涡轮流场影响端壁气膜冷却的实验研究

采用压力敏感漆技术对高压涡轮动叶平面叶栅端壁气膜冷却特性进行了实验研究,对比分析了气膜冷却射流吹风比和叶栅进口主流雷诺数对端壁气膜有效度分布的影响.实验中主流雷诺数分别为164476、226154、308392和359790,各主流雷诺数下气膜射流吹风比变化范围从0.4到1.4.端壁前缘气膜孔吹气角为45°,其余端壁气...     

密度比和吹风比对透平静叶气膜冷却的影响

燃气轮机中冷却空气和高温燃气的密度比和吹风比是影响透平叶片气膜冷却性能重要因素。本文采用压力敏感漆技术,对燃气轮机第一级静叶栅气膜冷却的冷却性能进行了实验研究。实验中测量了静叶栅在不同密度比（1．5／1．0）和不同吹风比条件下的冷却效率。密度比的改变射流的出口动量,造成射流出口的流动特征发生变化,从而影响冷却效率,影响...     

气热耦合多孔气膜冷却流动的数值研究

对具有气膜冷却的某涡轮叶栅,提取中部截面型线进行了平面叶栅的气热耦合数值模拟,研究了多孔射流气膜冷却流动的特点.主流与固壁气流耦合计算表明,冷却气流在冷却腔内的流动过程中,被固体壁面加热,在喷射入主流场之前温度升高幅度较大,使得沿程后部的冷却效果减弱,同时研究了多射流孔附近区域三维定常流动的流场.     

透平叶栅气膜冷却损失分析

本文通过数值模拟的方法,研究了在不同吹风比条件下透平叶片压力面和吸力面气膜冷却对叶栅气动损失的影响,采用损失分离方法,分析了各部分损失的变化规律。结果表明,气膜冷却引起的损失与冷气射流与主流的动能比成正比;孔内损失随吹风比迅速增加,高吹风比下不可忽略;低速条件下温差传热不可逆损失是气膜冷却不可逆损失的主要来源;气膜冷却有可能减小边界层内的损失。     

不同吹风比下平面叶栅气膜冷却数值模拟

本文对具有多排冷却孔的某叶栅进行了气膜冷却数值模拟,计算了三种湍流模型在不同吹风比下叶片表面的气膜冷却效率。将数值计算结果与采用压力敏感漆实验技术测量的叶片表面气膜冷却效率分布进行了对比,比较了不同湍流模型的预测准确性,并验证了数值计算对平面叶栅气膜冷却定性预测的可行性。     

透平静叶叶身全覆盖气膜冷却有效度实验研究

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。     

主流流向压力梯度对气膜冷却效率的影响

气膜冷却被广泛地应用在现代透平冷却设计中.由于叶栅环境的复杂性,叶栅气膜冷却特性与平板气膜冷却表现很不相同,主流流向压力梯度是叶栅流动的重要特征之一。本文采用PSP技术研究了不同流向压力梯度下的绝热气膜冷却效率,并同时进行了相应工况下的数值研究,来获得更详细的流场信息,以揭示流向压力梯度对气膜冷却有效度的影响机理.研究发现,低吹风比下,气膜冷却效率随流向顺压增大而提高,而高吹风比下,流向压力梯度对气膜冷却效率影响不大。     

扇形孔气膜冷却应用的综合特性

扇形孔气膜冷却是为避免圆孔气膜冷却吹离而产生的,然而这两种孔在实际叶栅运用中的特性往往受到叶栅流动以及各种参数的影响而显得极为复杂。本文首先探讨平板扇形孔在不同密度比、吹风比下的特性,得到扇形孔的流动和传热特性以及各参数对其的影响。然后结合扇形孔在叶栅上的应用,研究了压力面和吸力面不同的流动特性对于扇形孔应用的影响,以及在叶栅冷却中冷气参数对扇形孔的综合影响。     

定出流面积条件下气膜冷却孔型的研究

本文采用数值模拟的方法,在保持冷却射流出口面积不变的条件下,分析比较了圆柱形孔、扇形孔、双射流孔和带双肩形孔这几种气膜孔的冷却效果。研究结果表明:对于圆柱形孔,气膜冷却效率在吹风比M=0.5左右效率较高;对于扇形孔,在对应圆柱形孔吹风比M=1.5时的效率要优于低吹风比情况;对于双射流孔和带双肩形孔,在对应圆柱形孔吹风比M=1.0时的冷却效果更好。原因在于高吹风比情况下,圆柱形孔结构中冷却射流与高温主流形成较强的肾形涡,会使冷却气体脱离壁面,并将高温主流卷入冷却气膜层,从而破坏冷却效果,而扇形孔、双射流孔以及带双肩形孔能有效地抑制肾形涡对冷却流的提升作用,从而保持冷却气膜的贴壁性,提高了气膜冷却效率。     

气膜和冲击复合冷却结构耦合传热数值研究

本文采用数值方法研究了气膜和冲击复合冷却结构的耦合传热和综合冷效。复合冷却平板模型布置有两个交错气膜孔和若干排冲击孔,气膜孔和冲击孔均采用圆柱孔型。分别研究了吹风比和冷气量分配对综合冷效、流场结构和对流换热特性等的影响规律,结果表明:复合冷却综合冷效明显受到吹风比影响;适当调节冷气量的分配,能够明显提高综合冷效。     

Experimental and Numerical Study of Film Cooling with Internal Coolant Cross-Flow Effects

This study experimentally and numerically analyzes the effect of the coolant cross-flow on film-cooling effectiveness. The three kinds of film holes considered are cylindrical, fan-shaped, and trenched holes. The results show that the internal coolant flow has a large effect on film cooling. The film-cooling effectiveness of the cross-flow coolant model is larger than that of the plenum model for the cylindrical and trenched holes, but it is less for the fan-shaped hole. A comparison of the experimental and numerical results shows that the Reynolds averaged Navier–Stokes model exaggerated the coolant diffusion downstream but underestimates the lateral distribution.     

冷气喷射对直叶栅型面压力及气动损失分布影响的实验研究

提高燃气涡轮比功率，降低比油耗要通过升高涡轮入口温度和压气机压比实现，但必须对涡轮叶片实施诸如气膜冷却等保护措施。Ito和Goldstein[1]，Yamamoto[2]等分别研究了冷气喷射对在叶栅气动性能的影响。本文通过实验研究了冷气喷射对叶型型面压力和叶栅流道内气动损失的影响，并得出了一些有意义的结论。1实验装置实验在哈尔滨工业大学发动机气体动力研究中心低速风洞实验台[3]上进行。图1及表1给出了实验用叶片型线（取自一典型涡轮导向器叶型），冷气喷射孔位置及静压孔分布。叶片表面前缘、吸力面后部和压力面后部开了三列孔，每列孔…     

Numerical simulation of a flat plate film cooling with a coolant supply into different shape indentations

Results of a film cooling numerical simulation over a flat plate with coolant supply into indentations of different shape are reported. The calculations were performed for the blowing-ratio changed from 0.5 to 2.0. For comparison, data for traditional film cooling scheme with one row of discrete cylindrical inclined holes were used. At small value of blowing ratio (m = 0.5), the average film-cooling efficiency is roughly identical for all indentations tested. With blowing ratio growth, the scheme with a coolant supply into the transverse trench demonstrates the best results.     

涡轮动叶吸力侧单排气膜孔冷却性能研究

本文通过数值模拟的方法,针对涡轮叶片吸力侧的单排气膜孔,研究了无量纲气膜孔出流位置、气膜孔复合角度和冷却空气质量流量占比对其气膜冷却效率与气动掺混损失的影响.结果表明,对于近前缘气膜孔,0.5％的冷却空气质量流量可以在保证较好的气动效率的同时在下游附近提供较高的绝热气膜冷却效率;对于中后部气膜孔,90°的气膜孔导致的掺...     

湍流度对单排圆孔及后扩孔气膜冷却的影响

通过传热-传质类比法研究了湍流度对单排圆柱孔及后扩孔气膜冷却效率的影响.计算结果表明,小吹风比M=0.5时,圆柱孔与后扩孔的壁面冷却效率相当,湍流度趋向于在整个下游区域使冷却效果恶化;大吹风比M=2时,后扩孔产生的壁面气膜冷却效率的提高明显,而湍流度的提高强化了冷却剂向壁面的扩散,削弱了冷却气膜脱离壁面的现象,趋向于在整个下游区域提升冷却效率.     

出流角对旋转涡轮叶片前缘气膜冷却影响

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   

Computation of leading edge film cooling from a CONSOLE geometry (CONverging Slot hOLE)

The aim of this study is to investigate the effect of mass flow rate on film cooling effectiveness and heat transfer over a gas turbine rotor blade with three staggered rows of shower-head holes which are inclined at 30° to the spanwise direction, and are normal to the streamwise direction on the blade. To improve film cooling effectiveness, the standard cylindrical holes, located on the leading edge region, are replaced with the converging slot holes (console). The ANSYS CFX has been used for this computational simulation. The turbulence is approximated by a k-ε model. Detailed film effectiveness distributions are presented for different mass flow rate. The numerical results are compared with experimental data.     

非定常激波对气膜冷却影响的数值模拟

利用数值计算的方法研究了非定常激波对下游涡轮叶片表面气膜冷却的影响.冷却气流在激波和尾迹经过的过程中,发生了上扬和重新被压制回壁面的现象.考察了壁面上特定点在有气膜和无气膜情况下的换热量.通过计算发现,有气膜时的换热量有不同程度的下降,而且换热量随时间变化的趋势也发生了很大的变化.气膜的覆盖减小了主流场对壁面换热量的影响.     

Application of local indentations for film cooling of gas turbine blade leading edge

The paper presents results of computer simulation of the film cooling on the turbine blade leading edge model where the air coolant is supplied through radial holes and row of cylindrical inclined holes placed inside hemispherical dimples or trench. The blowing factor was varied from 0.5 to 2.0. The model size and key initial parameters for simulation were taken as for a real blade of a high-pressure high-performance gas turbine. Simulation was performed using commercial software code ANSYS CFX. The simulation results were compared with reference variant (no dimples or trench) both for the leading edge area and for the flat plate downstream of the leading edge.     

Interaction Mechanism and Loss Analysis of Mixing between Film Cooling Jet and Passage Vortex

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.