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。     

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...     

多参数对叶顶气膜冷却的影响

基于压力敏感漆(PSP)实验技术,本文研究了某F级重型燃机一级动叶平面叶顶和凹槽叶顶在不同冷却射流与主流质量流量比,不同密度比和不同叶顶间隙大小等多参数影响下的气膜冷却特性。平面叶顶冷却射流在气膜孔后往吸力面覆盖,凹槽叶顶在槽内形成回旋涡,冷却射流往压力面覆盖并向尾缘形成累积效应。平面叶顶和凹槽叶顶气膜冷却效率均随质量流量比的增大而增大。密度比增大,冷却射流出口动量减小,抑制了叶顶气膜垂直射流的吹离趋势,从而提高气膜冷却效果。叶顶间隙与叶顶形状、质量流量比等参数对气膜冷却效率有关联影响;间隙增大,气膜冷却效率在不同工况下的表现不同。另外凹槽叶顶的整体气膜冷却效果优于同等条件的平面叶顶。     

新型双射流冷却孔对气膜冷却效率影响的研究

气膜冷却是现代航空燃气轮机涡轮冷却技术的一种重要方法,冷却孔形状的改进是提高气膜冷却效率的重要手段。本文对双射流冷却孔形状进行了改型,并对新型双射流冷却孔在吹风比分别为0．5,1．0,1．5,2．0时的冷却效率进行了数值模拟。模拟结果表明新型双射流冷却孔与原双射流冷却孔相比在各吹风比下均优化了气膜在热表面上的分布,抑制...     

新型反对称涡气膜冷却结构设计及其数值研究

针对中.高吹风比下容易产生反向涡对的问题,为了改善中、高吹风比下气膜孔的冷却效率,进行了新型抗涡气膜孔的设计和研发工作.根据造型参数不同,设计了四种新型反对称涡气膜孔结构,首先研究了不同几何结构的新型气膜冷却孔对平板气膜冷却特性的影响.然后将反对称涡新型气膜冷却结构运用于叶栅端壁,前缘冷却孔排采用了不同冷却结构的单,双...     

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。     

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。     

涡轮叶栅双排孔气膜冷却数值模拟

采用具有三阶精度TVD性质的有限差分格式、自由型曲面技术以及分区网格算法,对某型具有冷气孔形状的涡轮叶栅进行了全三维N-S方程数值求解,描述了相邻两排冷气射流在叶栅吸力面形成的冷却气膜以及壁面附近冷却射流运动的特点,分析了不同吹风比和喷射角度情况下冷却绝热效率的分布规律。结果表明,在较大的吹风比和喷射角下,交错排列的两排冷却射流运动规律非常复杂,在两排孔之间的区域与冷气孔下游区域冷却气膜的形成规律具有明显的区别。     

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。     

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   

基于BP神经网络的多参数气膜冷却效率研究

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。     

气膜孔角度对动叶前缘冲击/气膜复合冷却的影响

本文针对GE-E3第一级动叶前缘的冲击/气膜复合冷却结构进行了热流耦合数值研究。采用标准k-ω湍流模型,分析了前缘气膜孔对称布置时,其角度对透平动叶前缘冲击/气膜复合冷却特性的影响;在五种冷气质量流量比(MFR=0.005,0.010,0.016,0.020,0.025)下,研究了气膜孔在不同角度(β=20°,25°,30°,40°,50°,60°)时的透平动叶前缘冷却换热效果。研究结果表明:在本文研究范围内,气膜孔角度越小,透平动叶前缘的平均综合冷却效率越高;随着冷气质量流量比增大,透平动叶前缘的平均综合冷却效率逐渐提高。     

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.     

耦合传热和冷却流通道流动对气膜冷却的影响

本文通过数值模拟的方法同时考虑了耦合传热和冷却流通道流动对气膜冷却的影响.计算结果表明,在考虑耦合传热的情况下,冷却流通道流动的影响仍然存在,但随着壁面导热系数的增大,这种影响减弱;同时在考虑耦合传热的情况下,受保护壁面温度场分布更加均匀,冷却效果更好.计算结果还表明吹风比为0.5时的冷却效果优于吹风比为1.0的情况.     

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.     

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.     

波纹曲面气膜冷却特性数值模拟

本文对波纹曲面的气膜冷却特性进行数值模拟,主要研究了吹风比和主流雷诺数对有效温比和主流侧换热系数的影响.研究结果表明:波谷区域的冷却效果要明显优于波峰区域;有效温比受吹风比的影响较大,并随着吹风比的增大而增大;主流侧换热系数受主流雷诺数的影响较大,并随着主流雷诺数的增大而增大.     

Effect of control modes and turbine cooling on the part load performance in the gas turbine cogeneration system

This work aims to analyse the part load performance in a cogeneration system which consists of a single shaft gas turbine and a heat recovery steam generator. Two distinct part load control modes are considered: the constant air flow and the variable air flow. Meanwhile, the effect of variation in the coolant fraction is evaluated, whose purpose is to maintain the blade temperature as high as possible and thus minimise the coolant consumption. The design point parameters of the heat recovery steam generator are determined by the limiting factors on the part load operation, which are represented by the pinch point temperature difference and the approach temperature difference. It turns out that for both air flow control modes, the variable control of coolant fraction leads to improvement of the gas turbine efficiency, while it reduces the heat recovery potential. On the whole, the variable control of coolant fraction has a favourable effect on the overall fuel economy in the cogeneration system.