引:2,自引:0,他引:2
本文采用数值模拟的方法,对比分析了1+1/2对转涡轮四种不同的叶顶冷却布置方案对叶顶传热、冷却性能以及气动特性的影响。四种布置方案分别是:靠近压力面垂直叶顶方向、靠近压力面且与叶顶有30°出射角、中弧线位置垂直叶顶方向、中弧线位置有30°出射角。研究表明,气膜孔沿压力面布置与气膜孔沿中弧线布置相比可以降低叶顶传热系数;由于气膜孔倾斜布置气膜射流动量降低,且削弱了肾形涡的影响,气膜的侧向覆盖范围增大。因此气膜孔靠近压力面布置可以提高气膜冷却效率;气膜孔靠近压力面且有30°出射角比垂直布置叶顶热负荷减少2.7%。另外,气膜孔靠近压力面布置可以降低主流的泄漏流量,有利于减小泄漏损失和提高涡轮效率。 相似文献
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超音速气膜冷却及其受斜激波的影响 总被引:2,自引:0,他引:2
选取了一组接近超燃发动机内部实际工况的边界条件,对二维平行缝槽形式的超音速气膜冷却进行了数值计算,比较了吹风比、缝槽高度和隔板厚度等因素对壁面冷却效率的影响,并考虑了不同强度的斜激波入射气膜冷却边界层对壁面冷却效果和压力分布的影响.通过回归分析,不受激波影响的超音速气膜冷却的壁面冷却效率可以整理成统一的关联式.计算结果表明,斜激波入射将使入射点及其下游的壁面冷却效率降低,但是这个影响没有向上游传播. 相似文献
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