燃气轮机叶片气膜冷却研究进展

综述了近年来燃气轮机涡轮叶片气膜冷却技术的研究成果.介绍了气膜冷却的基本原理,总结了叶片端壁、顶部、前缘及尾缘区域气膜冷却的研究进展和气膜孔流量系数的研究状况,阐述了影响气膜冷却效果的各种因素及气膜冷却对气动损失的影响.最后指出将气膜冷却与其它涡轮叶片冷却技术相结合的复合冷却,应是未来涡轮叶片冷却技术的发展方向.     

航空发动机涡轮叶片气膜冷却孔设计与制备技术研究进展

随着先进航空发动机对涡轮前燃气温度需求不断提升,涡轮叶片高效冷却设计技术成为亟待解决的瓶颈技术,而气膜孔冷却是涡轮叶片高效冷却设计的核心技术。本文基于航空发动机涡轮叶片采用耐高温复合材料与高效气膜冷却结构相结合的技术发展背景,综述国内外相关研究工作的进展,从涡轮叶片气膜孔的冷却机理、气膜孔的空间几何结构设计技术、气膜孔表面完整性制备技术等方面,深入总结分析涡轮叶片气膜冷却设计与制备技术领域取得的研究成果,重点论述了各国异型气膜冷却孔的设计与制备技术,并提出我国在该技术上存在的差距及未来研究重点。     

气膜孔与肋的相对位置及通道截面形状对气膜孔流量系数的影响

本文基于航空发动机涡轮叶片的放大模型,研究了在同时带肋和气膜孔出流的内流通道中气膜孔与肋的相对位置以及通道截面形状对流量系数Cd的影响情况。实验在内流通道进口雷诺数Re为20000～80000、通道总出流比SR为0.30～0.60以及肋角为60°、120°的范围进行,分析了肋与气膜孔的相对位置及通道截面形状对气膜孔流量系数的影响情况,发现肋的存在明显改变了气膜孔的流量系数。由于肋所导致的回流区的影响,位于肋下游的气膜孔流量系数低于中间孔和肋上游孔,而通道截面的不同则影响了气膜孔里的雷诺数大小,从而影响了气膜孔的流量系数。本文的实验结果对于航空发动机涡轮叶片冷却结构设计具有参考价值。     

航空发动机涡轮叶片冷却技术综述

本文综述了当前航空发动机涡轮叶片冷却技术的研究情况,着重介绍了气膜冷却、涡轮叶片内流冷却技术和气膜孔流量系数的研究进展,指出了内流冷却和外部气膜冷却相互影响,在冷却结构设计中应予以考虑。     

重型燃气轮机涡轮叶片冷却技术研究进展

综述了重型燃气轮机涡轮叶片内部冷却技术、气膜冷却技术、蒸汽冷却技术的研究进展。提出了叶片内部冷却技术将集中在更真实运行条件下的流动与传热研究。新型气膜孔的优化与应用仍然是叶片气膜冷却技术的重点,优化气膜冷却效果需要更深入探究复合冷却流动与传热机理。蒸汽冷却技术的实际应用还较少,其基础理论研究也还在进行中。最后指出未来燃气轮机冷却技术研究集中在对已有结构冷却潜能的深入挖掘和对新式冷却技术的进一步探索。     

旋转状态下燃气涡轮叶片内部冷却的研究进展

在现代高性能燃气涡轮发动机中,随着涡轮前燃气温度的不断提高,旋转涡轮叶片的冷却问题日益受到重视。在众多的冷却技术中,内部冷却具有明显的优势和较强的应用前景。综述了近年来旋转状态下燃气涡轮叶片内部冷却技术的研究成果,总结了光滑壁面旋转对流场和传热的影响、旋转对冲击冷却影响以及旋转扰流式肋片冷却介质通道传热的研究现状,阐述了旋转状态下内部冷却和气膜冷却相互影响的研究情况。最后指出进一步优化内流通道结构,研究旋转对扰流柱通道流动及换热的影响以及在旋转状态下深入探讨内部流动与外部气膜冷却相互影响的机理是今后工作的重点。     

燃气轮机透平叶片传热和冷却研究：内部冷却

随着燃气轮机透平进口温度的不断提高,其换热与冷却问题已然成为现代高性能燃气轮机研发中亟待解决的核心关键技术之一.透平叶片的冷却可以分为内部冷却和外部冷却,结合作者近年的研究工作,详细综述了燃气轮机透平叶片内部换热与冷却问题的研究现状与进展,着重介绍了叶片内部蛇形通道冷却、叶片内部冲击冷却和前缘的旋流冷却及尾缘柱肋冷却,指出了它们各自在相关方面需要进一步开展的工作.其中：在蛇形通道冷却方面,需要进一步研究旋转状态下蛇形通道内流动与换热特性、发展高性能的扰流装置及通道弯头结构、设计新颖高效的叶顶内部冷却结构、获得带气膜孔或冲击孔的蛇形通道内的换热与冷却特性;在叶片前缘内部冲击冷却方面,需要研究不同曲率面上的冲击冷却换热特性、旋转条件下的冲击冷却以及冲击气膜复合冷却特性;在旋流冷却方面,需要对其结构参数的影响开展进一步的广泛研究,并开展旋转状态下旋流冷却特性的研究;在尾缘柱肋冷却方面,需要进一步研究复杂流场下柱肋阵列通道中的流动换热与众敏感因子之间的关系.     

液态金属冷却法制备工业燃气轮机涡轮叶片的研究进展

发电用工业燃气轮机涡轮叶片与航空发动机用叶片相比,在尺寸、运行环境及制备工艺方面都有很大的差异。文章介绍了用定向凝固技术中液态金属冷却（LMC）法,制备工业燃气轮机涡轮叶片的工艺及工艺参数、模拟技术方面的研究进展。     

上游V形肋对气膜冷却性能影响的数值模拟研究

利用数值模拟的方法研究气膜孔上游布置V形肋对气膜冷却绝热效率的影响,分析了5种肋片高度对气膜冷却流动和冷却性能的影响规律。研究表明:上游布置V形肋会使主流产生一对与肾形涡旋转方向相反的涡。该主流涡抑制了肾形涡的膨胀,使得冷却空气的流动分离减小并更贴近壁面,同时加强了冷却空气的展向扩散;在本文研究的工况中,气膜孔上游布置h=0.3 Dh的V形肋时,冷却空气的展向分布最均匀;上游布置V形肋还会使气膜冷却的总压损失系数增加,且随着肋高h的增加总压损失系数进一步增加;此外,上游布置V形肋能改善气膜孔下游底面的冷却性能,且冷却效率随h的增加先增大后减小,在h=0.3 Dh时达到最大值。     

基于快响应压敏漆和高温磷光热图的气膜冷却非定常实验测量技术综述

涡轮内部流动及冷却射流的湍流特性决定了气膜冷却具有强烈的非定常性,精确获取高时空分辨率的气膜冷却换热特性对揭示其内在机理尤为重要。本文针对气膜冷却的非定常测试需求,聚焦于气膜冷却中涉及的壁面气膜动态覆盖以及叶片表面温度测量,从测量原理、测试系统及实际应用方面依次介绍了两种气膜冷却非定常实验测量技术。基于快响应压敏漆能够测量涡轮叶片、叶身及端壁的非定常气膜冷却,进而利用高温磷光热图评估近发动机工况下高温叶片表面的动态温度分布。     

基于CFD DEM微细带肋内冷通道中颗粒沉积特性比较研究

航空发动机全天候全域长航时运行时,颗粒随着二次流空气系统进入到涡轮叶片内部,沉积堵塞在涡轮叶片内冷通道中,严重影响了涡轮叶片的冷却性能。本文采用计算流体力学和离散单元法(CFD-DEM)相结合的方法研究了涡轮叶片带肋细小矩形内冷通道中微尘颗粒的流动和沉积特性。所研究的内冷通道肋片周期性布置在通道的一侧,肋片阻塞比和肋间距比分别为0.024和10,考虑了平行直肋、45°斜肋和45°V肋3种肋结构,详细分析了雷诺数、颗粒斯托克斯数、入口颗粒体积分数和肋片的类型对颗粒流动和沉积特性的影响规律。结果表明：颗粒沉积主要发生在第1根肋片的前缘处;颗粒的沉积质量均随着雷诺数、斯托克斯数和颗粒体积分数增加而减小;在所有的肋片类型中,直肋布置时颗粒沉积现象最明显,其次是V肋,斜肋拥有最小的颗粒沉积质量。     

Analysis of parameters affecting the performance of gas turbines and combined cycle plants with vapor absorption inlet air cooling

The integration of an aqua‐ammonia inlet air‐cooling scheme to a cooled gas turbine‐based combined cycle has been analyzed. The heat energy of the exhaust gas prior to the exit of the heat recovery steam generator has been chosen to power the inlet air‐cooling system. Dual pressure reheat heat recovery steam generator is chosen as the combined cycle configuration. Air film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor–pressure ratio, compressor inlet temperature, turbine inlet temperature, ambient relative humidity, and ambient temperature on performance parameters of plants has been carried out. It has been observed that vapor absorption inlet air cooling improves the efficiency of gas turbine by upto 7.48% and specific work by more than 18%, respectively. However, on the adoption of this scheme for combined cycles, the plant efficiency has been observed to be adversely affected, although the addition of absorption inlet air cooling results in an increase in plant output by more than 7%. The optimum value of compressor inlet temperature for maximum specific work output has been observed to be 25 °C for the chosen set of conditions. Further reduction of compressor inlet temperature below this optimum value has been observed to adversely affect plant efficiency. Copyright © 2013 John Wiley & Sons, Ltd.     

冷却通道参数对发汗冷却性能影响的数值研究

为了解决传统多孔材料孔隙结构不可控的问题,制备具有可控微冷通道的冷却结构对提高涡轮叶片冷却效率有着重要意义。为了研究不同冷却通道参数对叶片发汗冷却效率的影响,通过数值模拟方法研究了不同注入比下,仿生树形通道和传统直孔通道发汗冷却多孔板的换热特性及流动机理。同时,研究了6种不同模型参数多孔板在不同注入比下的冷却性能及流场的变化情况。研究结果表明：在内表面比和冷却剂出口面积基本一致的条件下,仿生树形多孔板具有更高的冷却效率;当注入比为2%时,仿生树形多孔板的平均冷却效率提高了5%,且存在一个最佳的注入比使得整体的冷却效率最高;冷却剂的出口面积是影响发汗冷却效率的关键性独立参数,与冷却剂的注入比大小有关;孔隙率对整体的冷却效率影响较小,内表面积比越大,发汗冷却的整体冷却效率越高。     

基于流热耦合的燃气轮机透平叶顶冷却设计

燃气轮机透平叶顶区域存在复杂的流动和换热问题,承受很高的热负荷。为了降低透平动叶叶顶温度,在透平叶顶现有结构的基础上提出气膜冷却和气膜+内冷通道冷却两种叶顶冷却方案,并通过流热耦合计算分析冷却升级前后叶顶区域的换热和流动特性。研究发现：叶顶气膜冷却方案可有效降低叶顶温度,特别是叶顶前缘至中弦区域;而气膜＋内冷通道冷却方案基于外部气膜冷却,结合内部冷却通道设计,可进一步降低叶顶尾缘的温度;与原型叶片相比,气膜+内部冷气通道的复合冷却设计可以使叶顶尾缘最高温度降低24 K。     

Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.     

Thermodynamic assessment of advanced SOFC-blade cooled gas turbine hybrid cycle

This paper focuses on novel integration of high temperature solid oxide fuel cell coupled with recuperative gas turbine (with air-film cooling of blades) based hybrid power plant (SOFC-blade cooled GT). For realistic analysis of gas turbine cycle air-film blade cooling technique has been adopted. First law thermodynamic analysis investigating the combine effect of film cooling of blades, SOFC, applied to a recuperated gas turbine cycle has been reported. Thermodynamic modeling for the proposed cycle has been presented. Results highlight the influence of film cooling of blades and operating parameters of SOFC on various performance of SOFC-blade cooled GT based hybrid power plant. Moreover, parametric investigation has also been done to examine the effect of compressor pressure ratio, turbine inlet temperature, on hybrid plant efficiency and plant specific work. It has been found that on increasing turbine inlet temperature (TIT) beyond a certain limit, the efficiency of gas turbine starts declining after reaching an optimum value which is compensated by continuous increase in SOFC efficiency with increase in operating temperature. The net result is higher performance of hybrid cycle with increase in maximum cycle temperature. Furthermore, it has been observed that at TIT 1600 K and compression ratio 20, maximum efficiency of 73.46% can been achieved.     

Energetic and exergetic performance analyses of a combined heat and power plant with absorption inlet cooling and evaporative aftercooling

In this paper, exergy method is applied to analyze the gas turbine cycle cogeneration with inlet air cooling and evaporative aftercooling of the compressor discharge. The exergy destruction rate in each component of cogeneration is evaluated in detail. The effects of some main parameters on the exergy destruction and exergy efficiency of the cycle are investigated. The most significant exergy destruction rates in the cycle are in combustion chamber, heat recovery steam generator and regenerative heat exchanger. The overall pressure ratio and turbine inlet temperature have significant effect on exergy destruction in most of the components of cogeneration. The results obtained from the analysis show that inlet air cooling along with evaporative aftercooling has an obvious increase in the energy and exergy efficiency compared to the basic gas turbine cycle cogeneration. It is further shown that the first-law efficiency, power to heat ratio and exergy efficiency of the cogeneration cycle significantly vary with the change in overall pressure ratio and turbine inlet temperature but the change in process heat pressure shows small variation in these parameters.